INTRODUCTION
TO THE READER
• This manual is written for an experienced technician
to provide technical information needed to maintain
and repair this machine.
• Be sure to thoroughly read this manual for correct
product information and service procedures.
• If you have any questions or comments, at if you
found any errors regarding the contents of this
manual, please contact using “Service Manual
Revision Request Form at the end of this manual.
(Note: Do not tear off the form. Copy it for usage.):
Publications Marketing & Product Support
Hitachi Construction Machinery Co. Ltd.
TEL: 81-298-32-7173
FAX: 81-298-31-1162
ADDITIONAL REFERENCES
• Please refer to the materials listed below in addition
to this manual.
• Operation Manual of the Engine
• Parts Catalog of the Engine
• Hitachi Training Material
• The Operator’s Manual
• The Parts Catalog
MANUAL COMPOSITION
• This manual consists of three portions: the Techni-
• Information included in the Technical Manual
(Troubleshooting):
technical information needed for operational performance tests, and troubleshooting procedures.
• Information included in the Technical Manual
(Operational Principle):
technical information needed for redeliver and
delivery, operation and activation of all devices
and systems.
• Information included in the Workshop Manual:
technical information needed for maintenance
and repair of the machine, tools and devices
needed for maintenance and repair, maintenance
standards, and removal/installation and assemble/disassemble procedures.
cal Manual (Operational Principle), the Technical
Manual (Troubleshooting) and the Workshop Manual.
PAGE NUMBER
• Each page has a number, located on the center
lower part of the page, and each number contains
the following information:
Example : T 1-3-5
Consecutive Page Number for Each Group
Group Number
Section Number
T: Technical Manual W: Workshop Manual
IN-01
INTRODUCTION
SAFETY ALERT SYMBOL AND HEADLINE
NOTATIONS
In this manual, the following safety alert symbol and
signal words are used to alert the reader to the
potential for personal injury of machine damage.
This is the safety alert symbol. When you see this
symbol, be alert to the potential for personal injury.
Never fail to follow the safety instructions prescribed
along with the safety alert symbol.
The safety alert symbol is also used to draw attention
to component/part weights.
To avoid injury and damage, be sure to use appropriate lifting techniques and equipment when lifting heavy
parts.
•
CAUTION:
Indicated potentially hazardous situation which
could, if not avoided, result in personal injury or
death.
• IMPORTANT:
Indicates a situation which, if not conformed to the
instructions, could result in damage to the machine.
•
NOTE:
Indicates supplementary technical information or
know-how.
UNITS USED
2
• SI Units (International System of Units) are used in
Example : 24.5 MPa (250 kgf/cm , 3560 psi)
this manual.
MKS system units and English units are also
indicated in parenthheses just behind SI units.
Quantity
Length
Volume
Weight
Force
Torque
To Convert
From
mm
mm
L
L
3
m
kg
N
N
N⋅m
N⋅m
Into
in
ft
US gal
US qt
3
yd
lb
kgf
lbf
kgf⋅m
lbf⋅ft
A table for conversion from SI units to other system
units is shown below for reference purposees.
Quantity
Multiply By
0.03937
0.003281
0.2642
1.057
1.308
2.205
0.10197
0.2248
1.0197
0.7375
Pressure
Power
Temperature
Velocity
Flow rate
IN-02
To Convert
From
MPa
MPa
kW
kW
°C
km/h
-1
min
L/min
mL/rev
Into
Multiply By
2
kgf/cm
psi
PS
HP
°F
mph
rpm
US gpm
cc/rev
10.197
145.0
1.360
1.341
°C×1.8+32
0.6214
1.0
0.2642
1.0
SECTION AND GROUP
CONTENTS
SECTION 1 GENERAL
Group 1 Specification
Group 2 Component Layout
Group 3 Component Specifications
SECTION 2 SYSTEM
TECHNICAL MANUAL
(Operational Principle)
Group 1 Control System
Group 2 Hydraulic System
Group 3 Electrical System
SECTION 3 COMPONENT OPERATION
Group
Group
Group
Group
Group
Group
Group
Group
1
2
3
4
5
6
7
8
Pump Device
Swing Device
Control Valve
Pilot Valve
Travel Device
Signal Control Valve
Others(Upperstructure)
Others(Undercarriage)
TECHNICAL MANUAL (Troubleshooting)
All information, illustrations and specifications in this manual are based on
the latest product information available
at the time of publication.
The right is reserved to make changes
at any time without notice.
COPYRIGHT(C)2001
Hitachi Construction Machinery Co., Ltd.
Tokyo, Japan
All rights reserved
SECTION 4 OPERATIONAL PERFORMANCE TEST
Group 1 Introduction
Group 2 Standard
Group 3 Engine Test
Group 4 Excavator Test
Group 5 Component Test
Group 6 Adjustment
SECTION 5 TROUBLESHOOTING
Group 1 General
Group 2 Component Layout
Group 3 Troubleshooting A
Group 4 Troubleshooting B
Group 5 Troubleshooting C
Group 6 Electrical System Inspection
Group 7 ICX
WORKSHOP MANUAL
SECTION 1 GENERAL INFORMATION
Group 1 Precautions for Disassembling and Assembling
Group 2 Tightening Torque
SECTION 2 UPPERSTRUCTURE
Group 1 Cab
Group 2 Counterweight
Group 3 Main Frame
Group 4 Pump Device
Group 5 Control Valve
Group 6 Swing Device
Group 7 Pilot Valve
Group 8 Pilot Shut-Off Valve
Group 9 Signal Control Valve
Group 10 Solenoid Valve
SECTION 3 UNDERCARRIAGE
Group 1 Swing Bearing
Group 2 Travel Device
Group 3 Center Joint
Group 4 Track Adjuster
Group 5 Front Idler
Group 6 Upper and Lower Roller
Group 7 Track
SECTION 4 FRONT ATTACHMENT
Group 1 Front Attachment
Group 2 Cylinder
SECTION 1
GENERAL
CONTENTS
Group 1 Specification
Specifications ...........................................T1-1-1
Working Ranges.......................................T1-1-5
Group 2 Component Layout
Main Components Layout .........................T1-2-1
Electrical Component Layout (Overview) ..T1-2-2
Electrical System (Rear Deck) ..................T1-2-3
Electrical System (Around Battery) ...........T1-2-4
Electrical System (Pressure Sensor) ........T1-2-4
Electrical System
(Monitors and Switches) .........................T1-2-5
Engine......................................................T1-2-6
Pump Device............................................T1-2-7
Swing Device ...........................................T1-2-7
Control Valve............................................T1-2-8
Solenoid Valve
(Swing Preference Circuit) ......................T1-2-9
Solenoid Valve Unit ..................................T1-2-9
Travel Device .........................................T1-2-10
Counterweight Removal Device
(Optional) .............................................T1-2-10
Group 3 Component Specifications
Engine......................................................T1-3-1
Engine Accessories ..................................T1-3-4
Hydraulic Component ...............................T1-3-5
Electrical Component ...............................T1-3-8
17VT-1-1
(Blank)
17VT-1-2
GENERAL / Specifications
SPECIFICATIONS
ZAXIS800 (Backhoe)
T17V-01-01-021
Model
Type of Front-End Attachment
Bucket Capacity (Heaped)
Operating Weight
Basic Machine Weight
Engine
ZX800
3.6 m (11 ft 10 in) Arm (Backhoe)
3
3
3
PCSA 3.4 m (4.4 yd ), CECE 3.0 m
73900 kg (162900 lb)
57400 kg (126500 lb)
-1
ISUZU BB-6WG1XQA 338.3 kW@1800 min
(460 PS/1800 rpm)
A: Overall Width
(Excluding Back Mirrors)
B: Cab Height
C: Rear End Swing Radius
D: Minimum Ground Clearance
E: Counterweight Clearance
F: Engine Cover Height
G: Overall Width of Upperstructure
H: Undercarriage Length
I: Undercarriage Width(Extended/Retracted)
J: Sprocket Center to Idler Center
K: Track Shoe Width
L: Overall Hight
Ground Pressure
Swing Speed
Travel Speed (fast/slow)
Gradeability
4360 mm (14 ft 4 in)
3520 mm (11 ft 7 in)
4300 mm (14 ft 1 in)
*880 mm (35 in)
*1590 mm (5 ft 3 in)
*3430 mm (11 ft 3 in)
3850 mm (12 ft 8 in)
6350 mm (20 ft 10 in)
4100 mm (13 ft 5 in) / 3480 mm (11 ft 5 in)
5110 mm (16 ft 9 in)
650 mm (26 in)(Grouser Shoe)
3930 mm (12 ft 11 in)
2
101 kPa (1.03 kgf/cm , 14.6 psi)
–1
8.2 min (rpm)
4.3 km/h (2.7 mph) / 3.09 km/h (1.9 mph)
35° (tanθ = 0.70)
NOTE: The dimensions do not include the height of
the shoe lug.
T1-1-1
GENERAL / Specifications
ZAXIS800H (Backhoe)
T17V-01-01-022
Model
Type of Front-End Attachment
Bucket Capacity (Heaped)
Operating Weight
Basic Machine Weight
Engine
ZX800H
3.6 m (11 ft 10 in) H Arm (Backhoe)
3
3
3
PCSA 3.4 m (4.4 yd ), CECE 3.0 m
75900 kg (167300 lb)
57800 kg (127400 lb)
-1
ISUZU BB-6WG1XQA 338.3 kW@1800 min
(460 PS/1800 rpm)
A: Overall Width
(Excluding Back Mirrors)
B: Cab Height
C: Rear End Swing Radius
D: Minimum Ground Clearance
E: Counterweight Clearance
F: Engine Cover Height
G: Overall Width of Upperstructure
H: Undercarriage Length
I: Undercarriage Width(Extended/Retracted)
J: Sprocket Center to Idler Center
K: Track Shoe Width
L: Overall Hight
Ground Pressure
Swing Speed
Travel Speed (fast/slow)
Gradeability
4360 mm (14 ft 4 in)
3640 mm (11 ft 11 in)
4300 mm (14 ft 1 in)
*880 mm (35 in)
*1590 mm (5 ft 3 in)
*3430 mm (11 ft 3 in)
3850 mm (12 ft 8 in)
6350 mm (20 ft 10 in)
4100 mm (13 ft 5 in) / 3480 mm (11 ft 9 in)
5110 mm (16 ft 9 in)
650 mm (26 in)(Grouser Shoe)
3930 mm (12 ft 11 in)
2
104 kPa (1.06 kgf/cm , 15.1 psi)
–1
8.2 min (rpm)
4.3 km/h (2.7 mph) / 3.09 km/h (1.9 mph)
35° (tanθ = 0.70)
NOTE: The dimensions do not include the height of
the shoe lug.
T1-1-2
GENERAL / Specifications
ZAXIS800 (Loading Shovel)
T17V-01-01-021
Model
Type of Front-End Attachment
Bucket Capacity (Heaped)
Operating Weight
Basic Machine Weight
Engine
A: Overall Width
(Excluding Back Mirrors)
B: Cab Height
C: Rear End Swing Radius
D: Minimum Ground Clearance
E: Counterweight Clearance
F: Engine Cover Height
G: Overall Width of Upperstructure
H: Undercarriage Length
I: Undercarriage Width
(Extended/Retracted)
J: Sprocket Center to Idler Center
K: Track Shoe Width
L: Overall Hight
Ground Pressure
Swing Speed
Travel Speed (fast/slow)
Gradeability
NOTE:
ZX800
Loading front attachment
3
3
3
3
4.0 m (5.2 yd )(Bottom damp type)
4.4 m (5.8 yd )(Tilt damp type)
77700 kg (171300 lb)
76700 kg (169100 lb)
57400 kg (126500 lb)
-1
ISUZU BB-6WG1XQA 338.3 kW@1800 min (460 PS/1800 rpm)
4360 mm (14 ft 4 in)
3520 mm (11 ft 7 in)
4300 mm (14 ft 1 in)
*880 mm (35 in)
*1590 mm (5 ft 3 in)
*3430 mm (11 ft 3 in)
3850 mm (12 ft 8 in)
6350 mm (20 ft 10 in)
4100 mm (13 ft 5 in) / 3480 mm (11 ft 9 in)
5110 mm (16 ft 9 in)
650 mm (26 in) (Grouser Shoe)
3930 mm (12 ft 11 in)
2
2
106 kPa (1.08 kgf/cm , 15.4 psi)
101 kPa (1.03 kgf/cm , 14.6 psi)
-1
8.2 min (rpm)
4.3 km/h (2.7 mph) / 3.1 km/h (1.9 mph)
35° (tanθ = 0.70)
* The dimensions do not include the height
of the shoe lug.
T1-1-3
GENERAL / Specifications
ZAXIS800H (Loading Shovel)
T17V-01-01-022
Model
Type of Front-End Attachment
Bucket Capacity (Heaped)
Operating Weight
Basic Machine Weight
Engine
A: Overall Width
(Excluding Back Mirrors)
B: Cab Height
C: Rear End Swing Radius
D: Minimum Ground Clearance
E: Counterweight Clearance
F: Engine Cover Height
G: Overall Width of Upperstructure
H: Undercarriage Length
I: Undercarriage Width
(Extended/Retracted)
J: Sprocket Center to Idler Center
K: Track Shoe Width
L: Overall Hight
Ground Pressure
Swing Speed
Travel Speed (fast/slow)
Gradeability
NOTE:
ZX800H
Loading front attachment
3
3
3
3
3.6 m (4.7 yd )(Bottom damp type)
4.0 m (5.2 yd )(Tilt damp type)
78400 kg (172800 lb)
77300 kg (170400 lb)
57800 kg (127400 lb)
-1
ISUZU BB-6WG1XQA 338.3 kW@1800 min (460 PS/1800 rpm)
4360 mm (14 ft 4 in)
3640 mm (11 ft 11 in)
4300 mm (14 ft 1 in)
*880 mm (35 in)
*1590 mm (5 ft 3 in)
*3430 mm (11 ft 3 in)
3850 mm (12 ft 8 in)
6350 mm (20 ft 10 in)
4100 mm (13 ft 5 in) / 3480 mm (11 ft 9 in)
5110 mm (16 ft 9 in)
650 mm (26 in) (Grouser Shoe)
3930 mm (12 ft 11 in)
2
2
107 kPa (1.09 kgf/cm , 15.5 psi)
105 kPa (1.07 kgf/cm , 15.2 psi)
-1
8.2 min (rpm)
4.3 km/h (2.7 mph) / 3.1 km/h (1.9 mph)
35° (tanθ = 0.70)
* The dimensions do not include the height
of the shoe lug.
T1-1-4
GENERAL / Specifications
WORKING RANGE
ZAXIS800 (Backhoe)
T17V-01-01-023
Boom Category
Arm Category
Item
7.10 m (23 ft 4 in) 10.0 m (32 ft 10 in)
8.25 m (27 ft 1 in)
BE Boom
Boom
3.6 m (11 ft 10 in) 4.40 m (14 ft 5 in) 5.40 m (17 ft 9 in) 2.95 m (9 ft 8 in) 5.40 m (17 ft 9 in)
Arm
Arm
Arm
BE Arm
Arm
A: Maximum Digging
Reach
mm
(ftxin)
13990
(45’11’’)
14870
(48’9’’)
15700
(51’6’’)
12410
(40’9’’)
17440
(57’3’’)
B: Maximum Digging
Depth
mm
(ftxin)
8880
(29’2’’)
9670
(31’9’’)
10550
(34’7’’)
7240
(23’9’’)
12060
(39’7’’)
C: Maximum Cutting
Height
mm
(ftxin)
12530
(41’1’’)
13310
(43’8’’)
13520
(44’4’’)
11680
(38’4’’)
14490
(47’6’’)
D: Maximum Dumping
Height
mm
(ftxin)
8530
(27’12’’)
9210
(30’3’’)
9770
(32’1’’)
7820
(25’8’’)
10790
(35’5’’)
E: Transport Height
mm
(ftxin)
*4480
(14’8’’)
*4900
(16’1’’)
*5500
(18’1’’)
*5010
(16’5’’)
*5250
(17’3’’)
F: Overall Transport
Length
mm
(ftxin)
14320
(46’12’’)
14270
(46’10’’)
14030
(46’0’’)
13230
(43’5’’)
15880
(52’1’’)
G: Minimum Swing
Radius
mm
(ftxin)
6360
(20’10’’)
6240
(20’6’’)
6240
(20’6’’)
5520
(18’1’’)
7620
(25’0’’)
NOTE:
* The dimensions do not include the height
of the shoe lug.
T1-1-5
GENERAL / Specifications
ZAXIS800H (Backhoe)
T17V-01-01-023
Item
Boom Category 8.20 m (26 ft 11 in)
7.10 m (23 ft 4 in) BE Boom
H Boom
Arm Category
3.6 m (11 ft 10 in) 3.60 m (11 ft 10 in) 2.95 m (9 ft 8 in)
H Arm
H Arm
BE Arm
A: Maximum Digging
Reach
mm
(ftxin)
13800
(45’4’’)
12790
(41’12’’)
12410
(40’9’’)
B: Maximum Digging
Depth
mm
(ftxin)
8860
(29’1’’)
7800
(25’7’’)
7240
(23’9’’)
C: Maximum Cutting
Height
mm
(ftxin)
12000
(39’4’’)
11710
(38’5’’)
11680
(38’4’’)
D: Maximum Dumping
Height
mm
(ftxin)
8270
(27’2’’)
7860
(25’9’’)
7820
(25’8’’)
E: Transport Height
mm
(ftxin)
*4570
(14’12’’)
*4760
(15’7’’)
*5010
(16’5’’)
F: Overall Transport
Length
mm
(ftxin)
14250
(46’9’’)
13160
(43’2’’)
13230
(43’5’’)
G: Minimum Swing
Radius
mm
(ftxin)
6340
(20’10’’)
5380
(17’8’’)
5520
(18’1’’)
NOTE:
* The dimensions do not include the height
of the shoe lug.
T1-1-6
GENERAL / Specifications
ZAXIS800, 800H
(Loading Shovel)
T17V-01-01-020
T17V-01-01-019
Backet Type
Item
Bottom dump type
Tilt dump type
A: Min. digging distance
mm (ftxin)
3350 (10’12’’)
3160 (10’4’’)
B: Min. Level crowding distance
mm (ftxin)
5780 (18’12’’)
5780 (18’12’’)
C: Level crowding distance
mm (ftxin)
3820 (12’6’’)
3820 (12’6’’)
D: Max. digging reach
mm (ftxin)
10000 (32’10’’)
10000 (32’10’’)
E: Max. digging depth
mm (ftxin)
5060 (16’7’’)
5060 (16’7’’)
F: Max. cutting height
mm (ftxin)
10850 (35’7’’)
10850 (35’7’’)
G: Max. dumping height
mm (ftxin)
7900 (25’11’’)
4960 (16’3’’)
55°
49°
1600 (5’3’’)
ҥ
H: Max. bucket tilting angle on ground
I:
Max. bucket opening width
(°)
mm (ftxin)
T1-1-7
GENERAL / Specifications
(Blank)
T1-1-8
GENERAL / Component Layout
MAIN COMPONENT LAYOUT
3
2
4
5
1
6
7
8
9
10
11
12
23
22
13
21
12345-
Bucket
Bucket Cylinder
Arm
Arm Cylinder
Boom
6 - Boom Cylinder
78910 11 -
20
14
19
Swing Bearing
Center Joint
Swing Device
Fuel Tank
Control Valve
18
15
17
13 14 15 16 17 -
12 - Radiator / Oil Cooler / Inter
Cooler / Air Condenser
T17V-01-02-023
16
Engine
Pump Device
Pilot Filter
Travel Device
Oil Filter
18 - Signal Control Valve
T1-2-1
19 20 21 22 23 -
Pump Dram Filter
Solenoid Valve Unit
Hydraulic Tank
Travel Pilot Valve
Front Attachment Swing
Pilot Valve
GENERAL / Component Layout
ELECTRICAL COMPONENT LAYOUT
(Overview)
Monitor
Horn
· Rear Deck
Battery
Refer to electrical system
(Rear Deck) group
·
·
·
·
Fusible Link
Safety Relay
Battery Relay
Glow Plug
Refer to electrical system
(Around Battery) group
Washer Motor
· 4-Spool Pressure
Sensor
· 5-Spool Pressure
Sensor
Refer to electrical system
(Pressure Sensor) group
Fuel Sensor
Hydraulic
Temperature Sensor
· Pressure Sensor (Swing)
· Pressure Sensor (Travel)
Air Cleaner Restriction
Switch
Refer to signal control
valve group
Solenoid Valve
(Swing Preference
Circuit)
Outside Temperature
Sensor
· Solenoid Valve Unit
Refer to solenoid valve
unit group
· Pressure Sensor
(Swing + Front)
· Pressure Sensor
(Arm Roll-In)
· Pressure Sensor
EC Motor, EC Sensor
(Bucket Roll-In)
· Pressure Sensor
(Boom Raise)
Refer to electrical system
(Pressure Sensor) group
T17V-01-02-001
• Pump 1 ⋅ 2 Displacement Angle
Sensor
• Pump 1 ⋅ 2 Delivery Pressure
Sensor
• Pump 1 ⋅ 2 Control Proportional
Solenoid Valve
Refer to pump device group.
N Sensor
Engine Oil Pressure Switch
Oil Level Sensor
Overheat Switch (95 °C)
Overheat Switch (105 °C)
Coolant Temperature Switch
(QOS)
Refer to engine device.
