User manual BENDIX BP-R1 BOBTAIL PROP RELAY VALVE

[. . . ] Bendix® BP-R1TM Bobtail Proportioning Relay Valve CONTROL EXHAUST SERVICE CONTROL SERVICE EXHAUST SUPPLY DELIVERY SUPPLY DESCRIPTION The BP-R1TM bobtail proportioning relay valve is a combination of two individual valves in a single housing. The lower portion, or body, of the BP-R1TM valve contains a "standard" service brake relay valve, which functions as a relay station to speed up brake application and release. The upper portion, or cover, houses a brake proportioning valve, which reduces normal service brake application pressure when the tractor is not towing a trailer. Used in tractor air brake systems only, the BP-R1TM valve is installed in place of a standard relay valve. [. . . ] 34 SEALING RING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 EXHAUST COVER . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 SERVICE PISTON QUIRED O-RING FIGURE 10 - BP-R1TM BOBTAIL BRAKE PROPORTIONING RELAY VALVE 4. Connect the tractor service and emergency "glad hands" (hose couplings) to hose couplings that have been plugged, or alternatively, to a trailer. Build the tractor system air pressure to governor cut-out and make 4 to 5 full brake applications. Check the air fittings at the BP-R1TM valve for leakage. With the trailer supply valve (dash control w/red octagonal button) and system park control (dash control with yellow diamond button) activated for tractor/trailer operation, apply, hold, then release the brakes several times varying the application pressures while watching the reaction of the gauges installed on the BP-R1TM valve. Check that a prompt application occurs and that it can be held then promptly released. 6 6. Check the BP-R1TM valve differential pressure by applying 10 psi to the service port and noting the pressure registered at the delivery port. Subtract delivery port pressure from the 10 psi service pressure to obtain the differential. Compare the measured differential with the pressure specified for the BP-R1TM valve part number. Note: For BP-R1TM valves not incorporating a relay piston return spring (14), the measured differential should be approximately 4 psi. When a spring is in use, the differential will be higher (see the I. D. Make and hold a full (100 psi or greater) brake application and note that full pressure is delivered to the chambers. Activate the dash mounted trailer supply valve for bobtail tractor operation. Then make a slow brake application, increasing the pressure at the BP-R1TM valve service port to 20 psi while watching the reaction at the delivery port gauge. Note that delivery pressure rises to approximately 5 to 10 psi and remains constant while service pressure continues to rise to 20 psi. Make another brake application and slowly increase the pressure at the BP-R1TM valve service port to between 60 and 70 psi while observing the gauge installed at the delivery port. Note that when service port pressure rises to between 20 and 30 psi, delivery pressure begins to rise above the initial pressure noted in step 6. The rise of delivery pressure should be at a proportioned rate of approximately 3:1. At 70 psi service pressure, delivered pressure should be 15 to 25 psi. Make a full brake application and note that both test gauges register the same pressure. [. . . ] Make certain the retaining ring is fully seated in its groove. Make sure the valve is straight against the exhaust seat and free to move. Install both the large and small diameter o-rings (27 & 29) on the proportioning piston (28). Install both the large and small diameter o-rings (25 & 26) on the blend back piston (24), then insert the small diameter of the proportioning piston (28) into the small diameter end of the blend back piston (24). [. . . ]