JLG 4017 Service Manual - Manual (Page 103)

8.3 4017
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.
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.
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
using the handle provided in the tool kit.
Note: 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 System
Schematics,” in this manual.
8.3 HYDRAULIC PRESSURE DIAGNOSIS
JLG Parts Department has a kit available to use for
hydraulic system maintenance and troubleshooting: the
JLG Pressure Test Kit. The kit is contained in a durable
polyethylene carrying case for demanding field service
conditions.
Pressure Test Kit
The hydraulic pressure test kit is used to pressure test the
various hydraulic components in the hydraulic system.
The kit includes:
• Gauges for testing high and low pressure circuits
• Fittings, couplers and hoses
Contact your JLG Parts Department for ordering
information.
WARNING:
Relieve hydraulic pressure
before servicing any hydraulic component.
Escaping hydraulic fluid under pressure can
penetrate the skin causing death or serious injury.
Part
Number
Description Approximate
Weight
Price and
Availability
80904003 Hydraulic Pressure Test Kit 10 lbs. Consult Factory
MZ1460