•
•
•
•
•
•
T1-2-2
GENERAL / Component Layout
ELECTRICAL SYSTEM
(Rear Deck)
5
8
7
6
9
4
10
3
11
2
12
1
13
14
(Located at
back side of
sheet)
T17V-01-02-024
24
19
23
18
26
22
17
25
16
21
15
20
1 - GPS ON/OFF Switch
(Satellite Navigation
System Equipped
Machines Only)
2 - Boom Mode Switch
3 - Auto-Lubrication Switch
4 - QOS Controller
5 - ICX (Information Controller)
6 - Power Transistor
(Auto-Lubrication)
7 - MC (Main Controller)
T16J-01-01-010
8 - GPS Controller (Optional)
15 - Load Damp Relay (R1)
21 - Wiper Relay A (R7)
910 11 12 -
16 17 18 19 -
22 23 24 25 -
Fuse Box
Learning Switch
Precision Mode Switch
Dr.EX Connector to MC
13 - Download Connector (Not
Provided on GPS Equipped
Machines)
14 - Dr.EX Connector to ICX
Washer Relay (R2)
Work Light Relay 3 (R3)
Work Light Relay 2 (R4)
Work Light Relay 1 (R5)
20 - Horn Relay (R6)
T1-2-3
Wiper Relay B1 (R8)
Wiper Relay B2 (R9)
Wiper Relay B3 (R10)
Auto-Lubrication Normal
Rotation Relay (R11)
26 - Auto-Lubrication Reverse
Rotation (R12)
GENERAL / Component Layout
ELECTRICAL SYSTEM (Around Battery)
1
2
3
4
5
6
T17V-01-01-012
ELECTRICAL SYSTEM
(Pressure Sensor)
Control
Valve
7
8
Forward
9
10
View A
A
T17V-01-01-013
Signal Control
Valve
T17V-01-02-030
Forward
B
13
11
12
View B
T17V-01-02-031
Signal Control
Valve
14
T16J-03-06-001
1 - Safety Relay
2 - Glow Relay
3 - Fusible Link (45 A)
4 - Fusible Link (75 A)
5 - Battery Relay
6 - Battery
7 - Pressure Sensor
(Swing + Front)
8 - Pressure Sensor
(Arm Roll-In)
9 - Pressure Sensor (Boom Raise)
10 - Pressure Sensor (Bucket Roll-In)
11 - 5-Spool Pressure Sensor (SB)
T1-2-4
12 - 4-Spool Pressure Sensor (SA)
13 - Pressure Sensor (Swing)
14 - Pressure Sensor (Travel)
GENERAL / Component Layout
ELECTRICAL SYSTEM
(Monitors and Switches)
1
2
23
22
21
24
3
20
19
4
25
18
5
26
17
16
6
7
8
15
14
27
13
28
12
9
11
10
T17V-02-01-025
M178-01-091
1 - Coolant Temperature
Gauge
2 - Fuel Gauge
3 - Display Selection Switch
8 - Alternator Indicator
15 - Preheat Indicator
22 - Auto-Acceleration Indicator
9 - Coolant Level Indicator
10 - Quick Idle Indicator
4567-
11 12 13 14 -
16 - Overheat Indicator
17 - Trench Digging Mode
Indicator
18 - Digging Mode Indicator
19 - Attachment Mode Indicator
20 - Liquid Crystal Display
21 - Auto-Idle Indicator
23 - Engine Control Dial
24 - Auto-Idle / Acceleration
Selector
25 - Power Mode Switch
26 - Travel Mode Switch
27 - Work Light Switch
28 - Wiper / Washer Switch
SET Switch
Work Mode Switch
Fuel Level Indicator
Air Filter Restriction Switch
Precision Mode Indicator
Auto-Lubrication Indicator
Engine Oil Level Indicator
Engine Oil Pressure
Indicator
T1-2-5
GENERAL / Component Layout
ENGINE
6
1
A
5
View A
4
T17V-01-01-011
3
2
T17V-01-02-026
7
8
10
9
T17V-01-02-027
1 - N Sensor
4 - Oil Level Sensor
2 - Starter
3 - Engine Oil Pressure Switch
5 - Compressor
6 - Alternator
7 - Coolant Temperature
Sensor
8 - Overheat Switch (95 °C)
T1-2-6
9 - Coolant Temperature
Switch (QOS)
10 - Overheat Switch (105 °C)
GENERAL / Component Layout
PUMP DEVICE
Transmission
2
1
Pump 1
Pump 2
5
3
Pilot Pump
A
T17V-03-01-001
4
6
View A
T17V-01-02-028
SWING DEVICE
7
7
1 - Pump 1 Displacement
Angle Sensor
2 - Pump 2 Displacement
Angle Sensor
T17V-01-01-005
3 - Pump 2 Control Proportional
Solenoid Valve
4 - Pump 1 Control Proportional
Solenoid Valve
5 - Pump 2 Delivery Pressure
Sensor
6 - Pump 1 Delivery Pressure
Sensor
T1-2-7
7 - Swing Relief Valve
GENERAL / Component Layout
CONTROL VALVE
Forward
1
2
Right Block
(4-Spool)
11
10
9
Left Block
(5-Spool)
6
5
8
3
Forward
7
Right Block
(4-Spool)
4
T17V-03-03-001
T16J-03-03-002
Left Block
(5-Spool)
1 - Arm Flow Rate Control
Valve
2 - Boom Overload Relief
Selector Valve
3 - Overload Relief Valve
(Swing)
4 - Overload Relief Valve
(Arm)
5 - Holding Valve Shift Valve
(Arm)
6 - Overload Relief Valve
(Boom Mode)
7 - Main Relief Valve
8 - Holding Valve Shift Valve
(Boom)
9 - Overload Relief Valve
(Bucket)
T1-2-8
10 - Overload Relief Valve
(Boom)
11 - Make-Up Valve (Arm)
GENERAL / Component Layout
SOLENOID VALVE
(Swing Preference Circuit)
1
2
SOLENOID VALVE UNIT
3
T17V-01-01-008
4
1 - Check Valve
2 - Signal Control Valve
3 - Solenoid Valve (Swing
Preference Circuit)
4 - Pilot Relief Valve
5
6
7
5 - Solenoid Valve Unit (SA)
6 - Solenoid Valve Unit (SB)
T1-2-9
T17V-01-01-016
7 - Solenoid Valve Unit (SC)
GENERAL / Component Layout
TRAVEL DEVICE
2
1
T183-01-02-012
COUNTERWEIGHT REMOVAL DEVICE
(Optional)
3
6
4
7
5
T17V-01-01-015
T17V-01-01-014
1 - Travel Relief Valve
2 - Counterbalance Valve
3 - Counterweight Removal
Pilot Valve
4 - Pressure Sensor
(Counterweight)
5 - Block
6 - Stop Valve
T1-2-10
7 - Check Valve
GENERAL / Component Specifications
ENGINE
Manufacturer ................................................ISUZU
Model ...........................................................BB-6WG1XQA
Type .............................................................Diesel, 4-Cycle, Water-cooled, Inline, Direct Injection
Cyl. No.- Bore × Stroke ................................6-147 mm×154 mm (5.79 in×6.06 in)
3
3
Piston Displacement ....................................15681 cm (957 in )
-1
Rated Output................................................338 kW/1800 min (460 PS/1800 rpm)
Compression Ratio ......................................16.4
Dry Weight ...................................................1185 kg (2612 lb)
Firing Order ..................................................1-5-3-6-2-4
Rotation Direction.........................................Clockwise (Viewed from fan side)
COOLING SYSTEM
Cooling Fan..................................................Dia. 1016 mm (40 in), 6 Blades, Draw-in Type
Fan Pulley Ratio ...........................................Engine rpm × 0.98
Thermostat...................................................Cracking Temperature at Atmospheric Pressure: 83 °C (181 °F)
.....................................................................Full Open (Stroke: 8 mm or more) Temperature: 95 °C (203 °F)
Water Pump .................................................Centrifugal Belt Driven Type
LUBRICATION SYSTEM
Lubrication Pump Type ................................Gear Pump
Oil Filter........................................................Combined System of Full Flow and Bypass Type
Oil Cooler .....................................................Water Cooled Integral Type
STARTING SYSTEM
Motor ............................................................Reduction Type
Voltage / Output ...........................................24 V / 7 kW
PREHEAT SYSTEM
Preheating Method.......................................Glow Plug (QOS Type)
ENGINE STOP SYSTEM
Stop Method.................................................Fuel Shut-Off
T1-3-1
GENERAL / Component Specifications
ALTERNATOR
Type .............................................................AC Type (With IC Regulator)
Voltage / Output ...........................................24 V / 50 A
SUPERCHARGING SYSTEM
Type .............................................................Exhaust-Turbocharger Type IHI-RHC9
FUEL SYSTEM
Type .............................................................BOSCH Type
Governor ......................................................Centrifugal All Speed Control RSV Type
Injection Nozzle ...........................................Multi-Hole Type
PERFORMANCE
Lubricant Consumption ................................Less than 100 mL/h at Rated Output
-1
Fuel Consumption Ratio...............................Less than 208±13.6 g/kW⋅h at 338.3 kW / 1800 min
(With Cooling Fan) (Isuzu Delivery Standard)
Injection Timing ............................................9.74 ° (0.17 rad) before T.D.C.
-1
Maximum Output Torque..............................More than 1945 N⋅m (198 kgf⋅m) at approx. 1500 min
(Isuzu Delivery Standard)
2
Injection Pressure ........................................17.7 to 22.1 MPa (180 to 225 kgf/cm )
(Two-step open valve) (Isuzu Delivery Standard)
2
-1
Compression Pressure ................................2940 kPa (30 kgf/cm ) / 200 min
Valve Clearance (Inlet / Exhaust).................0.4 / 0.4 mm (when cool)
-1
No Load Speed ...........................................Slow: 900 ± 100 min
-1
Fast: 2050 ± 30 min
T1-3-2
GENERAL / Component Specifications
Engine Performance Curve (BB-6WG1XQA) (Isuzu Delivery Standard)
Test Condition: 1. In conformity with JIS D1005 (Performance Test Method for Diesel Engine Used for Construction Machinery) under standard atmospheric pressure.
2. Equipped with the fan and alternator.
Torque
(N⋅m)
Output
(kW)
Fuel
Consumption
Ratio
(g/kW h)
Engine Speed min-1 (rpm)
T1-3-3
× 100
T17V-01-01-001
GENERAL / Component Specifications
ENGINE ACCESSORIES
RADIATOR ASSEMBLY
Type .............................................................Radiator/Oil Cooler / Intercooler Tandem Type Assembly
Weight..........................................................600 kg (1323 lb)
Radiator
Core Row .....................................................4
Fin Pitch .......................................................5/2
Fin Type .......................................................Wave Fin
2
2
Radiating Area .............................................86.15 m (927 ft )
Capacity .......................................................49 L (12.9 US gal)
2
Air-Tight Test Pressure.................................90 kPa (0.9 kgf/cm , 13 psi)
2
Cap Opening Pressure.................................49 kPa (0.5 kgf/cm , 7 psi)
Oil Cooler
4
3
Plate Fin
2
2
90.58 m (975 ft )
34 L (9 US gal)
2
1250 kPa (12.7 kgf/cm , 181 psi)
−
Intercooler
Core Row .....................................................1
Fin Pitch .......................................................4.2/2
Fin Type .......................................................Straight Fin
2
2
Radiating Area .............................................32.68 m (352 ft )
Capacity .......................................................25 L (6.6 US gal)
2
Air-Tight Test Pressure.................................200 kPa (2 kgf/cm , 28.4 psi)
Cap Opening Pressure.................................
−
BATTERY
Type .............................................................195G51-MF
Capacity .......................................................170 Ah (20-Hour Rate)
Voltage .........................................................12 V
Height × Width × Length ..............................257 × 222 × 508 mm (10 × 8.7 × 20 in)
Weight..........................................................49.0 kg (108 lb) × 2
T1-3-4
GENERAL / Component Specifications
HYDRAULIC COMPONENT
PUMP DEVICE
Drive Gear Speed Ratio ...............................Main Pump 45/46
Pilot Pump: 1
Weight..........................................................240 kg (529 lb)
MAIN PUMP
Type .............................................................Variable Displacement Swash Plate Plunger Pump
3
3
Displacement (Theoretical value) ................278 cm /rev. (17.0 in /rev)
Maximum Flow (Theoretical Value)..............490 L/min (129 US gpm) × 2
PILOT PUMP
Model ...........................................................HY / ZFS 11 / 16.8 R
Type .............................................................Fixed Displacement Type Gear Pump
3
3
Displacement (Theoretical value) ................16.8 cm /rev. (1.03 in /rev)
Maximum Flow (Theoretical Value)..............30.2 L/min (7.98 US gpm)
CONTROL VALVE
Model ...........................................................UH36-302
Type .............................................................Pilot Pressure Operated Type (4-Spools + 5-Spools)
2
Main Relief Set-Pressure .............................Normal: 31.9 MPa (325 kgf / cm , 4621 psi) at
100 L/min (26 US gpm)
2
Precision Mode: 34.3 MPa (350 kgf / cm ) at
420 L/min (110 US gpm)
2
Overload Relief Set-Pressure ......................33.3 MPa (340 kgf / cm , 4835 psi) at 110 L/min (29 US gpm)
(Arm Roll-in, Bucket, Boom, Lower, Swing)
2
34.3 MPa (350 kgf / cm , 4977 psi) at 110 L/min (29 US gpm)
(Arm Roll-out, Boom Raise)
2
32.3 MPa (330 kgf / cm , 4693 psi) at 110 L/min (29 US gpm)
(Auxiliary)
2
13.7 MPa (140 kgf / cm , 1991 psi) at 50 L/min (13 US gpm)
(Auxiliary)
Weight..........................................................390 kg (860 lb)
SWING DEVICE
Type .............................................................Two-Stage Reduction Planetary Gear
Reduction Gear Ratio...................................19.77
SWING MOTOR
Model ...........................................................M2X210-CAB-10A-301290
Type .............................................................Swash-Plate Type, Fixed Displacement Axial Plunger Motor
Weight..........................................................66 kg (146 lb) × 2
VALVE UNIT
Type .............................................................Non Counterbalance Valve Type
2
Relief Set-Pressure ......................................28.4 MPa (290 kgf / cm , 4124 psi) at 90 L/min
SWING PARKING BRAKE
Type .............................................................Multi-Disc-Wet Negative Type
2
Release Pressure ........................................2.65 MPa (27 kgf/cm , 384 psi)
T1-3-5
GENERAL / Component Specifications
TRAVEL DEVICE
Type .............................................................Three-Stage Reduction Planetary Gear
Reduction Gear Ratio...................................90.826
Weight..........................................................1085 kg (2392 lb)
TRAVEL MOTOR
Type .............................................................Swash-Plate Type Variable Displacement Axial Plunger Motor
3
3
Displacement (Theoretical value) ................Fast speed: 228.6 cm /rev. (13.9 in /rev)
3
3
Slow speed: 337.2cm /rev. (20.6 in /rev)
Weight..........................................................134 kg (295 lb)
TRAVEL BRAKE VALVE
Type .............................................................Counter Balance Valve Type
2
Relief Set Pressure ......................................36.7 MPa (375 kgf/cm , 5333 psi) at 120 L/min
TRAVEL PARKING BRAKE
Type .............................................................Multi-Disc-Wet Negative Type
2
Cracking Pressure for Release ...................1.8 MPa (18 kgf/cm , 261 psi)
CYLINDER
(Backhoe)
Boom
Rod Dia. .......................................................140 mm (5.5’’)
Cylinder Bore................................................200 mm (7.9’’)
Stroke...........................................................1795 mm (5’11’’)
Fully Retracted Length .................................2660 mm (8’9’’)
Plating Thickness .........................................30 µm (1.18 µin)
Weight..........................................................700 kg (1540 lb)
Bucket (BE)
Rod Dia. .......................................................150 mm (5.9’’)
Cylinder Bore................................................215 mm (8.5’’)
Stroke...........................................................1495 mm (4’11’’)
Fully Retracted Length .................................2425 mm (7’11’’)
Plating Thickness .........................................30 µm (1.18 µin)
Weight..........................................................830 kg (1830 lb)
(Loading Shovel)
Boom
Rod Dia. .......................................................140 mm (5.5’’)
Cylinder Bore................................................200 mm (7.9’’)
Stroke...........................................................1795 mm (5’11’’)
Fully Retracted Length .................................2660 mm (8’9’’)
Plating Thickness .........................................30 µm (1.18 µin)
Weight..........................................................700 kg (1540 lb)
Bucket
Rod Dia. .......................................................130 mm (5.1’’)
Cylinder Bore................................................180 mm (7.1’’)
Stroke...........................................................1420 mm (4’8’’)
Fully Retracted Length .................................2505 mm (8’3’’)
Plating Thickness .........................................30 µm (1.18 µin)
Weight..........................................................580 kg (1279 lb)
Arm
Bucket
150 mm (5.9’’)
130 mm (5.1’’)
215 mm (8.5’’)
190 mm (7.5’’)
2175 mm (7’2’’)
1555 mm (5’1’’)
3080 mm (10’1’’)
2385 mm (7’10’’)
30 µm (1.18 µin)
30 µm (1.18 µin)
1025 kg (2260 lb)
600 kg (1320 lb)
Bucket (For 5.4 m Arm)
120 mm (4.7’’)
180 mm (7.1’’)
1375 mm (4’6’’)
2190 mm (7’2’’)
30 µm (1.18 µin)
490 kg (1080 lb)
Arm
140 mm (5.5’’)
200 mm (7.9’’)
1425 mm (4’8’’)
2320 mm (7’7’’)
30 µm (1.18 µin)
712 kg (1570 lb)
Dump
80 mm (3.1’’)
130 mm (5.1’’)
350 mm (1’2’’)
895 mm (2’11’’)
30 µm (1.18 µin)
106 kg (227 lb)
FRONT ATTACHMENT PILOT VALVE
Model ...........................................................HVP06A-040-101
Plunger Stroke .............................................1, 3 port: 6.5 mm (0.256 in)
2, 4 port: 8.0 mm (0.315 in)
T1-3-6
Bucket
140 mm (5.5’’)
200 mm (7.9’’)
685 mm (2’3’’)
1580 mm (5’2’’)
30 µm (1.18 µin)
483 kg (1065 lb)
GENERAL / Component Specifications
TRAVEL PILOT VALVE
Model ...........................................................HVP05F-040-101
1, 2, 3, 4 port: 4.5 mm (0.177 in)
SOLENOID VALVE UNIT
Function .......................................................⋅ SA
⋅ SB
⋅ SC
: Power Digging Control, Precision Mode Control
: Travel Motor Swash Angle Control
: Boom Mode Selector Control
PILOT PRESSURE SIGNAL CONTROL VALVE
Function .......................................................⋅ Pump Flow Rate Control
⋅ Swing Parking Brake Release
⋅ Flow Combiner Valve Control
PILOT SHUT-OFF VALVE
Type .............................................................Rotary Type
OIL COOLER BYPASS CHECK VALVE
2
Cracking Pressure .......................................343 kPa (3.5 kgf/cm ) @ 40 L (10.6 US gal) /min
RESTRICTION VALVE
2
Cracking Pressure .......................................98 kPa (1.0 kgf/cm , 14 psi)
at 40 Liters (10.6 US gal) /min
T1-3-7
GENERAL / Component Specifications
ELECTRICAL COMPONENT
BATTERY RELAY
Voltage / Current ............................................24 V / 100 A
GLOW RELAY
Voltage ........................................................... 24 V
HORN
Voltage / Current ............................................ 26 V⋅2.6 A
Sound Pressure ............................................. 115±5 dB (A)
ILLUMINATION
Specifications ................................................. Work Light : Halogen 24V, 70 W
Cab Light : 24 V, 10 W
AIR CONDITIONER
Refrigerant .................................................... 134 a
Cooling Ability................................................. 16.7 MJ/h(4000 kcal/h)
3
Cool Air Volume ............................................. 550 m /h or More
Heating Ability ................................................ 21.0 MJ/h (5000 kcal/h) or More
3
Warm Air Volume ........................................... 400 m /h or More
Temperature Adjusting System ...................... Electronic Type
Refrigerant Quantity ....................................... 1100±50 g
+15
3
Compressor Oil Quantity................................ 180 0 cm
T1-3-8
MEMO
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SECTION 2
SYSTEM
CONTENTS
Group 1 Control System
Outline .....................................................T2-1-1
Engine Control .........................................T2-1-2
Pump Control .........................................T2-1-19
Valve Control..........................................T2-1-36
Other Controls........................................T2-1-47
Group 2 Hydraulic System
Outline .....................................................T2-2-1
Pilot Circuit...............................................T2-2-2
Main Circuit ............................................T2-2-12
Counterweight Removal Circuit ..............T2-2-20
Group 3 Electrical System
Outline .....................................................T2-3-1
Main Circuit ..............................................T2-3-2
Electric Power Circuit (Key Switch: OFF) ..T2-3-3
Indicator Light Check Circuit
(Key Switch: ON) ....................................T2-3-4
Accessory Circuit .....................................T2-3-5
Preheat Circuit (Key Switch: Heat)............T2-3-6
Starting Circuit (Key Switch: Start)............T2-3-8
Charging Circuit (Key Switch: ON) ..........T2-3-10
Serge Voltage Prevention Circuit ............T2-3-14
Engine Stop Circuit.................................T2-3-16
17VT-2-1
(Blank)
17VT-2-2
SYSTEM / Control System
OUTLINE
The main controller (MC) is used to control machine
operations. Electronic signals from the engine control
dial, various sensors and switches are sent to the MC.
After processing the received signals in the logic circuit,
the MC sends out control signals to the EC motor, solenoid valve units, pump control solenoid valve, and
other control circuits to regulate the engine, pumps,
motors and valves.
Input Signals
• EC Sensor
• Engine Control Dial
• Pump 1 Displacement Angle Sensor
• Pump 2 Displacement Angle Sensor
• Pump 1 Delivery Pressure Sensor
• Pump 2 Delivery Pressure Sensor
• Pump Control Pressure Sensor (4-Spool)
• Pump Control Pressure Sensor (5-Spool)
• N sensor
• Pressure Sensor (Travel)
• Pressure Sensor
(Front Attachment⋅Swing)
• Pressure Sensor (Swing)
• Pressure Sensor (Boom Raise)
• Pressure Sensor (Arm Roll-In)
• Pressure Sensor (Bucket Roll-In)
• Pressure Sensor (Aux. Attachment) (OP)
• Pressure Sensor
(Counterweight Removal Device) (OP)
• Hydraulic Oil Temperature Sensor
• Auto-Idle/Acceleration Selector
• Power Mode Switch (HP/E/P)
• Travel Mode Switch (Fast/Slow)
• Work Mode Switch
(Digging/Trench Digging/Attachment)
• Learning Switch
• Precision Mode Switch
• Quick Idle Switch
• Key Switch
• Boom Mode Selection Switch
Output Signals
→
→
→
→
→
→
→
→
→
→
→
→
→
→
→
→
MC
→
→
→
→
→
→
→
→
→
→
→
NOTE: OP: Optional.
Only on the machines equipped with the
corresponding optional ports.
T2-1-1
Engine Control (EC Motor)
Engine Control Dial
HP Mode Control
P Mode Control
E mode Control
Auto-Idle Control
Auto-Acceleration Control
Quick Idle Control
Auto-Warming Up Control
Engine Learning Control
Pump Control
Pump Flow Rate Control
Speed Sensing Control
E Mode Control
Horse Power Control
Relief Flow Rate Reducing Control
Swing Horse Power Reducing Control
Pump Maximum Flow Rate Control
Bucket Flow Rate Control
Attachment Mode Control
Counterweight Removal and Installation
Control
Valve Control
Main Relief Pressure Shift Control
Precision Mode Control
Travel Motor Swash Angle Control
Boom Mode Selection Control
Swing Preference Control
Other Controls
Work Mode Control
Auto Lubrication Control (OP)
Travel Alarm Control (OP)
SYSTEM / Control System
ENGINE CONTROL
The engine control system is grouped as follows:
•
•
•
•
•
•
•
•
•
Engine Control Dial Control
P Mode Control
HP Mode Control
E Mode Control
Auto-Idle Control
Auto-Acceleration Control
Quick-Idle Control
Auto-Warming Up Control
Engine Learning Control
Engine Control System Layout
Learning Switch
Pressure Sensor
Travel
Front Attachment⋅Swing
Swing
Boom Raise
Key Switch
Quick-Idle
Switch
Engine
Control Dial
Auto-Idle /
Acceleration
Selector
Pump 2
Delivery
Pressure
Sensor
Arm Roll-In
Pump 1
Delivery
Pressure
Sensor
EC Sensor
Auto-Idle
EC Motor
Auto-Acceleration
Power Mode Switch
Pump 2
Displacement
Angle Sensor
HP Mode
E Mode
Pump 1
Displacement
Angle Sensor
Hydraulic Oil
Temperature
Sensor
P Mode
T17V-02-01-001
T2-1-2
SYSTEM / Control System
(Blank)
T2-1-3
SYSTEM / Control System
Engine Control Dial Control
Function: Controls the engine speed in response to
the rotation angle of the engine control dial
-1
and reduces the engine speed by 100 min
to reduce fuel consumption and noise level
when all control levers are in neutral during
P mode or HP mode.
This control is performed when the engine
-1
speed is 1850 min .
Operation: The MC drives the governor lever in response to the rotation angle of the engine
control dial to regulate the engine speed.
ȀȀ
ȀȀ
Engine
Speed
HP Mode
(2050 min-1 )
P Mode
(1950 min-1 )
1850 min-1
Engine speed is reduced by 100 min-1
ȀȀȀ
Minimum
NOTE: During P mode or E mode, even if the control dial is rotated to the full speed position,
the governor lever doesn’t come in contact
with the full speed stopper. (Refer to the HP
mode control.)
