STEERING CONTROL

UNIT

H3.50-5.50XM (H70-120XM) [K005, L005];

S3.50-5.50XM (S70-120XM) [E004, F004]

PART NO. 1466241

1600 SRM 732

SAFETY PRECAUTIONS

MAINTENANCE AND REPAIR

• When lifting parts or assemblies, make sure all slings, chains, or cables are correctly

fastened, and that the load being lifted is balanced. Make sure 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 Mainte-
nance section.

• Keep the unit clean and the working area clean and orderly.

• 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 all nuts, bolts, snap rings, and other fastening devices are removed before

using force to remove parts.

• Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs,

or if the unit needs repairs.

• Be sure to follow the WARNING and CAUTION notes in the instructions.

• Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel

are flammable. Be sure to 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 is well ventilated.

NOTE:

The following symbols and words indicate safety information in this

manual:

WARNING

Indicates a condition that can cause immediate death or injury!

CAUTION

Indicates a condition that can cause property damage!

Steering Control Unit

Table of Contents

TABLE OF CONTENTS

General ...............................................................................................................................................................

Description .........................................................................................................................................................

Operation............................................................................................................................................................

Steering Wheel and Column Assembly Repair ................................................................................................

Remove and Disassemble ..............................................................................................................................

Assemble and Install .....................................................................................................................................

Steering Control Unit ....................................................................................................................................

Disassemble ...............................................................................................................................................

Clean ..........................................................................................................................................................

Assemble ....................................................................................................................................................

System Air Removal ..........................................................................................................................................

Troubleshooting..................................................................................................................................................

This section is for the following models:

H3.50-5.50XM (H70-120XM) [K005, L005];

S3.50-5.50XM (S70-120XM) [E004, F004]

"THE

QUALITY

KEEPERS"

HYSTER

APPROVED

PARTS

1600 SRM 732

Operation

General

This section contains description and repair pro-
cedures for the steering housing and steering
control unit.

Additional information on parts

of the steering system are in the following sec-
tions: for H3.50-5.50XM (H70-120XM) models, see

Steering Axle 1600 SRM 733. For S3.50-5.50XM
(S70-120XM) models, see Steering Axle 1600 SRM
326. For both models, see Hydraulic System 1900
SRM 743.

Description

The steering control unit is a hydrostatic unit that
is controlled by the steering wheel. See Figure 1.
The control unit is installed on a bracket at the cowl
and is operated by the column assembly and steering
wheel. The steering control unit has a control section
and a metering section.

The steering system is a hydraulic system that does
not have a mechanical connection between the steer-
ing wheel and steering axle. Control of the steering
is through a hydraulic circuit.

If the hydraulic pump for the steering system does
not operate, steering is still possible. A check valve
permits the steering control unit to control the steer-
ing cylinder. The lift truck is difficult to steer when
the steering pump is not operating, but the steer-
ing control unit can operate the steering cylinder and
make steering possible.

Operation

The steering control unit is a rotary valve operated by
the steering wheel. See Figure 1. During the steer-
ing operation, the steering control unit controls the
direction of flow and amount of oil that flows to the
steering cylinder. The steering cylinder in the axle
actuates the steering linkage to move the steering
tires. Hydraulic oil returns from the steering cylin-
der to the steering control unit and then returns to
the hydraulic tank.

Turning the steering wheel actuates three main
parts of the steering control unit: (1) the spool for
the control section, (2) the sleeve for the control
section, and (3) the rotor in the metering section.
When the steering wheel is not moving, the spool
and sleeve are held in the neutral (center) position
by springs. During this time, oil flows freely through
the steering control unit, but does not flow to the
steering cylinder.

As the steering wheel is turned, the spool begins to
rotate. The springs try to move the sleeve to keep the
neutral position between the spool and sleeve. The
force necessary to turn the rotor is greater than the
pressure of the springs. The springs begin to bend,
letting the spool move a small amount within the

sleeve. The spool stops moving when it touches the
center pin. In this position, the holes in the sleeve
and the spool are aligned. Oil coming into the con-
trol unit flows to the metering section.

Further rotation of the steering wheel causes the
spool to rotate the pin. This action causes the ro-
tation of the sleeve and the rotor in the metering
section. Oil then flows to one side of the steering
cylinder. Hydraulic oil from the other side of the
steering cylinder returns through the control section
of the steering control unit.

