Repair
17
309512
Air Motor Piston and Cylinder
Repair
Disassembly
To repair the piston rod, order Repair Kit 234042. Parts
included in the kit are marked, for example (4†).
1.
Disconnect the displacement pump from the air
motor (page 15).
2.
Remove the air valve (29) and gaskets (34*) (page
16).
3.
Remove the screws (12). Remove the cylinder cover
(32) from the air motor. Remove the pilot valve (14)
and the o-ring (23*) from the cover. See F
4.
Remove the round cover (20) and cylinder (21).
Inspect the inside surface of the cylinder for
scratches or other damage. See F
. 8.
5.
Remove screws (10) and lock washers (11). Verify
the piston (19) is in its fully extended position
(threaded insert (3) protrudes from the top of the
housing.
6.
Remove the threaded insert (3) from the top of the
housing and pull the piston (19) and rod (4†)
straight out of the bottom of the housing. Do not tilt
the piston to prevent damage to the rod. Remove
the o-ring (27*). See F
7.
Inspect the piston rod (4†) for wear or damage. If
the rod is damaged, disassemble the piston assem-
bly. Keep the piston (19) for reuse. Discard the pis-
ton rod (4†) and the cap screw (22†). These parts
must be replaced together.
8.
Remove the o-ring (23*) and pilot valve (14) from
the air motor base (13). Use a clip removal tool to
take out the c-clip (25*), then remove the washer
(18*), ring and seal (17A* and 17B*). Note the orien-
tation of these parts. See F
. 8.
Reassembly
1.
Lubricate the o-ring and the center bore in the base
(13). Install the seal (17B*) with the groove facing
away from the bellows, then install the ring (17A*) in
the groove with notches facing up. Install the washer
(18*) with the flat side facing up, then the retaining
ring (25*). See F
2.
Install the o-ring (23*) and the pilot valve (14) on the
air motor base. Torque the pilot valve to 25 N•m (18
ft-lb).
3.
If the piston was disassembled, reassemble the cap
screw (22†), piston (19) and rod (4†), using Loctite
®
from the kit on threads. See F
. 8. Make sure the
flat side of the piston faces down. Torque the cap
screw to 150-163 N•m (110-120 ft-lb).
4.
Replace bearing (26*) and seal (28*).
5.
Place the o-ring (27*) on the piston (19). Grease the
piston rod (4†) and o-ring (27*), and carefully insert
the piston rod through the hole in the base (13).
Align the hole in the piston with the orientation bolt
(15) in the base until the piston rests against the
base.
6.
Install lock washers (11) and screws (10). Torque to
10-11 N•m (90-100 in-lb).
7.
Replace o-ring (1*).
8.
Install the threaded insert (3) onto the end of the rod
from the opposite end and tighten.
9.
Generously grease the lower half of the cylinder’s
(21) inside surface. Install the cylinder and the side
cover (20). See F
10. Install the o-ring (23*) and the pilot valve (14) on the
inside surface of the bottom cover (32). Torque the
pilot valve to 25 N•m (18 ft-lb). Lubricate the o-ring.
Install the bottom cover (32), making sure the air
valve porting (Y
1
) faces the same way as the porting
on the base (Y
2
). Torque the screws (12) to 10-11
N•m (90-100 in-lb). See F
11. Reinstall the air valve with new gaskets (34*) (page
16).
12. Reconnect the displacement pump to the air motor
(page 15).
•
Air Motor Seal Repair Kits are available.
Order repair kit 234041.Parts included in the
kit are marked, for example (1*).
•
For replacement of o-rings (2* and 24*), refer
to Bellows Repair on page 19.
•
For replacement of o-rings (51*), refer to Air
Valve Repair on page 16.
•
For replacement of seal (36*) and pin (38*),
refer to the exploded view of the Air Motor,
page 25.
