TM 5-3805-258-24-1
T R O U B L E S H O O T I N G
S T E E R I N G
S Y S T E M
STEERING SYSTEM TROUBLESHOOTING
The 5S5123 Hydraulic Test Group or 5P5224
Pressure Gauge Kit is used to make the-pressure test
of the steering system. Before any tests are made,
visually inspect the complete hydraulic system for
leakage of oil and for parts that have damage. For
some of the tests, a magnet and
(either for inches or millimeters)
WARNING
a measuring rule
are usable tools.
When testing and adjusting the steering
system, move the machine to a smooth hori-
zontal location. Move away from personnel and
machines that are at work. There must be only
one operator. Keep all other personnel away
from the machine.
VISUAL CHECKS
A visual inspection of the steering system and its
components is the first step when a diagnosis of a
problem is made. Stop the engine and lower the
implements to the ground. To remove the tank filler
cap, slowly turn the filler cap until it is loose. If oil
comes out the bleed hole, let the tank pressure lower
before the filler cap is removed. Make the inspections
that follow:
1. Measure the oil level.
2. Look for air in the oil that is in the tank. Do this
immediately after the machine is stopped. Use a
clear bottle or container to get a sample of the
oil. Look for air bubbles in the oil that is in the
bottle.
3. Remove the filter elements and look for particles
removed from the oil by the filter elements. A
magnet will separate ferrous particles from non-
ferrous particles (piston rings, O-ring seals,
etc.).
4. Check all oil lines and connections for damage.
PERFORMANCE TESTS
PROBLEM: Steering wheel is hard to turn.
PROBABLE CAUSE:
1.
2.
3.
4.
5.
6.
7.
Oil is cold.
Restriction in hand metering unit (HMU) pilot
lines.
Pilot lines to HMU are not connected to proper
ports.
Restriction across ball check valve at HMU sup-
ply port in steering control valve.
Steering pump pressure is low.
Bolts are too tight for metering section of HMU.
Timing of HMU drive is not correct [pin (1)
must align with valley of internal pump gear
(2)].
T I M I N G O F H M U D R I V E
1. Pin. 2. Internal pump gear.
PROBLEM: Steering wheel is hard to turn when steering
quickly away from a full turn.
PROBABLE CAUSE:
1. Not enough clearance between ball check and
plug assembly in neutralizer valve.
PROBLEM: Steering wheel can be turned when the ma-
chine is at full turn.
PROBABLE CAUSE:
1. Adjustment of striker (stud assembly) for neu-
tralizer valve is not correct.
2. Seat for the neutralizer ball check has a defect.
3. Relief valve opens before striker moves the neu-
tralizer valve stem.
PROBLEM: Machine does not turn smoothly.
PROBABLE CAUSE:
1. Flow control valve does not move freely.
2. HMU supply line has been installed in field test
port (in the steering valve body) instead of its
Performance tests of the steering system can be
used for a diagnosis of poor performance and to find
the source of oil leakage inside the hydraulic system.
correct location.
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