PART NO. 897671

2000 SRM 576

SAFETY PRECAUTIONS

MAINTENANCE AND REPAIR

•

When lifting parts or assemblies, make sure that all slings, chains or cables
are correctly fastened and that the load being lifted is balanced. Make sure
that the crane, cables and chains have the capacity to support the weight of
the load.

•

Do not lift heavy parts by hand. Use a lifting mechanism.

•

Wear safety glasses.

•

DISCONNECT THE BATTERY CONNECTOR before doing any
maintenance or repair on electric lift trucks. Disconnect the battery ground
cable on internal combustion lift trucks.

•

Always use correct blocks to prevent the unit from rolling or falling. See
“How To Put The Lift Truck On Blocks” in the OPERATING MANUAL or
the PERIODIC MAINTENANCE section.

•

Keep the unit and working area clean and in order.

•

Use the correct tools for the job.

•

Keep the tools clean and in good condition.

•

Always use

HYSTER

APPROVED

parts when making repairs.

Replacement parts must meet or exceed the specifications of the original
equipment manufacturer.

•

Make sure that all nuts, bolts, snap rings and other fastening devices are
removed before using force to remove parts.

•

Always fasten a DO NOT OPERATE sign to the controls of the unit when
making repairs or if the unit needs repairs.

•

Make sure you follow the DANGER, WARNING and CAUTION notes in
the instructions.

•

Gasoline, Liquid Petroleum Gas (LPG), and Diesel are flammable fuels.
Make sure that you follow the necessary safety precautions when handling
these fuels and when working on these fuel systems.

•

Batteries generate flammable gas when they are being charged. Keep fire and
sparks away from the area. Make sure the area has ventilation.

1

INTRODUCTION

GENERAL

This section has a description and the repair procedure
for the main control valve.

DESCRIPTION
(See FIGURE 1)

The main control valve is a manually actuated valve that
controls the operation of the lift, tilt and auxiliary cylin-
ders. The main control valve is installed to the right of
the operator’s seat. It is fastened to a bracket on the
frame of the lift truck. The main control valve has the
following sections:

•

operating inlet and lift section

•

tilt section

•

auxiliary section(s)

The sections are held together with through bolts.

Each function of the main control valve is made as a
separate section having a spool and valve body. The out-
er section body castings are the same, as are the center
section body castings. The control spools are different
for each function. Additional sections may be added be-
tween the outer sections and the center section to control
optional auxiliary functions.

Each spool has a spring that returns the spool to the neu-
tral position when the control lever is released. Each
valve section has a check valve in the valve body.

AUXILIARY SECTION 2

AUXILIARY SECTION 1

TILT SECTION

OPERATING INLET AND LIFT SECTION

FIGURE 1 – MAIN CONTROL VALVE

2

COUNTERBALANCE SPOOL

0.47 IN

DIAMETER

RELIEF VALVE

SECONDARY

RELIEF

PRIMARY

RELIEF

ALTERNATE PRESSURE PORT

(IN “R” INLET BODY)

HYDRAULIC CONTROL VALVE

4 SPOOL ARRANGEMENT

SATURATION/DAMPING

ORIFICE

0.173 IN
DIAMETER
PARTIAL FLOW
BY-PASS ORIFICE

FROM PUMP

TO FILTER
AND TANK

FIGURE 2 – MAIN CONTROL VALVE SCHEMATIC

AUXILIARY 2

AUXILIARY 1

TILT

LIFT

OPERATION
(See FIGURE 2)

The main control valve is an open center, parallel circuit
valve. When open center valve spools are in the neutral
position, the hydraulic oil flows through the valve with
minimum restriction. The oil returns through the drain
passage and is directed through the filter to the hydraulic
tank. In a parallel circuit valve, each spool can be oper-
ated without preventing the flow of oil to another spool.

