Lull 1044C-54 Series II Service Manual - Manual (Page 87)

Supply, Pressure, and Return Hydraulics
31200079 5-5
as the oil passes through. A high quality hydraulic oil contains many
additives which work to keep contaminants from damaging the system.
However, these additives lose their effectiveness after a period of time.
Therefore, change the oil at recommended intervals to make sure the
additives do their job.
The system filter can absorb only a limited amount of dirt particles and
other contaminants from the oil. Therefore, replace the filter element at the
recommended intervals so the cleaning process can be maintained.
Checking Hydraulic Lines
Inspect hydraulic lines and fittings for gouges, nicks, kinks, leaks, and
collapsed or deteriorating hoses.
Note: Even small leaks can be detected by oil stains or build-up of dirt or other
foreign material in a suspect area.
Replace any tube lines that are pinched or dented.
Replace a hose if any of the following conditions exist:
• Any evidence of hydraulic oil leakage at the surface of the hose or its
junction with the metal end couplings.
• Any blistering or abnormal deformation to the outer covering of the
hose.
• Hydraulic oil leakage at any threaded or clamped joint that cannot be
eliminated by normal tightening.
• Evidence of excessive abrasion or scrubbing on the outer surface of
hose or hoses.
Important: When tightening loose lines or connections, use two wrenches to
avoid twisting hose or tubes. Tighten loose connections only until the
leak stops. An over-tightened fitting may result in overstressing and/or
cracking. Replace any connectors that continue to leak. See
“Hydraulic Fitting Torques” in Section 3 for torque specifications for
hydraulic fittings and hydraulic line connections.