1999 LAND ROVER DISCOVERY Workshop Manual

STEERING
57-12 DESCRIPTION AND OPERATION
PAS pump - V8
1Bolt 2 off
2Nut
3Stud
4Auxiliary housing
5PAS pump6Outlet
7Inlet
8Bolt 3 off
9Drive pulley
The PAS pump is located on the auxiliary housing and is attached by two bolts, the bolts go through flanged bushes
in the auxiliary housing. A stud passes through the PAS pump and through a flanged bush in the auxiliary housing,
the auxiliary housing and PAS pump are secured by a nut. As the two bolts and nut are tightened the bushes move
slightly and the flange of each bush clamps the PAS pump. A drive pulley is attached to the pump drive shaft with
three bolts, and is belt driven at a ratio of 1.4 crankshaft revolutions to 1 of the drive pulley. Fluid is drawn into the
PAS pump inlet from the reservoir through a flexible hose at low (suction) pressure. Fluid at high pressure from the
PAS pump outlet is supplied to the rotary control valve on the steering box.
The PAS pump is a roller vane type and has an internal pressure regulator and flow control valve. The roller vanes
can move in slots in the pumps rotor and are moved outwards by centrifugal force as the pump rotates. The pump
rotor rotates in the pump housing, the internal shape of the housing forms a 'cam' shape. Due to the 'cam' shape the
volume of the housing decreases between the inlet and outlet ports.
As the pump rotor rotates towards the pump inlet the volume between the roller vanes and the pump housing
increases, this action causes a depression in the chamber between the pump roller vanes and the housing. As the
rotation continues the chamber is opened to the pump inlet, and the depression in the chamber causes fluid to be
drawn in. The roller vanes continue past the inlet port, closing off the inlet port and trapping the fluid in the chamber
between the rollers and the pump housing.

STEERING
DESCRIPTION AND OPERATION 57-13
The internal 'cam' shape of the pump housing causes the rollers to move closer together as the pump rotor rotates
towards the outlet port. The reduced volume of the chamber between the roller vanes causes the fluid to become
pressurised. When the chamber is opened to the outlet port of the pump the fluid escapes at high pressure. The roller
vanes continue turning and go past the outlet port, closing off the chamber between the two roller vanes.
As rotation continues the inlet sequence begins again. The inlet and pressurisation/outlet sequences continue as the
pump rotates, and is repeated between each two roller vanes. The pump is a positive displacement type and the
potential pump output increases with engine (drive pulley) speed. The pressure relief and flow control valve regulates
flow/pressure by diverting fluid back to the pump inlet through internal recirculation passages in the pump body.

STEERING
57-14 DESCRIPTION AND OPERATION
PAS pump - diesel
1Drive pulley
2Mounting bracket
3Bolt 2 off
4Bolt
5PAS pump
6Coupling7Auxiliary housing
8Outlet
9Inlet adaptor pipe and seal
10Bolt 2 off
11Bolt 2 off
12Bolt 3 off
The PAS pump is located on the auxiliary housing, two bolts go through the PAS pump, mounting bracket and into
the auxiliary housing. One bolt also attaches the mounting bracket to the PAS pump, two bolts secure the mounting
bracket to the auxiliary housing. An inlet adaptor pipe with a seal is secured to the bottom of the pump with two bolts.
A drive pulley is attached to the pump drive shaft with three bolts, and is belt driven at a ratio of 1.35 crankshaft
revolutions to 1 of the drive pulley. A coupling on the rear of the PAS pump rotates the water pump impeller located
in the auxiliary housing. Fluid is supplied to the PAS pump inlet from the reservoir through a flexible hose at low
(suction) pressure. Fluid at high pressure from the PAS pump outlet is supplied to the rotary control valve on the
steering box.
The PAS pump is a roller vane type and has an internal pressure regulator and flow control valve. The roller vanes
can move in slots in the pumps rotor and are moved outwards by centrifugal force as the pump rotates. The pump
rotor rotates in the pump housing, the internal shape of the housing forms a 'cam' shape. Due to the 'cam' shape the
volume of the housing decreases between the inlet and outlet ports.

