Range Rover. Manual — part 174
STEERING
5
DESCRIPTION AND OPERATION
Hydraulic fluid flow
Fluid from the hydraulic pump (18) flows into an
annular chamber and surrounds the part of the valve
body which houses the two valve spools. When the
valve is in the neutral position, see illustration
57M7022, the fluid flows through the inlet grooves
(13) and (14) to the radial grooves (7) and (8). The
radial grooves are connected via oilways to the right
and left hand cylinder chambers. Fluid also flows back
to the fluid reservoir (17) through the open return
grooves (15) and (16). When the steering wheel is
turned clockwise, see illustration 57M7023, the piston
(2) moves to the right in the power cylinder. At the
same time the valve spools are moved into their
working position. Valve spool (11) moves to the right,
inlet groove (13) is opened. Valve spool (12) moves to
the left, closing inlet groove (14). Pressure fluid now
flows via radial groove (8) to the left hand side of the
cylinder, assisting movement of the steering wheel.
The fluid in the right hand cylinder is pushed out by
the piston, and flows back to the fluid reservoir via
radial groove (7) and return groove (15). When the
steering wheel is turned anti-clockwise the valve
operation is reversed, pressure fluid flowing to the
right hand side of the cylinder.
The quantity of fluid required for the system is
adjusted by the pressure and flow limiting valve (19) in
the PAS pump. The flow limiting valve ensures that
maximum demand for pressure fluid is met regardless
of engine speed.
Steering limit valve
A steering limit valve is incorporated in the piston
head (2) as a safeguard against overloading the
steering linkage, lock stops and hydraulic pump. This
ball valve is always shut by pressure in the left or right
hand cylinder. However shortly before the piston
reaches full travel in either direction, the valve is
opened by a pin, resulting in pressure drop. Hydraulic
assistance is greatly reduced, and full lock can only
be achieved with increased manual effort by the
driver.
Adjustment
The shape of the sector shaft gearing makes axial
adjustment of the shaft possible. This allows any play
between the two gears, which might occur after a long
period in service, to be eliminated using the sector
shaft adjuster screw.
STEERING
1
FAULT DIAGNOSIS
STEERING SYSTEM FAULTS
This section covers possible mechanical and hydraulic
faults that could occur in the steering system
components. Visual checks of components within the
system should be carried out before undertaking
detailed fault diagnosis procedures.
Symptom - Insufficient Power Steering Assistance.
POSSIBLE CAUSE
REMEDY
1. Low fluid level in oil reservoir.
1. Top up reservoir to correct level.
2. Leaking oil from steering
system caused by loose
pipe/hose connections or
worn/damaged steering
components.
2. Tighten all relevant connections or check for visual/damage etc and
renew if necessary.
3. Loose drive belt.
3. Check/renew drive belt tensioner or renew drive belt.
Refer to Drive belt tensioner.
See ELECTRICAL, Repair. or
Refer to Alternator drive belt.
See ELECTRICAL, Repair.
4. Faulty PAS pump or steering
box.
4. Carry out PAS Test to check hydraulic pressures. If necessary,
renew steering box or pump.
Refer to Power steering box.
See Repair. or
Refer to Power steering pump.
See Repair.
5. Engine idle speed too low.
5. Refer to TestBook .
Symptom - Excessive Kick Back Through Steering Wheel - When Driven On Rough Terrain.
POSSIBLE CAUSE
REMEDY
1. Worn/damaged steering
damper.
1. Renew steering damper.
See Repair.
2. Free play in steering ball joints
and linkage.
2. Check components for wear and renew as necessary.
See Repair.
3. Free play in front hub
assembly.
3. Check components for wear and renew as necessary.
See FRONT
SUSPENSION, Repair.
4. Worn front suspension
component bushes.
4. Check component bushes for wear and renew as necessary.
See
FRONT SUSPENSION, Repair.
57
STEERING
NEW RANGE ROVER
2
FAULT DIAGNOSIS
Symptom - Heavy Steering
POSSIBLE CAUSE
REMEDY
1. Insufficient power assistance
1. Carry out PAS Test to check cause and rectify as necessary.
2. Front tyres under inflated.
2. Inflate tyres to correct pressures.
See GENERAL SPECIFICATION
DATA, Information.
3. Incorrect tyres fitted.
3. Fit tyres of correct specification.
See GENERAL SPECIFICATION
DATA, Information.
4. Seized steering ball joints and
linkage.
4. Check components for wear and renew as necessary.
See Repair.
5. Seized front hub assembly
components.
5. Check components for wear and renew as necessary.
See FRONT
SUSPENSION, Repair.
6. Seized or worn steering box
internal components.
6. Check components and renew as necessary.
See Repair.
7. Steering column intermediate
shaft universal joint stiff or
seized.
7. Inspect universal joints and lubricate if joints are okay. Renew
intermediate shaft if universal joint is badly seized.
See Repair.
8. Steering column bearings
and/or universal joint stiff or
seized.
8. Inspect universal joint and lubricate if joint is okay. If universal joint
is okay this would indicate seized column bearings. Renew steering
column.
See Repair.
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