JLG 4017 Service Manual - Manual (Page 108)

Hydraulic System
8.8 4017
c. Cleaning and Drying
If contaminated hydraulic oil or foreign material is in the
tank, the tank can usually be cleaned.
Note: If a leak is suspected in the hydraulic oil reservoir,
contact JLG Service Department.
To clean the hydraulic oil reservoir:
1. Have a dry chemical (Class B) fire extinguisher near
the work area.
2. Clean the hydraulic oil reservoir with a high-pressure
washer, or flush the tank with hot water for five
minutes and drain the water. Dispose of
contaminated water properly.
d. Inspection
Note: If a leak is suspected in the fuel or hydraulic oil tank,
contact JLG Service Department.
1. Inspect the hydraulic oil reservoir thoroughly for any
cracks, slices, leaks or other damage.
2. With the hydraulic oil reservoir removed from the
machine, plug all openings except one elbow fitting.
Install the elbow fitting, and apply approximately
.06-1 bar (1-1.5 psi) of air pressure through the
elbow. Check the reservoir for leaks by applying a
soap solution to the exterior and look for bubbles to
appear at the cracked or damaged area.
e. Assembly
The hydraulic oil reservoir is a one piece-unit and cannot
be disassembled. The hydraulic oil level sight-glass and
hydraulic oil filler cap can be removed and reused on the
new replacement tank. Dispose of the old tank according
to local regulations concerning hazardous materials
disposal regulations.
f. Hydraulic Oil Tank Installation
1. Lift the hydraulic oil reservoir into place and install
the six bolts, washers and nuts.
2. Uncap and connect the suction hose and return
hose. Tighten both clamps.
3. Uncap and connect the four small return hoses to
the fittings on the hydraulic oil reservoir.
4. Install the hydraulic fluid level sight-glass using
special designed and drilled capscrews and gaskets.
5. Install hydraulic filler neck components and secure.
6. Fill the hydraulic oil reservoir according to
specifications. Refer to Section 2.4, “Fluids,
Lubricants and Capacities.”
7. Check the hydraulic oil reservoir for leaks.
8. Connect the negative (-) battery cable to the
negative battery terminal.
9. Close and secure the engine cover.
8.6 ENGINE IMPLEMENT PUMP
8.6.1 Pump Description
For internal service instructions contact your local JLG
distributor.
8.6.2 Pump Failure Analysis
The pump is the “heart” of the hydraulic system, and
whenever there is a problem in the system, the pump
often is blamed. However, pump failure is seldom due to
failure of pump components. Pump failure usually
indicates another problem in the hydraulic system.
According to pump manufacturer statistics, 90-95 percent
of pump failures are due to one or more of the following
causes:
• Aeration
• Cavitation
• Contamination
• Excessive Heat
• Over-Pressurization
• Improper Fluid
In the event of pump failure, investigate further to
determine the cause of the problem.
8.6.3 Pump Replacement
a. Pump Removal
1. Park the machine on a firm, level surface, lower the
boom to the ground, place the transmission control
lever in (N) NEUTRAL, engage the park brake and
shut the engine OFF.
2. Place an Accident Prevention Tag on both the
ignition key switch and the steering wheel, stating
that the machine should not be operated.
3. Open the engine cover. Allow the system fluids to
cool.
4. Remove the negative (-) battery cable from the
battery negative terminal.
5. Relieve any trapped pressure in the hydraulic
system by using the lever (supplied in the tool box)
or a 9mm wrench and move the double nut on the
side of the actuator module on each valve section
back and forth