When the steering wheel stops moving, the metering
action in the metering section also stops. The neu-
tral position springs return the sleeve to the neutral
position stopping oil flow to or from the cylinder. The
pressure stays in the steering cylinder to keep the
steering tires in position. Oil from the pump flows
through the steering control unit to the tank or other
parts of the system. To return the steering tires to
the straight position, the steering wheel must be ro-
tated in the opposite direction. The steering control
unit will operate as described, but all parts will ro-
tate in the opposite direction.

Operation

1600 SRM 732

CONTROL SECTION

MEASURING SECTION

CHECK VALVE CHANGES CONTROL UNIT TO
HAND OPERATED UNIT WHEN ENGINE IS OFF

CENTERING SPRINGS RETURN VALVE TO
NEUTRAL

SPOOL AND SLEEVE ASSEMBLY

HORN CONTACT ARRANGEMENT

TYPICAL STEERING SHAFT ASSEMBLY

SHAFT AND COLUMN ASSEMBLY

Figure 1. Steering Control Unit

1600 SRM 732

Steering Wheel and Column Assembly Repair

The upper end of the steering shaft has splines for the
steering wheel. A large nut holds the steering wheel
onto the steering shaft. The horn button is the cover
for the center of the steering wheel. The lower end of
the steering shaft has splines to engage the steering
control unit. Contacts at the horn button, a wire in
the column, and slip ring contacts in the column as-
sembly allow for horn operation by the operator (see
Figure 1).

The steering column assembly is adjustable and held
in position by a latch. The assembly position can
be changed as needed for operator comfort. See Fig-
ure 2.

REMOVE AND DISASSEMBLE

CAUTION

Disconnect the negative battery cable on inter-
nal combustion trucks. Disconnect the battery
before removing any covers.

Attach a tag on the battery connector or negative
cable stating DO NOT CONNECT BATTERY.
Move steering column to most forward position.

Remove screws that fasten column housing to
bracket. Remove front housing from steering col-
umn assembly. See Figure 2.

Remove horn button. Loosen screw that connects
horn wire to horn button and remove wire from
horn button. Remove nut and steering wheel.

Disconnect microswitch on shift lever. Remove
the four bolts holding shift lever assembly to
bracket. Remove shift lever assembly by sliding
it up steering column.

For lift truck models

H3.50-5.50XM (H70-120XM), if necessary, dis-
assemble shift lever assembly as described
in section Two-Speed Powershift Trans-
mission - Repairs 1300 SRM 728 or section
Single-Speed Powershift Transmission -
Repairs 1300 SRM 752. For lift truck models
S3.50-5.50XM (S70-120XM), if necessary, dis-
assemble direction control lever as described

in Single-Speed Powershift Transmission -
Repairs 1300 SRM 397.

NOTE:

To aid in installation, tag hydraulic hoses at

steering control unit during removal.

Disconnect hydraulic hoses from bottom of steer-
ing control unit. Install caps on hoses and plugs
in ports to prevent dirt from entering hydraulic
system. Remove steering control unit.

Remove screws, washers, and lockwashers that
fasten steering column and steering control unit
to bracket.

If necessary, disassemble steering control unit as
shown in Steering Control Unit, Disassemble.

Remove steering column.

Remove horn wire

cover on side of steering column. Pull horn wire
out of steering column.

If necessary, remove all parts of latch from
bracket. If necessary, remove all parts of spring
mechanism and pivot to remove bracket from
cowl of lift truck.

ASSEMBLE AND INSTALL

If removed, install bracket, pivot, and spring
mechanism on cowl of lift truck.

If removed,

install latch on bracket. See Figure 2.

Push horn wire through hole in lower end of
steering column. Install screws that fasten the
wire harness cover to steering column. Attach
horn wire to horn.

If necessary, assemble steering control unit as
shown in Steering Control Unit, Assemble.

Install steering column and steering control unit
in the bracket. Install screws, washers, and lock-
washers that fasten steering column and steer-
ing control unit to bracket.