Approx. 1 second after all control levers are
in neutral (the pressure sensors on the
travel and front attachment⋅swing are detecting pressure of 0 to 98 kPa) during P
mode or HP mode, the MC drives the EC
motor so that the engine speed is reduced
-1
from the maximum speed by 100 min (P
mode) and 200 min-1 (HP mode).
The engine speed is reduced from the
-1
maximum speed by 100 min (P mode) and
-1
200 min (HP mode). Therefore, when the
engine speed set by the engine control dial
is already slower than the maximum speed
-1
by 100 min during P mode, the engine
speed remains unchanged. This engine
speed reduction control is activated regardless of whether the auto-idle and/or autoacceleration control is activated or not.
T2-1-4
Maximum
Engine Control Dial Position
SYSTEM / Control System
Pressure Sensor
Travel
Front Attachment⋅Swing
Engine
Control Dial
EC Motor
Power
Mode
Switch
T17V-02-01-002
NOTE: The figure indicates during HP mode.
If neither HP mode nor E mode is selected,
the MC recognizes P mode.
T2-1-5
SYSTEM / Control System
P Mode Control
Function: Performs at the normal work. When operations such as arm roll-in, boom raise and
travel are performed while excavating
deeply, the engine torque increases and the
work is easy to be performed.
Operation: The MC drives the EC motor to slightly increase the engine speed set by the engine
control dial when all the following conditions
exist with the power mode switch is in the
HP position.
Engine
Speed
**1800 min-1
(Governor Lever:
Maximum Speed)
**1700 min-1
(Governor Lever:
Position Reduced
from Maximum
Speed by
100 min-1 )
1450 min-1
1300 min-1
* Arm Roll-In,
Boom Raise, Travel
Maximum
speed
increases
by
100 min-1 .
1300 min-1
-1
• Engine Control Dial: Set at 1300 min or faster.
• Boom Raise and/or Arm Roll-In and/or Travel
Control: In Operation
• Average Delivery Pressure of Pumps 1 and 2:
2
19.2 MPa (196 kgf/cm , 2785 psi)
NOTE: When the engine control dial is turned to
the maximum speed position under the
condition as upward, the governor lever
comes in contact with the engine stopper.
T2-1-6
Minimum
NOTE:
Maximum
Engine
Control
Dial
Position
* Refer to the conditions.
** The engine speed with loads is reduced from the one without loads by
-1
approximate 150 min .
SYSTEM / Control System
Pressure Sensor
Travel
Boom Raise
Arm Roll-In
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
EC Motor
Power Mode Switch
P Mode
T17V-02-01-003
NOTE: The figure indicates during P mode.
If neither HP mode nor E mode is selected,
the MC recognizes P mode.
T2-1-7
SYSTEM / Control System
HP Mode Control
Engine
Speed
Function: Increases digging power when the maximum horsepower is required during digging
work. In response to the engine control dial
position except the pump delivery pressure,
the HP mode control increases the engine
horsepower.
HP Mode
2050 min-1
(Governor Lever:
Maximum Speed)
Operation: The MC drives the EC motor to slightly increase the engine speed in response to the
engine control dial when the power mode
switch is in the HP position. At maximum
speed the governor lever comes in contact
with the engine stopper.
T2-1-8
P Mode
(Arm Roll-In,
Boom Raise,
Travel)
P Mode
(Other
Operation)
Minimum
Speed
Minimum
Maximum
Engine
Control
Dial
Position
SYSTEM / Control System
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
EC Motor
Power Mode Switch
HP Mode
T17V-02-01-019
T2-1-9
SYSTEM / Control System
E Mode Control
Function: Reduces the fuel consumption by decreasing the maximum engine speed when the
engine load is light.
Operation: When the power mode switch is in the E
mode position, the MC limits the EC motor
operating range so that the maximum engine speed decreases.
Engine
Speed
P Mode
(without loads)
1950 min-1
E Mode
(without loads)
1820 min-1
NOTE: Refer to the pump E mode control. (T2-124)
Minimum
T2-1-10
Maximum
Engine
Control Dial
Position
SYSTEM / Control System
EC Motor
Power Mode Switch
E Mode
T17V-02-01-021
T2-1-11
SYSTEM / Control System
Auto-Idle Control
Function: Reduces the engine speed when all control
levers are in neutral to reduce fuel consumption and noise level.
Operation: Approx. 3.5 seconds after all control levers
are return to neutral, the MC drives the EC
motor so that the engine speed is reduced
to the auto-idle speed. As soon as a control
lever is operated (the travel and/or front attachment ⋅ swing pressure sensor detects
the pressure becomes 0 to 98 kPa (0 to
2
kgf/cm )), the MC drives the EC motor so
that the engine speed is increased to the
original engine speed (set by the engine
control dial)
Engine
Speed
Maximum
Speed
Engine speed is reduced to the auto-idle
speed 3.5 seconds
later.
Auto-Idle
Speed
(1250 min-1 )
Minimum
Speed
(900 min-1 )
Minimum
Auto-Idle System Deactivation Requirements:
• Control Levers: Being operated (Either travel or
swing ⋅ front attachment pressure sensor detects
the pressure.)
• Power Mode Switch: When the E mode is
changed to P mode or the P mode is changed to
the E mode.
• Engine Control Dial: When engine speed is
changed.
T2-1-12
Maximum
Engine
Control Dial
Position
SYSTEM / Control System
Pressure Sensor
Travel
Front Attachment⋅Swing
Engine
Control Dial
Auto-Idle/
Acceleration
Selector
Auto-Idle
EC Motor
Power Mode Switch
E Mode
T17V-02-01-004
T2-1-13
SYSTEM / Control System
Auto Acceleration Control
Function: Automatically regulates the engine speed to
meet the machine operating conditions.
When all the control levers are in neutral,
the engine speed is reduced to reduce fuel
consumption and noise level.
Operation: When a control lever is operated with the
auto-idle / acceleration selector in auto acceleration position, the MC calculates the
most proper engine operating speed corresponding to the signals from pressure sensors (travel, swing, boom raise, and arm
roll-in), pump control pressure sensors (4spool, 5-spool) and the pump delivery pressure sensors. Then, the MC drives the EC
motor so that the engine speed is set from
the auto-idle engine speed to the rotation
speed calculated by the MC.
When all control levers are returned to neutral, the engine speed is reduced by the
-1
maximum 450 min from the calculated rotation speed. Then, 3.5 seconds later, the
engine speed is further reduced to the
auto-idle speed.
The input signals from the pressure sensors
of 4-spool and 5-spool sides , boom raise,
arm roll-in and travel turn in response to the
lever stroke. These input signals make the
engine speed reduced by the lever stroke
-1
turn between 200 and 450 min .
The input signal from the pump delivery
pressure sensor turns in response to the
load. This input signal makes the engine
speed reduced by the load turn between 0
-1
and 450 min .
The engine speed is sure to be reduced by
more less turn.
Engine
Speed
Engine speed is reduced from the maximum speed by 450
min-1 .
Maximum
Speed
Auto Acceleration
Speed
ȀȀAuto-Idle
Speed
(1250 min-1 )
Engine speed is reduced to the auto-idle
speed 3.5 seconds
later.
Minimum
Speed
Minimum
Maximum
Engine
Control Dial
Position
Operating Time Progress VS. Engine Speed Change
Control Lever Stroke
Full Stroke
Neutral
Position
Time
Engine Speed
Max. Engine
Speed (P Mode)
In response to the control
lever stroke and the pump
delivery pressure, the optimum engine speed is
selected.
Auto Acceleration Control
Auto-Idle
Engine Speed
Time
NOTE: When all control levers are returned to neutral, the engine speed is reduced by 450
-1
-1
min from the maximum speed (1950 min
at P mode without loads). In case the engine speed is set by the engine control dial
-1
and is running at a speed (1950 min at P
mode without loads) slower than the maxi-1
mum speed by 100 min , the engine speed
-1
will be reduced by 350 min .
T2-1-14
SYSTEM / Control System
Pressure Sensor
Pump Control Pressure Sensor (4-Spool)
Pump Control Pressure Sensor (5-Spool)
Travel
Swing
Boom Raise
Arm Roll-In
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Auto-Idle/
Acceleration
Selector
AutoAcceleration
EC Motor
T17V-02-01-005
T2-1-15
SYSTEM / Control System
Quick-Idle Control
Function: Decreases the engine speed a moment and
reduces the fuel consumption. This control
is useful to wait for dump trucks.
Operation: When the quick-idle switch on the right control lever is turned into ON, the signal is sent
to MC. MC activates the EC motor and operates the governor lever to decrease the
-1
engine speed into 900 ± 100 min .
When the quick-idle switch is turned into
OFF, the engine speed comes back to the
set speed by the engine control dial.
Engine
Speed
900 min-1
Minimum
Maximum
Engine
Dial Control
Position
Quick-Idle
Switch
EC Motor
T17V-02-01-007
T2-1-16
SYSTEM / Control System
Auto Warming Up Control
Function: Automatically warms up the hydraulic system (similar to the auto choke on automobiles).
Engine
Speed
Maximum
Speed
ȀȀȀȀȀ
Operation: When the hydraulic oil temperature is below -2 °C (28 °F), the MC drives the EC motor in response to signals from the key
switch and the hydraulic oil temperature
sensor to run the engine at the auto warm
up speed for 15 minutes after starting the
engine.
Auto
Warm Up
Speed
(980 min-1 )
Increasing
Speed
Minimum
Speed
(900 min-1 )
Minimum
Maximum
Engine
Control Dial
Position
IMPORTANT: When adjusting the auto-idle speed
deactivate the auto warming up control function using Dr. EX, or wait to
adjust until 15 minutes after starting
the engine.
Key Switch
Engine
Control Dial
EC Motor
Hydraulic Oil
Temperature
Sensor
T17V-02-01-006
T2-1-17
SYSTEM / Control System
Engine Learning Control
Function: Inputs the governor lever stopper positions
on both the STOP and FULL sides as the
standard data to control the engine.
Operation: When the learning switch in the rear console is turned to the engine learning position, the EC motor is driven by the signals
from the MC. The EC motor moves the
governor lever from the IDLE to FULL and
to STOP positions in this order. The EC
sensor detects the stopper positions of the
governor lever on both the FULL and STOP
sides and sends each stopper position signal to the MC. The MC stores these signals
in its memory.
IMPORTANT: Be sure to perform the engine learning if the following repair work is
done. (Refer to the Troubleshooting
Section in T/M.)
After performing the engine learning,
check that the engine learning has
been performed correctly using Dr.
EX.
• After the engine, engine control
cable, or EC motor has been removed or replaced.
• After the MC has been replaced.
NOTE: The engine learning is not required when
the batteries are replaced.
Learning Switch
Key Switch
EC Sensor
EC Motor
T17V-02-01-008
T2-1-18
SYSTEM / Control System
PUMP CONTROL
The pump control system has the following functions:
•
•
•
•
•
•
•
•
•
•
Pump Flow Rate Control
Speed Sensing Control
E Mode Control
Horse Power Control
Relief Flow Rate Reducing Control
Swing Horse Power Reducing Control
Pump Maximum Flow Rate Control
Bucket Flow Rate Control
∗
Attachment Mode Control
∗
Counterweight Removal and Installation Control
∗
NOTE: Only on the machines equipped with the
corresponding optional parts.
Pump Control System Layout
Pressure Sensor
Pump Control Pressure Sensor (4-Spool) (Pump 1)
Pump Control Pressure Sensor (5-Spool) (Pump 2)
Travel
Front Attachment⋅Swing
Swing
Attachment (OP)
Counterweight (OP)
Engine
Control Dial
Bucket Roll-In
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Boom Mode Selection Switch
Precision Mode
Switch
Fast
Pump 1
Displacement
Angle Sensor
Slow
Travel Mode Switch
Pump 2
Displacement
Angle Sensor
Power Mode Switch
HP Mode
E Mode
P Mode
Work
Mode
Switch
Digging Trench Attachment
Mode
Digging Mode
Overheat
Mode
Switch
T2-1-19
Pump 2 Control
Solenoid Valve
Pump 1 Control
Solenoid Valve
T17V-02-01-032
SYSTEM / Control System
Pump Flow Rate Control
Function: Has the main pump deliver the required oil
flow to each actuator in proportion to control lever stroke.
Operation: When control lever is operated:
Pilot pressure oil from the pilot valve flows
into the signal control valve. The pressure
oil is selected by the shuttle valve in the
signal control valve, actuating the pump 1
flow rate control valve or pump 2 flow rate
control valve to send pressure oil corresponding to the operated amount. Detecting this pressure, the pump control pressure sensor (4-spool) or pump control
pressure sensor (5-spool) sends signals to
the MC. Consequently, the MC calculates
the required oil flow and, at the same time,
compares it with the actual pump displacement angle which is detected by the
pump 1 or pump 2 displacement angle
sensors. Then, the MC actuates the pump
control solenoid valve, increasing the main
pump displacement angle, thus increasing
the main pump flow rate.
T2-1-20
When control lever is in neutral:
When the control lever is in neutral, pilot
pressure is turned to zero as the flow of oil
into the signal control valve ceases. Detecting this disappearance of pressure, the
pump control pressure sensor (4-spool) or
pump control pressure sensor (5-spool)
sends signals to the MC. Consequently, the
MC calculates the required oil flow and, at
the same time, compares it with the actual
pump displacement angle which is detected by the pump 1 or pump 2 displacement angle sensors. Then, the MC actuates the pump control solenoid valve, reducing the main pump displacement angle
to the minimum angle, thus decreasing the
main pump flow rate to the minimum.
SYSTEM / Control System
Pump Control
Pressure Sensor (4-Spool)
Pump Control
Pressure Sensor (5-Spool)
Pump 1 Flow Rate
Control Valve
Pump 2 Flow Rate
Control Valve
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
T17V-02-01-009
Pump 2 Control
Solenoid Valve
T2-1-21
Pump 1 Control
Solenoid Valve
SYSTEM / Control System
Speed Sensing Control
Function: Controls the pump flow rate in response to
engine speed changes due to variations in
load so that the engine output can be utilized more efficiently. (Engine stall is prevented when the machine operates under
adverse conditions such as operating at
high altitude.)
Q
Engine Speed: More
than 1400 min-1
Increase
Frow
Rate
Decrease
Base Torque
Operation:
1. The target engine operating speed is set by controlling the engine control dial.
2. The MC calculates the difference in speed between the target operating speed and the actual
operating speed monitored by the N sensor. Then,
the MC sends signals to the pump control solenoid valve.
3. The pump control solenoid valve delivers pilot
pressure oil in response to the signals received
from the MC to the pump regulator, controlling the
pump flow rate.
4. If the engine load increases and the actual engine
operating speed becomes slower than the target
operating speed, the pump swash angle is reduced so that pump flow rate will be reduced.
Therefore, the engine load is reduced, preventing
engine stall.
5. If the actual engine operating speed becomes
faster than the target operating speed, the pump
swash angle is increased so that the pump flow
rate will increase, by which the engine output can
be utilized more efficiently.
T2-1-22
Pressure
P
T111-05-02-004
Pump P-Q Curve
Q
Engine Speed:Less
than 1400 min-1
Frow
Rate
Decrease
Base Torque
Pressure
P
T166-02-01-014
SYSTEM / Control System
N Sensor
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
T16J-02-01-008
Pump 2 Control
Solenoid Valve
T2-1-23
Pump 1 Control
Solenoid Valve
SYSTEM / Control System
E Mode Control
Function: Increases fuel efficiency by reducing the
load applied to the engine, i.e. lowering the
pump driving torque to 85% of the torque in
the P mode. This control also functions to
prevent the engine from stalling when the
machine is operated in severe environments, such as when operating at high altitude.
Operation: When the E mode is selected, the power
mode switch sends a signal to the MC.
Subsequently, also having a signal from the
pump delivery pressure sensor, the MC
calculates a target pump displacement angle.
Then, comparing the target pump displacement angle with the actual pump displacement angle detected by the pump displacement angle sensor, the MC actuates
the pump control solenoid valve to compensate for the difference between the actual and target pump displacement angles,
reducing the pump displacement angle,
thus reducing the main pump flow rate.
T2-1-24
Q
Flow
Rate
Decrease
Base Torque
E Mode
Pressure
P
T166-02-01-006
SYSTEM / Control System
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Pump 1
Displacement
Angle Sensor
EC Motor
E Mode
Pump 2
Displacement
Angle Sensor
Power Mode Switch
Pump 2 Control
Solenoid Valve
Pump 1 Control
Solenoid Valve
T17V-02-01-033
T2-1-25
SYSTEM / Control System
Horsepower Control
Function: Effectively utilizes engine horsepower by
controlling the delivery rate of each main
pump so that the sum of the two main
pumps torque does not exceed the engine
output torque.
Operation: Delivery pressure of each main pump usually differs from each other: i.e. the larger
the load applied to a main pump, the higher
the delivery pressure and vice versa. The
pump delivery pressure sensors and the
pump displacement angle sensors detect
the actual status (conditions) of two main
pump, sending signals to the MC.
Then, the MC calculates a target pump displacement angle using signals from two
pump delivery pressure sensors and compares them with the actual pump displacement angles detected by the pump delivery
pressure sensors. Subsequently, the MC
actuates the pump control solenoid valve of
the larger load applied main pump, increasing the delivery rate of the larger load applied main pump to the extent that the sum
of the two main pumps torque does not exceed the engine output torque. Consequently, the sum of the two main pumps
torque is approximately the same as the
engine output torque.
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
T16J-02-01-009
Pump 2 Control
Solenoid Valve
T2-1-26
Pump 1 Control
Solenoid Valve
SYSTEM / Control System
Relief Flow Rate Reducing Control
Function: Reduces hydraulic energy loss and to prevent the hydraulic oil temperature from rising.
If the work mode switch is in precision
mode position, the pressure sensor (travel)
detects travel pilot pressure or the pressure
sensor (swing) detects swing pilot pressure,
the MC cancels the relief flow rate reducing
control to the main pump (relief cut off override).
Operation: When an actuator is operated, the pump
delivery pressure varies due to changing
load applied to each actuator. Detecting the
pump delivery pressure, the pump delivery
pressure sensor sends signals to the MC.
When the pump delivery pressure reaches
2
30.9 MPa (315 kgf/cm ), MC compares the
pump delivery pressure with the actual
pump displacement angle by the displacement angle sensor, and marks the pump
control solenoid valve operate. Therefore
the pump delivery flow rate decreases to be
the minimum flow rate.
Qm
Relief Cut Off Override
Flow
Rate
Relief Cut Off
Relief Flow Cut
Qo
Pc
Pr
P
Pressure
T162-01-02-012
Pressure Sensor
Travel
Swing
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Work Mode
Switch
Pump 1
Displacement
Angle Sensor
Precision Mode
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
T2-1-27
Pump 1 Control
Solenoid Valve
T17V-02-01-034
SYSTEM / Control System
Swing Horsepower Reducing Control
Consequently, the MC actuates the main
pump 2 control solenoid valve to adjust the
difference between the actual and target
displacement angle, decreasing the pump
flow rate.
If the combined operation is operated, the
pressure sensors (swing, travel and front
attachment ⋅ swing) detect the travel or
front attachment ⋅ swing pilot pressure and
send a signal to the MC. The MC increases
the pump flow rate by actuating the main
pump 1 control solenoid valve.
Function: Effectively utilizes engine horsepower by
reducing the flow rate of the main pump 2
in which the swing circuit is located and by
increasing the flow rate of the main pump 1
when the pressure sensor (swing) detects
swing pilot pressure, i.e. when the swing
lever is operated.
Operation: The pressure sensor (swing) sends a signal to the MC as it detects swing pilot pressure, i.e. when the swing function is operated. The MC calculates the target pump
displacement angle by taking a signal from
the pump delivery pressure sensor into account. Then, the MC compares this calculated target angle with the actual pump displacement angle detected by the pump displacement angle sensor.
NOTE: The figure indicates during combined operation of front attachment, travel and/or
swing.
Q
Q
Flow
Rate
Flow
Rate
Main Pump 2
Pressure
P
T162-02-01-010
Main Pump 1
Pressure
P
T16J-02-01-036
Pressure Sensor
Travel
Front Attachment ⋅ Swing
Swing
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
T2-1-28
Pump 1 Control
Solenoid Valve
T17V-02-01-020
SYSTEM / Control System
Pump Maximum Flow Rate Control
Function: Prevents the engine from overheating by
reducing the main pump maximum flow
rate setting and pump torque, thus reducing
the load applied to the engine when the
overheat switch is turned on.
Operation: When the overheat switch is turned on (95
°C, 203 °F), a signal from the switch/sensor
is sent to the MC. The MC calculates the
target pump displacement angle by considering a signal from the pump delivery pressure sensor. Then, the MC compares the
actual pump displacement angle detected
by the pump displacement angle sensor
with the target pump displacement angle.
Consequently, the MC decreases 7% from
maximum pump flow rate by actuating the
pump (1 and 2) control solenoid valve in
accordance with the difference between the
actual and targeted displacement angles. In
addition, the pump torque is also lowered.
Q
Flow
Rate
Pressure
P
T162-02-01-013
Pressure Sensor
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
Overheat
Switch
Pump 1 Control
Solenoid Valve
T17V-02-01-014
T2-1-29
SYSTEM / Control System
Bucket Flow Rate Control
Function: Increases the flow rate of the pump 2 according to the job when the bucket is rolled
in. The bypass shut-out valve on 5-spool
side works when the bucket is rolled in. The
pressure oil from the main pump 2 is fed
into the 4-spool side control valve from 5spool side control valve. Then the pressure
oil is combined with that in the main pump 1
to actuate the bucket cylinder. This control
is necessary because a pump control pressure sensor on 5-spool side cannot detect
bucket pilot pressure and the minimum flow
rate through the main pump 2 is left unchanged. Refer to the pages of Bypass
Shut-out Valve in Control Valve group in
COMPONENT OPERATION section.
Operation: When the bucket is rolled in, a pressure
sensor (bucket roll-in) detects the bucket
roll-in pilot pressure, and sends signal to
MC. Then MC regulates the pump 2 control
solenoid valve according to bucket roll-in pilot pressure to increase the flow rate of the
pump 2. This control is applicable in other
modes than the Attachment mode.
T2-1-30
SYSTEM / Control System
Pressure Sensor
Bucket
Bucket Roll-In
4-Spool Side
Pump 2
Delivery
Pressure
Sensor
Engine
Control Dial
5-Spool Side
Pump 1
Delivery
Pressure
Sensor
Bypass
Shut-Out
Valve
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
Work Mode Switch
Pump 2 Control
Solenoid Valve
Pump 1 Control
Solenoid Valve
T17P-02-01-024
T2-1-31
SYSTEM / Control System
Attachment Mode Control
NOTE: This control system functions only on machines equipped with the attachment optional kit.
Function: When the attachment pilot valve is operated with the work mode switch in the attachment mode, the maximum flow rate of
main pump 2 (490 L/min (130 US gal)) is
changed according to the attachment select switch, as follows.
Maximum Flow Rate
BREAKER
MODE 1
BREAKER
MODE 2
BREAKER
MODE 3
Operation: When the attachment mode is selected by
the work mode switch, because of operation of the breaker (attachment pilot valve)
the pressure sensor (attachment) measures the attachment pilot pressure and
sends the signal to MC.
Then the signal of the attachment select
switch is sent to the MC.
The value is monitored by the displacement
angle sensor. The MC is kept instructed by
the signal from the sensor. Therefore, when
the pump displacement angle of the main
pump 2 increases to a point of maximum
flow rate with the attachment select switch,
the MC operates the pump 2 control solenoid valve so that the pump displacement
angle is held in that position.
The attachment is controlled by the auxiliary spool in the 5-spool side control valve.
Therefore, only maximum flow rate of the
main pump 2 is regulated.
