REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
Table of contents
1. Introduction ........................................................................................................................................................ 3
1.1. Scope of use ................................................................................................................................................. 3
1.2. General remarks ........................................................................................................................................... 3
1.3. Contact Hyva................................................................................................................................................. 3
1.4. Precautions ................................................................................................................................................... 4
1.5. Spare parts.................................................................................................................................................... 4
1.5.1. Prior to use ................................................................................................................................................. 4
1.6. Recycling and Reuse of components ........................................................................................................... 4
1.6.1. General ....................................................................................................................................................... 4
1.6.2. Reuse of components ................................................................................................................................ 4
1.7. Warranty........................................................................................................................................................ 5
2. Disassembly ....................................................................................................................................................... 6
2.1. Components UM ........................................................................................................................................... 6
2.2. Components UL ............................................................................................................................................ 7
2.3. Removing the cylinder from the vehicle ........................................................................................................ 8
2.3.1. UMB and ULB removal ............................................................................................................................... 8
2.3.2. UME and ULE removal ............................................................................................................................... 8
2.3.3. Removing the cylinder from the cradle ....................................................................................................... 9
2.4. Dismantling the cylinder .............................................................................................................................. 10
2.4.1. Opening the base of the UL cylinder ........................................................................................................ 10
2.4.2. Opening the base of the UM cylinder ....................................................................................................... 11
2.4.3. Removing the piston ................................................................................................................................. 11
2.4.4. Removing the stages ................................................................................................................................ 12
3. Cylinder Assembly ........................................................................................................................................... 13
3.1. Replacing packset ....................................................................................................................................... 13
3.2. Replacing stages ........................................................................................................................................ 14
3.3. Replace piston ............................................................................................................................................ 15
3.4. Closing the cylinder ..................................................................................................................................... 15
3.4.1. UL Bottom plate ........................................................................................................................................ 15
3.4.2. UM Bottom................................................................................................................................................ 16
3.5. Refitting the cylinder to the vehicle ............................................................................................................. 16
4. Connecting and testing the cylinder ................................................................................................................. 17
4.1. Connection of the hydraulic system ............................................................................................................ 17
4.2. Final Checks ............................................................................................................................................... 18
4.3. Painting the cylinder .................................................................................................................................... 18
5. Spare part codes .............................................................................................................................................. 19
6. Exploded view UMB cylinder ........................................................................................................................... 20
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
1.
Introduction
1.1.
Scope of use
This manual is for repair workshops and service partners repairing the Hyva under body cylinders, manufactured
from 2010 onwards (the UM and UL series), where it is necessary to disassemble the cylinder to replace parts that
are subject to wear (i.e. seal kit).
The Hyva underbody cylinder range includes Underbody-Medium-Ball (UMB), Underbody-Medium-Eye (UME),
Underbody-Light-Ball (ULB) and Underbody-Light-Eye (ULE) cylinders. Separate instructions are available for other
types of cylinders.
Always use original Hyva components.
1.2.
General remarks
Specification sheets are available for all Hyva cylinders; these sheets contain all relevant dimensional and
application information about your cylinder.
The Hyva cylinder has been developed for lifting purposes only and its use for any other purpose is prohibited.
The cylinder is not to be used as a stabiliser and any kind of side-load must be avoided whenever possible.
For two- or three-way tipping a cradle has to be used. For a vehicle designated for rear or side tipping, Hyva highly
recommend to use a cradle for cylinders with a stroke of 1000 mm and more. This is to minimise side load and to
ensure a longer packset life.
Warning
Applying side-load to any cylinder is dangerous.
The cylinder should be mounted with a minimum pull out of 15 mm and a
maximum pull out of 50 mm (the closed length of the cylinder on the Hyva
specification sheet already includes 20 mm pull out).
The advice given in these pages is by no means complete and should not be used as an alternative to common
sense.
See Hyva document OIL-0002 for recommended oils.
1.3.
Contact Hyva
If you have any questions concerning the application, installation, operation or repair of any Hyva product - please
contact your nearest Hyva Service Partner and check the Hyva website (both for documentation as for service
partner coordinates):
www.hyva.com
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
1.4.
Precautions
Ensure there is enough free working space for mounting the cylinder.
If the tipper body is on the truck chassis, lift the body using an overhead crane or a similar device.
If the tipper body is raised to create working space, support the body using body props before mounting the
cylinder.
Danger
Working under an unsupported tipper body is a danger to life.
To avoid damage to the truck cabin, cover the rear of the cab with a tarpaulin.
