Lull 944E-42 Service Manual - Manual (Page 119)

8-3 944E-42
Hydraulic System
8.2 SAFETY INFORMATION
Petroleum-based hydraulic fluids are used in this
machine. The temperature of hydraulic fluid increases
during the operation of various hydraulic functions. A
heated petroleum-based hydraulic fluid presents a fire
hazard, especially when an ignition source is present.
Hydraulic fluid has a flash point that ranges from
300-600° F (150-318° C) and an auto-ignition temperature
of 500-750° F (262-402° C).
Accordingly, periodically inspect all hydraulic system
components, hoses, tubes, lines, fittings, etc. Carefully
examine any deterioration and determine whether any
further use of the component would constitute a hazard.
If in doubt, replace the component.
Operate the hydraulic controls after the engine has
stopped to relieve trapped pressure.
Note: Residual pressure may remain in hydraulic
cylinders, hoses, valve bodies, components, etc. If the
hydraulic lines going to or coming from a component are
taut, slowly and cautiously relieve (“bleed off”) pressure.
Whenever you disconnect a hydraulic line, coupler, fitting
or other component, slowly and cautiously loosen the part
involved. A hissing sound or slow seepage of hydraulic
fluid may occur in most cases. After the hissing sound
has ceased, continue removing the part. Any escaping oil
should be directed into an appropriate container. Cap or
otherwise block off the part to prevent further fluid seepage.
Hydraulic system maintenance will, at times, require that
the engine be operated. Always follow safety precautions.
A major cause of hydraulic component failure is
contamination. Keeping the hydraulic fluid as clean as
possible will help avoid downtime and repairs. Sand, grit
and other contaminants can damage the finely machined
surfaces within hydraulic components. If operating in an
exceptionally dirty environment, change filters and
inspect the fluid more often. When servicing the system,
cap or plug hydraulic fittings, hoses and tube assemblies.
Plug all cylinder ports, valves and the hydraulic reservoir,
and pump openings until installation occurs. Protect
threads from contamination and damage.
Some hydraulic functions are actuated by interfacing with
electrical system components (switches, solenoids and
sensors). When the hydraulic system is not functioning
properly, check the electrical aspect of the malfunctioning
circuit also. Refer to Section 9.5, “Electrical Schematics.”
in this manual.
WARNING
DO NOT service the machine without following all
safety precautions as outlined in Section 1, “Safety
Practices,” of this manual.