375 L/min (99.1 US gal)
325 L/min (85.9 US gal)
272 L/min (71.9 US gal)
M16J-12-002
Attachment Select Switch
Q
(L/min)
490
375
325
272
Pressure
T2-1-32
P
SYSTEM / Control System
Control Valve
Pressure Sensor
4-Spool Side 5-Spool Side
Attachment
Engine
Control Dial
Pump 2
Delivery
Pressure
Sensor
Auxiliary
Spool
(Attachment)
Pump 1
Delivery
Pressure
Sensor
Pump 1
Displacement
Angle Sensor
Attachment Select
Switch
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
Work Mode Switch
Attachment
Mode
Pump 1 Control
Solenoid Valve
T17V-02-01-015
T2-1-33
SYSTEM / Control System
Counterweight Removal and Installation Control
(Optional)
Function: Applies back pressure on the main relief
valve to increase main relief pressure, so
that the hoist / lower power increases.
Operation: When the counterweight hoist / lower lever
is operated, the pressure sensor
(counterweight) measures the pilot pressure and the signal is sent to the MC. The
MC actuates solenoid valve unit (SA) to allow pressure oil to direct from the pilot
pump to the shuttle valve. Therefore, the
spring of the main relief valve is compressed and its preload increased, so that
the relief valve opening pressure increases
2
from 31.9 MPa (325 kgf/cm , 4622 psi) to
2
34.3 MPa (350 kgf/cm , 4977 psi).
Also, the MC actuates the pump control solenoid valves according to the signals from
the pump delivery pressure sensors and
pump displacement angle sensors, so that
the setting of upper limit for the delivery
flow rate changes to 97 L/min (25.6 US gal).
(It is decreased approximately 80 % from
the maximum.)
NOTE: Refer to COUNTERWEIGHT REMOVAL /
INSTALLATION CIRCUIT (Optional) in Hydraulic System group / SYSTEM.
T2-1-34
SYSTEM / Control System
Pressure Sensor
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Counterweight
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
Pump 1 Control
Solenoid Valve
Main Relief Valve
T17V-02-01-035
T2-1-35
SYSTEM / Control System
VALVE CONTROL
The valve control system functions as follows:
•
•
•
•
•
Main Relief Pressure Shift Control
Precision Mode Control
Travel Motor Swash Angle Control
Boom Mode Selection Control
Swing Preference Control
T2-1-36
SYSTEM / Control System
Pressure Sensor
Travel
Pump 2
Delivery
Pressure
Sensor
Pump 1
Delivery
Pressure
Sensor
Engine
Control Dial
Precision
Mode Switch
Pump 1
Displacement
Angle Sensor
Fast
Pump 2
Displacement
Angle Sensor
Slow
Travel Mode Switch
Pump 2 Control
Solenoid Valve
Solenoid Valve Unit
Pump 1 Control
Solenoid Valve
Solenoid Valve
(Swing Priority)
Main Relief Valve
Travel Motor
Boom Overload
Relief Selector
Valve
T17V-02-01-036
T2-1-37
SYSTEM / Control System
Main Relief Pressure Shift Control
Function: Increases main relief pressure.
Operation: The MC actuates solenoid valve unit (SA)
when the pressure sensor (travel) detects
travel pilot pressure. The pressure oil from
the pilot pump flows into the shuttle valve,
so that the spring of the main relief valve is
compressed and increased its preload.
Therefore, the relief valve opening pres2
sure increases from 31.9 MPa (325 kgf/cm ,
2
4622 psi) to 34.3 MPa (350 kgf/cm , 4977
psi).
T2-1-38
SYSTEM / Control System
Pressure Sensor
Travel
Travel
Mode
Switch
Main Relief Valve
T17V-02-01-037
T2-1-39
SYSTEM / Control System
Precision Mode Control
Function: Increases main relief pressure and reduces
pump flow rate allowing precision work.
Operation: When the precision mode switch is turned
on, a signal is sent to the MC. The MC actuates solenoid valve unit (SA) to allow
pressure oil to direct from the pilot pump to
the shuttle valve. Therefore, the spring of
the main relief valve is compressed and its
preload increased, so that the relief valve
opening pressure increases from 31.9 MPa
2
(325 kgf/cm , 4622 psi) to 34.3 MPa (350
2
kgf/cm , 4977 psi).
Also, the MC actuates the pump control solenoid valves according to the signals from
the pump delivery pressure sensors and
pump displacement angle sensors, so that
the setting of upper limit for the delivery
flow rate changes to 197 L/min (52 US gal)
(It is decreased approximately 60 % from
the maximum).
T2-1-40
SYSTEM / Control System
Pump 2
Delivery
Pressure
Sensor
Precision
Mode
Switch
Pump 1
Delivery
Pressure
Sensor
Pump 1
Displacement
Angle Sensor
Pump 2
Displacement
Angle Sensor
Pump 2 Control
Solenoid Valve
Pump 1 Control
Solenoid Valve
Main Relief Valve
T17V-02-01-038
T2-1-41
SYSTEM / Control System
Travel Motor Awash Angle Control
• Slow Travel Mode:
With the travel mode switch turned to the
position, no electrical current flows to solenoid
valve unit (SB). As solenoid valve unit (SB) is not
activated (shifted), the pressure oil from the pilot
pump is not supplied to the travel mode shift valve.
For this reason, the travel mode shift valve is not
shifted, and the pressure oil in the main control
valve travel circuit is not supplied to the tilt pistons.
Consequently, the travel motors rotate in the slow
speed mode.
(Refer to the heading Travel Motor in the Travel
Device group, the COMPONENT OPERATION
section for travel motor displacement angle shift.)
From the Main Pump
Brake
Valve
Solenoid Valve
Unit (SB)
Pilot Pump
Travel Mode
Shift Valve
Travel Motor
Travel Mode
Switch
MC
Parking Brake
T2-1-42
Tilt Piston
SYSTEM / Control System
• Fast Travel Mode:
With the travel mode switch turned to the
position, electrical current flows to solenoid valve
unit (SB). As solenoid valve unit (SB) is activated
(shifted), the pressure oil from the pilot pump is
supplied to the travel mode shift valve. For this
reason, the travel mode shift valve is shifted, and
the pressure oil in the main control valve travel
circuit is supplied to the tilt pistons. Consequently,
the travel motors rotate in the fast speed mode.
(Refer to the heading Travel Motor in the Travel
Device group, the COMPONENT OPERATION
section for travel motor displacement angle shift.)
From the Main Pump
Brake Valve
Solenoid Valve
Unit (SB)
Pilot Pump
Travel Mode
Shift Valve
Travel Motor
Travel Mode
Switch
MC
Parking Brake
Tilt Piston
T2-1-43
SYSTEM / Control System
Boom Mode Selector Control
Function: Reduces the vibration of the machine at
digging and grading work.
Operation: When the boom mode selector switch is
turned on, the MC sends a signal to solenoid valve unit (SC) to it turns on.
The pressure oil from the pilot pump applies the boom overload relief selector
valve via solenoid valve unit (SC).
When the boom overload relief selector
valve shifts, the pressure from the boom
cylinder rod which applies as pressure pilot
at the overload relief valve is blocked. By
this, the setting of the overload relief valve
relief pressure is reduced to 9.8 MPa ((100
2
kgf/cm , 1422 psi) @110 L/min (29 US
gpm)).
(Refer to Boom Overload Selector Valve in
COMPONENT OPERATION / Control
Valve group.)
T2-1-44
SYSTEM / Control System
Main Pump 2
MC
Boom Mode
Selector Switch
Pilot Pump
Main Pump 1
Solenoid Valve Unit (SC)
T2-1-45
T17V-02-01-039
Boom Overload Relief
Selector Valve
SYSTEM / Control System
Swing Preference Control
• Swing/Boom Raise Combined Operation (in the
digging mode, front attachment mode, or precision mode)
With the work mode set in any of the three work
modes indicated above, the MC actuates the solenoid valve (swing priority). For this reason, the
boom raise operating pressure 1A flows to 1B,
shifting both boom 1 and 2 spools. The swing
spool is also shifted at the same time.
Solenoid Valve (Swing Priority)
From the MC.
1A
P
S
F
1A - Boom 1 Raise Section Operating Pressure
1B - Boom 2 Raise Section Operating Pressure
D2 - To the hydraulic oil tank.
1B
D2 G
T166-02-01-002
• Swing/Boom Raise Combined Operation (in the
trench digging mode)
In swing/boom combined operation with the work
mode in the trench digging mode, the MC deactivates the solenoid valve (swing priority).
Consequently, boom raise operating pressure 1A
does not flow to 1B and the boom spool (raise)
operating pressure line is connected to the hydraulic oil tank line. For this reason, pressure oil
from the pump 1 flows only to the swing circuit in
swing/boom raise combined operation. (Swing
Preference Control)
Solenoid Valve (Swing Priority)
From the MC.
1A
P S
F
1B
1A - Boom 1 Raise Section Operating Pressure
1B - Boom 2 Raise Section Operating Pressure
D2 - To the hydraulic oil tank.
D2 G
T166-02-01-003
T2-1-46
SYSTEM / Control System
OTHER CONTROLS
Work Mode Control
Four work modes, digging, trench digging, precision
and front attachment, are available by operating the
work mode switch.
• Digging Mode:
Standard work mode. Designed for general digging and truck loading.
• Trench Digging Mode:
In swing/boom raise operation, the swing preference circuit shift valve is actuated so that only one
boom section (out of two) in the control valve is
operated, giving priority to swing movement during trenching work. (Refer to page T2-1-46.)
• Precision Mode:
Main pump flow rate is decreased approximately
60 % from that in the general purpose mode. At
the same time, the MC actuates the solenoid
valve unit (SA), raising the main relief pressure.
This mode is designed for work in confined work
areas that require precision front attachment
movement. (Refer to page T2-1-40.)
• Front Attachment Mode:
Ȁ Functions only when a front attachment in the optional kit is operated. The pump flow rate (Refer to
T2-1-32) is controlled so as to match the installed
front attachment operation in response to the
movement of the auxiliary valve spool. The pump
flow rate control setting is made by using Dr. EX.
T2-1-47
SYSTEM / Control System
Auto Lubrication Control (Optional)
Function: Controls the auto lubrication system
Operation:
1. When the auto lubrication switch turns on, MC
sends signal to auto lubrication normal rotation input terminal in the power transistor.
2. The normal rotation output terminal is connected
to GND terminal in the power transistor to excite
the coil at the auto lubrication normal rotation relay.
3. The normal rotation relay goes on, the auto lubrication motor rotates normal direction, and auto
lubrication starts.
4. When auto lubrication pressure reaches 22.5 to
2
25.5 MPa (230 to 260 kgf/cm ), the pressure
switch goes on and MC stops sending signal to
the auto lubrication normal rotation input terminal
in the power transistor. Thereby, auto lubrication
stops.
5. When auto lubrication pressure drops to 17.5 to
2
21.5 MPa (180 to 220 kgf/cm ), the pressure
switch goes off and MC resends signal to the auto
lubrication normal rotation input terminal in the
power transistor. Thereby, auto lubrication resumes.
6. MC repeats Steps 1 to 6 in the preset lubrication
time (normally 5 minutes).
7. After passing the preset auto lubrication time, MC
sends signal to the auto lubrication reverse rotation output terminal in the power transistor.
8. The reverse rotation output terminal is connected
to GND terminal in the power transistor to excite
the coil at the auto lubrication reverse rotation relay.
9. The reverse rotation output relay goes on, and the
auto lubrication motor reverses to release the
pressure from the auto lubrication circuit.
10. After passing the preset pressure release time,
MC stops sending signal to the auto lubrication
input terminal in the power transistor. Thereby,
pressure releasing stops.
11. After passing the preset interval, MC sends signal
to the auto lubrication normal rotation input terminal to resume auto lubrication.
12. Lubrication time and interval can be set in the
Service mode of the Dr. EX.
T2-1-48
SYSTEM / Control System
Auto Lubrication Reverse Rotation Output Terminal
Auto Lubrication Normal Rotation Relay
Auto Lubrication Normal
Rotation Output Terminal
Pressure Switch
To Auto Lubrication
Indicator
Auto Lubrication
Device
Auto Lubrication
Motor
Auto Lubrication
Switch
Power Transistor
Auto Lubrication Reverse Rotation Input Terminal
Auto Lubrication Normal Rotation Input Terminal
MC
T17P-02-01-025
T2-1-49
SYSTEM / Control System
Travel Alarm Control (Only on the machines
equipped with the travel alarm device)
Function: Sounds the buzzer while traveling.
Operation: As long as the MC receives signals from
the travel pressure sensor when travel operation is made, the MC sends out signals
to the travel alarm device to sound the
buzzer.
NOTE: After traveling continuously for more than
13 seconds, the buzzer can be stopped
with the buzzer deactivation switch.
Pressure Switch
Travel
Travel Alarm
Device
(Optional)
Buzzer Deactivation
Switch (Optional)
Buzzer
(Optional)
T16J-02-01-034
T2-1-50
SYSTEM / Hydraulic System
OUTLINE
The hydraulic system is broadly divided into two circuits, the main circuit and the pilot circuit.
Pilot Circuit:
Power Source
Pilot Pumps
Controller
→
Pilot Circuit
→
Pilot Valves
Operation Control Circuit
Pump Regulators
Pump Control Circuit
Solenoid Valve Unit
Valve Control Circuit
Signal Control Valve
Swing Parking Brake Release Circuit
Travel Motor Swash Angle Control Circuit
Hydraulic Oil Heat Circuit
Main Circuit:
Power Source
Main Pumps
Controller
→
Control Valves
Actuator
→
Motors
Cylinders
Front Attachmens (Optional)
T2-2-1
SYSTEM / Hydraulic System
PILOT CIRCUIT
Outline
• Pressure oil from the pilot pump is used to operate the operation control circuit, pump control circuit, valve control circuit, swing parking brake release circuit, travel motor swash angle control circuit, and hydraulic oil heat circuit.
T2-2-2
SYSTEM / Hydraulic System
Operation Control Circuit
Left Pilot
Valve
Travel Pilot
Valve
Swing Parking Brake
Release Circuit
Right Pilot
Valve
Auxiliary Pilot
Valve
Swing Motor
Pump
Control Circuit
Pump Control Solenoid
Valve
Pilot Shut-Off
Valve
Signal Control Valve
Hydraulic Oil
Heat Circuit
Solenoid Valve
(Swing Priority)
To Control Valve
Spools
2
1
2
1
Holding Valve
Regulator
Arm Regenerative Valve
Bypass Shut-Out Valve
Flow Combiner Valve
Valve
Control
Circuit
SA
SB
Main Relief Valve
Boom Overload Relief Selector
Valve
SC
Control Valve
Hydraulic
Oil Tank
Solenoid
Valve Unit
Travel Motor Swash
Angle Control Circuit
Travel Motor
Travel Motor
Suction
Filter
Relief Valve
Pilot Pump
Pilot Filter
T2-2-3
SYSTEM / Hydraulic System
Operation Control Circuit
• The pilot valves control the pressure oil from the
pilot pump to operate the control valve spools.
• The signal control valve is provided between the
pilot valves and the control valve. The shockless
valve (in the boom raise circuit) built in the signal
control valve dampens quick spool movement in
the control valve. The other shockless valve is
separately provided for the boom lower circuit
(Refer to the COMPONENT OPERATION / Signal
Control Valve group.)
T2-2-4
SYSTEM / Hydraulic System
Travel Pilot Valve
Pilot Valve (Left)
Pilot Valve (Right)
Shockless
Valve
Signal
Control
Valve
Shockless
Valve
11 12 9 10 7
8 4
3 2
1 6
5
Solenoid
Valve
(Swing
Priority)
1A
1B
3
6
5
4
3
4
1B
1
2
1
Auxiliary
1A
8
7
11
12
10
9
Control Valve
Pilot Pump
1 - Boom Raise
2 - Boom Lower
3 - Arm Roll-Out
4 - Arm Roll-In
5 - Left Swing
6 - Right Swing
T17V-02-02-009
7 - Bucket Roll-In
8 - Bucket Roll-Out
9 - Left Travel Forward
T2-2-5
10 - Left Travel Reverse
11 - Right Travel Forward
12 - Right Travel Reverse
SYSTEM / Hydraulic System
Pump Control Circuit
• Pump Flow Rate Control by Pump Control Pressure
Sensors (4-spool, 5-spool)
• Pressure oil from the pilot valve is selected by the
shuttle valves in the signal control valve. Then, the
selected pressure oil is routed further to either
pump 1 flow rate control valve or pump 2 flow rate
control valve in the same signal control valve,
shifting either of the flow rate control valves.
Therefore, pilot pressure oil is supplied to the
pump control pressure sensor (4-spool or 5spool).
• A signal from the pump control pressure sensor
(4-spool or 5-spool) is sent to the MC.
Ȁ The MC actuates the pump control solenoid valve
to control the delivery rate of the pump.
NOTE: The delivery flow rate control to the main
pump 2 is used for the boom (raise), arm
(roll-in/out), auxiliary, and/or travel (left) operations.
The delivery flow rate control to the main
pump 1 is used for the boom (raise/lower),
arm (roll-in/out), bucket (roll-in/out), and/or
travel (right) operations.
T2-2-6
SYSTEM / Hydraulic System
Travel
(Left)
Travel
(Right)
Swing
Boom
Arm
Bucket
Auxiliary
Pump
Control
Pressure
Sensor
(4-Spool)
Pump
Control
Pressure
Sensor
(5-Spool)
Pump 2 Flow Rate
Control Valve
Pump 1 Flow Rate
Control Valve
4-Spool
Control Valve
5-Spool
Pump 2
Pump 2 Control
Solenoid Valve
Pilot Pump
Pump 1
Pump 1 Control
Solenoid Valve
T17V-02-02-002
T2-2-7
SYSTEM / Hydraulic System
Valve Control Circuit (Refer to the COMPONENT
OPERATION / Control Valve group.)
• The following valves are controlled by pressure oil
from the pilot valves, solenoid valve unit (SA and
SC), the flow combiner valve control spool and the
bucket flow rate control valve control spool in the
signal control valve.
• Solenoid Valve Unit (SA):
Main Relief Valve (Increasing the set-pressure)
(Refer to the Control System / Valve Control)
• Solenoid Valve Unit (SC):
Boom Overload Relief Selector Valve
(Refer to the Control System / Valve Control)
• Solenoid Valve (Swing Priority):
Boom 2 spool
(Refer to the Control System / Valve Control)
• Bucket Roll-In Pilot Pressure, Attachment Pilot
Pressure (Optional):
Bypass Shut-Off Valve
• Flow Combiner Valve Control Spool:
Flow Combiner Valve
• Boom Lower Pilot Pressure, Arm Roll-In Pilot
Pressure:
Holding Valve
T2-2-8
SYSTEM / Hydraulic System
Arm (Roll-In, Roll-Out)
Boom (Lower)
Bucket (Roll-In)
Flow Combiner
Valve Control
Spool
1A
Solenoid
Valve
(Swing
Priority)
Holding Valve
(Arm)
Pilot Pressure
Oil from Aux. Pilot
Valve (Optional)
1B
Bypass
ShutOff
Valve
Holding Valve
(Boom)
Boom
Overload
Relief
Selector
Valve
Solenoid Valve Unit
1B
1A
SA
SB
SC
Main
Relief
Valve
Bypass
Shut-Off
Valve
Flow Combiner
Valve
Control Valve
Pilot
Pump
T17V-02-02-010
T2-2-9
SYSTEM / Hydraulic System
Swing Parking Brake Release Circuit (Refer to the
COMPONENTS OPERATION / Swing Device
group.)
• When the front attachment and/or swing function
is operated, the pilot oil pressure selected by the
shuttle valves in the signal control valve shifts the
swing parking brake release spool.
• Consequently, the release signal oil pressure is
routed to the swing motor, releasing the swing
parking brake.
Travel Motor Swash Angle Control Circuit (Refer
to the COMPONENTS OPERATION / Travel Device
group.)
• The pilot oil pressure from solenoid valve (SB)
regulates the travel motor swash angle control
change over valve.
Hydraulic Oil Heat Circuit (Refer to the COMPONENTS OPERATION / Others (Upperstructure)
group.)
• When the pilot shut-off valve is closed, the pilot oil
pressure is routed to the signal control valve so
that hydraulic oil is warmed while passing through
the orifice in the signal control valve.
• The warmed pilot pressure oil flows to the signal
control valve and pilot valves so that the pilot system components are warmed.
T2-2-10
SYSTEM / Hydraulic System
Swing
Arm
Boom
Bucket
Hydraulic Oil
Heat Circuit
Swing Parking Brake
Release Spool
Swing Motor
Solenoid
Valve Unit
Control Valve
SB
Travel Motor Swash Angle
Control Change Over Valve
Travel Motor
T2-2-11
T17V-02-02-004
SYSTEM / Hydraulic System
MAIN CIRCUIT
Outline
• Main pumps (1 and 2) draw hydraulic oil from the
hydraulic oil tank. Main pump 1 and main pump 2
deliver pressure oil to the 4-spool control valve
and the 5-spool control valve respectively.
• Delivered pressure oil is routed to the motor(s) or
cylinder(s) in response to operation(s) of the
spool(s) in the control valve(s).
• The return oil from the motor(s) and/or cylinder(s)
flows back to the hydraulic oil tank via the control
valve and/or the oil cooler.
• When the oil temperature is low (high viscosity),
the oil flow resistance increases in the oil cooler,
which opens the bypass check valve, allowing hydraulic oil to return directly to the hydraulic oil tank
without passing through the oil cooler.
T2-2-12
SYSTEM / Hydraulic System
Low Pressure
Relief Valve
Swing Motor
5-Spool
Side
Swing
Arm 2
Arm 1
Boom 1
Boom 2
Bucket
Auxiliary
Travel (Right)
Travel (Left)
Arm Cylinder
4-Spool
Side
Boom Cylinder
Control Valve
Main
Pump 1
Main
Pump 2
Attachment
(Auxiliary)
Bucket Cylinder
Suction
Filter
Hydraulic
Oil Tank
Bypass Check
Valve
Travel Motor (Left)
Oil
Cooler
T2-2-13
SYSTEM / Hydraulic System
Neutral Circuit
• When the control lever is in neutral, pressure oil
from the main pump passes through the control
valve and returns to the hydraulic oil tank.
Single Operation Circuit
• Pressure oil from main pump 1 is routed to the 4spool control valve and is further routed to each
spool of the travel (right), bucket, boom 1, and
arm 2.
• Pressure oil from main pump 2 is routed to the 5spool control valve and is further routed to each
spool of the swing, arm 1, boom 2, auxiliary and
travel (left).
• The boom and arm are actuated by pressure oil
from two main pumps. Pressure oil from each
main pump is combined and supplied together.
T2-2-14
SYSTEM / Hydraulic System
5-Spool
Side
Swing
Boom
Cylinder
Swing
Motor
Arm 1
Arm 2
Boom 2
Arm Cylinder
Boom 1
Bucket
Cylinder
Auxiliary
Bucket
Travel
(Left)
Travel (Right)
4-Spool
Side
Travel Motor (Right)
Pump 1
Pump 2
T2-2-15
Travel Motor (Left)
T17V-02-02-011
SYSTEM / Hydraulic System
Combined Operation Circuit
• Swing and Boom Raise Operation
• When the boom is raised while swinging, the pilot
oil pressure shifts the swing, boom 1, and boom 2
spools.
• Pressure oil from pump 1 flows into the boom cylinders via the parallel circuit and the boom 1 spool,
raising the boom.
• Pressure oil from pump 2 flows into the swing motor via the swing spool.
• At the same time, pressure oil from pump 2 flows
through the parallel circuit and after being combined with pressure oil from pump 1, flows into the
boom cylinders, raising the boom together with
pressure oil from pump 1.
