User manual BENDIX R-12P PILOT RELAY VALVE

[. . . ] Note that additional air lines for a towing trailer are shown as dashed lines. The R-12PTM valve uses the R-12TM valve family lower body and standard Bendix mounting brackets. The body and cover are die-cast aluminum, and the valve's weight is approximately 2. 3 lbs. 2 4 1 1 Size 1/2" 3/8" 1/4" -1 Supply (SUP) Delivery (DEL) Control (CON) Exhaust (EXH) SD-03-1063 TRAILER BRAKE SYSTEM WITH R-12PTM PILOT RELAY VALVE VENTED CUT-OUT COCK DELIVERY CONTROL CONTROL R-12PTM VALVE SUPPLY SINGLE CHECK VALVE SPRING BRAKE VALVE SERVICE RELAY VALVE RESERVOIR QUICK RELEASE VALVE SUPPLY VENTED CUT-OUT COCK BRAKE CHAMBER SLACK ADJUSTER -- -- -- -- -- ADDITIONAL PLUMBING FOR TOWING TRAILER FIGURE 2 - TYPICAL R-12PTM PILOT RELAY VALVE SYSTEM SCHEMATIC OPERATION CHARGING When the air brake system is charging, the relay piston's exhaust seat is against the inlet/exhaust valve due to the force of the reserve spring. [. . . ] Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Stop the engine and remove ignition key when working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed. Where circumstances require that the engine be in operation, EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically charged components. Do not attempt to install, remove, disassemble or assemble a component until you have read and thoroughly understand the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools. If the work is being performed on the vehicle's air brake system, or any auxiliary pressurized air systems, make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle. If the vehicle is equipped with an AD-IS® air dryer system or a dryer reservoir module, be sure to drain the purge reservoir. 5 5. Following the vehicle manufacturer's recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle. Never exceed manufacturer's recommended pressures. Never connect or disconnect a hose or line containing pressure; it may whip. Never remove a component or plug unless you are certain all system pressure has been depleted. Use only genuine Bendix® replacement parts, components and kits. Replacement hardware, tubing, hose, fittings, etc. must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. Components with stripped threads or damaged parts should be replaced rather than repaired. Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle and component manufacturer. Prior to returning the vehicle to service, make certain all components and systems are restored to their proper operating condition. For vehicles with Antilock Traction Control (ATC), the ATC function must be disabled (ATC indicator lamp should be ON) prior to performing any vehicle maintenance where one or more wheels on a drive axle are lifted off the ground and moving. SERVICE CHECKS 1. Visually inspect the valve's exterior for excessive corrosion or physical damage. Inspect all air lines connected to the valve for signs of wear or physical damage. Test air line fittings for excessive leakage and tighten or replace as necessary. OPERATIONAL AND LEAKAGE TESTS 1. [. . . ] Place the exhaust cover on the inlet/exhaust valve spring. Then depress the cover against the spring's force into the body. Install o-rings(4) and (5) onto the relay piston. Then place the reserve spring in the piston and install the piston into the body. [. . . ]