STEERING CONTROL

UNIT

A1.00-1.50XL (A20-30XL) [C203]

PART NO. 1482617

1600 SRM 797

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 ................................................................................................

Steering Column Assembly Repair ...................................................................................................................

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

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

Steering Control Unit, Disassemble .............................................................................................................

Steering Control Unit, Clean ........................................................................................................................

Steering Control Unit, Assemble ..................................................................................................................

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

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

This section is for the following models:

A1.00-1.50XL (A20-30XL) [C203]

"THE

QUALITY

KEEPERS"

HYSTER

APPROVED

PARTS

1600 SRM 797

Operation

General

This section has the description and repair procedures for the steering housing and the steering control unit.
Additional information on parts of the steering system are in the following sections: Steering System 1600
SRM 796 and Hydraulic System 1900 SRM 802.

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 the steering column
assembly and controlled by the steering wheel. The
steering control unit has a control section and a me-
tering section.

The steering system is a hydraulic system that does
not have a mechanical connection between the steer-
ing wheel and the steering axle. The 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
steering operation, the steering control unit controls
the direction of flow and amount of oil that flows
to the steering motor. The steering motor operates
the steering chain that drives the Master Drive Unit
(MDU) to move the steering tire. Hydraulic oil re-
turns from the steering motor 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 motor.

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. The oil then flows to one side of the steering
motor. Hydraulic oil from the other side of the steer-
ing motor 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 steering mo-
tor. The pressure stays in the steering motor to keep
the steering tire in position. Oil from the pump flows
through the steering control unit to the tank or other
parts of the system. To return the steer wheel to the
straight position, the steering wheel must be rotated
in the opposite direction. The steering control unit
will operate as described, but all parts will rotate in
the opposite direction.

Operation

1600 SRM 797

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 797

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 (see Figure 1) allow for horn operation by the
operator.

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.

Figure 2. Steering Wheel and Steering Column Assembly

Steering Column Assembly Repair

1600 SRM 797

Legend for Figure 2

UPPER STEERING COLUMN COVER

KNOB SPINNER

STEERING WHEEL

HORN BUTTON

STEERING CONTROL UNIT

STEERING COLUMN

STEERING CONTROL UNIT

LOWER STEERING COLUMN COVER

TILT LATCH

10. STEERING COLUMN BRACKET

Steering Column Assembly Repair

REMOVE AND DISASSEMBLE

Attach a tag on the battery connector stating DO
NOT CONNECT BATTERY. Move the steering
column to the most forward position. See Fig-
ure 2.

Remove the screws that fasten the column hous-
ing to the bracket. Remove the front housing
from the steering column assembly.

Remove the horn button. Loosen the screw con-
necting the horn wire to the horn button and re-
move the wire from the horn button. Remove the
nut and steering wheel.

Disconnect the harness from the microswitches
on the shift lever. Remove the four bolts holding
the shift lever assembly to the bracket. Remove
the shift lever assembly by sliding it up the steer-
ing column. If necessary, disassemble the shift
lever assembly as described in Steering System
1600 SRM 796.

NOTE:

To aid in installation, tag the hydraulic hoses

at the steering control unit during removal.

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

Remove the screws, washers, and lockwashers
that fasten the steering column and steering con-
trol unit to the bracket.

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

If necessary, remove all parts of the latch from
the bracket.

If necessary, remove all parts of

the spring mechanism and pivot to remove the
bracket from the cowl of the lift truck.

If necessary, disassemble the steering control
unit as shown in Steering Control Unit, Disas-
semble. Disconnect the microswitch connections.

ASSEMBLE AND INSTALL

If removed, install the bracket, pivot, and spring
mechanism on the cowl of the lift truck. If re-
moved, install the latch on the bracket. See Fig-
ure 2.

If necessary, assemble the steering control unit
as shown in Steering Control Unit, Assemble. In-
stall the steering control unit onto the steering
column.

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

Install the steering column and steering control
unit in the bracket. Install the screws, washers,
and lockwashers that fasten the steering column
and steering control unit to the bracket.

1600 SRM 797

Steering Column Assembly Repair

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.

WARNING

Installation of the hydraulic hoses to the steer-
ing control unit requires minimal torque.
Torque the four 11/16-inch fittings to 30 N•m
(22 lbf ft) and the 9/16-inch fitting to 25 N•m
(18 lbf ft). Failure to follow these torque rec-
ommendations can snap the fittings and cause
injury.

Connect the hydraulic hoses to the bottom of the
steering control unit.

