4000 SRM 481 Free-Lift Cylinder Repair
1. ROD
2. RETAINER
3. WIPER RING
4. SEAL
5. O-RING
6. BACKUP RING
7. BLEED SCREW
AND SEAL
8. SHELL
9. CHAIN ANCHOR
10. LOWERING
CONTROL VALVE
(ALL CYLINDERS)
11. STEEL BALL
12. PLUG
13. WEAR PLUG
Figure 5. Free-Lift Displacement Cylinders
CAUTION
A difficult and important step in assembling
lift cylinders is the correct installation of the
seals. Most lift cylinder maintenance is caused
by seal leaks. Special installation sleeves come
in the seal kits.
1. Install the internal check valve, if installed. See
Figure 5. Make sure the arrow on the internal
check valve is toward the base of the piston.
2. Install the wear ring, single lip seal, and backup
ring onto the piston assembly. If a spacer is used,
installit. Useshimmaterialandaclampasa
guide to move the seal over the threads of the
shell.
3. Carefully push the piston and rod assembly into
the shell. Release the clamp on the seal when the
seal travels past the threads of the shell.
4. Install the seal, O-ring, wear ring, and wiper ring
in the retainer. If the wiper ring has a spring for a
backup ring, the spring must be toward the base
of the lift cylinder.
5. Carefully install the retainer on the piston rod.
6. Engage the threads and tighten the retainer
in the shell to the proper torque. Refer to Ca-
pacities and Specifications 8000 SRM 1198,
Capacities and Specifications 8000 SRM
1028, Capacities and Specifications 8000
SRM 1380, or Capacities and Specifications
8000 SRM 972 for your truck model. Use the cor-
rect spanner wrench. DO NOT hit the retainer
with a hammer and driver.
CAUTION
Wrong in
stallation of the special washer and
spring c
an make the load lower too fast.
7. Install
the lowering control valve. Make sure the
special
washer and the spring are installed cor-
rectly.
A wrong installation can cause the load to
lower to
ofast.
8. See the s
ection Mast, Repair 4000 SRM 482 for
cylind
er installation in the mast assembly.
7
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