Repairing the Air Motor and Piston

Service

NOTE: Parts marked with an asterisk are included in a repair kit, for example, (23*). See pages 38 and 39 for repair kit part numbers. Use all the parts in the kit for the best results.

Disassembly

1.Relieve the pressure.

WARNING

PRESSURIZED EQUIPMENT HAZARD

To reduce the risk of a serious injury whenever you are instructed to relieve pressure, follow the Pres- sure Relief Procedure on page 10.

2.Disassemble the pump as instructed under Re- pairing the Fluid Piston and Seal.

3.Remove the screws (3 & 4), washers (46), nuts (1), and lockwashers (2) from the cylinder cap (25). See Fig. 7.

4.Remove the pump from the mounting bracket (44).

5.Remove the cylinder cap (25) from each end of the air motor. If the hoses aren’t disconnected or the pilot valves removed, be careful not to pull on the hoses when removing the caps.

CAUTION

The shaft wiper (21) and bearing (22) are meant to remain in place. Remove only to replace. Removal will damage them.

6.Remove the shaft wiper (21) and bearing (22); only if they need to be replaced, and u-cup (23*) from each of the cylinder caps (25). Use a 0.875 in. di- ameter shaft to remove the bearing.

7.Remove the piston assembly (A) from the air mo- tor cylinder (27). Remove the seal (28).

8.Do not remove the piston shafts (15) unless re- placement is necessary as a high strength sealant was used on the threads. If the rods must be re- moved, heating the joint to 300_ F will ease disas- sembly. Place wrenches on the flats of the piston shaft to disconnect them from the piston stud (30).

9.Clean all parts and inspect for wear or damage. Replace as needed.

Assembly

1.Apply lithium base grease to all packings, seals, and the inside of the air motor cylinder (27) before assembling.

2.If the piston shafts (15) were removed from the piston stud (30), apply high strength sealant (such as Loctiter) to the threads of the piston stud, and assemble as shown in Fig. 7.

3.Install the quad ring (28*) in the groove on the pis- ton (29). Install the piston assembly (A) into the air motor cylinder (27).

4.Install a u-cup (23*) into each of the cylinder caps

(25).The lips of the u-cup must face in, towards the center of the pump, as shown in Fig. 8.

5.If the bearings (22) were removed, install a bearing into each cylinder cap (25). Press fit the bearing to flush, using an arbor press.

6.Install a shaft wiper (21) into each cylinder cap

(25)with the brass part of the wiper facing out, away from the center of the pump, as shown in Fig. 8. Carefully press the wiper into place, taking care to avoid damaging the brass piece.

7.Install an o-ring (26*) into the groove in each of the cylinder caps (25). Slide a cylinder cap (25) onto each end of the air motor. Align flat edges with air valve.

8.Secure the mounting bracket (44) and cylinder caps (25) on the pump with the screws (3 and 4), washers (46), nuts (1), and lockwashers (2). Tor- que the screws oppositely and evenly to 7.4 to 12.5 ft-lb (10 to 17 NSm).

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