STEERING
DESCRIPTION AND OPERATION 57-15
As the pump rotor rotates towards the pump inlet the volume between the roller vanes and the pump housing
increases, this action causes a depression in the chamber between the pump roller vanes and the housing. As the
rotation continues the chamber is opened to the pump inlet, and the depression in the chamber causes fluid to be
drawn in. The roller vanes continue past the inlet port, closing off the inlet port and trapping the fluid in the chamber
between the rollers and the pump housing.
The internal 'cam' shape of the pump housing causes the rollers to move closer together as the pump rotor rotates
towards the outlet port. The reduced volume of the chamber between the roller vanes causes the fluid to become
pressurised. When the chamber is opened to the outlet port of the pump the fluid escapes at high pressure. The roller
vanes continue turning and go past the outlet port, closing off the chamber between the two roller vanes.
As rotation continues the inlet sequence begins again. The inlet and pressurisation/outlet sequences continue as the
pump rotates, and is repeated between each two roller vanes. The pump is a positive displacement type and the
potential pump output increases with engine (drive pulley) speed. The pressure relief and flow control valve regulates
flow/pressure by diverting fluid back to the pump inlet through internal recirculation passages in the pump body.
Steering damper
The steering damper is located behind and just below the first cross member of the chassis. The ends of the steering
damper have steel 'eyes' welded on, rubber bushes are installed in each 'eye'. The steering damper is attached
between brackets on the chassis rail and the drag link. Each end of the steering damper is secured by a bolt and
locknut. The hydraulic damper absorbs shocks in the steering, caused by road wheel deflections when operating on
rough terrain.

STEERING
57-16 DESCRIPTION AND OPERATION
Operation
Hydraulic fluid is supplied to the PAS pump inlet from the PAS reservoir, the PAS pump draws in and pressurises the
fluid. The PAS pump self regulates internal flow rates and operating pressure, and supplies pressurised fluid from the
PAS pump outlet to a rotary control valve in the steering box. At neutral the fluid is circulated by the PAS pump and
flows around the system at a lower pressure and a constant flow rate. With most of the fluid being returned to the
reservoir the pressure inside the system remains very low. When a control input turns the rotary control valve in the
steering box, pressure in the system will rise as the control valve directs fluid to give power assistance.
The action of turning the steering wheel turns the steering column and intermediate shaft. The intermediate shaft turns
the input shaft of the steering box. The input shaft moves the rotary control valve in the steering box, the rotary valve
controls the pressure used inside the steering box for power assistance. The input shaft also turns a worm gear, the
worm gear acts on a roller attached to the output shaft. As the worm gear turns the roller, the roller travels along the
lands of the worm gear. As the roller is attached to the output shaft the output shaft turns.
As the output shaft of the steering box turns, hydraulic pressure is supplied via the rotary control valve to the steering
box. The hydraulic pressure acts on a rack that assists with the movement of the output shaft of the steering box. A
drop arm is attached to the output shaft of the steering box. The drop arm is connected to a drag link by a ball joint.
The drag link is connected via ball joints to one front steering knuckle and road wheel. A track rod connected to this
steering knuckle links the two steering knuckles together. As one steering knuckle and road wheel is turned by the
drag link, the other steering knuckle and wheel is moved by the track rod.

STEERING
ADJUSTMENTS 57-17
ADJUST ME NTS
Steering box - check and adjust
$% 57.10.13
Check
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove nut securing drag link to drop arm.
3.Using LRT-57-036, break taper joint and
release drag link.
4.Ensure steering is centralised.
5.With the drop arm held, check for rotational
movement at the intermediate shaft universal
joint. If any movement exists, the steering box
requires adjusting.Adjust
1.Loosen lock nut on steering box adjuster and
tighten adjuster until movement is removed at
universal joint.
CAUTION: Ensure that steering box is
centralised before adjustment. Never over
adjust, free play should just be eliminated.
2.When adjustment is correct, hold the adjuster
and tighten adjuster locknut.
3.Turn steering wheel from lock to lock and check
no tightness exists.
4.Fit drag link to drop arm, and tighten nut to 80
Nm (59 lbf.ft).
5.Remove stands and lower vehicle.

