Iveco Stralis AT/AD. Manual — part 231
4
STEERING
S
TRALIS
AT/AD
Base - January 2003
Steering system
Hydraulic
Power steering
ZF8098 recirculating ball type with
integral pressure limiting valve and
hydraulic device with automatic
adjustment to limit the steering angle
Variable working pressure
150+ 15 bar
vehicles
Variable reduction ratio
Chassis cab
and tractor
6x2 C
Excluding tractors
6x2 C
straight ahead
22.2 : 1
17 : 1
full lock
26.2 : 1
20 : 1
no. of turns of steering wheel from
straight ahead to full lock
3.1
2.4
Power steering pump
ZF
Minimum
rpm
500
Maximum
rpm
3500
Maximum pressure
(without limiting valve)
bar
150
165*
Capacity
dm
3
/min
16
20*
*
vehicles: 6x2 p / FS-PS
Main power steering operating faults :
1
-
Steering stiff when turning right and left
2
-
Steering stiff only when turning left or right
3
-
Steering stiff when the wheel is turned quickly
4
-
When steering, heavy jolts are felt at the wheel
1
YES
NO
YES
NO
YES
NO
YES
NO
YES
STEERING STIFF WHEN TURNING
RIGHT AND LEFT
Insufficient fluid in system
With motor running, check fluid level; top up fluid to
upper mark on dipstick and bleed system.
Air in hydraulic circuit
Check intake tube and pump shaft seal for leaks and top
up the fluid. Bleed system .
Pump regulating valve jammed or blocked
Take down valve, wash and check. Throttling orifice must
not be blocked
Insufficient oil pump flow
Replace pump.
Universal joint not serviceable
Make joint free to slide by moving it to and fro several
times so that it tilts under its own weight
5
-
Torsional vibration of the steering wheel
6
-
Excessive play at the steering wheel
7
-
Loss of fluid
8
-
Insufficient pressure in the circuit
NO
YES
Lubrication
of
the
transmission
lever
bearings
insufficient (for vehicles with steering third axle).
Grease the transmission lever bearings
(Continued)
STEERING
5
S
TRALIS
AT/AD
FAULT DIAGNOSIS
2
YES
NO
YES
YES
NO
YES
NO
YES
STEERING STIFF ONLY WHEN
TURNING LEFT OR RIGHT
Internal seals not serviceable
Send steering gear to a ZF service centre
Incorrect position of hydraulic centre (when wheel is
released, the steering does not return to one end of
travel by itself)
Have valve adjusted by a ZF service centre
3
STEERING STIFF WHEN THE WHEEL
IS TURNED QUICKLY
Regulating valve in pump clogged
Dismantle valve, rinse and clean
Insufficient hydraulic pump flow
Overhaul or replace the hydraulic pump.
Air in steering circuit
Check intake tube and pump shaft seal for leaks and top
up fluid. Bleed system
YES
NO
YES
Bearings for internal transmission levers worn (for
vehicles with steering third axle)
Overhaul the transmission levers and replace worn
parts
Hydraulic cylinders not working (for vehicles with
steering third axle)
Replace the cylinders
6
STEERING
S
TRALIS
AT/AD
Base - January 2003
YES
NO
Insufficient fluid in system
Top up fluid and bleed system
4
YES
NO
YES
NO
YES
NO
YES
YES
NO
YES
NO
YES
NO
WHEN STEERING, HEAVY JOLTS
ARE FELT AT THE WHEEL
Play in universal joint
Replace the universal joint
Send steering unit to a ZF service centre
Internal failure of steering unit
Wheel geometry incorrect
Check and adjust according to the characteristic data
given in the “AXLE” section
Wheels out of balance
Balance in accordance with instructions given in the
section ”Wheels and tyres”
Steering rod joints loose on the arms
Replace any worn parts
Irregular pump operation
Replace pump
Leakage of fluid from power steering circuit couplings
Check coupling seals for serviceability, and replace any
which are worn
STEERING
7
S
TRALIS
AT/AD
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