TM 5-3805-258-24-1
T R O U B L E S H O O T I N G
PROBLEM: Machine turns too slow in both directions.
PROBABLE CAUSE:
1. Springs for flow control valve are not adjusted
correctly.
2. Not enough flow from primary steering pump
section.
3. Main control spool does not move all the way.
PROBLEM: Machine turns too slow in one direction.
PROBABLE CAUSE:
1. Flow balance adjustment of main control spool is
not correct.
(See Steering Time Check in Testing and
Adjusting).
PROBLEM: Machine turns correctly when roading (mov-
ing), but is slow in both directions when the
machine turns against a load (high
resistance).
PROBABLE CAUSE:
1. Leakage past relief valve seat or seals.
2. Leakage past both ball resolver seats.
3. The fit of the flow control valve in the bore is not
correct.
PROBLEM: Machine turns correctly when roading (mov-
ing), but is slow in one direction when the
machine turns against a load (high
resistance).
PROBABLE CAUSE:
1. Right turn: leakage past upper ball resolver seat
or seal.
2. Left turn: leakage past lower ball resolver seat or
seal.
PROBLEM: Machine does not turn when steering wheel is
turned.
PROBABLE CAUSE:
1. Flow control valve will not move from the open
position.
2. A defect in the pilot relief valve or seat.
3. Failure of the seal around the seat for the pilot
relief valve at higher system pressures.
NOTE: Some steering “slip” is normal. See Steering
Slip Check in Testing and Adjusting.
S T E E R I N G
S Y S T E M
PROBLEM: Machine turns by itself (operator does not
turn the steering wheel).
PROBABLE CAUSE:
1.
2.
3.
*4.
5.
Spool in steering valve does not return to neutral
correctly.
The mounting bolts for the steering control valve
are too tight.
The bolts are too tight for the end covers of the
steering control valve.
Manufacturing tolerances on spool in steering
control valve do not permit spool to go back to
neutral.
Steering wheel turns without operator turning it.
a. Foreign material causes sleeve valves in HMU
to stick.
b. HMU centering (leaf) springs are broken or
damaged.
*This can be corrected on some machines by turning
the spool in steering control valve around in its bore
(turn end for end). To do this, the spring, retainer,
and shims must be installed on the opposite end of
the spool. An adjustment may be necessary for the
steering times.
PROBLEM: Machine turns too fast to make small steering
corrections when the machine moves at fast
speeds.
PROBABLE CAUSE:
1.
2.
3.
Flow control valve adjustment is not correct.
(See Steering Time Check in Testing and
Adjusting).
Main control spool does not move freely.
Metering orifices on main control spool are filled
with foreign material or were not drilled
correctly.
PROBLEM: Pump makes noise and the steering cylinder
rod does not move smoothly.
PROBABLE CAUSE:
1.
2.
3.
4.
5.
6.
Air in the steering hydraulic circuit.
The pump has too much wear.
Loose connection of the oil line on the inlet side
of the pump.
The viscosity of the oil is wrong.
The relief valve opens at low oil pressure.
The oil level in the tank is low.
4-100
