JLG 4017RS Service Manual - Manual (Page 149)

8-19 3614RS, 4017RS
Hydraulic System
9. Remove the Do Not Operate Tag from the ignition key
switch and the steering wheel.
d. Steering Test
Refer to Section 8.5.1, “Hydraulic Pressures.”
1. Conduct a pressure check of the steering hydraulic
circuit.
2. Check each steering mode for proper function.
8.10 HYDRAULIC CYLINDERS
8.10.1 General Cylinder Removal Instructions
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.
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.
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.
a. General 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.
Note: 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.
3. If applicable, remove the counterbalance valve from the
side of the cylinder barrel.
Note: 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.
4. Extend the rod as required to allow access to the base of
the cylinder.
Note: Protect the finish of the rod at all times. Damage to the
surface of the rod can cause seal failure.
5. Using a pin spanner wrench, unscrew the head gland
from the tube. A considerable amount of force will be
needed to remove the head gland. Carefully slide the
head gland down along the rod toward the rod eye,
away from the cylinder barrel.
Note: When sliding the rod and piston assembly out of the
barrel, prevent the threaded end of the barrel from damaging
the piston. Keep the rod centered within the barrel to help
prevent binding.
6. Carefully pull the rod assembly along with the head
gland out of the cylinder barrel.
7. Fasten the rod eye in a soft-jawed vise, and place a
padded support under and near the threaded end of
the rod to prevent any damage to the rod.
8. Remove the set screw from the piston head.
Note: It may be necessary to apply heat to break the bond of
the sealant between the piston and the rod before the piston
can be removed.
MZ0400
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.