If necessary, assemble the shift lever assembly
as described in Steering System 1600 SRM
796. Slide shift lever assembly down steering
column. Install the four screws that fasten the

shift lever assembly to the bracket. Connect the
microswitches.

Install steering wheel and nut. Pull horn wire
through the steering column and attach it to the
horn button. Install the horn button in the steer-
ing wheel. Install the column housing over the
bracket. Insert housing plugs if necessary. In-
stall the screws that fasten the housing to the
bracket.

Remove the battery tag and connect the battery
connector 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 not connected correctly,
it can rotate with a strong force and cause se-
rious injury. If this action occurs, disassemble
the control unit and correct the problem.

Operate the steering system to check for correct
operation and leaks.

STEERING CONTROL UNIT, DISASSEMBLE

STEP 1.

Put the control unit in a vise with soft jaws. Make an
identification mark on the length of the control unit.

STEERING CONTROL UNIT

VISE

Steering Column Assembly Repair

1600 SRM 797

STEP 2.

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

CAPSCREW

COVER

O-RING

CHECK BALL

STEP 3.

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

STATOR

ROTOR

DISTRIBUTOR
PLATE

O-RING

CENTER SHAFT

STEP 4.

Remove the check valve assembly. Remove and dis-
card shaft seal.

CHECK VALVE ASSEMBLY

SHAFT SEAL

1600 SRM 797

Steering Column Assembly Repair

STEP 5.

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

SPOOL AND SLEEVE ASSEMBLY

DUST SEAL

THRUST WASHER

THRUST BEARING

RETAINING RING

CENTER PIN

SPOOL

SLEEVE

NEUTRAL POSITION SPRINGS

10. HOUSING

STEERING CONTROL UNIT, 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 precau-
tions.

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.

Clean all the parts in solvent. Dry the parts with
compressed air. Do not dry the parts with a cloth.
Make sure all surfaces are free of scratches and sharp
edges.

Steering Column Assembly Repair

1600 SRM 797

STEERING CONTROL UNIT, ASSEMBLE

NOTE:

Use new seals, O-rings, and NEUTRAL po-

sition springs during assembly. Lubricate all parts
with clean hydraulic oil.

STEP 1.

Install dust seal and shaft seal in housing.

HOUSING

DUST SEAL

SHAFT SEAL

STEP 2.

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

SPOOL

SLEEVE

1600 SRM 797

Steering Column Assembly Repair

STEP 3.

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

NEUTRAL POSITION SPRINGS (FLAT)

NEUTRAL POSITION SPRINGS (CURVED)

CENTER PIN SPOOL

RETAINING RING

STEP 4.

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

HOUSING

SPOOL AND SLEEVE ASSEMBLY

THRUST WASHER

THRUST BEARING

CENTERING PIN

Steering Column Assembly Repair

1600 SRM 797

STEP 5.

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

CHECK VALVE ASSEMBLY

HOUSING

O-RING

DISTRIBUTOR PLATE

STEP 6.

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

CENTER PIN

CENTER SHAFT

ROTOR

STATOR

O-RING

1600 SRM 797

System Air Removal

STEP 7.

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

1600 SRM 797

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

The

steering

wheel

does

not move when the steering
wheel is turned.

The oil level is low or there is no oil
in the tank.

Fill tank to the correct level. Check
for leaks.

The steering control unit is dam-
aged.

Repair or install new control unit.

No oil flow from the steering control
unit to the steering motor.

Repair or install new components.
Check for leaks.

The sleeve and spool in the control
unit will not move.

Install new components.

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 the steering system
is damaged or not adjusted correctly.

Replace the relief valve.

Low oil pressure from the hydraulic
pump.

Check for restrictions.

See Trou-

bleshooting Chart, Hydraulic Sys-
tem.

Seal in the steering motor has a leak.

Repair motor. Install new seal or new
motor.

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 the tire
in the wrong direction.

The hydraulic lines are not con-
nected correctly at the steering mo-
tor or at the steering control unit.

Connect lines correctly. Remove air
from the system.

Steering

function

contin-

ues after the steering wheel
stops.

The steering control unit is assem-
bled wrong or has damage.

Repair or install new control unit.

1600 SRM 797

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

The steering operation is not
smooth.

The oil level in the tank is low.

Fill tank. Check for leaks.

Air was not removed after repair to
the hydraulic system.

Remove air from the system.

The steering control unit is assem-
bled wrong or has damage.

Repair or install new control unit.

The hydraulic pump has a leak at the
inlet.

Fix leaks. Remove air from the sys-
tem.

NOTES

____________________________________________________________

TECHNICAL PUBLICATIONS

1600 SRM 797

3/00 Printed in United Kingdom

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