Steering Wheel and Column Assembly Repair

1600 SRM 732

Figure 2. Steering Wheel and Steering Column Assembly

1600 SRM 732

Steering Wheel and Column Assembly Repair

Legend for Figure 2

SCREW

STEERING COLUMN HOUSING (LOWER)

PLUG

HORN BUTTON

SCREW

HORN WIRE

NUT

STEERING WHEEL

MICROSWITCH

10. SHIFT LEVER ASSEMBLY
11. HEX HEAD BOLT
12. LOCKWASHER
13. WASHER
14. STEERING COLUMN
15. STEERING CONTROL UNIT
16. BRACKET
17. SCREW
18. COVER
19. SCREW

20. LATCH (KNOB)
21. SPRING
22. WASHER
23. ROD
24. LATCH (GEAR)
25. PIN
26. COTTER PIN
27. SPRING
28. HEX HEAD BOLT
29. LOCKWASHER
30. PLATE
31. SHAFT
32. NUT
33. HEX HEAD BOLT
34. STEERING COLUMN HOUSING (UPPER)
35. NUT
36. LOCKWASHER
37. HEX HEAD BOLT
38. BRACKET

WARNING

The hydraulic hoses MUST be connected to
the correct ports and fittings or the steering
system will not operate properly.

Improper

operation can cause damage or personal in-
jury. Make sure the hoses are identified and
connected correctly.

Connect hydraulic hoses to bottom of steering
control unit.

For

lift

truck

model

H3.50-5.50XM

(H70-

120XM), if necessary, assemble shift lever as
described in section Two-Speed Powershift
Transmission - Repairs 1300 SRM 728 or sec-
tion Single-Speed Powershift Transmission
- Repairs 1300 SRM 752. For lift truck models
S3.50-5.50XM (S70-120XM), if necessary, assem-
ble direction control lever as described in Single
Speed Powershift Transmission - Repairs
1300 SRM 397. Slide shift lever assembly down
steering column.

Install the four screws that

fasten shift lever assembly to bracket. Connect
the microswitch.

Install steering wheel and nut. Pull horn wire
through steering column and attach it to horn
button. Install horn button into steering wheel.
Install column housing over the bracket. Insert
housing plugs if necessary. Install screws that
fasten housing to bracket.

Remove battery tag and connect battery connec-
tor or cable.

WARNING

After making repairs, do not extend the hands
or arms through the center of the steering
wheel. If the control unit was not assembled
correctly or the hoses are not connected cor-
rectly, it can rotate with a strong force and
cause serious injury.

If this action occurs,

disassemble the control unit and correct the
problem.

Operate steering system to check for correct op-
eration and leaks.

Steering Wheel and Column Assembly Repair

1600 SRM 732

STEERING CONTROL UNIT

Disassemble

Disassemble steering control unit as follows:

STEP 1.

Place steering control unit in a vise with soft jaws.
Make an identification mark the length of control
unit to aid in proper assembly of steering control
unit.

STEERING CONTROL UNIT

VISE

STEP 2.

Remove capscrews and cover on the bottom of steer-
ing control unit. Remove and discard O-ring. Remove
check ball.

CAPSCREW

COVER

O-RING

CHECK BALL

1600 SRM 732

Steering Wheel and Column Assembly Repair

STEP 3.

Put a mark on the stator so that the same side will
be toward the body of the control unit at assembly.
Remove stator, rotor, and distributor plate. Remove
and discard O-rings. Remove center shaft.

STATOR

ROTOR

DISTRIBUTOR PLATE

O-RING

CENTER SHAFT

STEP 4.

Remove check valve assembly. Remove and discard
shaft seal.

CHECK VALVE ASSEMBLY

SHAFT SEAL

Steering Wheel and Column Assembly Repair

1600 SRM 732

STEP 5.

Turn spool and sleeve assembly until centering pin is horizontal. Remove spool and sleeve assembly from
housing. Remove and discard dust seal. Remove thrust washers and thrust bearing from spool and sleeve
assembly. Remove retaining ring and centering pin from spool and sleeve assembly. Remove spool from sleeve.
Remove neutral position springs from spool.

SPOOL AND SLEEVE
ASSEMBLY

DUST SEAL

THRUST WASHER

THRUST BEARING

RETAINING RING

CENTER PIN

SPOOL

SLEEVE

NEUTRAL POSITION
SPRINGS

10. HOUSING

Clean

WARNING

Cleaning solvents can be flammable and toxic and can cause skin irritation. When using cleaning
solvents, always follow the solvent manufacturer’s recommended safety precautions.

Clean all parts in solvent.

WARNING

Compressed air can move particles so that they cause injury to the user or to other personnel.
Make sure that the path of the compressed air is away from all personnel. Wear protective goggles
or a face shield to prevent injury to the eyes.

Dry parts with compressed air. Do not dry parts with a cloth.

Make sure all surfaces are free of scratches and sharp edges.

