JLG G5-18A Service Manual - Manual (Page 94)

Hydraulic System
8-4 G5-18A, 2505H, 25.5
8.2 SAFETY INFORMATION
8.3 GENERAL 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.
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.
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.
8.4 SPECIFICATIONS
Refer to Section 4, “After connection has been properly
tightened, mark a straight line across the connecting
parts, not covering dots indicating that connection has
been properly tightened.,” for hydraulic system
specifications.
8.5 HOSES, TUBE LINES, FITTINGS, ETC.
There are numerous hydraulic hoses, tubes, fittings, etc.
used on this machine. Periodically inspect all of these
and carefully examine any signs of wear, abrasion and/or
deterioration. Determine whether any further use of the
component would constitute a hazard. If in doubt, replace
the component.
8.5.1 Replacement Considerations
Conditions including, but not limited to, the following are
sufficient for considering component replacement:
1. Any evidence of hydraulic fluid leakage at the
surface of a flexible hose or its junction with the
metal and couplings.
2. Any blistering or abnormal deformation to the outer
covering of a hydraulic hose.
3. Hydraulic oil leakage at any threaded or clamped
joint that cannot be eliminated by normal tightening
or other recommended procedures.
4. Evidence of excessive abrasion or scrubbing on the
outer surface of a hose, rigid tube, or hydraulic
fitting. Modification must be made to eliminate the
interference of the elements in contact with one
another, or to otherwise protect the components
from contact with one another. Slightly moving a
hose or adjusting a plastic tie wrap may often be all
that is necessary to eliminate interference; evaluate
each situation and proceed as required by the
individual circumstances.
8.5.2 Hose, Tube, Line and Fitting
Replacement
Before removing a hydraulic hose or component, always
mark or otherwise label the related parts and the exact
location of the hose or component to aid in proper
reinstallation. Hydraulic fluid is a good cleaner and can
remove most liquid-ink type markings, so make sure the
mark or label will remain intact. Alternative methods to
using markers include color-coded tie wraps, number-tag
sets, alpha-numeric stampings or markings, and suitably
labeled pieces of tape. Select an appropriate marking
method for the conditions and proceed accordingly.
WARNING
DO NOT service the machine without following all
safety precautions as outlined in the “Safety Practices”
section of this manual.