Usage:
NOTE: The valve shown removed is the secondary brake valve. The retarder valve is removed the same way. Photos are of a 785 Truck.
1. Remove the cover from the front of the cab.
2. Release the air pressure in the system.
Typical Examples
3. Remove setscrew (2) from the adapter on secondary brake valve (4).
Typical Example
4. Remove two bolts (8) that hold the brake valve to the cab.
5. Pull secondary brake valve (4) off the shaft assembly.
 |
To prevent possible personal injury, make sure the air pressure in the system is zero before disconnecting any lines. |
 |
6. Disconnect air lines (6) and (7) from secondary brake valve (4), and remove the valve from the machine.
NOTE: The following steps are for installation of the retarder valve and secondary brake valve.
NOTE: Air line (6) is from the parking brake control valve. Air line (7) is from the brake release air reservoir. Air line (3) to retarder valve (1) is from the brake air check valve. Air line (5) to the retarder valve is from the service brake valve.
7. Connect air lines (6) and (7) to secondary brake valve (4).
8. Put the brake valve in position on the shaft, and install two bolts (8).
9. Install setscrew (2) to hold the adapter on the brake valve to the shaft.
10. Install the cover on the front of the cab.
Disassemble Retarder Valve Or Secondary Brake Valve
Start By:
a. remove retarder valve or secondary brake valve
NOTE: The valve that is shown disassembled is the retarder valve. The secondary brake valve is disassembled the same way.
1. Remove setscrew (1) from the adapter. Remove adapter (2) from the cover. Remove the O-ring seal from the cover.
NOTE: The secondary brake valve does not have the O-ring seal.
2. Turn the valve over, and remove screws (3) and (4) that hold the cover to the body.
3. Remove cover (5) and cam and follower (6).
NOTE: Before the adjusting ring is removed, make a note of the position of the adjusting ring in the cover, and install it in approximately the same position.
4. Remove lockring (7) and adjusting ring (8) from the cover.
5. Separate the cam and follower. Inspect the lobes on the cam and follower for too much wear. Make a replacement of the cam and follower if needed.
6. Remove spring (9), piston (10) and spring (12) from body (13). Remove O-ring seal (11) from the piston.
7. Remove the screws that hold valve assembly (14) in place. Remove valve assembly (14). Remove O-ring seal (15) from the valve assembly.
Assemble Retarder Valve Or Secondary Brake Valve
1. Inspect all the O-ring seals, and make replacements if needed. Make sure all the parts are clean.
2. Install O-ring seal (15) on valve assembly (14). Put valve assembly (14) in position in the body. Install the two screws that hold the valve assembly in the body.
3. Install spring (12), O-ring seal (11), piston (10) and spring (9) in body (13).
NOTE: Put the adjusting ring in approximately the same position it was when removed.
4. Install adjusting ring (8) in the cover.
NOTE: Make sure the lockring tang on the lockring is in alignment with the groove (slot) in the cover. Make sure the vertical tangs on the lockring are in alignment with the inside diameter grooves (slot) in the adjusting ring.
5. Install lockring (7).
6. Put 5P0960 Multipurpose Grease on the lobes of the follower and cam.
7. Put the cam and follower together. Install the gasket between the body and the cover. Install cam and follower (6) and cover (5).
NOTE: The secondary brake valve does not have the O-ring seal.
8. Install the O-ring and adapter (2) on the cover. Make an alignment of the hole in the follower with the hole in the adapter.
9. Install setscrew (1) in the adapter.
10. Make adjustments to the retarder valve after installation. See Testing And Adjusting for the correct procedure.
End By:
a. install retarder valve or secondary brake valve