This valve has three parallel passages through the valve.
See FIGURE 2. When the spools are in the neutral posi-
tion, the oil flows through the open center passage. At
the end of the valve, the oil returns through the drain pas-
sage and returns to the hydraulic tank. A spool makes a
restriction in the open center passage when the spool is
moved from the neutral position. This restriction causes
an increase in pressure in the parallel passage. The par-
allel passage is common to all sections of the valve, but
oil cannot flow freely through it. The increased pressure
in the parallel passage causes the oil to flow through a
check valve into a supply cavity in the valve body. The
spool gives a path from the supply cavity to the hydrau-
lic cylinder to do work.

The control valve can have three or four control levers.
The first lever to the right of the operator controls the
lifting and lowering of the mast. The second lever con-
trols the tilt function. The third control lever is for at-
tachments and has two methods of operation depending
on the attachment.

•

Control Lever With Detent – Required For
Attachments With a Clamp Action: The lever
is spring-loaded toward the operator. The lever is
operated by moving it to the right, then forward or
backward.

•

Control Lever Without a Detent –
Attachments Without a Clamp Action: The
lever is operated by moving forward or
backward.

The fourth control lever has a detent and is spring-
loaded toward the operator. The lever is operated by
moving it to the right, then forward or backward.

Lift Section

When the spool is moved to the Lift position, the spool
makes a restriction in the open center passage. The in-
creased pressure in the parallel passage causes oil to
flow through the check valve to the supply cavity. The

3

oil flows from the supply cavity through a section of the
spool to the lift cylinder.

When the spool is in the Lower position, the spool opens
a path from the lift cylinder to the drain cavity. The spool
is made so that the oil flow through the open center pas-
sage is not stopped.

Tilt Section

The basic operation of the tilt spool is the same as the
other spools in this control valve. However, the tilt spool
is designed with a counterbalance spool built into the tilt
spool, which adds an additional sequence to the tilt for-
ward function. The counterbalance spool is used to pre-
vent the forks from tilting forward faster than the pump
can supply oil and prevent premature tilt.

TILT BACKWARD

When retracted past Neutral position the tilt spool
causes a restriction of the oil flow through the open cen-
ter passage. The increased pressure in the parallel pas-
sage causes the oil to flow through the check valve to the
supply cavity. The oil flows from the supply cavity
through a section of the spool to the tilt cylinders. The
check valve prevents the movement of the load until the
system pressure is great enough to control the load. Oil
from the piston end of the tilt cylinder returns through
the main control valve and to the hydraulic tank.

TILT FORWARD

The tilt control counterbalance spool, that is inside of
the tilt spool, operates during the tilt forward function.
The counterbalance spool prevents cavitation in the pis-
ton end of the tilt cylinders. Cavitation occurs when the

available fluid does not fill the space in a closed system.
The high vacuum causes some of the fluid to change to
bubbles of gas. When cavitation occurs in the tilt cylin-
ders, the tilt forward function is not smooth. The tilt con-
trol counterbalance spool will keep the mast from mov-
ing forward if the tilt spool is actuated when the motor is
not running.

During the tilt forward, the tilt control counterbalance
spool controls the flow of oil from the tilt cylinders to
maintain a positive pressure at the piston end of the cyl-
inder to prevent cavitation. This action makes sure that a
vacuum cannot occur at the piston ends of the tilt cylin-
ders. It also provides for better control of the mast and
the load.

The center sections of the main control valve, tilt and
auxiliary (when used), have pressure compensated flow
controls. These controls are externally adjustable to
maximize the flow and speeds for the tilt and auxiliary
functions.

Relief Valve

Pressure relief valves control the maximum system op-
erating pressures. The main relief valve senses the lift
and tilt system pressure. When the pressure rises to 19.3
MPa (2800 psi), the relief valve opens to protect the lift
and tilt system. The secondary relief valve senses the
auxiliary system pressure and is set to open at 15.5 MPa
(2250 psi). The relief pressures are preset at the factory
and should require no further adjustments. These set-
tings should be good for all mast options – Two stage
with limited free lift, Two stage with full free lift or
Three stage with full free lift.

