5/10/2013
ANSWERS to TECHNICAL QUESTIONS General concepts across Many Product Lines
Every thing you ever wanted to know about HOIST BRAKES ©
1. HOIST BRAKES Torque Requirement
2. 2nd BRAKE SYSTEMS
ALSO SEE HANDOUT 3. DC vs. AC
4. Regenerative Brakes
Mike D. James
Vice President & GM Industrial Cranes
5. Mechanical Load brakes
6. SHOE Brakes vs. DISC Brakes
7. Disc Brakes vs. DISC Brakes 8. IS there a “BEST” Brake ?
9. What should YOU specify ?
NOT JUST LIFTING THINGS,
BUT ENTIRE BUSINESSES
COMMON Brake TERMONOLOGY
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Brake Shoes, Linings
Brake Discs
Dynamic Braking “Modules”
Braking Resistors
Brake Alternator
“Off” position Braking
Traverse Brake = Bridge, Trolley
Hoist Brakes
Motor Mounted Brake
•Brake Wheels
•Lock Nut
•“Slotted ‐Unslotted
•Tapper Bore
•Supernut™
•Material types:
•Cast Iron, Steel , Carburized
COMMON Brake TERMONOLOGY
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Brake Pot
Brake Coil
Brake Armature
Link, Arm, Rod etc
Brake Rectifier
Impulse Actuator
“Thruster”®
•Hydraulic Brake
•Master Cylinder
•Brake Cylinder
•SBE‐SBM‐SBI‐SB
•GP‐GPE‐GPI‐GPM
•CD
•SD
HOIST BRAKES •Load Brakes vs. Motor Brakes vs. Dynamic Brakes, vs Magnetorque Brakes
Magnetorque = Eddy Current
DISC BRAKES
What is an EDDY Current ?
WHY DC ? Vs AC ?
brakes
SHOE Brakes (larger motors)
Thruster type actuator vs. Magnet actuator
While I will attempt to touch on most of these items I will focus on just 2:
1.HOLDING vs. Control brakes
2.Regenerative Braking
Your handout will fill in many of the blanks. WESTON TYPE Mechanical LOAD Brake
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5/10/2013
Brakes:
Overhead Crane Safety Considerations
Meeting Current Standards
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ASME B30.2 ‐ American National Standard for Overhead and Gantry Cranes. Rev. 1996 w/1998 Addenda •
OSHA (Code of Federal Regulations) Article 29, Part 1910.179, Rev. 7/1/97
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CMAA Specs #70 and #74, Revised 1999
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AIST Spec 6 , •
NEMA •
FEM, ISO and others…….
Hoists shall have a holding brake and a control braking means.
ASME B30.2
Equipment Safety Requirements
DISC Type HOLDING BRAKE
Shoe type holding brake
Eddy current control brake
with DC MAGNET actuator coil
COMMON Brake TERMONOLOGY
•HOLDING BRAKES
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There are AC Brakes
•Control Braking Means
STOP & Holds
Motor Brake
Shoe Brake
Electric Disc Brake
Mechanical Load Brake
“Locking” Worm Gear
Load Brake
And – Slows / Controls speed
– Mechanical Load Brake
• Weston type
• “Locking” Worm Gear
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DC Brakes
Magnetorque
Eddy Current
Dynamic Braking
Regenerative
Countertorque
WHICH are Better ?
SOME BASIC ELECTRICAL FACTS
Fail Safe = Spring set & Requires Electrical Power to release
DC vs AC DISC Brake Advantages.
DC vs. AC and “eddy” currents
+
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DC = ONE WAY power
ALL AC coils use LAMINATED cores
Circulating Eddy currents GENERATE HEAT
Laminations help break up & Isolate Eddy currents & Heat
+ + + +
60 HZ
‐ ‐ ‐ ‐
• FACTS: •
•
ALL AC COILS GET HOT due to “EDDY CURRENTS”
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AC coils use Laminated steel poles to break up and minimize EDDY Currents.
Laminations fail / vibrate …Buzzz
cause coil failure
HOT coil adds to Brake lining heat
AC reacts releases very fast = Hammering action
SHORTER
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•
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– coil life – Lining life
•DC coil = NO EDDY currents
•DC coil = “COOL” no extra heat
•DC coil = SOLID no lamination construction
•DC coil = SLOW release •mili‐seconds to create DC
•Slower flux buildup
•BETTER POSITIONING
PLUS all DC brakes are NOT EQUAL
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5/10/2013
TYPICAL DC DIRECT ACTING Hoist Brake
P&H D.C. Rectified Disc Brake
Sizes Models
•SD‐1….4‐10 ft lbs
ƒ DC Rectified for cooler operation & positive positioning
•CD‐1
ƒ 150% Braking Torque Min to as much as (170‐220%)
•CD‐2
CDH
•CD‐3
CDD‐
•CD‐4
ƒ SOME MANUFACTURERS offer :
•CD‐5
Minimal if any Brake adjustments for life of the lining and 1 Million operations
•CD‐6…...450. Ft lbs
2nd DC ELECTRIC HOLDING BRAKE is usually an AVAILABLE OPTION
TORQUE LIMITS
Typical SHOE Brakes
Self‐Adjusting SHOE Brakes
Most brakes
must be
continually
adjusted as
the lining
wears-and
this involves
troublesome
mechanical
linkages,
starwheels,
or like
devices.