• When the trench digging mode operation, the pilot
oil pressure shift only boom 1 spool. (Refer to
page T2-1-46)
T2-2-16
SYSTEM / Hydraulic System
Parallel Circuit
5-Spool
Side
Swing
Swing
Motor
Boom
Cylinder
Boom 2
Boom 1
4-Spool
Side
Pump 1
Pump 2
T2-2-17
T17V-02-02-012
SYSTEM / Hydraulic System
• Travel and Arm Roll-In Operation
• When the arm is rolled in while traveling, the pilot
oil pressure shifts the travel, arm 1 and 2 spools.
• At the same time, the right travel pilot oil pressure
shifts the flow combiner valve control spool in the
signal control valve. Pressure oil from the flow
combiner valve control spoolȀis routed to the flow
combiner valve, shifting the flow combiner valve.
• Pressure oil from pump 1 drives the right travel
motor via the right travel spool.
• At the same time,Ȁ pressure oil from pump 1
passes through the flow combiner valve and the
left travel spool and drives the left travel motor.
• Pressure oil from pump 2 flows into the arm cylinder via the arm 1 spool, moving the arm.
• Consequently, pressure oil from pump 2 is used
only to operate the arm. Pressure oil pump 1 is
equally routed to both the right and left travel motors, ensuring that the machine can travel straight.
T2-2-18
SYSTEM / Hydraulic System
5-Spool
Side
Swing
Motor
Boom
Cylinder
Arm 1
Arm
Cylinder
Arm 2
Bucket Cylinder
Left
Travel
Right
Travel
4-Spool
Side
Flow Control Valve
From Flow Combiner Valve Control Spool
Travel Motor (Right)
Pump 1
Pump 2
T2-2-19
Travel Motor (Left)
T17V-02-02-013
SYSTEM / Hydraulic System
COUNTERWEIGHT REMOVAL CIRCUIT
(Optional)
When the counterweight hoist/lower control lever
(optional) is operated, pressure oil from the pilot pump
flows through the counterweight pilot valve and shifts
the auxiliary spool in the 5-spool control valve to remove/install the counterweight.
Pressure oil from main pump 2 flows into the counterweight removal cylinder via the parallel passage and
auxiliary spool in the 5-spool control valve.
When hoisting the counterweight, pressure oil flows
into the cylinder bottom via the check valve in the slow
return valve.
When lowering the counterweight, pressure oil flows
into the cylinder rod side.
The return oil flow from the cylinder bottom is regulated
by the slow return valve and flows to the hydraulic oil
tank via the holding valve.
The holding valve is opened by the pressure in the rod
side, allowing the return oil from the bottom side to flow
through.
Holding Valve
Lock Valve
Counterweight
Removal Cylinder
Auxiliary
Slow Return Valve
Main Pump 2
T2-2-20
T17V-02-02-014
SYSTEM / Electrical System
OUTLINE
The electrical circuit is broadly divided into the main
circuit, monitor circuit, and control circuit.
• Main Circuit
The engine and accessory operation related circuit.
• Monitor Circuit
The electrical circuit group consists of the monitors,
sensors, and switches, and displays the machine
operation status.
• Control Circuit (Refer to the SYSTEM / Control System group.)
The control circuit is categorized into the engine,
pump, and valve control circuits. Each circuit consists of the actuators such as solenoid valves, MC
(main controller), switch boxes, sensors and pressure switches.
T2-3-1
SYSTEM / Electrical System
MAIN CIRCUIT
The major functions and circuits in the main circuit are
as follows.
• Electric Power Circuit: Supplies all electric power
to all electrical systems on this machine. [Key
Switch, Batteries, Fuses (Fuse Boxes, Fusible
Links), Battery Relay]
• Indicator Light Check Circuit
Checks all indicator bulbs for burning.
• Accessory Circuit
Becomes operative when the key switch is turned
to the ACC position.
• Preheat Circuit
Assists the engine to start in cold weather. [Key
Switch, QOS Controller, Coolant Switch, Glow
Plug Relay, Glow Plugs]
• Starting Circuit
Starts the engine. [Key Switch, Starter, Starting
Relay]
• Charging Circuit
Charges the batteries. [Alternator, Regulator]
• Serge Voltage Prevention Circuit
Prevents the occurrence of serge voltage developed when stopping the engine. [Load Damp Relay]
• Engine Stop Circuit
Stops the engine using the EC motor. [MC, EC
Motor]
T2-3-2
SYSTEM / Electrical System
ELECTRIC
POWER
SWITCH: OFF)
CIRCUIT
(KEY
The battery ground terminal is connected to the vehicle
frame. Current from the battery plus terminal flows as
shown below when the key switch is OFF.
Battery
↓
Fusible Link
→Glow Plug Relay
ȈPowerȉ
→Terminal #1:
Monitor (Backup Power)
→Key Switch (B)
→Load Damp Relay
→Fuse Box
Radio (Backup Power)
ICX Controller (Backup Power)
→Terminal #2:
MC (Power)
→Terminal #3:
MC (EC Motor Power)
→Terminal #10: Auto-Lubrication
Key Switch
Battery
Load
Damp
Relay
AutoLubrication
Glow
Plug
Relay
Radio, Monitor,
ICX Controller
Optional
MC
MC
T16J-02-03-001
T2-3-3
SYSTEM / Electrical System
INDICATOR LIGHT CHECK CIRCUIT (KEY
SWITCH: ON)
• When the key switch is turned ON, terminal B is
connected to terminals ACC and M in the key
switch.
• Current from key switch terminal M excites the
battery relay.
• Therefore, the battery current enters the monitor
controller via the battery relay and fuse #7 and
checks the indicator bulbs.
Key Switch
Battery
Battery
Relay
Fuse
Box
Monitor
Controller
T16J-02-03-002
T2-3-4
SYSTEM / Electrical System
ACCESSORY CIRCUIT
• When the key switch is turned to the ACC position,
terminal B is connected to terminal ACC in the key
switch.
• Current from key switch terminal ACC flows to
horn (fuse #15), radio (fuse #16), lighter (fuse
#17), cab light (fuse #18) and auxiliary (fuse #19)
through the fuse box, making each accessory operable.
Fuse
Box
Horn
Radio
Lighter
Cab Light
Auxiliary
T16J-02-03-003
T2-3-5
SYSTEM / Electrical System
PREHEAT CIRCUIT (KEY SWITCH: ON /
START)
• When the key switch is turned ON or to the
START position, terminal B is connected to terminal M in the key switch. Current from terminal M is
routed to QOS controller terminal #1 through fuse
#20.
• When the key switch is ON or in the START position with the coolant switch OFF (when the coolant
temperature is 10 °C (50 °F) or below), QOS controller terminal #4 is connected to terminal #5
(ground).
• Accordingly, the glow plug relay is turned ON,
routing current to the glow plugs so that preheating begins.
• When preheating begins, QOS controller terminal
#6 is connected to terminal #5 for 8 seconds, turning the preheat indicator ON. (When preheating is
not performed, the preheat indicator comes ON
for 2 seconds for indicator light check.)
T2-3-6
NOTE: After preheating has been performed, heating will continue for approx. 30 seconds after the engine starts.
SYSTEM / Electrical System
Monitor
Preheat Indicator
Coolant Temperature Switch
QOS
Controller
Key Switch
Fuse
Box
Glow
Plug
Relay
Glow Plug
T16J-02-03-004
T2-3-7
SYSTEM / Electrical System
STARTING
START)
CIRCUIT
(KEY
SWITCH:
• When the key switch is turned to the START position, terminal B is connected to terminals M and
ST in the key switch.
Starter Relay Operation
• When the key switch is turned to the START position, key switch terminal B is connected to terminal ST so that current is routed to the base in
transistor (Q2) through resistance R4 in the
starter relay. Then, transistor (Q2) is turned ON,
allowing current to flow to coil (L) in the starter relay. Therefore, starter terminal B is connected to
terminal C, rotating the starter.
• As current from terminal M excites the battery relay, battery current is routed to starter terminal B
and starter relay terminal B via the battery relay.
• Key switch terminal ST is connected to starter relay terminal S so that current flows through the
starter relay coil.
• After the engine starts, the alternator starts generating electricity, increasing voltage at starter relay terminal R.
• Then, the starter relay is turned ON, allowing current to flow from starter relay terminal C to starter
terminal C.
• When this voltage increases up to 21 to 22 V,
Zener diode (Z) is turned ON so that transistor
(Q1) is turned ON. Then, current to the base of
transistor (Q2) is not routed, turning transistor
(Q2) OFF. At this moment, starter terminal B is
disconnected from terminal C, stopping the
starter.
• Consequently, the relay in the starter is turned ON
so that the starter begins rotating.
• On the other hand, current from key switch terminal M flows to the MC via fuse #6 as a signal indicating that the key switch is in the ON or START
position.
Condenser C1 is used to stabilize the operating voltage and diode D4 protects the circuit in case the battery terminals are reversely connected.
• As soon as the MC receives this signal, the MC
drives the EC motor, moving the governor lever to
the engine start position.
Starter Relay
ȳ
Ȣ
Ȥȓ
Ȉȑȉ
Ȭ
ȲȔ
Ȳȓ
To Alternator
Terminal L
Ȳ
Ⱥ
ȲȒ
ȈȒȉ
ȤȒ
ȱȑ
ȣ
Ȉȑȉ
ȭ
ȱȒ
ȣ
Ȣ
ȈȒȉ
ȥ
ȤȔ
ȣȑ
ȣ
Starter
Ȣ
ȑȒȶ
ȳȴ
Key Switch
ȑȒȶ
Battery
T107-04-04-003
T2-3-8
SYSTEM / Electrical System
Key Switch
Battery
Battery
Relay
Starter
Fuse
Box
C
C
Starter Relay
Alternator
EC Motor
IC Regulator
MC
T16J-02-03-005
T2-3-9
SYSTEM / Electrical System
CHARGING CIRCUIT (KEY SWITCH: ON)
• After the engine starts and the key switch is released, the key switch moves to the ON position.
• Then, key switch terminal B is connected to terminals ACC and M in the key switch.
• When the alternator starts generating electricity,
current flows from alternator terminal B to the batteries via the battery relay, charging the batteries.
• Current from alternator terminal L flows to the
monitor controller and the ICX controller, turning
the alternator indicator OFF.
Key Switch
Monitor
Controller
Battery
ICX
Controller
Battery
Relay
Alternator
T16J-02-03-006
T2-3-10
SYSTEM / Electrical System
(Blank)
T2-3-11
SYSTEM / Electrical System
Alternator Operation
• The alternator consists of field coil FC, stator coil
SC, and diodes D. The regulator consists of transistors (T1 and T2), Zener diode ZD, and resistances (R1 and R2).
• At the beginning, no current is flowing through
field coil FC. When the rotor starts turning, alternate current is generated in stator coil SC by the
rotor remanent magnetism.
• When current starts to flow through field coil FC,
the rotor is further magnetized so that the generating voltage increases. Thereby, current flowing
through field coil FC increases and generating
voltage is increased further, to charge the batteries.
• Alternator terminal B is connected to base B of
transistor T1 through the circuit [B → R → RF
→ ( R ) → (R1)].
• When battery relay BS is ON, the battery voltage
is applied to base B of transistor T1 so that collector C is connected to emitter E. Therefore, field
coil FC is grounded via transistor T1.
Alternator
Ȣ
Ȣȳ
Ȳ
ȲȦ
Regulator
Ȭ
ȈȲȉ
Ȳȓ
Ȳȕ
ȲȔ
ȲȖ
Ȥ
ȺȤ
ȲȒ
Battery
Ȣ
ȳȣ
ȥ
Ȳȑ
Ȧȣ
Ȥȑ
ȣ
Ȣ
ȣ
ȴȒ
ȥ
ȴȑ
ȈȦȉ
ȥ
Ȉȥȉ
T157-04-02-008
T2-3-12
SYSTEM / Electrical System
Regulator Operation
• When generating voltage increases more than the
set-voltage of Zener diode ZD, current is routed to
base B of transistor T2, connecting collector C to
emitter E.
• When generating voltage decreases lower than
the set-voltage of Zener diode ZD, transistor T2 is
turned OFF, causing transistor T1 to turn ON
again.
• Then, current flows through field coil FC, increasing generating voltage at the stator coil. The
above operation is repeated so that the alternator
generating voltage is kept constant.
• Then, current which was routed to base B of transistor disappears, turning transistor T1 OFF.
• Therefore, no current flows through filed coil FC,
reducing generating voltage at stator coil SC.
Ȣȳ
ȲȦ
Ȳȓ
ȲȔ
Ȳȕ
ȲȖ
Battery
ȺȤ
ȲȒ
Ȣ
ȳȣ
ȡ
ȥ
ȣ
Ȧȣ
Ȳȑ
Ȣ
ȣ
ȴȒ
ȥ
ȴȑ
ȈȦȉ
ȥ
Ȥȑ
Ȉȥȉ
T157-04-02-009
T2-3-13
SYSTEM / Electrical System
SERGE VOLTAGE PREVENTION CIRCUIT
• When the engine is stopped (key switch: OFF),
current from key switch terminal M is disconnected, turning the battery relay OFF.
• The engine continues to rotate due to inertia force
just after the key switch is turned OFF so that the
alternator continues to generate electricity.
• As the generating current cannot flow to the battery, surge voltage arises in the circuit, possibly
causing failures of the electronic components,
such as the controller. To prevent the occurrence
of surge voltage, the surge voltage prevention circuit is provided.
T2-3-14
• When the alternator is generating electricity, generating current from alternator terminal L flows to
monitor controller terminal #A-2 so that the monitor controller connects terminal #C-3 to ground.
• Then, current flows through the load damp relay
exciting circuit, turning the load damp relay ON.
Current from the load damp relay flows to battery
relay terminal S, exciting the battery relay so that
the batteries charge, allowing the generating current from alternator to flow to the batteries.
• Accordingly, even if the key switch is turned OFF
while the engine is rotating, the battery current
continues to excite the battery relay via the load
damp relay until the alternator stops generating.
Therefore, the battery relay is kept ON, allowing
the generating current to flow to the batteries.
SYSTEM / Electrical System
Key Switch
Battery
Battery
Relay
Load
Damp
Relay
Alternator
Monitor Controller
Ground
T16J-02-03-007
T2-3-15
SYSTEM / Electrical System
ENGINE STOP CIRCUIT
• When the key switch is turned from the ON position to the OFF position, the signal current indicating that the key switch is ON stops flowing from
terminal M to MC terminal C-31.
• Then, the MC drives the EC motor to the engine
stop position.
Key Switch
EC Motor
MC
T16J-02-03-008
T2-3-16
MEMO
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SECTION 3
COMPONENT OPERATION
—CONTENTS—
Group 1 Pump Device
Group 4 Pilot Valve
Outline .....................................................T3-1-1
Outline .....................................................T3-4-1
Main Pump ...............................................T3-1-2
Operation .................................................T3-4-2
Regulator .................................................T3-1-4
Pilot Pump..............................................T3-1-12
Group 5 Travel Device
N Sensor (Engine Speed Sensor) ...........T3-1-12
Outline .....................................................T3-5-1
Pump Delivery Pressure Sensor .............T3-1-12
Travel Reduction Gear..............................T3-5-1
Pump Displacement Angle Sensor .........T3-1-12
Travel Motor .............................................T3-5-2
Travel Brake Valve ...................................T3-5-4
Group 2 Swing Device
Travel Speed Control..............................T3-5-10
Outline .....................................................T3-2-1
Swing Motor .............................................T3-2-2
Valve Unit .................................................T3-2-4
Parking Brake.........................................T3-5-12
Group 6 Signal Control Valve
Swing Parking Brake ................................T3-2-6
Outline .....................................................T3-6-1
Swing Reduction Gear..............................T3-2-7
Pilot Port ..................................................T3-6-2
Shuttle Valve ............................................T3-6-6
Group 3 Control Valve
Shockless Valve .......................................T3-6-8
Outline .....................................................T3-3-1
Hydraulic Circuit .......................................T3-3-6
Flow Combiner Valve..............................T3-3-10
Main Relief Valve.................................... T3-3-11
Overload Relief Valve .............................T3-3-12
Make-Up Valve .......................................T3-3-12
Pump 1 and Pump 2 Flow Rate
Control Valves ......................................T3-6-10
Flow Combiner Valve Control Spool,
Swing Parking Brake Release Spool .....T3-6-12
Group 7 Others (Upperstructure)
Holdding Valve .......................................T3-3-13
Pilot Shut-Off Valve ..................................T3-7-1
Arm Regenerative Valve .........................T3-3-14
Solenoid Valve Unit ..................................T3-7-2
Bypass Shut-Out Valve ...........................T3-3-16
Pilot Relief Valve ......................................T3-7-2
Boom Overload Relief Selector Valve .....T3-3-18
Accumulator .............................................T3-7-3
EC Motor ..................................................T3-7-4
Group 8 Others (Undercarriage)
Swing Bearing ..........................................T3-8-1
Center Joint..............................................T3-8-2
Track Adjuster ..........................................T3-8-3
17VT-3-1
(Blank)
17VT-3-2
COMPONENT OPERATION / Pump Device
OUTLINE
The pump device consists of transmission, main pump
(pump 1 and pump 2) and pilot pump.
The engine output is transmitted to the transmission
via the coupling. After being distributed by the gears,
the engine power drives the pumps. Gear speed ratio
of the engine and main pump is 46:45, and the engine
and pilot pump are 1:1.
The main pump is a variable displacement swash plate
plunger type pump. The two main pumps are placed in
parallel to supply high pressure oil for operation to the
main circuit.
The pilot pump is a gear pump, and it supplies hydraulic oil to the pilot circuit.
Transmission
Main Pump 1
Main Pump 2
Pilot Pump
Regulator
Regulator
T17V-03-01-001
T3-1-1
COMPONENT OPERATION / Pump Device
MAIN PUMP
The shaft is connected to the cylinder block via a spline
coupling. The plungers are inserted into the cylinder
block bores.
Engine driving force is transmitted to the shaft via the
pump transmission. As the shaft rotates, the plunger
rotates align with cylinder block, sliding along the surface of the shoe plate. Because the swash plate is positioned at an angle against the plungers, the plungers
reciprocate in the cylinder block bores, drawing and
discharging hydraulic oil.
Shoe Plate
Servo Piston
Shaft
Swash Plate
Plunger
Cylinder Block
T3-1-2
T17V-03-01-003
COMPONENT OPERATION / Pump Device
Flow Rate Increasing/Decreasing Operation
The flow rate of the pump is varied by changing the
angle of the swash plate which changes the stroke of
the plunger. When pressure oil from the regulator
moves the servo piston, the swash angle changes
accordingly as the swash plate is connected to the
servo piston.
Servo Piston
Shaft
Valve Plate
Cylinder Block
Plunger
Swash Plate
T3-1-3
T142-02-01-001
COMPONENT OPERATION / Pump Device
REGULATORS
The regulators are provided on the top of the main
pumps to control the pump delivery rate. The pump
delivery (flow) rate is changed as the flow control
pressure from pump control solenoid valve (11)
increases or decreases.
Main pump delivery pressure P1 is routed to spool (3)
via check valve (10), acting on spool (3). Main pump
delivery pressure P1 is also routed into the small
chamber of servo piston (8) via passage (b) all the
time.
As pump control solenoid valve (11) is activated, servo
assist pressure Psv (delivery pressure from the pilot
pump) is reduced, becoming pump flow control pressure, which then acts on pilot piston (1) via passage (a).
Also, servo assist pressure Psv is combined with main
pump delivery pressure P1 via check valve (2) and
passage (b).
Pilot Pump
Psv
2
a
10
e
b
11
d
1
c
6
5
a
3
7
4
9
8
P1
Main Pump
T3-1-4
COMPONENT OPERATION / Pump Device
Psv
1
b
a
2
3 c 4
5
6
A
B
d
10
Small Chamber
9
Large Chamber
8
7
P1
Main Pump
Large
10 b
d
5
Displacement Angle
Small
T162-03-01-002
7
Cross Section B
Cross
Section A
e
a
b
11
Psv
Pilot Pump
9
T162-03-01-004
P1
8
T162-03-01-003
Main Pump
1 - Pilot Piston
2 - Check Valve
4 - Sleeve
5 - Pin
7 - Plug
8 - Servo Piston
3 - Spool
6 - Spring
a - Passage for Pump Control Solenoid Valve Output Pressure
b - Passage for Servo Assist Pressure to be Combined with Main
Pump Delivery Pressure P1
c - Servo Piston Large Chamber Side Tank Port
d - Passage to Servo Piston Small Chamber
10 - Check Valve
11 - Pump Control Solenoid
Valve
9 - Feedback Lever
e - Tank Port (Pump Control Solenoid Valve)
P1 - Main Pump Delivery Pressure
Psv- Servo Assist Pressure (Pilot Pump Delivery Pressure)
T3-1-5
COMPONENT OPERATION / Pump Device
Regulator Operation with Flow Rate Control
Pressure 0 (Minimum Flow Rate)
As servo piston (8) moves, feedback lever (9) rotates
counterclockwise around plug (7). Because the top
end of feedback lever (9) is connected to sleeve (4)
by pin (5), sleeve (4) moves to the left. Servo piston
(8) continues to move until the notch on spool (3) is
closed completely.
With the above operation, the pump displacement
angle becomes the minimum, obtaining the minimum
flow rate.
When the flow rate control pressure from pump
control solenoid valve (11) is 0, spool (3) is pushed to
the left by spring (6). As a result, main pump delivery
pressure P1 is routed into the servo piston (8) large
chamber via check valve (10), sleeve (4) and spool
(3). Although main pump delivery pressure P1 is also
routed into the small chamber, servo piston (8) moves
to the right due to the difference in pressure receiving
areas between the servo piston ends.
Pilot Pump
Psv
10
11
d
c
6
5
3
7
4
9
8
P1
Main Pump
T3-1-6
COMPONENT OPERATION / Pump Device
3
4
5
6
A
B
d
10
Small Chamber
9
Large Chamber
8
7
P1
Main Pump
Large
10
d
5
Displacement Angle
Small
162-03-01-002
7
Cross Section B
Cross
Section A
11
Psv
Pilot Pump
9
T162-03-01-004
P1
8
T162-03-01-003
Main Pump
3 - Spool
4 - Sleeve
6 - Spring
7 - Plug
5 - Pin
c - Servo Piston Large Chamber Side Tank Port
d - Passage to Servo Piston Small Chamber
8 - Servo Piston
9 - Feedback Lever
10 - Check Valve
11 - Pump Control Solenoid
Valve
P1 - Main Pump Delivery Pressure
Psv- Servo Assist Pressure (Pilot Pump Delivery Pressure)
T3-1-7
COMPONENT OPERATION / Pump Device
Regulator Operation with Flow Rate Control
Pressure Increasing (Increasing Flow Rate)
As servo piston (8) is moved to the left, feedback
lever (9) rotates clockwise around plug (7). Because
the top end of feedback lever (9) is connected to
sleeve (4) by pin (5), sleeve (4) moves to the right.
Servo piston (8) continues to move until the notch on
spool (3) is closed completely.
With the above operation, the pump displacement
angle is increased, increasing pump delivery rate.
Note that the rate of the increment is proportional to
the increment of the flow rate control pressure.
When pump control solenoid valve (11) is actuated,
flow control pressure, proportional to the movement
of pump control solenoid valve (11), acts on pilot
piston (1) via passage (a), moving spool (3) to the
right until spool (3) balances with spring (6).
When spool (3) moves to the right, the large chamber
of servo piston (8) is connected to the hydraulic oil
tank via passage (c) in spool (3). Since the main
pump pressure P1 is routed into the small chamber of
servo piston (8) via passage (d) all the time, servo
piston (8) moves to the left and oil in the large
chamber is returned to the hydraulic oil tank.