REPAIRS

MAIN CONTROL VALVE
(See FIGURE 3 and FIGURE 4)

Removal




Before making any repairs to the control valve, tilt
the forks until they are parallel with the floor. Lower
the mast until the forks rest on the floor. This action

will prevent the mast from lowering suddenly when
the hydraulic lines are disconnected.

1. Fully lower the mast.

2. Disconnect the battery. Remove the battery to gain
access to the mounting capscrews for the hydraulic con-
trol valve. Follow the instructions in PERIODIC
MAINTENANCE, 8000 SRM 528 or 8000 SRM 584
for battery removal information.

3. Operate the control valve levers in both directions to
relieve any hydraulic pressure.

4

4. Release the locking mechanism retaining the top
cover and raise the cover. Remove the capscrews secur-
ing the hydraulic control valve top front cover, and the
lower cover to remove the covers.

5. Mark and disconnect the hydraulic hoses at the el-
bows. Drain any excess hydraulic oil into a suitable con-
tainer. Install plugs in the hydraulic hoses and the el-
bows to prevent leaking and to prevent dirt from enter-
ing the system.

NOTE:

Remove the hoses starting from the outboard

top position, then the bottom position and then next the
top position until all the hoses are removed.

6. Disconnect the electrical connection to the hydrau-
lic circuit board. Tag and disconnect the wires to the cut
off switch. If the circuit board must be serviced or tested,
see ELECTRICAL SYSTEM, 2200 SRM 577 or 2200
SRM 585.




Be careful when removing or installing snap rings.
These snap rings can come loose during removal or
installation with enough force to cause an injury. Al-
ways use the correct snap ring pliers and wear eye
and face protection during removal and installation.

7. Remove the cotter pins and clevis pins retaining the
links to the hydraulic control valve. NOTE: On some
models there may be three links, while other models
have four links. Remove the snap ring retaining the piv-
ot pin for the lifting mechanism located on the outboard
side of the lift truck. Remove the nut and washer retain-
ing the pivot pin on the inboard side of the truck. Re-
move the pivot pins, spacers, washers bracket, torsion
spring and special screw. Note the order of disassembly
for proper installation at assembly. Remove the control
handles and linkage, along with the top rear cover from
the lift truck.




The hydraulic control valve is heavy. Be sure that all
lifting devices (hoists, cables, chains, slings etc.) are
suitable and of adequate capacity to lift the hydrau-
lic control valve. The hydraulic control valve can
weigh between 11.4 to 13.6 kg (25 to 30 lb) without
any attachments.

8. Support the hydraulic control valve. Remove the
four capscrews, washers, lockwashers, nuts and brack-

ets retaining the hydraulic control valve and the support-
ing bracket to the frame. Carefully lift the hydraulic con-
trol valve and the supporting bracket out of the lift truck.

9. Move the hydraulic control valve to a workbench
for disassembly. Clean the exterior of the control valve.

Installation




The hydraulic control valve is heavy. Be sure that all
lifting devices (hoists, cables, chains, slings etc.) are
suitable and of adequate capacity to lift the hydrau-
lic control valve. The hydraulic control valve can
weigh between 11.4 to 13.6 kg (25 to 30 lb) without
any attachments.

1. Make certain that the four rubber isolators are
installed on the supporting bracket. Position the hydrau-
lic control valve and supporting bracket in the lift truck.
Install the four capscrews, washers, lockwashers, nuts
and brackets to retain the control valve to the frame.




Be careful when removing or installing snap rings.
These snap rings can come loose during removal or
installation with enough force to cause an injury. Al-
ways use the correct snap ring pliers and wear eye
and face protection during removal and installation.

2. Align and install the hand levers and linkage by
installing the pivot pins, spacers, washers, bracket, tor-
sion spring and special screw on the inboard side of the
lift truck. Install the pivot pin, washers and spacers on
the outboard side of the truck. Install the snap ring to re-
tain the pin.

