S0302000
Page 6
General Maintenance Procedures
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HYDRAULIC SYSTEM CLEANLINESS AND OIL LEAKS
MAINTENANCE PRECAUTIONS FOR HYDRAULIC SYSTEM SERVICE
Whenever maintenance, repairs or any other type of troubleshooting or service is being performed, it’s
important to remember that the hydraulic system - including both the interior and exterior surfaces of
assemblies, and every drop of operating fluid - must be protected from contamination.
Dust and other foreign contaminants are major contributors to premature wear in hydraulic circuits. The
narrow tolerances, rapidly moving parts and high operating pressures of the system require that fluid be
kept as clean as possible. The performance and dependability of the machine (and the service lift of
individual components) can be noticeably reduced if proper precautions are not observed:
• Use a safe, non-combustible, evaporative-type, low-residue solvent and thoroughly clean
exterior surfaces of assemblies before any part of the circuit is opened up or disassembled.
NOTE:
It’s just as important to clean the cap and reservoir top before routine fluid changes or
quick checks as it is before major repairs. (Accumulated dirt attracts moisture, oil and
other fluids - and more dirt.)
• Keep dismantled parts covered during disassembly. Use clean caps, plugs or tape to protect the
disconnected openings of flanges, manifolds and piping.
• Do not allow cleaning solvents or other fluids to mix with the oil in the system. Use clean oil to
flush any traces of solvent or other residue before reassembly.
• If metal or rubber fragments are found in the system, flush and replace all fluid in the system
and troubleshoot the circuit to identify the source of contamination.
OIL LEAKAGE PRECAUTIONS
Oil that is visibly seeping from joints or seals should always serve as a "red flag" alarm.
Leaks must alert the machine operator and maintenance crew that air, water and dirt have an open, free
passageway through which to enter the circuit. Harsh, corrosive salt air, freezing and thawing
condensation cycles and working environments that are full of fine dust are especially hazardous. Clogging
of valve spools or external piping (especially pilot circuit piping) can gradually diminish or very suddenly
put a complete stop to normal hydraulic function. You can prevent having to make these types of repairs by
following recommended assembly procedures:
1. Use new O-rings and oil seals whenever hydraulic assemblies are rebuilt.
2. Prepare joint surfaces before assembly by checking alignment and flatness. Clean and repair
corrosion or any other damage.
3. Follow bolt torque recommendations and all other assembly requirements.
IMPORTANT
Make sure that cleaning solvents will be compatible with rubber materials used in the hydraulic
system. Many petroleum based compounds can cause swelling, softening, or other deterioration
of system sealing elements, such as O-rings, caps and other seals.
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