TM 5-3895-382-24
Testing and Adjusting
Troubleshooting
Troubleshooting can be difficult. A list of possible problems
and probable causes is on the pages that follow.
This list of problems and probable causes will only give an
indication of where a problem can be and what repairs am
needed. Normally, more or other repair work is needed
beyond the recommendations on the list. Remember that a
problem is not necessarily caused only by one part, but by the
relation of one part with other parts. This list cannot give all
possible problems and probable causes. The serviceman
must find the problem and its source, then make the necessary
repairs.
The 4C4890 Fittings Group can be used to make pressure
tests of the leveling blade system. Before any tests are made,
visually inspect the complete hydraulic system for leakage of
oil and for parts that are damaged. For some of the tests a
magnet and a mm (in) measuring rule will be needed.
When any test is made of the leveling blade hydraulic system,
the hydraulic oil must be at the normal temperature for
operation.
Sudden movement of the machine or pressure oil release
can cause injury to persons on or near the machine. To
prevent possible injury, do the procedure that follows
before testing and adjusting the leveling blade hydraulic
system.
1. Move the machine to a smooth horizontal location. Move
away from working machines and personnel. Stop the
engine.
2. Permit only one operator on the machine. Keep all other
personnel either away from the machine or in view of
the operator.
3.
Activate the parking brake.
4.
Move the steering wheel to all positions to release any
pressure in the hydraulic system.
5.
Carefully loosen the filler cap on the hydraulic tank to
release any pressure in the tank.
6.
Activate the parking brake.
7.
Make sure all hydraulic pressure is released before any
fitting, hose or component is loosened, tightened,
removed or adjusted.
8.
The pressure in the system has now been released and
lines or components can be removed.
Visual Checks
A visual inspection of the leveling blade system and its
components is the first step when a diagnosis of a problem is
made. Stop the engine, make the following inspections.
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 hydraulic filter element and look for
particles removed from the oil by the filter element.
4.
Check all oil lines and connections for damage.
Performance Tests
Performance tests of the leveling blade system can be used for
a diagnosis of poor performance and to find the source of oil
leakage inside the hydraulic system.
Problem: Steering pump makes noise and the blade
cylinder rod does not move smoothly.
Probable Cause:
Air in the leveling blade hydraulic circuit.
The steering pump is worn.
The steering priority valve is worn.
Loose oil line connection on the inlet side of the steering
pump.
Low oil level in the tank.
Viscosity of the oil is wrong.
Blockage at suction strainer.
Problem: Temperature of oil is too hot.
Probable Cause:
Low oil level in the tank.
Viscosity of the oil is wrong.
Air is mixed with the oil.
Steering priority valve relief valve damaged or
incorrectly adjusted.
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