3. Align the links with the hydraulic control valve and
install the clevis pins and new cotter pins.

4. Remove the caps from the hoses and the elbows and
connect the hydraulic hoses. See FIGURE 5.

NOTE:

Install the hoses starting with the inboard bot-

tom position, then the top position and then the next bot-
tom position until all the hoses are installed.

5. Connect the electrical wires to the cut off switch,
and the connector to the printed circuit board.

6. Check the level of the hydraulic oil in the tank. If
necessary add hydraulic oil.

5

14 12

13

13

13

14

14

14

12

8

9

7

8

9

6

10

1116 3

15

17

5

10

11

39

45

37

38

36

34

50

49 48

46

51

2

1

43

42

41

39

40

52

39

44

47

45

5

33

32

39

45

24

22

23

18

21

20 19

26

29

25

27

28

35

39

31 30

4

FIGURE 3 – MAIN CONTROL UNIT MOUNTING

1. SCREW
2. LOWER COVER
3. STAND-OFF
4. STAND-OFF
5. CAPSCREW
6. VANE-LIFT
7. VANE-PUMP
8. CAPSCREW
9. WASHER

10. LOCKWASHER

11. NUT

12. LINK
13. COTTER PIN
14. PIN
15. PIN
16. SNAP RING

17. WASHER-SHIMS
18. PIN
19. SPRING
20. NUT
21. LOCKWASHER
22. STUD
23. PIN-WELDMENT
24. SPACER
25. SWITCH
26. SCREW
27. LOCKWASHER
28. NUT

29. BRACKET
30. CAPSCREW
31. WASHER
32. LOCKWASHER
33. NUT
34. P.C. BOARD
35. CAPSCREW
36. WASHER
37. LOCKWASHER
38. NUT

39. BRACKET
40. CAPSCREW
41. WASHER
42. LOCKWASHER
43. NUT
44. RUBBER CHANNEL
45. RUBBER CHANNEL
46. CONTROL VALVE
47. CAPSCREW
48. WASHER
49. LOCKWASHER
50. NUT
51. CAPSCREW
52. VALVE BRACKET

6

7

11 10

9 31

35

36

40

30, 33 40

28

8

29

1

3

2

6

5

4

11

10

9

8 11

10

9

8

11

10

9

36

34

36

40

37
33

40

35

38

39

41

13

38

40

32
33

40

35

36

40

32

40 35 36

40 32

8

35

40

16

18

19

25

26

27

20

21

22

15

17

24

23

39

12

38

14

14

38

FIGURE 4 – MAIN CONTROL VALVE UPPER LEVER MOUNTING

1. SCREW
2. COVER–FRONT
3. COVER–REAR
4. HAND LEVER–LIFT
5. HAND LEVER–TILT
6. HAND LEVER–3RD FUNCTION
7. HAND LEVER–4TH FUNCTION
8. CAPSCREW
9. WASHER

10. LOCKWASHER

11. NUT

12. STANDOFF
13. STANDOFF
14. CAPSCREW
15. KNOB
16. PIN
17. LATCH ROD
18. LATCH
19. CAPSCREW
20. WASHER
21. LOCKWASHER
22. NUT

23. LOCKOUT STRAP
24. CAPSCREW
25. WASHER
26. LOCKWASHER
27. NUT
28. PIN
29. SPRING
30. CRANK
31. PIVOT
32. CRANK
33. SPACER

34. LINK
35. COTTER PIN
36. PIN
37. ROCKER ARM
38. SNAP RING
39. PIVOT PIN
40. FLANGE BEARING
41. LINKAGE FRAME

7

FEED FROM PUMP

TO FILTER

LIFT

TILT

AUXILIARY 2

AUXILIARY 1

FIGURE 5 – HYDRAULIC LINE ARRANGEMENT

7. Install the battery. Follow the instructions in PE-
RIODIC MAINTENANCE, 8000 SRM 528 or 8000
SRM 584 for battery installation information. Connect
the battery connector.

