Hydraulic system operating conditions (repetitive cycling, heavy work loads, fluid circulating
under high pressure) make it extremely critical that dust, grit or any other type of contamination
be kept out of the system. Observe fluid and filter change maintenance interval recommendations
and always pre-clean any exterior surface of the system before it is exposed to air. For example,
the reservoir filler cap and neck area, hoses that have to be disassembled, and the covers and
external surfaces of filter canisters should all be cleaned before disassembly.
MAINTENANCE SERVICE AND REPAIR PROCEDURE
GENERAL PRECAUTIONS
Fluid level and condition should always be checked whenever any other type of maintenance service or
repair is being performed.
NOTE: If the unit is being used in an extreme temperature environment (in sub-freezing climates or in
high temperature, high humidity tropical conditions), frequent purging of moisture condensation
from the hydraulic reservoir drain tap should be a regular and frequent part of the operating
routine. In more moderate, temperate climates, draining reservoir sediment and moisture may
not be required more than once or twice every few months.
Inspect drained oil and used filters for signs of abnormal coloring or visible fluid contamination at every oil
change. Abrasive grit or dust particles will cause discoloration and darkening of the fluid. Visible
accumulations of dirt or grit could be an indication that filter elements are overloaded (and will require more
frequent replacement) or that disintegrating bearings or other component failures in the hydraulic circuit may
be imminent or have already occurred. Open the drain plugs on the main pump casings and check and
compare drain oil in the pumps. Look for evidence of grit or metallic particles.
Vibration or unusual noise during operation could be an indication of air leaking into the circuit (Refer to the
appropriate Troubleshooting section for component or unit for procedures.), or it may be evidence of a
defective pump. The gear-type pilot pump could be defective, causing low pilot pressure, or a main pump
broken shoe or piston could be responsible.
NOTE: If equipped, indicated operating pressure, as shown on the multidisplay digital gauge on the
Instrument Panel ("F-Pump" and "R-Pump") will be reduced as a result of a mechanical problem
inside the pump. However, pressure loss could also be due to cavitation or air leakage, or other
faults in the hydraulic system.
Check the exterior case drain oil in the main pumps. If no metallic particles are found, make sure there is no
air in the system. Unbolt and remove the tank return drain line from the top part of the swing motor, both
travel motors and each main pump. If there is air in any one of the drain lines, carefully pre-fill the assembly
before bolting together the drain line piping connections. Run the system at low rpm.
General Maintenance Procedures S0302000
Page 5
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