SPECIFICATIONS

Vehicle Systems Testing And Adjusting
Testing and Adjusting
Troubleshooting
Troubleshooting can be difficult. A list of possible
problems and corrections are on the pages that fol-
low.
This list of problems and corrections will only give an
indication of where a problem can be and what
repairs are 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 can not give all
possible problems and corrections. The serviceman
must find the problem and its source, then make the
necessary repairs.
The pressure Gauge Kit or the Tetragauge Group
can be used to make the pressure tests of the
hydraulic system. Before any test is made, visually
inspect the complete hydraulic system for leakage of
oil and for parts that have damage.
To prevent personal injury when testing and
adjusting the hydraulic system, move the machine
to a smooth horizontal location and lower the
mast and carriage to the ground, make sure they
are blocked correctly to keep them from a fall that
is not expected. Move away from machines and
personnel that are at work. There must be only
one operator. Keep all other personnel away from
the machine or where the operator can see the
other personnel. Before any hydraulic pressure
plug, line or component is removed, make sure all
hydraulic pressure is released.
Visual Checks
A visual inspection of the hydraulic system and its
components is the first step when a diagnosis of a
problem is made. Lower the carriage to the floor and
follow these inspections;
1. Measure the oil level. Look for air bubbles in the
oil tank.
2. Remove the filter element and look for particles
removed from the oil by the filter element. A magnet
will separate ferrous particles from nonferrous
particles (piston rings, O-ring seals, etc.).
3. Check all oil lines and connections for damage or
leaks.
4. Check all the lift chains and the mast and carriage
welds for wear or damage.
Hydraulic System and Mast
During a diagnosis of the hydraulic system, remember
that correct oil flow and pressure are necessary for
correct operation. The output of the pump (oil flow)
increases with an increase in motor speed (rpm) and
decreases when motor speed (rpm) is decreased. Oil
pressure is caused by resistance to the flow of oil.
Visual checks and measurements are the first step
when troubleshooting a possible problem. Then do
the Operation Checks and finally, do instrument tests
with pressure gauges.
Use the Pressure Gauge Kit, a stop watch, a
magnet, a thermometer and a mm (inch) ruler for
basic test measurements.
1. The pressure of the oil required to open the relief
valve. Relief valve pressures that are too low will
cause a decrease in the lift and the tilt characteristics
of the lift truck. Pressures that are too high will
cause a decrease in the life of hoses and
components.
2. Drift rates in the cylinders. Cylinder drift is caused
by a leakage past cylinder pistons, O-ring seals in
the control valve, check valves that do not seat
correctly or poor adjustment or fit in the control
valve spools.
3. Cycle times in the lift and tilt circuits: Cycle times
that are too long are the result of leakage, pump
wear and/or pump speed (rpm).
Performance Test
The performance tests can be used to find leakage
in the system. They can also be used to find a bad
valve or pump. The speed of rod movement when
the cylinders move can be used to check the
condition of the cylinders and the pump.
Lift, lower, tilt forward and tilt back the forks several
times.
1. Watch the cylinders as they are extended and
retracted. Movement must be smooth and regular.
2. Listen for noise from the pump.
3. Listen for the sound of the relief valve. It must not
open except when the cylinders are fully extended
or retracted, when the forks are empty.
WARNING
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