Pilot Pump
Psv
10
11
d
c
3
1
6
5
a
7
4
9
Large Chamber
Small Chamber
8
P1
Main Pump
T3-1-8
COMPONENT OPERATION / Pump Device
Psv
a
1
3 c 4
5
6
A
B
d
10
Small Chamber
9
Large Chamber
8
7
P1
Main Pump
Large
10
d
5
Displacement Angle
Small
162-03-01-002
7
Cross Section B
Cross
Section A
a
11
Psv
Pilot Pump
9
T162-03-01-004
P1
8
T162-03-01-003
Main Pump
1 - Pilot Piston
3 - Spool
4acd-
5 - Pin
6 - Spring
8 - Servo Piston
9 - Feedback Lever
Sleeve
7 - Plug
Passage for Pump Control Solenoid Valve Output Pressure
Servo Piston Large Chamber Side Tank Port
Passage to Servo Piston Small Chamber
10 - Check Valve
11 - Pump Control Solenoid
Valve
P1 - Main Pump Delivery Pressure
Psv- Servo Assist Pressure (Pilot Pump Delivery Pressure)
T3-1-9
COMPONENT OPERATION / Pump Device
Regulator Operation with Flow Rate Control
Pressure Decreasing (Decreasing Flow Rate)
When the flow control pressure from pump control
proportional solenoid valve (11) decreases, spool (3)
is returned to the left until it balances with spring (6).
The pressure oil exerted on pilot piston (1) is returned
to the hydraulic oil tank via passages (a) and (e).
As spool (3) moves to the left, main pump pressure
P1 is routed into the large chamber of servo piston (8)
via check valve (10), sleeve (4), and spool (3).
Although main pump delivery pressure P1 is also
routed into the small chamber, servo piston (8) moves
to the right due to the difference in pressure receiving
areas between the servo piston ends.
As servo piston (8) moves, feedback lever (9) rotates
counterclockwise around plug (7). Because the top
end of feedback lever (9) is connected to sleeve (4)
by pin (5), sleeve (4) moves to the left. Servo piston
(8) continues to move until the notch on spool (3) is
closed completely.
With the above operation, the pump displacement
angle is reduced, decreasing the pump flow rate.
Note that the rate of the flow rate reduction is
proportional to the reduction of the flow rate control
pressure.
Pilot Pump
Psv
e
10
11
d
6
a
5
7
1
3
9
4
Large
Chamber
Small
Chamber
8
P1
Main Pump
T3-1-10
COMPONENT OPERATION / Pump Device
Psv
a
1
3
4
5
6
A
B
d
10
Small Chamber
9
Large Chamber
8
7
P1
Main Pump
Large
10
d
5
Displacement Angle
Small
T162-03-01-002
7
Cross Section B
Cross
Section A
11
e
a
Psv
Pilot Pump
9
T162-03-01-004
P1
8
T162-03-01-003
Main Pump
1 - Pilot Piston
3 - Spool
4ade-
5 - Pin
6 - Spring
8 - Servo Piston
9 - Feedback Lever
Sleeve
7 - Plug
Passage for Pump Control Solenoid Valve Output Pressure
Passage to Servo Piston Small Chamber
Tank Port (Pump Control Solenoid Valve)
10 - Check Valve
11 - Pump Control Solenoid
Valve
P1 - Main Pump Delivery Pressure
Psv -Servo Assist Pressure (Pilot Pump Delivery Pressure)
T3-1-11
COMPONENT OPERATION / Pump Device
PILOT PUMP
Drive gear (1) is driven by the engine via the transmission which in turn rotates driven gear (2) as they are
meshed together.
1 - Drive Gear
1
Inlet Port
2
2 - Driven Gear
Outlet Port
T137-02-03-005
6
N SENSOR (ENGINE SPEED SENSOR)
7
The N sensor detects the engine speed, which is used
to control various operations. The N sensor is located
close to the flywheel gear teeth so that the sensor converts the number of teeth passing by the sensor into
pulse signals, effectively sensing the engine speed.
3 - Coil
4 - Magnet
5 - Tooth
3
4
6 - Output
7 - Output
5
PUMP DELIVERY PRESSURE SENSOR
This sensor detects the pump delivery pressures,
which are used to control various operations. When oil
pressure is applied onto diaphragm (11), the diaphragm is deformed. The deformation of the diaphragm is detected as electrical signals.
8 - Ground
9 - Output
10 - Power Source (5V)
11 - Pressure Receiving Area
(Diaphragm)
T107-07-02-054
T107-02-03-020
8
9
10
T157-02-03-010
11
PUMP DISPLACEMENT ANGLE SENSOR
The pump displacement angle is transmitted to pump
displacement angle sensor (12) via lever (13). The
pump
displacement
angle
sensor
detects
displacement angle changes as changes in electrical
resistance.
12
13
12 - Pump Displacement Angle Sensor
13 - Lever
T162-03-01-010
T3-1-12
COMPONENT OPERATION / Swing Device
OUTLINE
The swing device consists of the valve unit, swing motor, and swing reduction gear. The valve unit prevents
cavitation in the swing circuit from occurring and protects the circuit from being overloaded. The swing motor is a swash plate type axial plunger motor with a
built-in swing parking brake. The swing motor is driven
by pressure oil delivered from the pump, and drives the
swing reduction gear.
The swing reduction gear converts the swing motor
output into slow large torque to rotate the shaft.
Thereby, the upperstructure is rotated.
Valve Unit
Swing Motor
Swing Reduction Gear
T162-03-02-001
T3-2-1
COMPONENT OPERATION / Swing Device
SWING MOTOR
The swing motor is a swash plate type axial plunger
motor.
The swing motor consists of shaft (4), swash plate (3),
shoes (2), plungers (5), rotor (6), valve plate (9),
housing (1), and parking brake.
The spherical end of plunger (5) is installed in shoe (2)
by a ball-and-socket joint. The shaft part of plunger (5)
is inserted into rotor (6). Rotor (6) is installed onto shaft
(4) with a spline coupling.
The parking brake is a wet-type multiple disc brake,
consisting of friction plates (7) and plates (8).
9
8
7
1
6
2
5
3
4
T142-02-02-002
1 - Housing
2 - Shoe
3 - Swash Plate
4 - Shaft
5 - Plunger
6 - Rotor
7 - Friction Plate
T3-2-2
8 - Plate
9 - Valve Plate
COMPONENT OPERATION / Swing Device
Operational Principle
Swing speed varies depending on the amount of oil
delivered from the pump.
When pressure oil is fed into the rotor bores via port
(A), the plungers are pushed from the top dead
center to the bottom dead center causing the shoes
to slide along the swash plate, developing rotational
force.
The rotational force is then transmitted to the swing
reduction gear via the shaft. As the rotor is rotated,
the plungers are moved to port (B) side one by one,
returning oil to the hydraulic oil tank. When pressure
oil is fed via port (B), the motor rotates in the opposite
direction
A
B
Plunger
Shoe
Shaft
T142-02-02-004
T3-2-3
COMPONENT OPERATION / Swing Device
VALVE UNIT
The valve unit consists of the make-up valve and the
relief valve.
Make-Up Valve
When swing is stopped, the upperstructure tends to
keep rotating due to swing inertia force, causing the
swing motor to continue rotating further, and to begin
drawing oil from the pump, developing cavitation the
motor.
The make-up valve draws hydraulic oil through the
Port M (Return Circuit) to compensate for the lack of
oil, and prevent cavitation.
Drain Port
Make-Up Valve
Port M
Make-Up Port
Relief Valve
Control Valve
T142-02-02-005
Relief Valve
Make-Up Valve
Port M
Control Valve
T140-02-04-002
T3-2-4
COMPONENT OPERATION / Swing Device
Relief Valve
When starting or stopping swing operation, oil
pressure in the swing circuit becomes high. The relief
valve prevents the circuit pressure from rising higher
than the specified pressure. Plunger is pushed to the
left by pressure Pp at port (P) and pressure-receiving
area A2.
However, plunger is also pushed back to the right by
spring force and pressure Pg at chamber (g) and
pressure-receiving area A1.
Chamber (g) is connected to port (P) through orifice
(m). When force acting on the right is higher than that
on the left, the relief valve operates.
Relief Valve
Control Valve
T142-02-02-005
Spring
A1
Plunger
A2
Port P
Chamber (g)
m
T142-02-02-006
T3-2-5
COMPONENT OPERATION / Swing Device
SWING PARKING BRAKE
The swing parking brake is a wet-type multiple disc
brake.
Also, the swing parking brake is a negative type, i.e.
the brake is released when brake release pressure is
routed into brake-piston chamber (b).
The brake release pressure is supplied from the pilot
pump when a control lever is operated.
When the control levers are in neutral (or while the
engine is stopped), the brake release pressure is
returned to the hydraulic oil tank and the swing parking
brake is automatically applied by spring (1).
(Refer to the pilot circuit diagram in the Hydraulic
System Group of the System Section.)
• When Parking Brake is Released (OFF) (When
Control Lever is Operated)
When a control lever is operated, the pressure in
the pilot signal circuit rises because the
corresponding control valve spool is shifted. The
pressure in the pilot signal circuit acts on the
switch valve of the parking brake release valve,
shifting it. As the switch valve is shifted, the brake
release pressure from the pilot pump is routed
into chamber (b) via the swing parking release
valve, acting on and pushing brake piston (2). As
a result, plates (3) and friction plates (4) become
contact free with each other, thus releasing the
parking brake.
• When Parking Brake is Applied (ON) (When
Control Levers are in Neutral.)
When the control levers are in neutral, the
pressure in the pilot signal circuit does not rise.
For this reason, the switch valve is not shifted and
the parking brake release pressure is not routed
to chamber (b). The pressure oil in chamber (b) is
released to the motor drain port.
Thus, plates (3), which are secured to the outer
circumference of rotor (6), and friction plates (4),
which are secured to the inner wall of motor
housing (5), are pushed by spring (1) via brake
piston (2), coming into tight contact with each
other. As a result, rotor (6) is secured immovable,
thus applying the swing parking brake.
1
2
3
4
-
Spring
Brake Piston
Plate
Friction Plate
When the brake is released (OFF):
Pressure Oil
from Pilot
Swing Parking Signal Circuit
Brake Release via Shuttle
Valve
Valve
1
Brake
Chamber (b) Release
Pressure from
2
Pilot Pump
6
3
5
4
T142-02-02-007
When the brake is applied (ON):
Drain Port
5 - Motor Housing
6 - Rotor
7 - Orifice
5
6
T3-2-6
3
4
7
Chamber (b)
T142-02-02-007
COMPONENT OPERATION / Swing Device
SWING REDUCTION GEAR
The swing reduction gear is a planetary-gear-type two
stage reduction gear.
Both first and second stage ring gears are immovable
because they are fixed to the housing.
The motor shaft rotates first stage sun gear (9). As the
first stage reduction takes place between first stage
planetary gears (1) and first stage carrier (7), second
stage sun gear (5) is rotated. Then, the second stage
reduction takes place between second stage planetary
gears (2) and second stage carrier (4) before the
rotational force is transmitted to shaft (3).
1
9
8
7
2
6
5
4
3
T162-03-02-003
1 - First Stage Planetary Gear
2 - Second Stage Planetary
Gear
3 - Shaft
4 - Second Stage Carrier
5 - Second Stage Sun Gear
6 - Second Stage Ring Gear
7 - First Stage Carrier
T3-2-7
8 - First Stage Ring Gear
9 - First Stage Sun Gear
COMPONENT OPERATION / Swing Device
(Blank)
T3-2-8
COMPONENT OPERATION / Control Valve
OUTLINE
The control valve controls oil pressure, flow rate, and
flow direction in the hydraulic circuit. The main control
valve has two sections, i.e. 4-spool section and 5-spool
section.
The major parts of the control valve are the main relief
valve, flow combiner valve and spools. The spools are
operated by pilot oil pressure.
In the 4-spool section, the right travel, bucket 1, boom
1, and arm 2 spools are arranged in that order as
viewed from the machine front.
In the 5-spool section, the left travel, auxiliary, boom 2,
arm 1, and swing spools are arranged in that order as
viewed from the machine front.
Travel (L)
Aux.
Front Side
Boom 2
Arm Regenerative Valve
Travel (R)
Bucket 1
Boom 1
Arm 2
Boom Overload
Relief Selector Valve
Make-Up
Valve
(Arm 2)
Right Block
(4-Spool Block)
Overload
Relief Valve
(Aux.)
Arm 1
Boom Overload Relief
Selector Valve
Overload
Relief Valve
(Swing)
Swing
Overload
Relief Valve
(Boom)
Overload
Relief Valve
(Bucket)
Left Block
(5-Spool Block)
Holding Valve
(Boom)
Right Block
Front Side
(4-Spool Block)
Main Relief
Valve
Shuttle Valve
T16J-03-03-002
T3-3-1
Holding Valve
(Arm)
Overload
Relief Valve
(Arm)
Left Block
(5-Spool Block)
T17V-03-03-001
COMPONENT OPERATION / Control Valve
Control Valve
3 4 5
2
6
7
8
9
10
11
12
1
39
Swing
38
13
Arm 1
Arm 2
37
36
Boom 2
14
15
16
17
18
19
20
Boom 1
35
Bucket
Aux.
Travel (R)
34
21
33
22
Travel
(L)
T17V-03-03-010
32
31 30
29 28
1 - Holding Valve Shift Valve
(Boom)
2 - Bypass Shut-Out Valve
3 - Load Check Valve
(Arm 2 Tandem Circuit)
4 - Load Check Valve
(Arm 2 Parallel Circuit)
5 - Check Valve
(Arm Flow Combining
Circuit)
6 - Check Valve
(Aux. Flow Combining
Circuit)
7 - Arm Regenerative Valve
8 - Check Valve
(Arm 1 (Roll-Out) Parallel
Circuit)
9 - Load Check Valve
(Arm 1 (Roll-In) Parallel Circuit)
10 - Load Check Valve
(Swing Tandem Circuit)
27
25 26
11 - Load Check Valve
(Arm 1 Tandem Circuit)
12 - Holding Valve Shift
Valve (Arm)
13 - Overload Relief Valve
(Arm)
14 - Holding Valve Check
Valve (Arm)
15 - Load Check Valve
(Boom 2 Tandem Circuit)
16 - Load Check Valve
(Boom 2 Parallel Circuit)
17 - Boom Overload Relief
Selector Valve
18 - Boom Overload Relief
Selector Valve
19 - Load Check Valve
(Aux. Tandem Circuit)
20 - Load Check Valve
(Aux. Parallel Circuit)
24
23
21 - Overload Relief Valve
(Aux.)
22 - Load Check Valve
(Travel Tandem Circuit)
23 - Bypass Shut-Out Valve
24 - Load Check Valve
(Travel Parallel Circuit)
25 - Check Valve
(Bucket Flow Combining Circuit)
26 - Check Valve
(Main Relief Pressure Combining Circuit)
27 - Check Valve
(Bucket Flow Combining Circuit)
28 - Flow Combiner Valve
29 - Check Valve
(Flow Combiner Valve Circuit)
30 - Check Valve
(Main Relief Pressure Combining Circuit)
T3-3-2
31 - Shuttle Valve
32 - Main Relief Valve
33 - Load Check Valve
(Bucket Tandem Circuit)
34 - Overload Relief Valve
(Bucket)
35 - Load Check Valve
(Boom 1 Parallel Circuit)
36 - Overload Relief Valve
(Boom)
37 - Holding Valve Check
Valve (Boom)
38 - Make-Up Valve (Arm 2)
39 - Overload Relief Valve
(Swing)
COMPONENT OPERATION / Control Valve
39
13
14
F
17,18
E
D
C
Cross Section A
21
B
31
A
32
30
Front Side
23
32
31
36
34
29
Cross Section B
T16J-03-03-006
28
T17V-03-03-003
37
40
Cross Section C
41
Right Travel
Left Travel
43
45
Bucket
34
Aux.
25
21
27
19
22
33
20
24
34
44
42
40 - Right Travel Forward Port
41 - Left Travel Forward Port
42 - Left Travel Reverse Port
43
6
43 - Right Travel Reverse Port
44 - Bucket (Roll-Out) Port
46
21
T17P-03-03-006
T16J-03-03-008
45 - Bucket (Roll-In) Port
46 - Aux. Port
T3-3-3
47 - Aux. Port
COMPONENT OPERATION / Control Valve
3 4 5
2
6
7
8
9
10
11
12
1
39
Swing
38
13
Arm 1
Arm 2
37
36
Boom 2
14
15
16
17
18
19
20
Boom 1
35
Bucket
Aux.
Travel (R)
34
21
33
22
Travel
(L)
T17V-03-03-010
32
31 30
29 28
1 - Holding Valve Shift Valve
(Boom)
2 - Bypass Shut-Out Valve
3 - Load Check Valve
(Arm 2 Tandem Circuit)
4 - Load Check Valve
(Arm 2 Parallel Circuit)
5 - Check Valve
(Arm Flow Combining
Circuit)
6 - Check Valve
(Aux. Flow Combining
Circuit)
7 - Arm Regenerative Valve
8 - Check Valve
(Arm 1 (Roll-Out) Parallel
Circuit)
9 - Load Check Valve
(Arm 1 (Roll-In) Parallel Circuit)
10 - Load Check Valve
(Swing Tandem Circuit)
27
25 26
11 - Load Check Valve
(Arm 1 Tandem Circuit)
12 - Holding Valve Shift
Valve (Arm)
13 - Overload Relief Valve
(Arm)
14 - Holding Valve Check
Valve (Arm)
15 - Load Check Valve
(Boom 2 Tandem Circuit)
16 - Load Check Valve
(Boom 2 Parallel Circuit)
17 - Boom Overload Relief
Selector Valve
18 - Boom Overload Relief
Selector Valve
19 - Load Check Valve
(Aux. Tandem Circuit)
20 - Load Check Valve
(Aux. Parallel Circuit)
24
23
21 - Overload Relief Valve
(Aux.)
22 - Load Check Valve
(Travel Tandem Circuit)
23 - Bypass Shut-Out Valve
24 - Load Check Valve
(Travel Parallel Circuit)
25 - Check Valve
(Bucket Flow Combining Circuit)
26 - Check Valve
(Main Relief Pressure Combining Circuit)
27 - Check Valve
(Bucket Flow Combining Circuit)
28 - Flow Combiner Valve
29 - Check Valve
(Flow Combiner Valve Circuit)
30 - Check Valve
(Main Relief Pressure Combining Circuit)
T3-3-4
31 - Shuttle Valve
32 - Main Relief Valve
33 - Load Check Valve
(Bucket Tandem Circuit)
34 - Overload Relief Valve
(Bucket)
35 - Load Check Valve
(Boom 1 Parallel Circuit)
36 - Overload Relief Valve
(Boom)
37 - Holding Valve Check
Valve (Boom)
38 - Make-Up Valve (Arm 2)
39 - Overload Relief Valve
(Swing)
COMPONENT OPERATION / Control Valve
Cross Section E
Cross Section D
51
49
48
Boom 1
5
7
52
Arm 2
Arm 1
14
Boom 2
12
38
17
36
18
15
35
16
9
4
11
3
1
13
36
37
T17V-03-03-009
40
53
51
Cross Section F
T17P-03-03-005
54
56
Swing
13
2
A
A
10
26
39
38
56
T17V-03-03-004
A-A
48 - Boom 1 (Lower) Port
49 - Boom 2 (Lower) Port
50 - Boom 1 (Raise) Port
51 - Boom 2 (Raise) Port
52 - Arm 2 (Roll-Out) Port
53 - Arm 1 (Roll-Out) Port
54 - Arm 2 (Roll-In) Port
55 - Arm 1 (Roll-In) Port
T3-3-5
22 24
56 - Swing (Left) Port
57 - Swing (Right) Port
T16J-03-03-019
COMPONENT OPERATION / Control Valve
HYDRAULIC CIRCUIT
Main Circuit
Pressure oil from pump 1 and from pump 2 is routed
to the 4-spool section and to the 5-spool section of
the control valve respectively. A parallel circuit is provided in both right and left main circuits, making
combined operations possible. An flow combining
circuit is provided in both the boom and arm circuits
so that when a single operation is made, pressure oil
from both pumps 1 and 2 is supplied to the boom or
arm cylinders.
The main relief valve is located in the main circuit
(between the pump and actuators), preventing oil
pressure in the main circuit from increasing more
than the set-pressure while the control valve spool (s)
[the control lever (s)] is (are) operated. The overload
relief valves are located in the boom, arm, bucket,
swing and aux. actuator circuits (between the control
valve and actuators).The overload relief valve prevents surge pressure from being developed by external loads in the actuator circuit and prevents pressure in the circuit from rising more than the setpressure when the control valve spool (s) [the control
lever (s)] is (are) in neutral.
T3-3-6
COMPONENT OPERATION / Control Valve
Flow Combining
Circuit
5-Spool Section
Parallel Passage
5-Spool
Section
4-Spool Section
Overload
Relief Valve
Swing Motor
Boom
Cylinder
Arm
Cylinder
Overload
Relief Valve
Auxiliary
Bucket
Cylinder
Overload
Relief Valve
Overload
Relief Valve
4-Spool Section
Parallel Passage
Main Relief Valve
Travel Motor (Right)
Pump 1
Pump 2
Travel Motor (Left)
T17V-03-03-011
T3-3-7
COMPONENT OPERATION / Control Valve
Pilot Control Circuit
Pilot pressure oil (indicated with numbers) from the
pilot valve exerts onto the spool ends in the control
valve, shifting them. In the following operations, the
pilot pressure oil exerts on the switch valves while
shifting the spools.
• The bypass shut-off valve is shifted by the bucket
roll-in pilot pressure oil and/or attachment pilot
pressure oil.
(Refer to the SYSTEM / Control System group.)
As the air bleed circuit is provided in the upper section of the control valve so that any air trapped in the
control valve will automatically be bled.
External Pilot Pressure Oil Circuit
• The main relief valve set-pressure is increased by
the pilot pressure oil delivered from solenoid valve
unit (SA).
• The boom overload relief selector valve is shifted
by the pilot pressure oil delivered from solenoid
valve unit (SC).
• The flow combiner valve is shifted by the pilot pressure oil delivered from the flow combiner valve control spool in the signal control valve.
(Refer to the SYSTEM / Control System group.)
T3-3-8
COMPONENT OPERATION / Control Valve
1
2
3
4
6
14
5
5
4
3
1
2
Arm
3
2
Auxiliary
Bucket
8
11
6
7
7
9
10
12
8
13
10
11
12
9
T17V-03-03-012
1234-
Pilot Pressure Oil from Boom Lower Pilot Valve
Bypass Shut-Off Valve
Pilot Pressure Oil from Aux. Pilot Valve (Optional)
Holding Valve Shift Valve (Arm)
5 - Pilot Pressure Oil from Arm Pilot Valve
6 - Boom Overload Relief Selector Valve
7 - Pilot Pressure Oil from Solenoid Valve Unit (SC)
8910 11 -
Pilot Pressure Oil from Bucket Roll-In Pilot Valve
Bypass Shut-Off Valve
Flow Combiner Valve
Pilot Pressure Oil from Flow Combiner Valve Control Spool in
Signal Control Valve
12 - Pilot Pressure Oil from Solenoid Valve Unit (SA)
13 - Main Relief Valve
14 - Holding Valve Shift Valve (Boom)
T3-3-9
COMPONENT OPERATION / Control Valve
FLOW COMBINER VALVE
1. When a combined operation of the front attachment and travel functions is made, the flow combiner control valve spool in the signal control valve
is shifted, causing pilot pressure oil to shift the
flow combiner valve spool.