If necessary tilt the vehicles cabin (see the truck manual for details).
Disconnect the vehicle’s battery leads before any welding.
Warning
Not using the appropriate equipment when lifting parts (such as the proper sling
for a cylinder) is a danger to life.
Some parts in the cylinder are mounted under tension (i.e. snap rings) they may
spring out when removed. They should be secured when removed to prevent
injury.
Ensure any oil spilt during installation and testing is disposed of in an environmental friendly way.
1.5.
Spare parts
To avoid ordering the wrong parts Hyva recommends ordering spare parts listed in this document, see also
www.hyva.com.
1.5.1. Prior to use
Clean all parts to remove any dust, dirt or protective coatings. Check parts for damage during transport or
storage. Do not use any damaged parts.
If for any reason the above conditions cannot be met contact your nearest Hyva Service
Partner for further guidance.
1.6.
Recycling and Reuse of components
1.6.1. General
Remove and dismantle the components as described in this manual. Clean all parts thoroughly (using degreaser
and compressed air). All oil products must be disposed of in an environmental friendly manner (usually by a
licensed disposal agent). The components can then be recycled in the normal way. For example; non-metal
components such as seals and wipers with plastic materials, clean steel parts with other scrap metals.
1.6.2. Reuse of components
When the Hyva cylinder is stripped (for example after inspecting a cylinder) some parts may be reused.
Warning
Never use parts from a cylinder that has been subject to overpressure.
Using second hand parts in cylinder repairs can change the function or operating
conditions of the cylinder and may affect the terms of warranty.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
Assuming the following parts are in good working condition (i.e. no visible damage such as scratches, imprints or
deformation, no corrosion and dimensionally correct) then they may be reused:





Base, Stages, and Piston,
Sliders, Bottom
Lift rings when not deformed during dismantling
Spherical Cup, Locking Ring Set and Circlip
Cradle, Brackets
The following parts must never be reused:


1.7.
Packset (seals, wear rings, wipers)
O-ring
Warranty
The Hyva International B.V. warranty terms are described in the General Sales Terms, Hyva document FOE000130.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.
Disassembly
2.1.
Components UM
FIGURE 1: CROSS-SECTION OF THE UMB CYLINDER
Components:
1
=
2
=
=
3
=
4
=
5
=
6
=
*
1 wiper
1 wear ring (stages shorter than 500 mm)
2 wear rings (stages longer than 500 mm)
1 seal
1 inner stop ring
1 slider
1 lift ring*
Stage diameters 091, 110, 129 & 149 have rectangular lift rings
Stage diameters 072, 169 & 191 have round lift rings
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.2.
Components UL
1
2
3
4
5
6
FIGURE 2: CROSS-SECTION OF THE ULB CYLINDER
Components:
1
=
2
=
3
=
4
=
5
=
6
=
1 wiper
1 wear ring
1 seal
1 inner stop ring
1 slider
1 lift ring (round)
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.3.
Removing the cylinder from the vehicle
Danger
Working under an unsupported tipper body is a danger to life!
2.3.1. UMB and ULB removal
Tip the body or lift this with another device and secure the
body with a support. Remove the circlip, locking ring set and
spherical piston cup (Figure 3).
Spherical
Locking
rings
Circlip
FIGURE 3
2.3.2. UME and ULE removal
Tip the body or lift this with another device and secure the body with a support. Remove the pivot pin from the
piston eye, the actual method will depend on eye and top bracket. In general remove the split-pin and then
remove the pivot pin (Figure 4).
FIGURE 4
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.3.3. Removing the cylinder from the cradle
Disconnect the hydraulic connection after having made sure there is no pressure left in the system. Unscrew the
bolts from the cradle, remove closing plates and remove cylinder (in case of no obstruction).
FIGURE 5: REMOVAL OF THE CYLINDER FROM THE CRADLE
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.4.
Dismantling the cylinder
Place the cylinder horizontal on a clean bench with the oil inlet facing down. Clamp the base securely to assure
safe working conditions (a “V” block arrangement is usually the best) and collect any waste oil.
2.4.1. Opening the base of the UL cylinder
Push with a soft-headed mallet or similar the bottom plate
inside (approximately 20mm). Remove the snap-ring by pushing
the tip of a screwdriver under the ring at one end and levering
the ring out (Figure 6). If necessary, remove paint before
removing bottom.
Warning
The snap-ring is mounted under tension, it may spring out
which can be dangerous.
FIGURE 6
Strike the head of the piston with a soft-headed mallet or
similar. This will push the bottom plate from the base tube.