Plus costly
downtime.
SHOE BRAKE Sizes
Uniform Torque Ratings
Uniform Shaft / Wheel Height
Uniform Mounting Bolt Dimensions
“GP” “AISE”
GP Brakes
•GPE
•GPI
•4”
•5”
•6”
•8”
•7”
•10”
•GPML
•9”
•13”
•GPMW
•11”
•16”
•12”
•19”
•15”
•23”
•18”
•30”
•GPM
•GPA
•NON‐NEMA sizes
•Lower cost
•Lighter duty
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5/10/2013
AISE/NEMA Rated Impulse® Brakes
Other “Thrustor®” style Brakes
Impulse Actuator or “Thruster”
Super NUT
Replaces DC Brake “Pot”
•Designed for Severe Duty Service
•NO RECTIFIER
•SMOOTH Set /release “SQUEEZING”
•NO POUNDING
•Unlimited duty cycle Actuator
AC (or DC) MOTOR Weston Type Mechanical Load Brake
“Weston Type ” Mechanical Load Brakes
What happens when Gearing fails?
The Load will fall !
Even with a Mechanical load brake!
HOW DOES IT WORK ?
MOTOR has to DRIVE to load both UP and DOWN
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5/10/2013
Rope Drum Brakes
Mechanical Load Brakes
Designs available on some
1. GENERATES HEAT IN the Gearbox
1. 2nd “Holding” Brake
2. Helps “share” work 2. Worn Lining debris of the main contaminates OIL
Holding brake
3. Can “Mask” failed 3. May Hold load if Main Brake
first brake doesn't
4. No Help if Gears fail
Big Crane Drum brakes
“Package hoists”
For SPECIAL applications requiring a second HOLDING BRAKE
Magnetorque® Eddy Current Brakes
• How Do they work
• Why / Where used ?
• Applicable control Schemes
• 5 step Full Magnetic Hoist
• Static Stepless®
• Advantages
• Competitors
• Stromag®
• Eaton Dynamatic®
Magnetorque®
SHOE type HOLDING BRAKE
(Eddy Current Brake)
Sizes / Model #
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Single Shaft Double Shaft
Foot Mtd
83
105
143
1412
2408
2412
Brake Rectifier
Magnetorque Brake
Motor / Flange Mtd
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5/10/2013
NAME THE BRAKE 1
Dynamic Braking = Energy Generation
2
Energy Generation = DYNAMIC BRAKING
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3
5
DYNAMIC or Regenerative Braking
STATOR FIELD ROTATES
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GENERATOR = MOTOR Electricity IN • Gravity / Wind / Force
• IN GENERATOR
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MOTOR
Squirrel cage motors
+ + + +
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60 HZ
+
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MOTOR ROTOR
2 pole @60 Hz = 3600RPM
Follows & tries to catch 4 pole @60 Hz = 1800 RPM
6 pole @60 Hz = 1200 RPM
8 pole @60 Hz = 900 RPM
Motor stator
2 pole @30 Hz = 1800 RPM
Electrical Stator field will either PULL the rotor around as a MOTOR
+
2 pole @15 Hz = 900 RPM
OR The rotor with the aid of Gravity will PUSH the ‐
Magnetic Field around the Stator GENERATING ELECTRICTY
instead of USING IT and the Stator will hold the rotor Back
acting like
a BRAKE
IF the Rotor LEADS or is pulled against
the the
ANTI –GRAVITY or FORCE Electricity OUT
OUT
STATOR rotation, POWER is Generated and REGENERATED back to the line and BRAKING occurs
2 speed & AFD Hoists
use DYNAMIC BRAKING / REGERATIVE BRAKING
TEST QUESTION + + + +
HZ
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STATOR FIELD ROTATING
WHAT DO YOU NEED FOR REGENERATIVE BRAKING TO OCCUR?
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NO Electrical Power to the motor = NO REGENERATIVE BRAKING +
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Inverters
REGENERATED ENERGY
IS BURNED OFF AS HEAT
DB Module
Resistor Banks on Large HP
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5/10/2013
LATEST VFD DRIVES
ELECTRIC CHAIN HOISTS TYPICAL BRAKES
TODAY
•Regenerative Speed Control Braking
• Optional Mechanical Load brake – A few Brands
1. Use regenerated energy off the DC BUSS to drive other motions
2. Convert Excess energy back into 60HZ AC and Pump it back into the line TEST – What did we learn?
•Direct acting Electric Disc Type Load / Motor Brake ‐FAIL SAFE
THANK YOU 1. Name 2 types of Holding Brakes.
2. Name 2 types of CONTROL BRAKING Means.
3. Name 2 reasons why A DC brake is superior to an AC Brake.
4. What are 3 weaknesses of using a Mechanical load brake
5. What is required for Regenerative Braking to work ?
6. Which brakes will work if there is a power outage ? 7. What are the 2 types of brakes required by ANSI /ASME?
8. What does Fail Safe mean ?
9. Why don’t Large capacity cranes use Weston type Mechanical load brakes?
10. Which Braking system is most likely to keep a load from falling.
NOT JUST LIFTING THINGS,
BUT ENTIRE BUSINESSES
Mike D. James
Vice President- Industrial Cranes
Konecranes Inc.
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