Service Manual User Manual

Hydraulic System
9-87
9.10.1 Attachment Tilt Cylinder
The attachment tilt cylinder (Fig. 9– 64) is attached at the
front of the inner boom inside the gooseneck.
a. Attachment Tilt Cylinder Removal
1. Park the vehicle on a firm, level surface, fully retract
all hydraulic cylinders, ground and remove the
attachment. Allow sufficient work space at the front of
the boom. Raise the boom enough to allow the quick
attach or the bottom of the gooseneck to clear the
ground. Place the travel select lever in NEUTRAL
(N), engage the park brake switch and shut the
engine OFF.
2. Unlatch, unlock and open the engine cover. Allow the
hydraulic fluid to cool.
3. Label or otherwise mark the hydraulic hoses in
relation to the attachment tilt cylinder. Disconnect
and cap both hoses and attachment tilt cylinder
fittings. Refer to
Section 3 Boom
as required.
4. Unbolt the lower pivot pin.
5. Screw an eyelet, hook, or other suitable fastener into
the tapped hole on top of the attachment tilt cylinder.
Make sure the device used can actually support the
cylinder. Attach a suitable sling to an overhead crane
or other appropriate lifting device and to the
attachment tilt cylinder at the eyelet or hook.
6. Remove the two 2" external retaining rings securing
the attachment tilt cylinder base pin to the boom.
7. Remove the attachment tilt cylinder base pin by
tapping it out through the top of the gooseneck.
8. Remove the lower attachment tilt cylinder pin by
tapping it out through the bottom of the quick attach
(if installed).
9. Remove the attachment tilt cylinder from the vehicle.
Wipe up any hydraulic fluid spillage in, on, near or
around the vehicle.
b. Attachment Tilt Cylinder Disassembly
Note: An additional O-ring may be included at the base
of the cylinder rod. This additional O-ring may be
discarded, as it served only in a temporarily protective
role to keep paint off the rod while the cylinder was
painted at the factory.
1. Clean the attachment tilt cylinder (Fig. 9– 64) with a
suitable cleaner before inspection.
2. Place the attachment tilt cylinder in a soft-jawed vise
or other acceptable holding equipment if possible.
DO NOT damage the tube. If necessary, remove the
grease fitting from the end of the rod weldment (18).
Note: Significant pressure may be trapped inside the
cylinder. Exercise caution when removing the counter-
balance valves (2) from the cylinder.
3. Remove the two 4000 psi (276 bar) counterbalance
valves (2) from the attachment tilt cylinder.
4. Extend the rod weldment (18) to allow access to the
base of the cylinder.
5. Using a pin spanner wrench, unscrew the head gland
(14) from the tube (3). The gland was originally
torqued to 300-400 lb/ft (407-542 Nm), so a
considerable amount of force is required to remove it.
Slide the gland down along the rod toward the eyelet
end, away from the cylinder tube (3).
IMPORTANT: Protect the finish on the rod at all times.
Damage to the surface of the rod can cause seal failure.
6. Carefully pull the rod (18) along with the head gland
and all attachments straight out of the tube (3).
IMPORTANT: When sliding the rod and piston assembly
in the tube, prevent the threaded end of the tube from
damaging the piston (6). Keep the rod centered within the
tube to help prevent binding.
7. Fasten the eye of the rod in a soft-jawed vise and put
a padded support below and near the threaded end
of the rod to help prevent damage to the rod.
8. Remove the 1.50-12 NF lock nut (4) from the rod
(18). The lock nut is a deformed-thread type nut
torqued at 1100-1250 lb/ft (1492-1695 Nm).
Note: It may be necessary to apply heat to break the
bond of the sealant between the 1.50-12 NF lock nut (4)
and the rod (18) before the piston (6) can be removed.
Some parts of cylinders are sealed with a special organic
sealant and locking compound. Before attempting to dis-
assemble these parts, remove any accessible seals from
the area of the bonded joint. Wipe off any hydraulic oil
and heat the joint uniformly to break the bond. A temper-
ature of 300° to 400° F (149° to 204° C) will destroy the
bond. Avoid overheating or the parts may become dis-
torted or damaged. Apply sufficient torque or pressure for
removal while the parts are still hot. Breakdown of seal-
ant will leave a white, powdery residue on threads and
parts. Clean the residue away with a soft brass wire
brush prior to reassembly, and wipe with Loctite “T”
cleaner before reinstallation.
WARNING: Hot hydraulic fluid can cause
severe burns. Wait for hydraulic fluid to cool
before servicing any hydraulic component.
WARNING: Escaping hydraulic fluid under
pressure can penetrate the skin, causing seri-
ous injury. Relieve hydraulic pressure before
servicing any hydraulic component.
Model 3606 • Origin 10/99