(Figure 7)
FIGURE 7
Remove the O-ring from the bottom plate (Figure 8).
FIGURE 8
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.4.2. Opening the base of the UM cylinder
Unscrew the locking screw from the bottom nut and use a
chain spanner to disassemble the bottom nut. Remove the Oring from the bottom.
FIGURE 9
2.4.3. Removing the piston
All pistons have two part sliders, these should be removed to avoid loss or damage.
To remove the piston, push the piston into the stage until the
lift ring is visible at the inside diameter of the larger stage
(Figure 10).
Warning
The lift ring is mounted under tension, it may spring out
which can be dangerous!
Remove the lift ring by pushing the tip of a screwdriver under
the ring at one end and levering the ring out (Figure 10).
FIGURE 10
The piston can now be removed through the bottom of the
cylinder (Figure 11).
FIGURE 11
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
2.4.4. Removing the stages
Warning
The stages must be placed on a clean surface to prevent scratches and other
damage.
Never remove a stop ring, if it shows signs of damage the whole stage must be
replaced.
The seals, wear rings and wipers must not be re-used.
Before a stage can be removed through the bottom of the
cylinder, the lift ring of the next stage must be removed.
Remove the lift ring in the same way as for the smallest stage.
The stage can then be removed through the bottom of the
cylinder.
Subsequent stages can be removed in the same way.
Remove the seal, wiper and wear rings from the internal
grooves at the top of each stage (Figure 12).
Warning
Do not remove the seals and wipers with a screwdriver or
other sharp instrument as this may irreparably damage the
grooves and cause leaks. Only the wear rings can be
removed with a screwdriver.
FIGURE 12
Clean each stage carefully and check each groove and the tube surface for any irregularities. Check also the sliders
on each tube; if these are damaged, they should be replaced.
If the slider is damaged, check the stop ring in the larger stage tube for signs of damage or twisting.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
3.
Cylinder Assembly
3.1.
Replacing packset
Clean each stage thoroughly and apply sufficient grease to the packset and the grooves (Figure 13).
Put a new packset into each stage (Figure 14); starting with the
seal,
… followed by the wear rings
FIGURE 13
… and the wiper
Caution
Ensure that each of the rings are seated correctly in the
grooves; incorrect fitting can cause seizure, leaks or
damage.
FIGURE 14
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
3.2.
Replacing stages
Slide the first (largest) stage almost fully in the base tube
(Figure 15), ensuring that the stage is not scratched when
passing the inner stop ring. Some resistance will occur when
the tube enters the packset.
To prevent damage and assemble easy, use grease at
bottom inside of the base tube.
FIGURE 15
Place the sliders at the bottom side of the stage (Figure 16).
Slide the tube further in to the base until the sliders are in
the base tube.
Sliders 149 and bigger for UM cylinder must be mounted with
the flat side facing upwards (which contacts inner stopring).
FIGURE 16
After mounting a stage, fit the lift ring (Figure 17) in the
previous stage (except for the cylinder base).
Subsequent stages can be mounted in the same way.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
3.3.
Replace piston
The piston tube is mounted in the reverse sequence to dismantling. Make sure that no sharp edges are at the top
side that can damage the packset.
3.4.
Closing the cylinder
3.4.1. UL Bottom plate
Clean the groove for the bottom plate O-ring. Fit a new O-ring to the bottom plate and slide the bottom plate into
the base (Figure 18) using plenty of grease (Figure 19) to avoid damage to the O-ring.
FIGURE 18
FIGURE 19
The bottom plate is mounted in the reverse sequence to dismantling.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
3.4.2. UM Bottom
Clean the groove for the bottom O-ring. Fit a new O-ring to the bottom and screw the bottom on the base (Figure
20) using plenty of grease to avoid damage to the O-ring.
FIGURE 20
The bottom is mounted in the reverse sequence to dismantling.
3.5.
Refitting the cylinder to the vehicle
The mounting instructions are described in Hyva document CYL-0024.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
4.
Connecting and testing the cylinder
4.1.
Connection of the hydraulic system
Connect the hydraulic system as specified by the hydraulic kit. Remove the plug from the oil-inlet and connect the
cylinder to the hydraulic system (Figure 21). Do not fully screw in oil inlet adaptor but leave 1-2 mm to give the
adaptor the possibility to rotate (swivel).
FIGURE 21. EXAMPLE OF A HYDRAULIC SYSTEM
Ensure there is sufficient hose length so it does not obstruct the movement of the cylinder while tipping.
It is not necessary to bleed air from the cylinder after assembly (air is
automatically discharged during the first few tips).