1600 SRM 732

Steering Wheel and Column Assembly Repair

Assemble

Use new seals, O-rings, and neutral position springs during assembly. Lubricate all parts with clean hydraulic
oil. Assemble steering control unit as follows:

STEP 1.

Install dust seal and shaft seal in housing.

HOUSING

DUST SEAL

SHAFT SEAL

STEP 2.

Assemble spool and sleeve. Make sure spool rotates
freely in the sleeve.

SPOOL

SLEEVE

Steering Wheel and Column Assembly Repair

1600 SRM 732

STEP 3.

Assemble the neutral position springs, and then push them into position in the spool. Make sure flat springs
are installed to the outside of the curved springs. Install retaining ring on sleeve (over the neutral position
springs). Retaining ring must rotate freely on sleeve. Install center pin.

NEUTRAL POSITION SPRINGS (FLAT)

NEUTRAL POSITION SPRINGS (CURVED)

CENTER PIN

SPOOL

RING

STEP 4.

Install thrust washers and thrust bearing on spool. Place housing horizontally in a vise with soft jaws. Guide
spool and sleeve assembly into housing with centering pin horizontal.

HOUSING

SPOOL AND SLEEVE
ASSEMBLY

THRUST WASHER

THRUST BEARING

CENTERING PIN

1600 SRM 732

Steering Wheel and Column Assembly Repair

STEP 5.

Install check valve assembly into port. Lubricate O-ring and install into housing. Install distributor plate.
Make sure holes in distributor plate are aligned with holes in housing.

CHECK VALVE ASSEMBLY

HOUSING

O-RING

DISTRIBUTOR PLATE

STEP 6.

Install center shaft so that it engages with center pin
in spool and sleeve assembly. Make sure center pin
is still parallel to the surface with the ports. Install
rotor on center shaft. Make sure that a valley in the
rotor aligns with the slot (center pin) in the center
shaft. Install O-ring and stator. Make sure to align
the marks made during disassembly.

CENTER PIN

CENTER SHAFT

ROTOR

STATOR

O-RING

Troubleshooting

1600 SRM 732

STEP 7.

Install O-ring and cover. Tighten capscrews for cover
in the sequence shown to 30 N•m (267 lbf in). Make
sure capscrew with pin fits in hole for the check ball.

O-RING

COVER

CAPSCREW

CHECK BALL

System Air Removal

Air can enter the system when a hydraulic line is dis-
connected. If operation is rough, start engine and ro-
tate steering wheel from stop to stop several times in

each direction. Air will be removed without discon-
necting any lines. If operation is still rough, check if
air is entering system at a loose fitting.

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

Steering tires do not move
when

steering

wheel

turned.

Oil level is low or there is no oil in
tank.

Fill tank to correct level. Check for
leaks.

Steering control unit is damaged.

Repair or install new control unit.

No oil flow from steering control unit
to steering cylinder.

Repair or install new components.
Check for leaks.

Sleeve and spool in control unit will
not move.

Install new components.

1600 SRM 732

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

Steering tires do not move
when

steering

wheel

turned. (Cont.)

Hydraulic hoses not connected or
have damage.

Check for leaks.

Tighten connec-

tions.

Install new components as

necessary.

Slow or difficult steering.

Relief valve for steering system is
damaged or not adjusted correctly.

Replace relief valve.

Low oil pressure from hydraulic
pump.

Check for restrictions.

See Trou-

bleshooting Chart in section, Hy-
draulic System 1900 SRM 743.

Seal in steering cylinder has a leak.

Repair cylinder. Install new seal or
new cylinder.

Hydraulic lines are too small or have
restrictions.

Remove restrictions. Install larger or
new hydraulic lines.

Steering control unit is worn, not as-
sembled correctly or has damage.

Repair or install new control unit.

Steering wheel turns tires in
the wrong direction.

Hydraulic lines are not connected
correctly at steering cylinder or at
steering control unit.

Connect lines correctly. Remove air
from system.

Steering function continues
after steering tires stop.

Steering control unit is assembled
wrong or has damage.

Repair or install new control unit.

Steering operation is not
smooth.

Oil level in tank is low.

Fill tank. Check for leaks.

Air was not removed after repair to
hydraulic system.

Remove air from system.

Steering control unit is assembled
wrong or has damage.

Repair or install new control unit.

Hydraulic pump has a leak at the in-
let.

Fix leaks. Remove air from system.

NOTES

____________________________________________________________

TECHNICAL PUBLICATIONS

1600 SRM 732

10/03 (11/01)(8/99) Printed in United Kingdom

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