JLG 4017 Service Manual - Manual (Page 110)

Hydraulic System
8.10 4017
8.7 CONTROL VALVES
8.7.1 Main Control Valve
The main control valve is mounted on the frame in the
engine compartment.
The main control valve assembly (1) consists of seven
working sections with their own valve assemblies, each
providing a specific hydraulic function. The section
assemblies from left to right are the outrigger (left),
outrigger (right), frame sway, auxiliary, tilt, crowd (boom
in/out), and lift sections.
All the main control valve functions are electronically
controlled through the joystick.
a. Main Control Valve 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 hydraulic fluid to
cool.
4. Disconnect the positive (+) and negative (-) battery
cables from the battery terminals and remove the
battery.
5. With the engine OFF, 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.
6. Thoroughly clean the main control valve and
surrounding area, including all hoses and fittings,
before proceeding.
7. Place a suitable container to catch hydraulic fluid
drainage beneath the frame.
8. Label or otherwise mark, disconnect, cap or plug all
the hydraulic hoses, tubes and wires at the main
control valve.
9. Wipe up any hydraulic fluid spillage in, on, near and
around the machine and the work area.
10. Support the valve and remove the four bolts securing
the main control valve bracket to the frame.
11. Remove the main control valve and bracket from the
frame and remove the four bolts holding the
mounting bracket to the valve.
MZ0290
1
MZ1340