STEERING
57-18 ADJUSTMENTS
Hydraulic system - bleed
$% 57.15.02
Bleed
1.Clean PAS fluid reservoir around filler cap and
fluid level indicators.
2.Remove filler cap from PAS fluid reservoir. If
necessary, fill PAS fluid reservoir to upper level
indicator with recommended fluid.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS, Fluids.
CAUTION: Ensure no dirt is allowed to enter
the steering reservoir when the cap is
removed.
3.Start engine and run to normal operating
temperature.
4.Position container to catch fluid spillage from
steering box.
5.With engine at idle speed, and an assistant
turning the steering from lock to lock, loosen
bleed screw on top of steering box. Keep PAS
fluid reservoir topped up and allow all air to
bleed from system. When fluid from bleed
screw is free of air, tighten bleed screw.
CAUTION: Do not hold steering at full lock
for longer than 10 seconds.
6.Stop engine.
7.Clean spilled PAS fluid from steering box and
surrounding area.
CAUTION: Power steering fluid will damage
paint finished surfaces. If spilled,
immediately remove fluid and clean area
with water.
8.Check fluid level in PAS fluid reservoir and fill to
upper level mark. If fluid is aerated, wait until
fluid is free from bubbles.
9.Fit PAS fluid reservoir filler cap.
Steering linkage - centralise
$% 57.35.05
The following procedure assumes that the front
wheel alignment is correctly adjusted.
Adjust
1.Raise front of vehicle, and position the road
wheels at straight ahead.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove nut securing drag link to drop arm.
Using tool LRT-57-036 break taper joint and
release drag link from drop arm.
3.Fit centralising bolt to steering box and ensure
that front road wheels are in the straight ahead
position.
4.Loosen clamp bolts on drag link.

STEERING
ADJUSTMENTS 57-19
5.Adjust drag link so that taper joint is centralised
in drop arm, then tighten drag link clamp bolts:
Tighten M8 bolts to 22 Nm (16 lbf.ft) and M10
bolts to 33 Nm (24 lbf.ft).
6.Connect drag link to drop arm and tighten nut to
80 Nm (59 lbf.ft).
7.Remove steering box centralising bolt.
8.Remove stand(s) and lower vehicle.
9.Road test the vehicle and check that the
steering wheel is centralised. If steering wheel
is not centralised, proceed as follows.
10.Slacken drag link adjuster clamp bolts.
11.Without disconnecting drag link from drop arm,
adjust the length of the drag link to bring the
steering wheel to the central position.
CAUTION: Repositioning the steering wheel
on its splines cannot correct small (less
than 5°) errors in steering wheel alignment.
Always rectify small errors in alignment by
adjusting the drag link as detailed above,
ensuring that steering box centralisation is
maintained.
12.Tighten drag link clamp bolts: Tighten M8 bolts
to 22 Nm (16 lbf.ft) and M10 bolts to 33 Nm (24
lbf.ft)
Wheel alignment - front
$% 57.65.01
The following is the only wheel alignment equipment
which has been approved.
lBeissbarth ML 4600 wheel alignment computer
(6 sensor).
lBeissbarth ML 4600-8 wheel alignment
computer (8 sensor).
lBeissbarth ML 4000 wheel alignment computer
(8 sensor wireless).
lHunter S411-14.
Check
1.Ensure tyre pressures are correct and vehicle
is at kerbside weight.
2.Roll vehicle backwards and forwards to relieve
stresses in steering and suspension.
3.Ensure road wheels are positioned straight
ahead.
4.Ensure that wheel alignment equipment is
properly calibrated.
5.Following the equipment manufacturer's
instructions, measure the front wheel
alignment. Compare with the figures given in
General Data.

+ GENERAL DATA, Steering.
Adjust
1.Loosen track rod and adjuster clamp bolts.
2.Rotate adjuster to obtain correct alignment.

+ GENERAL DATA, Steering.
3.Tighten track rod and adjuster clamp bolts:
Tighten M8 bolts to 22 Nm (16 lbf.ft) and M10
bolts to 33 Nm (24 lbf.ft).
4.Recheck front wheel alignment.