Q8-21. What is the main source of chemical
tests performed on the equipment) to assist in tracing
contaminants in hydraulic fluid?
the malfunction to its source. As previously stressed,
no unit should be removed and replaced (or adjusted)
1.
Fuel
unless there is sound reason to believe it is faulty.
2.
Oxidation
3.
Water
TROUBLESHOOTING
4.
Solvent
Most hydraulic troubles can be included in one or
Q8-22. What type of cloth should you use when
more of the following categories:
cleaning or wiping hydraulic system
Lack of fluid supply
components?
External leaks
1.
Cotton
2.
Polyester
Internal leaks
3.
Lintfree
Physically defective units, or related troubles
4.
Dirtfree
caused by mechanical control linkages and
Q8-23. At what time can a hydraulic system be
electrical control circuits
purged to remove contaminants?
Insufficient fluid in the system results in no pump
1. Only under direct supervision of the
delivery or, at best, a sluggish or erratic operation. The
cognizant engineering activity
reservoir must always contain enough fluid to fill the
2. When the AIMD hydraulics shop
system completely without letting the pump run dry.
accomplishes the maintenance
Always use the proper fluid to replenish a low system.
3. Only when the contamination level is
Do not mix hydraulic fluids or reuse old fluid. Ensure
above a class 5
all replenishment fluid is properly filtered prior to
4. Prior to the rework of the pump
being dispensed into the reservoir.
TROUBLESHOOTING AND
Remove and repair or replace defective units when
MAINTENANCE
there is an indication of external leakage of the unit.
If foreign particles are found when you remove and
LEARNING OBJECTIVES: Identify
disassemble a unit, identify and trace them to the
procedures for inspecting, checking, cleaning,
deteriorating source. For example, a common source of
testing, and adjusting hydraulic system
foreign particles is found in flexible hose. The cause
components. Identify procedures for
generally is improper installation or internal
troubleshooting and repairing hydraulic
deterioration; either can release slivers of the lining
systems.
into the system, causing units to leak or become
inoperative.
Every hydraulic system has two major parts or
sections--the power section and the actuating section.
To analyze malfunctions in hydraulic systems, like
A power section develops, limits, and directs the fluid
all other systems, you need to have a complete
pressures that actuate various mechanisms on the
understanding of the system and its operating
equipment. The actuating section is the section
c o m p o n e n t s . A l s o , y o u n e e d t o k n ow t h e
containing the various operating mechanisms and their
i n t e r r e l a t i o n s h i p s a m o n g t h e c o m p o n e n t s . Fo r
units, such as brakes, steering, lift cylinders, extend
instance, a complete understanding of a pressure
cylinders, and hydraulic motors.
regulator lends itself to troubleshooting the entire
system, as well as the regulator itself.
Since an actuating mechanism is dependent on the
power system, some of the troubles exhibited by the
Pressure regulators, like all hydraulic components,
actuating system may be caused by difficulties in the
are normally very reliable pieces of equipment.
power system. By the same token, a trouble symptom
Nevertheless, they can malfunction. Keep in mind,
indicated by a unit of the power system may be caused
though, that instead of being a source of trouble, the
by leakage from one of the units of an actuating
regulator can be a fairly reliable watchdog on the other
system. When any part of a hydraulic system becomes
units in the system. The particular behavior of the
inoperative, refer to the schematic diagrams located in
regulator may be the only indication of leakage in
the applicable technical manual (in conjunction with
places where no other indication is available. It should
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