Gradall 534B (9020-7317) Service Manual - Manual (Page 138)

Problem
9. Free Wheeling-Steering wheel
turns with slight resistance but re-
sults in little or no steered wheel
action.
10. Excessive free play at steering
wheel.
11. Excessive free play at steered
wheels.
12. Binding or poor centering of
steering wheel.
13. Steering unit locks up.
14. Steering wheel oscillates or
turns by itself.
15. Steered wheels turn in wrong
direction when operator activates
steering wheel
16.Steering wheel kicks at start
of steering.
Possible Cause
Steering control unit meter has a
lack of oil. This can happen on problem.
start-up, after repair, or long per-
iods of non use.
No flow to steering unit can be
caused by:
1. Low fluid level.
2. Ruptured hose.
3. Internal steering control unit
damage due to thermal shock*.
Piston seal blown out.
Loose steering wheel nut. Steering
column shaft worn or damaged.
There should be very little free play
in the unit itself.
Broken or worn linkage between
cylinder and steered wheels.
Leaky cylinder seals.
Binding or misalignment in steer-
ing column or splined input con-
nection.
High back pressure in tank line can
cause slow return to center. Should
not exceed 300 psi.
Large particles can cause binding
between the spool and sleeve (in
Orbitrol).
Large particles in meter section.
Severe wear and/or broken pin.
*Thermal shock.
Parts assembled wrong. Steering
unit improperly timed.
Lines connected to wrong ports.
Lines connected to wrong cylin-
der ports.
Sticking check valve on steering
control unit.
Correction
Usually starting engine will cure
problem.
Add fluid and check for leaks.
Replace hose.
Replace the unit.
Determine cause. Correct and re-
place seal.
Repair or replace steering wheel con-
nection or column.
Check for loose fitting bearings and
anchor points in steering linkage be-
tween cylinder and steered wheels.
Replace cylinder seals.
Align column pilot and spline to
steering control unit.
Check for restriction.
Clean the unit and filter the oil. If
another component has failed gen-
erating contaminents, flush the sys-
tem while bypassing the steering
control unit.
Clean the unit.
Replace the unit.
Replace the unit.
Correct timing.
Reconnect lines correctly.
Reconnect lines correctly.
Clean or replace check valve.
*Thermal shock-A condition caused when the hydraulic system is operated for some time without turning
the steering wheel so that fluid in the reservoir and system is hot and the steering control unit is relatively
cool (more than 50°F temperature differential). When the steering wheel is turned quickly the result is temp
orary seizure and possible damage to internal parts of the steering control unit. The temperary seizure may
be followed by total free wheeling.