Service manual
Section 9
9-96
2. Clean parts with trichlorethylene.
3. Check that the rod (17) is straight. If it is bent, install
a new rod.
e. Extend/Retract Cylinder Assembly
Note: Follow
Section 9.10 c. General Cylinder Assembly
Instructions
.
1. Install a new hytrel backup ring (2, Fig. 9– 66), small
O-ring (3) and another hytrel backup ring (2) into
forward end of the piston (4).
2. Install the capped T-seal (7) and both precision
wearbands (6) onto the piston (4).
Note: The T-seal actually consists of four components; a
wide, flexible inner band, the flexible T-seal band itself,
and two supportive split caps that mount on either side of
the “T” itself.
3. Install the precision wearbands (12) and the deep Z-
seal with backup (13) into the front end of the head
gland (14), and, at the rear end, install the sealed
outside diameter heavy-duty rod wiper (16).
4. Install a new O-ring (7), backup ring (10) and O-ring
(11) onto the head gland (14).
5. Fasten the rear 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.
6. Carefully slide the head gland (14), then the rod
spacer (8) onto the rod weldment (17).
7. Carefully slide the piston (4) onto the rod spacer (8)
and weldment (17). Apply Loctite Threadlocker #271
(red) and torque the piston to 1500-1700 lb/ft (2034-
2305 Nm).
8. Turn the rod spacer (8) as required to align the piston
set screw holes. The set screw is used to provide a
secondary lock on the piston. Thread the 5/16-18
UNC x 0.63 set screw (5) into the piston (4). Torque
the set screw to 72-82 lb/in (8-9 Nm).
9. Install a new locking insert (15) into its hole in the
head gland threads.
10. Secure the extend/retract cylinder in a soft-jawed
vise or other acceptable holding equipment if
possible. DO NOT damage the tube (19).
11. Lubricate the inside of the tube (19) and outside of
the piston (4) and head gland (14) with clean, filtered
hydraulic oil.
12. Apply a compression sleeve or other suitable tool to
the head and piston in order to compress the O-rings,
backup rings and seals while inserting the assembled
piston, rod and head into the tube (19). Carefully
insert the rod (17) with all attachments straight into
the tube (19).
IMPORTANT: When sliding the rod (17) and piston
assembly in the tube, prevent the threaded end of the
tube from damaging the piston (4). Keep the rod centered
within the tube to help prevent binding. Protect the finish
on the rod at all times. Damage to the surface of the rod
can cause seal failure.
13. Using a pin spanner wrench, thread the head gland
(14) into the tube (19). Torque the gland to 250-300
lb/ft (339-407 Nm).
14. Lubricate the counterbalance valves (18) with clean,
filtered hydraulic oil. Thread both counterbalance
valves into the rod weldment (17). Torque to 150-160
lb/ft (203-217 Nm).
IMPORTANT: DO NOT tamper with or attempt to reset
the counterbalance valve cartridges. If adjustment or
replacement is necessary, replace a counterbalance
valve with a new one.
15. Test the cylinder at low operating pressure (100 psi or
6,9 bar). Verify that the piston and the rod move
freely in both directions.
16. Increase the operating pressure to the maximum
amount for the cylinder (4000 or 275 bar) and again
check for free movement in both directions.
17. Retract the rod fully into the tube and cap and plug
the hydraulic hose ports.
f. Extend/Retract Cylinder Installation
Installation procedures are covered in
Section 3.2.1 Inner
Boom Replacement.
g. Extend/Retract Cylinder Pressure Checking and
Circuit Bleeding
1. Attach a 4000 psi (276 bar) gauge to the main control
valve at the extend base port relief to test the extend/
retract cylinder hydraulic system circuit pressure. The
unit is equipped with test fittings from the factory.
Pressure readings should be 3200 psi ± 100 psi
(220,6 ± 7 bar).
2. With no accessory installed on the quick attach, start
with the hoist and fork tilt cylinders fully retracted.
3. Fully extend the extend/retract cylinder. Hold the
joystick at full extend while fully raising the hoist
cylinder.
4. Fully retract the fork tilt cylinder. Hold the fork tilt
joystick at full retract while fully retracting the hoist
cylinder.
5. Repeat steps 3 and 4 five times.
Model 3606 • Origin 10/99