DOC-20230111-WA0038.

FRONT ATTACHMENT / Cylinder
Assemble Boom Cylinder
• Be sure to read “Precautions for Disassembly and
Assembly” thoroughly on page W1-1-1 before
starting any repair work.
1. Press bushing (7) into cylinder head (6) with a
press. Install snap ring (8) into the cylinder head.
Bushing Special Tool: 70 mm (ST 8017)
IMPORTANT: Install U-ring (4) with the lip facing
bushing (7).
Install buffer ring (5) with the protrusion
part and slits facing bushing (7).
2. Install backup ring (3), U-ring (4) and buffer ring
(5) into cylinder head (6).
3. Install wiper ring (2) into cylinder head (6) using
ST 8017.
Wiper Ring Specail Tools: ST 8017
IMPORTANT: Install backup ring (10) to the piston
rod (1) boss side of O-ring (11).
4. Install the O-rings (9, 11, 13) and backup rings (10,
12, 14) into cylinder head (6).
5. Install the cylinder head (6) assembly into piston
rod (1).
Cylinder Head Special Tool: ST 8017
IMPORTANT: After installing O-ring (20), check
there is no twisting.
6. Install O-ring (20) and seal ring (19) onto piston
(18) with a wooden spatula so that they are not
installed in the slide ring (17) groove.
IMPORTANT: While installing slide rings (17), (21),
be sure that their slit sections align
with each other.
7. Install slide rings (17), (21) onto piston (18).
IMPORTANT: Install cushion seal (15) with the slit
side facing piston (18).
Install cushion bearing (16) with the
wider split circumference side facing
cylinder head (6).
8. Install cushion seal (15) and cushion bearing (16)
into piston rod (1).
9. Install piston (18) and shim (22) into piston rod (1).
Tighten nut (23) using special tool (ST 5908) according
to the matching mark.
Nut Turning Special Tool: 75 mm (ST 3271)
: 2650 N⋅m (270 kgf⋅m, 1950 Ibf⋅ft)
ST 5908
W158-04-02-022
10. Align the holes on the piston rod (1) and nut (23).
Install steel ball (25) into nut (23). Then, tighten
set screw (24). Set screw (24) should be crimped
with a punch in 2 places after it is tightened.
:8 mm
: 31.5±5.9 N⋅m
(3.2±0.6 kgf⋅m, 23±4.3 Ibf⋅ft)
W4-2-23