8. Operate the hoist, tilt and auxiliary controls. Check
for leaks from the hydraulic hoses and valve connec-
tions.

9. Install the hydraulic control valve top front cover,
and the lower cover.

Disassembly
(See FIGURE 6)




The hydraulic control valve is heavy. Be sure that all
lifting devices (hoists, cables, chains, slings etc.) are
suitable and of adequate capacity to lift the hydrau-
lic control valve. The hydraulic control valve can
weigh between 11.4 to 13.6 kg (25 to 30 lb) without
any attachments.

NOTE:

Disassemble the main control valve as neces-

sary for repairs. Most repairs to the main control valve
are for the replacement of O-rings and seals to stop

leaks. The passages in the tilt spool are small and can
need cleaning if the hydraulic oil becomes dirty. The
section normally must be replaced if the spool or valve
section is damaged.

1. During disassembly, particular attention should be
given to the identification of the parts for assembly.
Spools are selectively fitted to the valve bodies and
must be returned to the same bodies from which they
were removed. Valve sections must be assembled in the
same order.

2. Plug all the fittings and clean the outside of the
valve before disassembly and repair.

3. Remove the four nuts and separate the valve sec-
tions. Be careful not to damage the springs and balls be-
tween the sections. Remove all the O-rings and retain-
ers.

4. Remove the two capscrews that secure each of the
dust covers. Remove the dust covers.

5. Slide the operating spool out of its bore and remove
the O-rings from the groove in the spool and from the
valve body around the spool bore. Remove the retainer,
sleeve, O-ring, quad ring.

8

1

2

3

4

1. OUTLET AND AUXILIARY

SECTION 2

2. AUXILIARY SECTION 1
3. TILT SECTION
4. OPERATING INLET AND

LIFT SECTION

5. AUXILIARY SPOOL 2
6. AUXILIARY SPOOL 1
7. TILT SPOOL
8. LIFT SPOOL

5

6

7

8

FIGURE 6 – MAIN CONTROL UNIT DISASSEMBLED

9

6. On the outer sections, use a punch through the hole
provided in the section to free the retainer. Remove the
retainer. Install a 10-24 UNF

1.5 capscrew in the

check valve plug. Grip the capscrew with pliers and pull
the plug out of the valve body. Remove the O-ring and
back-up ring. Remove the spring and ball from the valve
body.

7. On the center sections, use a punch through the hole
provided in the section to free the retainer. Use an Allen
wrench to remove the plug. Remove the O-ring and
back-up ring. To remove the relief seat, use an awl or
other pointed tool to tip the seat so that one of the ears are
out of the grooves in the valve body. Remove the spring
and poppet from the valve body.

8. Unscrew the plug on the outer section that retains
the relief valve and remove the O-ring from the plug.
Remove the spring and the relief valve. Remove the
plug, O-ring, spring and poppet valve.

9. If the operating inlet and lift secton must be re-
placed, remove the plug and O-ring from the blocked
cylinder port.

Cleaning and Inspection




Cleaning solvents can be flammable and toxic and
can cause skin irritation. When using cleaning sol-
vents, always follow the solvent manufacturer’s rec-
ommended safety procedures.

Discard all old seals and O-rings. Clean all parts of the
control valve with solvent.

1. Check the spools and bores for burrs or scoring. If
the scoring is not deep enough to cause objectional leak-
age, polish or stone the spool using crocus cloth. If the
burrs and scores cannot be removed, replace the spool or
valve section. Check the control valve spools for smooth
movement in their mating control valve bore.

2. Inspect the check valves and relief valves for dam-
age or erosion. Replace any damaged parts.

3. Check the parts of the linkage for the control valve
levers. Replace worn parts as necessary.

NOTE:

Check valve malfunctioning is usually the re-

sult of foreign matter lodging between the seat and the
poppet. Examine the seat for dirt or metal particles.
Check the seating face for nicks or scratches and, if pres-

ent, they can be removed by lapping using a fine lapping
compound. However, care must be exercised to prevent
the lapping compound from entering or remaining in the
valve. Examine the spring and replace if it is weak, bro-
ken or distorted.

