TM 5-3810-300-24 & P2
2. High speed shimmy.
a. Unequal tire pressure.
b. Wheels or tires eccentric or out of balance.
c. Badly and unevenly worn tires.
d. Any of the causes for low speed shimmy.
NOTE
DRIVER HABITS CAN INFLUENCE THE COMPLAINTS. THESE COMPLAINTS, EXCEPT FOR
SHIMMY, ARE OFTEN IDENTIFIED ERRONEOUSLY, ONE FOR THE OTHER. LOOK FOR THE SAME
THINGS WHICH CAUSE THE SAME TROUBLES WITH MANUAL STEERING.
System Chatter.
System chatter is sometimes induced by front wheel shimmy.
When chatter is a complaint, first make sure the system is stable by checking every connecting part of the steering system
for correct adjustment and tightness and no lash. (Refer to loose or too tight linkage connections).
Check for front end stability, particularly if shimmy also occurs. The front end must be as stable as with manual steering, or
more so. When system and front end are stable, and chatter persists, replacement of control valve may effect sufficient
changes to correct the condition.
Recovery.
Front wheels usually return after a turn to the straight ahead position. This is called recovery.
NOTE
ON SOME POWER STEERING INSTALLATIONS, THE RECOVERY MAY BE SLOWER THAN FOR
MANUAL STEERING.
In a power steering system, any friction that tends to keep the valve spool from returning to center, or friction that resists
the return of the parts back to straight ahead can stop recovery unless manually helped by driver.
Eliminate friction and binding in order to improve recovery.
1.
Tight ball sockets and other linkage connections.
2.
Bent piston rod, broken piston or rings.
3.
Tight knuckle pins, bushings.
4.
Bind in wheel tube or wheel tube bearing.
5.
Spool in valve sticking (not centering).
6.
Steering gear adjusted too tight.
Insufficient caster can be cause of lack of recovery.
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