BA-921 Bendix Air Compressor Caterpillar

Installation of the Unloader Piston

Illustration 1	g01263489
(1) Screw (unloader cap) (2) Unloader cap (3) Gasket (unloader cap) (4) Balance piston (5) Spring for the balance piston (6) O-ring (7) Unloader piston (8) O-ring (9) O-ring (10) Bore for the unloader piston (11) Cylinder head

1. Install a new 217-5237 Unloader Kit. The unloader kit contains the following components:
   • Gasket for the unloader cap (3)

   • Balance piston (4)

   • Spring for the balance piston (5)

   • Unloader piston (7)

   • Three O-rings (6), (8), and (9)

2. Install the O-rings (6), (8), and (9) onto the unloader piston (7). Carefully install the unloader piston (7) into the cylinder head (10). Be careful not to damage the O-rings.

3. Install the spring (5) into the unloader piston (7) .

4. Install the balance piston (4) through the center of the spring (5) .

5. Place the unloader cap (2) onto the cylinder head (11). The screw holes must align.

6. Press the cap (2) for the unloader piston (7) and hold the cap for the unloader piston. Install the two screws (1) in the cap for the unloader piston (2). Torque the screws (1) to 7.5 ± 0.5 N·m (66 ± 4 lb in).