Cylinder And Piston Repair - Graco NXT Instructions Manual

Repair

Cylinder and Piston Repair

Air Motor Seal Repair Kits are available. See the
parts lists on pages 26, 27, and 28 for the correct
kit for your size motor. Parts included in the kits are
marked with an asterisk (*). For the best results,
use all the parts in the kit.
Disassemble the Air Motor
1. Stop the pump at the middle of its stroke. Relieve
the pressure, page 16.
2. Disconnect the air line to the motor.
3. See F . 8 on page 16. Pry off the top cover (30).
IG
4. Remove the outer valve cover (47). See F
5. Remove the top two muffler screws (43) and the top
two screws (41). Loosen but do not remove the bot-
tom two muffler screws (43) and the bottom two
screws (41). Tilt the air valve (40) to make disas-
sembly easier.
6. For motors with DataTrak or the linear sensor:
a. DataTrak Models: Remove the two screws
(135). Carefully remove the DataTrak module
(131), see page 12. Disconnect the runaway
solenoid and sensor cables from the module
board. Remove the two screws (134) and care-
fully slide the housing (132) off the air valve.
b. Linear Sensor Models: Remove the screws
(134) and carefully slide the housing (132) off
the air valve. Disconnect the sensor cable from
the circuit board. See F
20
. 12.
IG
. 14 on page 23.
IG
7. Loosen the tie bolts (13). Using a rubber mallet, hit
the underside of the top cap (1) to separate. Lift the
top cap and bolts (13) off motor.
8. Disconnect the air motor from the lower (see your
separate pump manual). Leave the piston shaft
adapter (A) attached to the shaft (S).
9. Push the piston assembly (4) out the top of the cyl-
inder (2).
10. Inspect the piston o-ring (17). Check the piston (4)
and piston shaft (S) for scoring or damage. The
replacement piston (4) includes the piston, shaft (S),
adapter (A), and bumper (10).
11. Remove the cylinder (2). Check the inner surface for
scoring or other damage. Replace if damaged.
12. Remove the bumper (59), retaining ring (9), backup
packings (8), and v-packing (7) from the bottom
cover (3). Inspect these parts for wear or damage.
Inspect the bearing (B) in place. If the bearing is
damaged, replace the bottom cover (3).
311238G