2. When the flow combiner valve spool is shifted,
pressure oil from pump 1 flows to the left travel
spool.
3. Therefore, pressure oil from pump 2 is routed to
both right and left travel spools in parallel. Then,
pressure oil from pump 1 is routed to the front attachment.
Consequently, when a combined operation of
travel and front attachment is made, the machine
can travel straight.
To Hydraulic
Oil Tank
To Left Travel
Spool
Pressure Oil
from Pump 2
Spool
T178-03-03-010
Pilot Pressure Oil from Flow Combiner Valve Control Spool
Flow Combiner Valve
Pilot Pressure Oil from Flow Combiner Valve
Control Spool in Signal Control Valve
Travel Motor (Right)
Travel Motor (Left)
Pump 1
T17V-03-03-007
T3-3-10
COMPONENT OPERATION / Control Valve
MAIN RELIEF VALVE
The setting pressure of the main relief valve is shifted
in two stages by pilot pressure from solenoid valve unit
(SA).
The main relief valve is set to high pressure either during travel or precision mode and to low pressure in any
other situations.
At Low Pressure
1. When the precision mode is turned off or the
travel pressure switch is turned off, solenoid valve
unit (SA) is not energized, so that the pressure
(pilot signal pressure) is not applied on PF2 of the
shuttle valve.
At High Pressure
1. When the precision mode is turned on or the
travel pressure switch is turned on, solenoid valve
unit (SA) is energized via MC, so that pressure oil
(pilot signal pressure) is supplied to PF2 of the
shuttle valve.
2. PF1 is connected to the hydraulic oil tank. Therefore, the piston is not pressed to the left, so that
the power to push the pilot poppet is reduced.
2. Pilot signal pressure pushes the piston to the left.
The spring is compressed, so that the pushing
force of the pilot poppet increases. Therefore, the
setting pressure of the main relief valve increases.
The relief valve operation is similar to the action at
low pressure.
3. When pressure in HP reaches to the set spring
force, the pilot poppet opens.
4. Then, oil flows into LP via passage A.
When the pilot poppet opens, pressure in spring A
chamber decreases. The main poppet opens, so
that pressure oil in HP flows into LP.
Main Poppet
Pilot Poppet
Spring
Piston
LP
HP
LP
PF2
PF1
Shuttle Valve
Spring A Chamber
Passage A
Solenoid Valve Unit (SA)
T3-3-11
T16J-03-03-001
COMPONENT OPERATION / Control Valve
OVERLOAD RELIEF VALVE
(With Make-Up Function)
An overload relief valve is provided on each of swing,
boom, arm, and bucket actuator port, preventing
excessive pressure from arising in each actuator
circuit if each actuator should be forcibly moved by an
external force.
1. When the pressure at port HP overcomes the setup pressure of spring (4), pilot poppet (3) opens
and the pressure oil flows th port LP through the
circumference of main poppet (2).
2. As a result, the pressure of port HP is different
from that of chamber (a) because of the orifice.
When the pressure difference overcomes spring
(5), piston (1) and main poppet (2) open and the
pressure oil of port HP flows to port LP.
3. The overload relief valve draws oil from the hydraulic oil tank to prevent cavitation from occurring if the actuator circuit pressure becomes negative.
1 - Piston
2 - Main Poppet
3 - Pilot Poppet
1
a
2
3
4
HP
LP
5
1
2
Orifice
T111-02-05-019
a
HP
4 - Spring
5 - Spring
LP
T111-02-05-021
MAKE-UP VALVE
A make-up valve is provided on the cylinder ports of
boom 2 lower and arm 2, addition to the make-up
function of the overload relief valve.
7
6
d1
d2
HP
1. When the pressure at port HP is higher than that
at port LP, the pressure oil acts on chamber (b)
through the passage of poppet (7). Consequently
the pressures at port HP and Chamber (b) are
same.
2. The area difference between d1 and d2 of poppet
(7) makes the force bigger, to close poppet (7).
3. When the pressure at port HP is lower than that at
port LP, only spring (6) force closes poppet (7),
the pressure at port LP for the area difference between d1 and d2 is applied to poppet (7). Poppet
(7) moves to the right and opens.
LP
b
T111-02-05-023
HP
6 - Spring
7 - Poppet
LP
T111-02-05-024
T3-3-12
COMPONENT OPERATION / Control Valve
HOLDING VALVE
A holding valve is provided on the boom raise side and
arm roll-out side cylinder ports, preventing the boom
and arm cylinders from retracting when the control
levers are in neutral.
• Holding valve operation when the control levers
are in neutral.
The cylinder holding pressure at cylinder port C acts
on chamber (a) via orifice (b) in check valve (2).
Because of the difference in the pressure receiving
areas d1 and d2, check valve (2) is securely seated
on cylinder port C, closing the cylinder port.
1
External Force
g
2
a
a
d1
g
b
b
Holding Pressure
3
c
d2
d
c
3
Pi
f
f
d
e
T111-02-05-025
• Holding valve operation when the boom lower or
arm roll-in control lever is operated.
Pilot pressure Pi acts on poppet (1), connecting
chamber (a) and the hydraulic oil tank line.
As the pressure in chamber (a) decreases, check
valve (2) opens. At the same time, spool (3) is
moved to form a circuit ( (c) → (d) → (f) ) so that the
actuating cylinder (boom or arm) can move.
1
a
a
2
3
d
c
3
Pi
f
f
d
T111-02-05-026
1 - Poppet
2 - Check Valve
T3-3-13
3 - Spool
COMPONENT OPERATION / Control Valve
ARM REGENERATIVE VALVE
The arm regenerative valve is provided to help smooth
arm operation and to prevent arm hesitation from
occurring.
PB
PR
1
8
1. Return oil from cylinder rod side is restricted in
two stages at orifice (A) in spool (2) and at orifice
(B) in arm regenerative valve (7), increasing
cylinder rod side pressure PR.
2
h
3
2. When rod side pressure PR becomes larger than
bottom side pressure PB, check valve (3) opens,
routing the return oil from the rod side to
supplement the pump oil flow to the bottom side.
e
b
A
9
a
B
6
7
C
1
T16J-03-03-017
PR
PB
8
9
2
A
h
f
7
e
a
i
e
B
d
c
3
b
6
1 - Arm Cylinder
2 - Spool
3 - Check Valve
5
4 - Piston
5 - Spool
4
T16J-03-03-016
6 - Spring
7 - Arm Regenerative Valve
T3-3-14
8 - Holding Valve
9 - Load Check Valve
COMPONENT OPERATION / Control Valve
When bottom side pressure PB is higher than rod side
pressure PR, check valve (3) closes. Moreover, the
pressure oil from the main pump acts on piston (4) in
arm regenerative valve (7) via passage (b). As a result,
spool (5) is moved to the left, widening orifice (B), thus
returning rod side oil faster to hydraulic oil tank
passage (d).
PB
PR
1
8
2
h
3
e
b
A
9
a
B
6
4
C
1
T16J-03-03-017
PR
PB
8
9
2
A
h
f
7
e
a
i
e
B
d
c
3
b
6
1 - Arm Cylinder
2 - Spool
3 - Check Valve
5
4 - Piston
5 - Spool
4
T16J-03-03-020
6 - Spring
7 - Arm Regenerative Valve
T3-3-15
8 - Holding Valve
9 - Load Check Valve
COMPONENT OPERATION / Control Valve
BYPASS SHUT-OFF VALVE
The bypass shut-off valve controls to increase the flow
rate of the main pressure oil entering the cylinder by
blocking the hydraulic oil tank return circuit from each
main pump and combining pressure oil from the main
pump 1 and main pump 2.
1. When the bucket roll-in function is operated,
bucket roll-in pilot pressure moves the bypass
shut-off valve (5-spool) to the close side.
2. As the hydraulic oil tank return circuit from the
main pump 2 is blocked, pressure oil from the
main pump 2 is routed to the 4-spool side of the
control valve. The pressure oil is combined with
pressure oil from the main pump 1, then flows into
the bucket spool.
3. Also, when the crusher equipment (optional) is
operated at the crusher installed machine, pilot
pressure from the crusher pilot valve (optional)
moves the bypass shut-off valve (4-spool) to the
close side.
4. As the hydraulic oil tank return circuit from the
main pump 1 is blocked, pressure oil from the
main pump 1 is routed to the 5-spool side of the
control valve. The pressure oil is combined with
pressure oil from the main pump 2, then flows into
the auxiliary spool.
T3-3-16
COMPONENT OPERATION / Control Valve
Bypass
Shut-Off
Valve
(4-Spool)
Pilot Pressure Oil
from Crusher (Aux.)
Pilot Valve (Option)
Auxiliary
Spool
Bucket Cylinder
Auxiliary
Bucket Spool
Main Pump 1
Main Pump 2
Bypass Shut-Off Valve
(5-Spool)
Pilot Pressure Oil from
Bucket Roll-In Pilot Valve
T17V-03-03-013
T3-3-17
COMPONENT OPERATION / Control Valve
BOOM OVERLOAD RELIEF SELECTOR
VALVE
The boom overload relief selector valve is provided in
the actuator port of the boom. The boom overload relief selector valve is shifted by the pilot pressure from
the solenoid valve unit (SC) to reduce the setting pressure of the overload relief valve on the boom cylinder
(rod side) circuit.
1. Under general conditions, pressure oil in port HP
enters chamber (c) through piston (6) to act on
main poppet (5). Therefore, main poppet (5)
closes, so that the setting pressure of the overload relief valve is kept high.
2. When pilot pressure from solenoid valve unit (SC)
is applied on piston (1), piston (1) opens poppet
(2). When poppet (2) opens, chamber (a) and
chamber (b) are connected to port LP via the circumference of sleeve (7).
3. When pressure in chamber (c) reaches the setting pressure of spring (3), pilot poppet (4) opens.
When pilot poppet (4) opens, the pressure in
chamber (c) decreases, so that piston (6) and
main poppet (5) move to the left.
4. As main poppet (5) opens, pressure oil is routed
to LP from port HP, so that the setting pressure of
the overload relief valve reduces.
(Refer to SYSTEM / Control System group.)
T3-3-18
COMPONENT OPERATION / Control Valve
1
2
a
3
4
5
Pilot Pressure
6
HP
LP
7
d
b
c
T183-03-03-018
1
2
a
3
4
5
Pilot Pressure
6
HP
LP
b
c
T183-03-03-019
1
2
a
3
4
5
Pilot Pressure
HP
b
1 - Piston
2 - Poppet
6
3 - Spring
4 - Pilot Poppet
5 - Main Poppet
6 - Piston
T3-3-19
LP
7 - Sleeve
T183-03-03-020
COMPONENT OPERATION / Control Valve
(Brank)
T3-3-20
COMPONENT OPERATION / Pilot Valve
OUTLINE
The pilot valve controls the pilot oil pressure by which
the control valve spools are operated.
Two types of the standard pilot valves are located on
this machine. Both have four oil ports. One type is
used for the front attachment / swing function control.
Another is used for the travel function control. Optional
type has two oil ports.
The reducing valves in both the front attachment /
swing and travel pilot valves are identical construction
except for the pusher moving cam.
• Travel Pilot Valve
1
2
3
4
• Front Attachment / Swing Pilot Valve
Right
Left
Port
No.
1
2
3
4
1
2
3
4
ISO Control
Pattern
Bucket Roll-Out
Boom Lower
Bucket Roll-In
Boom Raise
Right Swing
Arm Roll-Out
Left Swing
Arm Roll-In
Hitachi Pattern
ұ
ұ
ұ
ұ
Arm Roll-In
Right Swing
Arm Roll-Out
Left Swing
Right Travel Reverse
Right Travel Forward
Left Travel Forward
Left Travel Reverse
Hydraulic
Symbol
P
3
T
4
2
1
T105-02-07-020
P
Hydraulic
Symbol
2
T
4
1
3
T105-02-07-020
T
P
3
4
2
1
1
T178-03-04-002
T
4
2
P
T178-03-04-001
3
T3-4-1
COMPONENT OPERATION / Pilot Valve
OPERATION
Spool (6) head comes in contact with the upper face of
spring guide (3) which is kept raised by return spring
(5).
Neutral (Output Diagram: A to B):
1. When neutral, spool (6) totally blocks pressure oil
port P (from the pilot pump).The output port is
opened to port T (hydraulic oil tank) through the
passage in spool (6). Therefore, oil pressure in
the output port (to the control valve) is equal to
that in port T.
2. When the control lever is slightly tilted, cam (1) is
tilted, moving pusher (2) downward. Then, pusher
(2) compress return spring (5) along with spring
guide (3). At this time, as oil pressure in the output
port is equal to that in port T, spool (6) moves
downward while keeping the under face of the
spool head in contact with spring guide (3).
3. This status continues until hole (7) on spool (6) is
opened to port P.
T3-4-2
E
F
D
Pilot
Pressure
C
A
B
Lever Stroke
T522-02-05-001
COMPONENT OPERATION / Pilot Valve
Front Attachment / Swing Pilot Valve
1
1
2
2
3
3
4
4
5
5
6
7
Port P
6
6
Output Port
Port T
Port T
7
7
Port P
Output Port
Port T
Port P
Output Port
T178-03-04-005
T178-03-04-007
Travel Pilot Valve
1
1
2
2
Port T
7
3
3
4
4
5
6
Output Port
5
6
Port P
Port T
Port T
6
Port P
7
Output Port
1 - Cam
2 - Pusher
Port P
7
Output Port
T178-03-04-006
3 - Spring Guide
4 - Balance Spring
5 - Return Spring
6 - Spool
T3-4-3
7 - Hole
T178-03-04-011
COMPONENT OPERATION / Pilot Valve
During Metering or Decompressing
(Output Diagram: C to D)
1. When the control lever is further tilted to move
pusher (2) downward more, hole (7) on spool (6)
is opened to port P, allowing pressure oil in port P
to flow into the output port.
2. Oil pressure in the output port acts on the bottom
face of spool (6) so that spool (6) is pushed
upward.
3. However, until upward force acting on the bottom
face of spool (6) overcomes balance spring (4)
force, balance spring (4) is not compressed. Then,
spool (6) is not raised, allowing oil pressure in the
output port to increase.
4. As oil pressure in the output port increases, force
to push spool (6) upward increases. When, this
force overcomes balance spring (4) force,
balance spring (4) is compressed so that spool (6)
is moved upward.
5. As spool (6) is moved upward, hole (7) is closed
so that pressure oil from port P stops flowing into
the output port, stopping pressure oil in the output
port to increase.
6. As spool (6) is moved downward, balance spring
(4) is compressed, increasing the spring force.
Therefore, oil pressure in the output port becomes
equal to the oil pressure acting on the bottom face
of spool (6) being balanced in position with the
spring force.
T3-4-4
E
F
D
Pilot
Pressure
C
A
B
Lever Stroke
T522-02-05-001
COMPONENT OPERATION / Pilot Valve
Front Attachment / Swing Pilot Valve
1
1
2
2
3
3
4
4
5
5
6
6
Port T
Port T
7
Port P
7
Output Port
Port P
Output Port
T178-03-04-008
T178-03-04-009
Travel Pilot Valve
1
1
2
2
3
3
4
4
5
5
6
6
Port T
Port P
7
Output Port
1 - Cam
2 - Pusher
Port T
Port P
7
Output Port
T178-03-04-012
3 - Spring Guide
4 - Balance Spring
5 - Return Spring
6 - Spool
T3-4-5
7 - Hole
T178-03-04-013
COMPONENT OPERATION / Pilot Valve
Full Stroke (Output Diagram: E to F)
1. When the control lever is fully stroked, pusher (2)
is moved downward until pusher (2) in the front
attachment / swing pilot valve comes in contact
with the casing shoulder, or cam (1) on the travel
pilot valve comes in contact with the casing.
2. At this moment, the bottom of pusher (2) directly
pushes spool (6). Therefore, even if oil pressure
in the output port increases further, hole (7) on
spool (6) is kept open.
3. Consequently, oil pressure in the output port is
equal to oil pressure in port P.
NOTE: Total lever strokes for the front attachment
and swing controls are determined by
stroke dimension (E) of pusher (2). Total
lever stroke for the travel control is
determined by stroke dimension (E) of cam
(1).
T3-4-6
E
F
D
Pilot
Pressure
C
A
B
Lever Stroke
T522-02-05-001
COMPONENT OPERATION / Pilot Valve
Front Attachment / Swing Pilot Valve
1
2
2
3
4
5
E
6
Port T
7
Port P
T178-03-04-010
Output Port
T178-03-04-005
Travel Pilot Valve
1
1
E
2
3
4
5
6
Port T
Port P
7
Output Port
1 - Cam
2 - Pusher
T178-03-04-006
T178-03-04-014
3 - Spring Guide
4 - Balance Spring
5 - Return Spring
6 - Spool
T3-4-7
7 - Hole
COMPONENT OPERATION / Pilot Valve
(Blank)
T3-4-8
COMPONENT OPERATION / Travel Device
OUTLINE
The device consist of travel motor (1), travel reduction
gear (2 to 11), sprocket (12) and travel brake valve
(15).
TRAVEL REDUCTION GEAR
Third stage carrier (2) does not rotate as it is fixed to
travel motor housing (12). Ring gear (1) and sprocket
(11) are bolted to drum (13) and they rotate together.
The travel reduction gear is a third stage planetary
gear type. When the travel motor rotates, shaft (7)
rotates, transmitting this motor-driving power to ring
gear (1) via first stage planetary gears (8), first stage
carrier (6), second stage sun gear (5), second stage
planetary gears (9), second stage carrier (4), third
stage sun gear (3), third stage planetary gears (10)
and third stage carrier (2).
12
14
13
4
5
13
1
6
7
8
9
Third
Stage
Second
Stage
First
Stage
T111-03-04-011
15
11
2
10
T17V-03-05-001
1 - Travel Motor
2 - Ring Gear
5 - Second Stage Carrier
6 - Second Stage Sun Gear
3 - Third Stage Carrier
4 - Third Stage Sun Gear
7 - First Stage Carrier
8 - Shaft
9 - First Stage Planetary Gear
10 - Second Stage Planetary
Gear
11 - Third Stage Planetary Gear
12 - Sprocket
T3-5-1
13 - Housing (Travel Motor)
14 - Drum
15 - Travel Brake Valve
COMPONENT OPERATION / Travel Device
TRAVEL MOTOR
The travel motor is a variable displacement swash
plate axial plunger type, consisting of swash plate (7),
rotor (16), plungers (4) with shoes, valve plate (1), output shaft (11), tilt pistons (9), casing (8), and so forth.
1
2
Four of tilt piston (9) are located in casing (8). The
pressure to change travel speed acts on these tilt
pistons (9) to change swash plate (7) angle.
Rotor (16) is preloaded against valve plate (1) by
spring (14) to prevent oil from leaking at the clearance between them.
Hydraulically released type disc parking brake (3) is
installed in the travel motor.
3
4
5
6
7
8
9
10
11
17
16
T183-03-05-003
15
12345-
Valve Plate
Spring
Parking Brake
Plunger
Holder
6789-
Retainer Plate
Swash Plate
Casing
Tilt Piston
14
10 11 12 13 -
T3-5-2
Spring
Output Shaft
Roller Bearing
Ball
13
12
14 15 16 17 -
Spring
Brake Piston
Rotor
Valve Cover
COMPONENT OPERATION / Travel Device
As output shaft (6) rotates, rotor (2) also rotates. Then,
when plungers (3) reach port B, oil is routed to the hydraulic oil tank.
Whether pressure oil from the pump is supplied to port
A or port B determines the travel direction.
Pressure oil from the pump flows to port A of valve
plate (1), and enters into one-sided bores in rotor (2)
located just behind the right-side crescent-shaped oil
port (port A side) of valve plate (1).
Then, plungers in the right half side of rotor (2) are
pushed out toward swash plate (5), and slide on the
swash plate to rotate rotor (2) and output shaft (6).
Port B
Port B
Port A
Port A
1
2
3
4
6
5
Valve Plate
T183-03-05-009
1 - Valve Plate
2 - Rotor
3 - Plunger
4 - Shoe
5 - Swash Plate
T3-5-3
6 - Output Shaft
COMPONENT OPERATION / Travel Device
TRAVEL BRAKE VALVE
The travel brake valve is located on the travel motor
head and consists of the following valves:
Counterbalance Valve:
ensures smooth starts and stops and prevents
overrunning when traveling down slopes.
Overload Relief Valve:
prevents overloads and surge pressure in the
motor circuit.
Check Valve:
ensures smooth starts and stops, and prevents
cavitation from occurring in the motor circuit by
functioning together with counterbalance valve.
Travel Speed Shift Valve:
controls the tilt pistons when travel mode switch is
operated.
Cross Section A-A-A
Overload Relief
Valve
Counterbalance
Valve
Travel Speed
Shift Valve
Check Valve
A
A
A
Overload Relief
Valve
Counterbalance
Valve
T183-03-05-004
T3-5-4
COMPONENT OPERATION / Travel Device
(Blank)
T3-5-5
COMPONENT OPERATION / Travel Device
Travel Operation
When supply oil from the main control valve is routed
to port P1, supply oil flows around spool CB, opens
check valve BC and is led to motor port BM. However,
return oil from motor port AM is blocked by spool CB
in the counterbalance valve.
As supply oil pressure at port P1 increases, supply oil
is routed to chamber G through orifice F in spool CB,
moving spool CB down against spring force. Consequently, return oil from motor port AM starts to flow
into port P2 through notch H in spool CB, allowing the
travel motor to rotate.
When the travel levers are returned to the neutral position, the oil in both ports P1 and P2 are routed to the
hydraulic oil tank through the control valve. Thus, oil
pressure in chamber G decrease, and spool CB is
moved back to the original position by spring force.
Then, the oil flow circuits is blocked, causing the
travel motors to stop rotating.
Descending Operation
When the machine travels down a slope, the travel
motors are forcibly driven by the machine weight so
that the motor draws oil like a pump. When the motor
draws oil, oil pressure at port P1 and chamber G decrease, causing spool CB to move upwards to restrict
return circuit from the motor.
Then, the return oil flow from the motor is restricted
by the spool, increasing pressure at port AM.
The increased pressure at port AM brakes the motor.
Thus, the restricted return oil flow from the travel motor increases the pressure at port P1 again, moving
spool CB back down. This repeated movement of the
spool (hydraulic brake action) prevents the machine
from overrunning.
T3-5-6
COMPONENT OPERATION / Travel Device
(Travel Operation)
BM
Check Valve
BC
G
Spool CB
G
Spool CB
F
P1
To BM
P1
H
P2
P2
AM
From AM
Counterbalance Valve
T183-03-05-005
(Descending Operation)
BM
G
Spool CB
G
Spool CB
P1
P1
To BM
P2
P2
From AM
AM
T183-03-05-006
T3-5-7
COMPONENT OPERATION / Travel Device
Circuit Protection
If pressure in the circuit increases over the setting
pressure of the overload relief valve, this valve opens
to relieve peak pressure to the lower pressure side to
protect the motor from overloading. This valve also
functions to release shock pressure caused by inertia
force developed when the motor stops.
Overload
Relief Valve
Poppet
Low Pressure
High Pressure
T3-5-8
T183-03-05-011
COMPONENT OPERATION / Travel Device
(Blank)
T3-5-9
COMPONENT OPERATION / Travel Device
TRAVEL MOTOR DISPLACEMENT ANGLE
CHANGE
The travel speed mode changes as the displacement
angle of swash plate (3) is changed by tilt piston (5).
