STAIR GP 4752891 - Caterpillar

Do not disconnect any air lines until the air pressure is zero.
1. Drain the air from the air tanks. 2. Disconnect air hose assemblies (1) from the brake actuator.3. Loosen screw (3). Loosen shaft (4) at the bottom of the slack adjuster until the pin that holds the rod in the actuator to the slack adjuster can be removed.4. Remove the cotter pin and pin (2).5. Remove the nuts (5) that hold the brake actuator in position, and remove the brake actuator. The following steps are for the installation of the brake actuator.6. Position brake actuator (6) on the bracket, and install the nuts that hold it. Tighten the nuts (5) to a torque of 180 25 N m (135 18 lb ft).7. Connect air hose assemblies (1) and (2) to the brake actuator.8. Put the slack adjuster in position on the rod for the brake actuator, and install pin (2) and the cotter pin that holds it.9. Make an adjustment to the brakes. See the topic, Adjustment Of Brakes.Disassemble & Assemble Brake Actuator
Start By:a. remove brake actuator 1. Remove yoke (1), locknut (19), boot (3), and retainer (4). Remove clamp (12), plate (11), and diaphragm (9).
Remove nut (2) very slowly and carefully to be certain all the pressure on the service brake spring is released.
2. Remove the locknut for nut (2). Remove nut (2) slowly to release pressure on service brake spring (7). Remove rod (10), retainer (15), spring (7) and the guide.
Be careful when using tooling (A) to compress and release parking brake spring (6). Serious injury could result if caution is not used during this process.
3. Install tooling (A) to compress parking brake spring (6) slightly. Remove eight bolts (13) (photo shows bolts removed.) Slowly remove nut (22) slowly to release pressure on spring (6).4. Remove tooling (A). Remove spring (6). Remove seal and wiper (17) from piston (5). 5. Remove wiper (23) and seal (24) from the cylinder assembly (14). The following steps are for the assembly of the brake actuator.6. Clean and inspect all parts. Make a replacement of all parts that are worn or damaged.7. Install seal (24) in the cylinder assembly (14).
Serious injury could result if tooling (A) is not used correctly and safely to compress parking brake spring (6).
8. Install seal and wiper (17) in piston (5). Install spring (6). Install tooling (A) to compress the parking brake spring.9. Slowly and carefully tighten nut (22) and compress parking brake spring (6). Install eight bolts (13) (photo shows bolts removed.) 10. Install the guide, spring (7), retainer (15) and rod (10).11. Install and tighten nut (2) to put pressure on the service brake spring (7). Tighten nut (2) until approximately 1/161/8 51.5 to 54.0 mm (2 to 2 in of rod (10) is out of the nut. Install the locknut on the rod above nut (2).12. Install diaphragm (9), plate (11) and clamp. Install retainer, boot (3), locknut (19), and yoke (1).End By:a. install brake actuator