JLG 534D-10 - Manual (Page 145)

8.21 534D-9, 534D-10 & 544D
Hydraulic System
8.8.4 Steering Orbitrol Valve
The steering orbitrol valve (4) is located at the base of the
steering wheel shaft. The valve is not serviceable and
must be replaced in its entirety if defective. For detailed
information refer to Section 4.3.1, “Steering Column and
Orbitrol Valve.”
8.9 HYDRAULIC CYLINDERS
8.9.1 General Cylinder Instructions
a. Cylinder Removal
1. Remove any attachment from the machine. Park the
machine on a firm level surface and fully retract the
boom. Allow sufficient work space around the
hydraulic cylinder being removed. Support the boom
if the lift/lower cylinder is being removed. Place the
travel select lever in (N) NEUTRAL, engage the park
brake, shut the engine OFF and chock wheels.
2. Place a Do Not Operate 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. Label, disconnect and cap or plug hydraulic hoses in
relation to the cylinder. Cap all fittings and openings
to keep dirt and debris from entering the hydraulic
system.
5. Attach a suitable sling to an appropriate lifting device
and to the cylinder. Make sure the device used can
actually support the cylinder.
6. Remove the lock bolt and/or any retaining clips
securing the cylinder pins. Remove the cylinder pins.
7. Remove the cylinder.
8. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
8.9.2 Cylinder Disassembly
1. Clean the cylinder with a suitable cleaner before
disassembly. Remove all dirt, debris and grease
from the cylinder.
2. Clamp the barrel end of the cylinder in a soft-jawed
vise or other acceptable holding equipment if
possible.
3. If applicable, remove the counterbalance valve from
the side of the cylinder barrel.
4. Extend the rod as required to allow access to the
base of the cylinder.
WARNING
Significant pressure may be trapped inside the cylinder.
Exercise caution when removing a counterbalance valve
or a pilot-operated check valve from a cylinder. Escaping
hydraulic fluid under pressure could penetrate the skin.
NOTICE
Avoid using excessive force when clamping the
cylinder in a vise. Apply only enough force to hold the
cylinder securely. Excessive force can damage the
cylinder tube.
NOTICE
DO NOT tamper with or attempt to adjust the
counterbalance valve cartridge. If adjustment or
replacement is necessary, replace the
counterbalance valve with a new part.
MZ0400