Service Manual User guide

Boom and Transfer
6-144 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
Overhaul, Extension Cylinder
Fig. 6-152: 3-Section Boom Extension Cylinder Assembly
(Ref. Fig. 6-152) The following steps are required to overhaul the boom
extension cylinder.
1. Mount or support cylinder vertically with rod end down. Hydraulic oil in
cylinder will drain out during disassembly. Place a suitable pan or tray
under the cylinder.
2. Release pressure in counterbalance valve cartridges (Items 2 and 3)
as follows:
WARNING: Counterbalance valve cartridges trap hydraulic pressure in the
cylinder. Wear proper eye and hand protection when removing
counterbalance valve cartridges. Hydraulic fluid under
pressure can be injected under skin or into eyes, resulting in
serious personal injury or death.
a. Place socket wrench over counterbalance valve cartridge. Wrap a
clean shop rag around the socket to cover the area of the
counterbalance valve cartridge.
b. Carefully and slowly, turn cartridge out of manifold block to release
pressure in cylinder.
3. Remove the counterbalance valve cartridges.
4. Slowly extend and retract cylinder by hand to remove most of the
hydraulic oil.
J1132
# Description
1 Hollow Hex O-ring Plug
2 Counterbalance Valve Cartridge
3 Counterbalance Valve Cartridge
4 Cylinder Barrel
5 Rod Nut
# Description
6 90° O-ring Elbow
7Piston
8 Rod Bearing Head
9Capscrew
10 Cylinder Rod
2
1
6
3
4
5
10
9
8
7