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
4.2.
Final Checks
The first tip should be slow and all movements are to be closely observed to check:
 Cylinder movement is smooth
 Hoses do not interfere with any parts
 Cylinder extends in a straight line
 While tipping, there is no contact between the rear/side end of the body and other parts of the
truck (such as towing-hooks, tail lamps etc.)
Tip the body 4 or 5 times and check there is no side-load on the cylinder and the clearances are correct.
If you find the cylinder movement is stiff, loosen the bolts and realign the cylinder. Protect hoses where they
move against metal parts (if they cannot be repositioned). It is not necessary to bleed air from the cylinder.
Tip
During the first few tips some packset grease may appear on the stages of the cylinder,
this is normal and does not mean the cylinder is leaking.
Where the installation does not operate as expected, see “Operating & Maintenance Instructions – Complete
Tipper” for full details of use including trouble-shooting guide (Hyva document: TIP-0005).
Cylinder stages should extend in right sequence: largest (first stage) extends first, then second stage etc. With a
new cylinder, a light empty body and high pump flow however, stages can extend in wrong sequence
(mismatching). But this will disappear in normal operation (loaded body).
4.3.
Painting the cylinder
When repainting, do not repaint the blank parts of the cylinder e.g. trunnion pins, piston, stages, wipers,
balls/eyes.
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
5.
Spare part codes
Tip
Use nylon rod (100 00 080) to ease the dismantling of the cylinder
Consult the appropriate specification sheet for each special cylinder version
I
Parts for piston ball mounting
Retainer kits for UMB and ULB cylinders. Retainer kits contain the spherical cup, locking rings and circlip.
Ball
Diameter
D45
D53
D65
D75
TABLE 1: RETAINER KITS
II
Retainer kit
017 45 100
017 45 101
017 45 102
017 45 103
Sealkits, bottom plate O-ring, oil inlets and retainer kits
Cylinder Type
Seal kit Part Number
Bottom Plate O-ring
UL 077-2
71906620K
75 x 4 70 shore
UL 077-3
71906630K
“
UL 093-3
71906730K
90 x 4 70 shore
UL 093-4
71906740K
“
UL 110-3
71906830K
107 x 4 70 shore
UL 110-4
71906840K
“
UL 110-5
71906850K
“
UM 129-3*
71904430K
01226680
UM 129-4*
71904440K
“
UM 129-5*
71904450K
“
UM 129-5 (>500) **
71904451K
“
UM 149-4*
71904540K
01226709
UM 149-5*
71904550K
“
UM 149-6*
71904560K
“
UM 169-4 (>500) **
71904641K
01226780
UM 169-5*
71904650K
“
UM 169-6*
71904660K
“
UM 169-7*
71904670K
“
UM 191-5*
71904750K
01226840
UM 191-6*
71904760K
“
UM 191-7*
71904770K
“
UM 191-8*
71904780K
“
TABLE 2: SEALKITS, BOTTOM PLATE O-RING, OIL INLETS AND RETAINER KITS
Oil inlet
Retainer kit
1/2" p/n:73103000
“
“
“
“
“
“
“
“
“
“
3/4" p/n:73103002
“
“
“
“
“
“
“
“
“
“
017 45 101
017 45 100
017 45 101
017 45 100
017 45 102
017 45 101
017 45 100
017 45 103
017 45 102
017 45 101
017 45 101
017 45 103
017 45 102
017 45 101
017 45 103
017 45 103
017 45 102
017 45 101
017 45 103
017 45 103
017 45 102
017 45 101
NOTES:
*
**
After opening an UM cylinder, a new locking screw M6 should be applied in the bottom after
remounting the bottom, p/n 01792571
Cylinders with a stage length bigger than 500 mm have a different packset: 2 wearrings per stage
instead of one
subject to change without notice
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REPAIR INSTRUCTIONS
UNDER BODY CYLINDER (UM, UL)
6.
Exploded view UMB cylinder
0 / 20 / 30 / 40- WIPER, WEARRING(S) AND SEAL
1- BASE
21- STAGE
31- STAGE
2- BOTTOM O-RING
22- SLIDER
32- SLIDER
3- BOTTOM
23- LIFT RING
33- LIFT RING
4- LOCKING SCREW
5- OIL INLET
41- STAGE
42- SLIDER
43- LIFT RING
100- RETAINER KIT
101- PISTON
102- SLIDER
The sealkit contains all relevant wipers, wearrings, seals and bottom O-ring for the specific cylinder.
subject to change without notice
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