4. All machined surfaces between the inlet and outlet
sections (which include the plunger sections) are ground
and must be free of dirt or any raised burrs. If present, the
burrs must be removed by lapping on a perfectly smooth
flat steel surface using a fine lapping compound. Clean
the section thoroughly to avoid lapping compound re-
maining in any of the valve passages.

Examine the machined O-ring counterbores. Make sure
the surfaces are smooth and completely free of dirt, pits,
rust or metal particles.

Assembly

NOTE:

Coat all the parts with clean hydraulic oil to

facillitate assembly and provide initial lubrication. Pe-
troleum jelly may be used to hold the O-rings in place
during assembly.

1. If the plug and O-ring were removed from the oper-
ating inlet and lift section, install the plug and a new O-
ring in the new section.

2. Install the poppet, spring, O-ring and cap in the out-
er auxiliary section. Install the relief valve, spring, O-
ring and plug in the other port.

3. Install the poppet, spring and relief seat in the center
section(s). Install a new O-ring, back-up ring and plug in
the port. Install the retainer to lock the plug in position.
Make certain that the retainer is seated in the groove in
the port.

4. Assemble the C-washers, springs, quad rings, O-
rings, sleeves and retainers on the spools. Install the
spools in the proper sections. Align the dust cover and
install the capscrews to retain the covers to the sections.

5. Align the sections and install the springs, O-rings,
retainers and balls between the sections.

6. Install the tie rods. All the tie rods are 9.6 mm (0.38
in) in diameter. Assemble the nuts on the tie rods and use
a torque wrench to tighten the nuts. Tighten the nuts to
38-41 N

m (28-30 lbf ft) torque.

7. Check the relief valves for proper adjustment. The
relief valve pressure for the tilt and lift functions should

10

open at 19.3 MPa (2800 psi), to protect the lift and tilt
system. The secondary relief valve for the auxiliary

functions should open at 15.5 MPa (2250 psi) to protect
the auxiliary system.

CHECKS AND ADJUSTMENTS

RELIEF VALVE

1. Install a tee in the inlet line to the main control
valve. Install a pressure gauge in the tee.

2. Check the operation of the relief valve as follows:

a. Run the pump at normal operating speed, so that

the pump is developing the proper flow and has
reached operating temperature.

b. Operate the tilt spool of the control valve until the

tilt cylinder is at the end of its stroke long enough
to get a pressure reading on the gauge.

3. Check the pressure reading with the recommended
pressure.

4. Remove the pressure gauge and the tee from the in-
let line.

VANE SETTINGS

Should the need arise to remove the control valve
printed circuit board, or the valve levers, the vanes on
the levers will need to be set up in relation to the printed
circuit optical interrupter switches. This procedure
should be done before installing the control valve cov-
ers.

1. Be sure the slotted section of each vane is aligned
with each optical interrupter both horizontally and verti-
cally. Make certain that the vanes are on the correct le-
vers. There are two different vanes used. The vane with
the two slots is only used on the lift lever to provide for
two speed operation.

2. Each vane has slotted holes to allow the vanes to be
moved up or down within the optical interrupter. On the
levers with the single slot, locate the slot in the center of
the optical interrupter switches. The two speed vane
should be located so the top ear of the vane passes
through the upper optical interrupter switch as soon as
the lever is moved to the rear. Loosen the capscrews and
nuts to move the vanes up or down as required, then
tighten the capscrews and nuts.

3. Test each lever for correct operation before putting
the lift truck back into service after making any adjust-
ments.

OPTICAL INTERRUPTER
SWITCH

VANE

FIGURE 7 – ALIGNING VANES




Failure to adjust the control valve properly may
cause either pump motor failure or fuse failure.