• Slow Speed Travel
Ȁ (Maximum Displacement Angle)
Ȁ While pilot pressure (7) that pressure is reduced by
the signal pressure from solenoid valve unit (SB) is
supplied to travel speed shift valve (1), spool A (8) is
held in neutral by spring (2), blocking pressure oil
from the control valve. Pilot pressure (7) is routed to
the parking brake through the passage of spool A (8)
via the circumference clearance of spool B (9) to release the parking brake. At the same time, the line to
tilt pistons (5) is opened to the hydraulic oil tank line
With the above, the swash plate (3) displacement angle is fixed to the large side, and thus the plunger (6)
stroke becomes maximum. Accordingly, the amount of
oil required to rotate the travel motor (per turn) becomes maximum, resulting in slow speed travel motor
operation.
(Refer to the Control System Group in the SYSTEM
Section for the control circuit.)
Travel Speed Shift Valve
9
7
8
1
2
6
5
To Hydraulic Oil Tank
Parking Brake
4
3
5
4
3
From Control Valve
1 - Travel Speed Shift Valve
2 - Spring
3 - Swash Plate
4 - Ball
5 - Tilt Piston
6 - Plunger
7 - Pilot Pressure (From Reducing Valve)
T3-5-10
T183-03-05-007
8 - Spool A
9 - Spool B
COMPONENT OPERATION / Travel Device
• Fast Speed Travel
Ȁ (Minimum Displacement Angle)
Ȁ While non-pressure-reduced pilot pressure (7) is
supplied to travel speed shift valve (1), pilot pressure
(7) is supplied to chamber (a) via the circumference
clearance of spool B (9), shifting spool A (8) to the
right. Also, the pilot pressure (7) is supplied to the
parking brake via chamber (b) in spool A (8) to release the parking brake. By the movement of spool
A (8), pressure oil from the control valve exerts on tilt
pistons (5).
5
Tilt pistons (5) push swash plate (3), changing the displacement angle to the minimum, resulting in the fast
speed travel motor operation.
(Refer to the Control System Group in the SYSTEM
Section for the control circuit.)
Travel Speed Shift Valve
6
9
a
7
b
8
1
2
From Travel
Speed Shift Valve
Parking Brake
4
3
5
4
3
From Control
Valve
T183-03-05-008
1 - Travel Speed Shift Valve
2 - Spring
3 - Swash Plate
4 - Ball
5 - Tilt Piston
6 - Plunger
7 - Pilot Pressure (From Reducing Valve)
T3-5-11
8 - Spool A
9 - Spool B
COMPONENT OPERATION / Travel Device
PARKING BRAKE
The friction plates are connected to the rotor, and the
plates to the casing via spline couplings respectively.
When the spring pushes the piston to the right, the
friction plates come into contact with the plates, applying the parking brake.
(Refer to the pilot circuit diagram in the Hydraulic Circuit Group, the SYSTEM Section, for pilot oil flow.)
The parking brake is a negative type brake released
when pilot oil pressure is applied to parking brake
chamber M. Whenever the travel control valve spools
are in neutral, the parking brake is automatically applied.
Spring
Piston
M
Plate
Friction Plate
Casing
Rotor
1 - Spring
2 - Piston
3 - Plate
4 - Friction Plate
5 - Casing
T3-5-12
T183-03-05-003
6 - Rotor
COMPONENT OPERATION / Travel Device
Brake ON
When the control lever is in the neutral position, the
friction plates and plates are pressed down by spring
force, braking the motor. Pressure oil in brake chamber M is released to the hydraulic oil tank.
Spring
M
Spring
Plate
Friction Plate
Casing
Rotor
T111-03-04-007
Brake OFF
When the control lever is operated, pilot oil is led to
brake chamber M and pushes the brake piston
against spring force. Consequently, the friction plates
are separated from the plates, releasing the parking
brake.
Spring
M
Spring
Plate
Friction Plate
Rotor
Casing
T111-03-04-008
T3-5-13
COMPONENT OPERATION / Travel Device
(Blank)
T3-5-14
COMPONENT OPERATION / Signal Control Valve
OUTLINE
The signal control valve is provided in the pilot circuit
between the pilot valve and the control valve and controls pilot signal pressure used to regulate the pumps
and various kinds of valves.
The major components of the signal control valve are,
shuttle valves, shockless valve, pump 1 flow rate control valve, pump 2 flow rate control valve, flow combiner valve control spool and swing parking brake release spool.
A
A
Pilot Valve Side
T178-03-06-016
Cross Section A-A
Shockless Valve
Auxiliary
Auxiliary
Pump 1 Flow Rate Control Valve
Pump 2 Flow Rate Control Valve
Swing Parking Brake
Release Spool
Flow Combiner Valve Control Spool
T178-03-06-002
T3-6-1
COMPONENT OPERATION / Signal Control Valve
PILOT PORT
Pilot Valve Side(ISO PATTERN)
Port Name
Connecting to
Port A
Right Pilot Valve
Port B
Right Pilot Valve
Port C
Left Pilot Valve
Port D
Left Pilot Valve
Port E
Left Pilot Valve
Port F
Left Pilot Valve
Port G
Right Pilot Valve
Port H
Right Pilot Valve
Port I
Travel Pilot Valve
Port J
Travel Pilot Valve
Port K
Travel Pilot Valve
Port L
Travel Pilot Valve
Port M
Auxiliary Pilot Valve
Port N
Auxiliary Pilot Valve
Port SA
Pump Control Pressure Sensor (4-spool)
Port SB
Pump Control Pressure Sensor (5-spool)
Port PI
Pilot Shut-Off Valve
Port PH
Pilot Shut-Off Valve
Port SH
Swing Parking Brake
Port DF
Hydraulic Oil Tank
Note
Boom Raise Pilot Pressure
Boom Lower Pilot Pressure
Right Swing Pilot Pressure(Label F)
Left Swing Pilot Pressure(Label E)
Arm Roll-Out Pilot Pressure(Label C)
Arm Roll-In Pilot Pressure(Label D)
Bucket Roll-In Pilot Pressure
Bucket Roll-Out Pilot Pressure
Left Travel Forward Pilot Pressure
Left Travel Reverse Pilot Pressure
Right Travel Forward Pilot Pressure
Right Travel Reverse Pilot Pressure
Auxiliary Open Pilot Pressure
Auxiliary Close Pilot Pressure
Pump 1 Flow Rate Control
Pump 2 Flow Rate Control
Primary Pilot Pressure
Primary Pilot Pressure (Heating Circuit)
Brake Release Pressure
Returning to Hydraulic Oil Tank
Pilot Valve Side(HITACHI PATTERN)
Port Name
Connecting to
Port A
Right Pilot Valve
Port B
Right Pilot Valve
Port C
Left Pilot Valve
Port D
Left Pilot Valve
Port E
Left Pilot Valve
Port F
Left Pilot Valve
Port G
Right Pilot Valve
Port H
Right Pilot Valve
Port I
Travel Pilot Valve
Port J
Travel Pilot Valve
Port K
Travel Pilot Valve
Port L
Travel Pilot Valve
Port M
Auxiliary Pilot Valve
Port N
Auxiliary Pilot Valve
Port SA
Pump Control Pressure Sensor (4-spool)
Port SB
Pump Control Pressure Sensor (5-spool)
Port PI
Pilot Shut-Off Valve
Port PH
Pilot Shut-Off Valve
Port SH
Swing Parking Brake
Port DF
Hydraulic Oil Tank
Note
Boom Raise Pilot Pressure
Boom Lower Pilot Pressure
Arm Roll-Out Pilot Pressure
Arm Roll-In Pilot Pressure
Left Swing Pilot Pressure
Right Swing Pilot Pressure
Bucket Roll-In Pilot Pressure
Bucket Roll-Out Pilot Pressure
Left Travel Reverse Pilot Pressure
Left Travel Forward Pilot Pressure
Right Travel Forward Pilot Pressure
Right Travel Reverse Pilot Pressure
Auxiliary Open Pilot Pressure
Auxiliary Close Pilot Pressure
Pump 1 Flow Rate Control
Pump 2 Flow Rate Control
Primary Pilot Pressure
Primary Pilot Pressure (Heating Circuit)
Brake Release Pressure
Returning to Hydraulic Oil Tank
T3-6-2
COMPONENT OPERATION / Signal Control Valve
Pilot Valve Side
C
PH
A
E
M
D
H
B
F
SB
G
PI
Pilot Valve
Side
N
K
I
SH
J
DF
SA
L
T178-03-06-016
T3-6-3
COMPONENT OPERATION / Signal Control Valve
Control Valve Side
Port Name
Port 1
Port 2
Port 3
Port 4
Port 5
Port 6
Port 7
Port 8
Port 9
Port 10
Port 11
Port 12
Port 13
Port 14
Port SE
Port SM
Port SN
Port SP
Port SL
Port SK
Connecting to
Control Valve through the Solenoid
Valve (Swing Preference)
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
Control Valve
ȀȀȀȀȀȀ
ȀȀȀȀȀȀ
ȀȀȀȀȀȀ
Hydraulic Oil Tank
ȀȀȀȀȀȀ
Hydraulic Oil Tank
Control Valve
ȀȀȀȀȀȀ
T3-6-4
Note
Boom Raise Pilot Pressure
Boom Lower Pilot Pressure
Arm Roll-Out Pilot Pressure
Arm Roll-In Pilot Pressure
Left Swing Pilot Pressure
Right Swing Pilot Pressure
Bucket Roll-In Pilot Pressure
Bucket Roll-Out Pilot Pressure
Left Travel Forward Pilot Pressure
Left Travel Reverse Pilot Pressure
Right Travel Forward Pilot Pressure
Right Travel Reverse Pilot Pressure
Plug
Plug
Plug
Returning to Hydraulic Oil Tank
Plug
Returning to Hydraulic Oil Tank
Flow Combiner Valve Control Pressure
Plug
COMPONENT OPERATION / Signal Control Valve
Control Valve Side
SM
3
5
1
13
2
4
SK
SE
Pressure Sensor
(S3: Swing)
8
14
Control Valve
Side
7
9
6
10
SN
SL
11
Pressure Sensor (TR: Travel)
12
T3-6-5
SP
T16J-03-06-001
COMPONENT OPERATION / Signal Control Valve
SHUTTLE VALVE
The shuttle valve selects the pilot pressure oil used to
perform each operation and routes it to the corresponding flow rate control valves and/or switch valve
spools. The flow rate control valves and/or switch valve
spools corresponding to each operation are as follows:
Boom Raise
Boom Lower
Arm Roll-Out
Arm Roll-In
Bucket Roll-In
Bucket Roll-Out
Right Swing
Left Swing
Right Travel
Left Travel
Auxiliary
Pump 1 Flow
Rate Control
Valve
{
{
{
{
{
{


{


Pump 2 Flow
Rate Control
Valve
{

{
{


{
{

{
{
Flow Combiner
Valve Control
Spool








{


Swing Parking
Brake Release
Spool
{
{
{
{
{
{
{
{


{
15
1
2
3
Left
Travel
Right
Travel
14
Swing
Arm
11
5
7
9
8
16
13 Boom
Bucket
Shockless Valve
Signal Control
Valve
17
T17V-03-06-001
Pump 2 Flow
Rate Control
Valve
Pump 1 Flow
Rate Control
Valve
Swing Parking
Brake Release
Spool
Flow Combiner
Valve Control
Spool
T3-6-6
10
6
4
12
COMPONENT OPERATION / Signal Control Valve
B
B
Pilot Valve Side
T178-03-06-016
Cross Section B-B
9
5
8
7
16
17
15
13
11
14
10
6
12
3
1
4
2
T178-03-06-009
1 - Left Travel
2 - Left Travel/Right Travel
6 - Boom/Arm/Bucket/Right Travel
7 - Boom/Arm
3 - Right Travel
8 - Boom
4 - Boom/Arm/Bucket/ Right Travel
5 - Arm
9 - Arm/Boom Raise
10 - Boom/Arm/Bucket/Left
Travel/Swing
T3-6-7
11 - Boom/Arm/Bucket
12 - Boom/Arm/Bucket/
Swing/Auxiliary
13 - Arm/Boom Raise/
Swing/Auxiliary
14 - Bucket
15 - Swing
16 - Swing/Auxiliary
17 - Auxiliary
COMPONENT OPERATION / Signal Control Valve
SHOCKLESS VALVE
The shockless valve is provided in the boom circuit
and functions during boom operation.
During Boom Lowering Operation
(Shock Reducing Operation)
1. When the boom is lowered, the return oil from the
boom raise spool port in the control valve is
routed to port 1.
2. Since the spool blocks the oil passage between
port 1 and port A, the return oil cannot flow directly
to port A.
3. Port 1 is connected to spring A side via inner passage 1 and to the oil chamber via inner passage
2.
4. The pressure oil in the oil chamber flows out of
clearance A between the spool and the housing,
reducing the pressure in the oil chamber. Then,
the spool is moved to the right by the pressure in
the spring A side. Thereby, clearance A between
the spool and the housing is closed, blocking the
pressure oil.
5. When clearance A is closed, the pressure in the
oil chamber increases, moving the spool to the left.
Therefore, clearance A is opened again, allowing
the pressure oil to flow to port A.
6. As operations in steps (4 and 5) are repeated, the
pressure oil is gradually returned to port A so that
the spool in the control valve returns slowly.
During Boom Raising Operation
(Shock Reducing Operation)
1. When the boom is raised, the return oil from the
boom lower spool port in the control valve is
routed to pump A2.
2. The pressure in chamber D flows from clearance
E between the plunger and the housing to port B,
reducing the pressure in chamber D.
Then the plunger is moved to the left by the pressure in the spring C side. Thereby, clearance E
between the plunger and the housing is closed,
blocking the pressure oil.
3. When clearance E is closed, the pressure in
chamber D increases, moving the spool to the
right.
Therefore, clearance E is opened again, allowing
the pressure oil to flow to port B.
4. As operations in steps (2 and 3) are repeated, the
pressure oil is gradually returned to port B so shat
the spool in the control valve returns slowly.
T3-6-8
COMPONENT OPERATION / Signal Control Valve
Shockless Valve (Located in Signal Control Valve)
(Boom Raise Circuit)
Pilot Valve Side
Port A
Inner Passage 1
C
Spool
Inner Passage 2
Spring A
Spring B
Oil Chamber
Port 1
T178-03-06-013
Control Valve Side
Shockless Valve (Outside of Signal Control Valve)
E
(Boom Lower Circuit)
Spring C
Port B
D
Port A2
Orifice
Ring
T3-6-9
T16J-03-06-003
Plunger
COMPONENT OPERATION / Signal Control Valve
PUMP 1 AND PUMP 2 FLOW RATE CONTROL VALVES
The pump flow rate control valve delivers the pilot oil
pressure to the 4-spool or the 5-spool pressure sensor
in response to the pilot oil pressure from the pilot valve.
The signal from the 4-spool or the 5-spool pressure
sensor is sent to MC, MC drives the pump control solenoid valve and controls the flow of the pump.
1. The pilot oil pressure from the pilot valve is routed
into the spring chamber side in either the pump 1
or the pump 2 flow rate control valve after being
selected by the shuttle valves in the signal pilot
pressure control valve.
2. Then, the spool is moved to the right, causing the
primary pilot pressure to flow into either port SA or
SB.
3. Therefore, the pressure in port SA or SB increases.
4. The oil pressure in port SA or SB acts on the right
end of the spool . Thus, the spool is moved back
to the left until the pressure in port SA or SB balances with the pilot pressure in the spring chamber so that the pressure in port SA or SB stops increasing.
NOTE: The pump 1 flow rate control valve operates when the boom (raise or lower), arm
(roll-in or out), bucket (roll-in or out), and
travel (right) functions are operated. The
pump 2 flow rate control valve operates
when the boom (raise), arm (roll-in or out),
swing (right or left), auxiliary, and travel
(left) functions are operated.
T3-6-10
COMPONENT OPERATION / Signal Control Valve
Spring
Port SA, SB
Spool
Primary Pilot Pressure
Pilot Pressure
Shuttle Valve
T178-03-06-017
T3-6-11
COMPONENT OPERATION / Signal Control Valve
FLOW COMBINER VALVE CONTROL
SPOOL, SWING PARKING BRAKE RELEASE SPOOL
Flow Combiner Valve Control Spool:
Swing Parking
To Hydraulic Brake Release
Pressure
Oil Tank
Spool
Spring
NOTE: The two captioned spools are identical in
operational principle.
The flow combiner valve control spool is shifted by the
right travel control pilot pressure, allowing the primary
pilot pressure to flow to the flow combiner valve in the
control valve.
The swing parking brake release spool is shifted by the
boom, arm, bucket, or auxiliary control pilot pressure,
allowing the primary pilot pressure to flow to the swing
motor.
Right Travel
Control Pilot
Pressure
T178-03-06-014
To Flow Combiner
Valve
Swing Parking Brake Release Spool:
To Hydraulic
Oil Tank
Primary Pilot
Pressure
Spool
Spring
T178-03-06-014
Pilot
Pressure
T3-6-12
To Swing Motor
COMPONENT OPERATION / Others (Upperstructure)
PILOT SHUT-OFF VALVE
The pilot shut-off valve is a manual-operated switch
valve. The spool in the pilot shut-off valve is rotated by
moving the pilot control shut-off lever to turn on or off
the pilot oil flow to the pilot valves.
• Valve Operation with Pilot Control Shut-Off
Lever in LOCK Position
The pilot shut-off valve is set in the neutral position.
Pressure oil from the pilot pump does not flow into
the pilot valves, but it is routed to the signal control
valve. Pilot oil on the pilot valve side is routed to the
hydraulic tank as drain passages in the pilot shut-off
valve open.
Section Z-Z
• Valve Operation with Pilot Control Shut-Off
Lever in UNLOCK Position
The pilot shut-off valve is set in the operating
position, allowing pressure oil from the pilot pump to
flow into the pilot valves. The pilot pressure can be
and will be routed to the control valve to operate the
respective hydraulic cylinders and/or motors as the
pilot valves are operated, in other words, as the
control levers are operated.
A2
To Signal
Control Valve
A1
From Pilot
Valve
T178-03-07-002
Z
Z
T1
T2
T3
A3
A4
P
A5
A1 - Right Pilot Valve
A2 - Travel Pilot Valve
A3 - Left Pilot Valve
T4
T178-03-07-003
A4 - Signal Control Valve
(Port PI)
A5 - Signal Control Valve
(Port PH)
P - Primary Pilot Pressure
T1 - Travel Pilot Valve
T2 - Left Pilot Valve
T3 - Right Pilot Valve
T3-7-1
T - Hydraulic Oil Tank
COMPONENT OPERATION / Others (Upperstructure)
SOLENOID VALVE
Solenoid Valve Unit
Controls the control valve and the travel motor valve
in response to the signal from MC (Main Controller).
The solenoid valve unit consists of three proportional
solenoid valves (SA, SB and SC).
(Refer to “SYSTEM/Control System”.)
Pilot Relief Valve
SA : raises the main relief valve pressure in the
control valve.
SB : controls the travel speed shift valve.
SC : control the overload relief pressure in the
boom cylinder (rod side) circuit.
(Boom Mode Selector Control)
Solenoid Valve (Swing Preference)
Gives priority to the swing or the boom raise during
the combined operation of the swing and the boom
raise.
MC controls the solenoid valve and changes boom 1
and boom 2 in the control valve at the same time.
T17V-01-01-016
SA SB SC
Pilot Relief Valve
Is combined with the solenoid valve unit.
The pilot relief valve functions to set the pilot pressure
delivered to port P to a certain level.
T17V-01-01-008
Solenoid Valve
(Swing Preference)
T3-7-2
COMPONENT OPERATION / Others (Upperstructure)
ACCUMULATOR
The accumulator is provided in the pilot circuit to buffer
fluctuations in oil pressure, and to maintain the pilot
pressure for a short time period after the engine is
stopped.
The accumulator mainly consists of body (5), holder
(4), bladder (2), which encloses nitrogen gas (N2), and
poppet (1).
• Pressure oil from the pilot pump enters into the
accumulator via port A. Pilot pressure
compresses the nitrogen gas in bladder (2) until
they balance against each other.
6
5
1
Nitrogen Gas
(N2 )
2
4
• When pressure supply is stopped due to engine
stall or any other reasons, bladder (2) starts
expanding, supplying accumulated oil into the pilot
circuit via port A.
Pilot Pressure Oil
3
A
T105-02-10-003
1 - Poppet
2 - Bladder
3 - Oil Port
T3-7-3
4 - Holder
5 - Body
6 - Gas Plug
COMPONENT OPERATION / Others (Upperstructure)
EC MOTOR
The EC motor is used to control engine speed. A worm
gear is incorporated into the EC motor to prevent a
loss of synchronism from occurring. The EC sensor is
provided to detect the degrees of the EC motor rotation
to calculate the governor lever position. (Refer to the
Control System Group in SYSTEM Section.)
Output
Gear
Output
Shaft
Worm
Gear
Motor
Sensor
Gear
EC
Sensor
Worm
Wheel
T157-02-05-018
T3-7-4
COMPONENT OPERATION / Others (Undercarriage)
SWING BEARING
The swing bearing supports the upperstructure weight
and functions to rotate the upperstructure smoothly.
This bearing is a single-row shear ball-type bearing,
comprising outer race (1), inner race (3), balls (6),
supports (5), rod/turn buckle assembly (7) and seals
(2), (4). Outer race (1) is bolted to the upperstructure
and inner race (3) is bolted to the undercarriage.
The internal gear of inner race (3) engages with the
output shaft of the swing reduction gear.
1
2
3
5
6
4
7
T162-03-07-001
1 - Outer Race
3 - Inner Race
5 - Support
2 - Seal
4 - Seal
6 - Ball
T3-8-1
7 - Rod/Turn Buckle
Assembly
COMPONENT OPERATION / Others (Undercarriage)
CENTER JOINT
The center joint is a 360° rotating joint. The center joint
functions to allow hydraulic oil to flow smoothly to and
from the travel motors without twisting hoses while the
upperstructure is rotated.
The spindle is attached to the main frame, and the
body is bolted to the swing center of the undercarriage.
Hydraulic oil flows to the right and left travel motors via
the spindle and the oil ports of the body. Seals prevent
oil leaks between the spindle and body into adjacent
passages.
Spindle
Body
Seal
T16J-03-07-001
T3-8-2
COMPONENT OPERATION / Others (Undercarriage)
TRACK ADJUSTER
The track adjuster located on the side frame is
composed of spring (5) and adjuster cylinder (6).
Spring (5) absorbs loads applied to the front idler.
Adjuster cylinder (6) adjusts track sag.
• Grease is applied through grease fitting into
chamber a of adjuster cylinder (6) as illustrated
below. The pressure of the grease pushes piston
rod (8) out and decreases track sag.
• To increases track sag, loosen valve (1) 1 to 1.5
turns counterclockwise to release grease from the
track adjuster cylinder through the grease
discharge hole.
1
Grease Fitting
CAUTION: The adjusting cylinder is highly
pressurized. Loosening valve (1) quickly
and/or excessively may cause valve (1) to fly
off and the highly pressurized grease to
spout out, possibly resulting in personal
injury.
Be sure to loosen valve (1) slowly and
gradually, keeping face and body parts away
from valve (1). In addition, never attempt to
loosen the grease fitting.
1
2
3
4
a
Grease Discharge Hole
M104-07-119
5
7
8
T17V-03-08-001
1 - Valve
2 - Nut
3 - Washer
4 - Spacer
5 - Spring
6 - Adjuster Cylinder
T3-8-3
7 - Flange
8 - Piston Rod
COMPONENT OPERATION / Others (Undercarriage)
(Blank)
T3-8-4
MEMO
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Hitachi Construction Machinery Co. Ltd
Hitachi Ref. No.
Attn: Publications, Marketing & Product Support
Fax: 81-298-31-1162
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