ELBOW 1217520 - Caterpillar

To prevent possible personal injury, make sure the pressure in the air system is zero before any air lines are disconnected.
2. Disconnect air lines (1), (2), (3) and (4) from brake relay valve (5).3. Remove the bolts that hold brake relay valve (5) to the frame. Remove the relay valve from the machine. The following steps are for installation of the brake relay valve.4. Put brake relay valve (5) in position, and install the bolts that hold it to the frame.5. Connect air lines (1), (2), (3) and (4) to brake relay valve (5).Disassemble Brake Relay Valve
Start By:a. remove brake relay valve The brake relay valve shown in the following procedure is similar to the one used in 793 Trucks. 1. Remove the four bolts, bracket (3) and cover (2) from brake relay valve (1). Remove the O-ring seal from the cover. 2. Use tool (A) to remove snap ring (4) from the body. 3. Remove retainer (5) and spring (6). Remove the O-ring seal from the retainer. 4. Remove valve (7) from body (1). 5. Remove piston (9) from body (1). Remove the O-ring seal from the piston.Assemble Brake Relay Valve
1. Install the O-ring seal on piston (9). Put piston (9) in position in body (1). 2. Put valve (7) in position in body (1). 3. Put the O-ring seal on retainer (5). Put spring (6) and retainer (5) in position in the body. Compress spring (6), and install the snap ring to hold the retainer in place with tool (A). 4. Put the O-ring seal in position on cover (2). Put the cover and bracket (3) in position on body (1) and install the four bolts that hold them in place.End By:a. install brake relay valve