4. Install the hydraulic control valve top front cover
and the lower cover using the capscrews.

MAST TILT ADJUSTMENT
(See FIGURE 8)



When a mast is being changed to one of a different
height, the mast tilt speed must be adjusted. Follow
the instructions in CAPACITIES AND SPECIFI-
CATIONS, 8000 SRM 571 or 8000 SRM 586.

If the mast is being changed to one of a different height,
make certain to adjust the travel tilt speed of the main
control valve for full back to full forward tilt.

Remove the nut from the bottom tie bolt. The bottom tie
bolt has a screwdriver slot to aid in the removal of the tie
bolt. Remove the tie bolt.

Install an Allen wrench in the adjusting screw and adjust
the screw to change the mast tilt speed. Turning the
screw counterclockwise will cause the tilt control to op-

11

erate faster. Adjust the screw to obtain the recom-

mended tilt speed as noted in CAPACITIES AND

SPECIFICATIONS, 8000 SRM 571 or 8000 SRM

586. The auxiliary section 1, adjacent to the tilt section,

can also be adjusted to increase or decrease the flow of

hydraulic oil through the valve. Follow the same proce-

dure to adjust auxiliary section 1 as listed for the tilt sec-
tion.

After the proper adjustment has been achieved, install
the tie bolt through the valve sections and install the nut
on the tie bolt. Tighten the nut to 38-41 N

m (28-30 lbf

ft) torque.

FIGURE 8 – CONTROL VALVE TILT ADJUSTMENT

TILT OR AUXILIARY 1
ADJUSTMENT SCREW

TROUBLESHOOTING

PROBLEM

CAUSE

Oil leaks at the end of a spool.

Seal for spool requires replacement.

Spool needs repair.

Valve body needs repair.

Spool will not move or is difficult to move.

Linkage is disconnected or needs repair.

Return spring is needs repair.

The spool or bore needs repair.

Spool will not return to NEUTRAL.

Linkage is disconnected or needs repair.

Spring is weak or broken.

Hydraulic pressure is above specifications.

Pressure relief valve(s) is not adjusted correctly or
needs repair.

Restriction in return line.

Tilt cylinders extend when the tilt spool is in the
NEUTRAL

iti

Cylinder seal have leaks.

NEUTRAL position.

Oil leaks between control valve spool and bore.

Hydraulic lines have leaks.

12

TROUBLESHOOTING

PROBLEM

CAUSE

Tilt cylinders extend suddenly when the tilt spool is

d t BACK TILT

iti

Check valve for tilt spool needs repair.

moved to BACK TILT position.

Check vane adjustment on tilt linkage.

Tilt cylinders extend suddenly when the tilt spool is

d t FORWARD TILT

iti

Tilt control spool inside the tilt spool needs repairis.

moved to FORWARD TILT position.

Check vane adjustment on tilt linkage.

Lift cylinders retract when the lift spool is in the
NEUTRAL

iti

Check valve for the lift spool needs repair.

NEUTRAL position.

Cylinder seals have leaks.

Hydraulic lines have leaks.

Leaks between the lift spool and the bore.

Return spring is weak or broken.

Dirt between spool and the bore.

Spool is bent or needs repair.

Motor not driving pump at proper speed.

Pump needs repair.

Slow or no movement of cylinders.

Linkage is disconnected or needs repair.

Pressure relief valve(s) not adjusted correctly or needs
repair.

Large leaks between spool and bore.

Spool is not fully extended or retracted.

Motor not driving pump at proper speed.

Pump needs repair.

Air is in the hydraulic system.

The hydraulic pump is worn or needs repair.

Restriction in the hydraulic lines.

Cylinder seals require replacing.

Load is greater than capacity.

TECHNICAL PUBLICATIONS

2000 SRM 576

6/95 (5/95)(6/94) Litho in U.S.A.

TECHNICAL PUBLICATIONS