User manual BENDIX SR-7 SPRING BRK MODULATING VALVE

[. . . ] The valve has one park control, one service control, one supply, one balance, four delivery NPTF ports, and an exhaust port protected by an exhaust diaphragm. The valve incorporates two mounting studs for mounting the valve to the frame rail or cross member (where applicable). 1 SD-03-9043 MAIN PISTON CONTROL PISTON O-RING SPRING GUIDE UPPER BODY RETAINING RING PARK CONTROL PORT O-RING O-RING SPACER IN-LINE SINGLE CHECK VALVE SPRING MAIN PISTON SPRING STATIC PISTON O-RING O-RING SUPPLY PORT O-RING STATIC PISTON SPRING O-RING O-RING O-RING LOWER BODY BALL CHECK VALVE SPRING O-RING O-RING VALVE SEAT RETAINING RING DIAPHRAGM DIAPHRAGM WASHER VALVE RETAINER SPRING 1/4-20 MACHINE SCREWS INLET / EXHAUST VALVE LOWER VALVE GUIDE EXHAUST PORT #10 TORX HEAD SCREW RETAINING RING DOUBLE CHECK VALVE CHECK VALVE COVER CHECK VALVE GUIDE O-RING FIGURE 2 - SECTIONAL VIEW OF SR-7TM SPRING BRAKE MODULATING VALVE USED IN RELAY VALVE APPLICATIONS OPERATION The operation guidelines shown in this manual represent the relay valve based SR-7TM (refer to system schematic shown in figure 3). A quick release based valve functions similarly to the relay valve based version with the exception that all air delivered to spring brakes passes through the park control port through the in-line single check valve. [. . . ] With parking control valve in "release" position, note gauge pressure reading. (Correct spring brake actuator hold-off pressure is 107 psi nominally. ) 3. Place parking control valve in "park" position - gauge reading should drop to zero promptly. A lag (more than 3 seconds) in drop of pressure would indicate faulty operation. With the parking control valve in the "park" position, gradually apply foot brake valve and note a pressure reading increase on the gauge installed in the SR-7TM valve delivery port. Drain the reservoir, which supplies the rear service brake circuit, apply the foot brake valve several times and note that pressure reading on gauge decreases each time foot brake valve is applied (spring brake modulation). After the foot brake valve has been applied several times, pressure on gauge will drop to the point where release of the spring brake actuators will no longer occur. PREVENTIVE MAINTENANCE Important: Review the Bendix Warranty Policy before performing any intrusive maintenance procedures. A warranty may be voided if intrusive maintenance is performed during the warranty period. No two vehicles operate under identical conditions; as a result, maintenance intervals may vary. Experience is a valuable guide in determining the best maintenance interval for air brake system components. At a minimum, the SR-7TM valve should be inspected every 6 months or 1500 operating hours, whichever comes first, for proper operation. Should the SR-7TM valve not meet the elements of the operational tests noted in this document, further investigation and service of the valve may be required. à à SECONDARY RESERVOIR CONSTANT PRESSURE à à BALANCE PORT PRIMARY CIRCUIT PRESSURE CONTROL PORT SECONDARY CIRCUIT PRESSURE à à 7 LEAKAGE TEST Place the park control valve in the "release" position; using a soap solution, coat all ports including the exhaust port. If the valve does not function as described, or if leakage is excessive, it is recommended that it be replaced with a new or remanufactured unit available from a Bendix parts outlet. THE VALVE CONTAINS HIGH SPRING FORCES THAT COULD RESULT IN PERSONAL INJURY IF DISASSEMBLY IS ATTEMPTED! SERVICING THE SR-7TM VALVE WARNING!PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH: When working on or around a vehicle, the following general precautions should be observed at all times. 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. [. . . ] Prior to returning the vehicle to service, make certain all components and systems are restored to their proper operating condition. VALVE REMOVAL 1. Prior to removing the SR-7TM valve, apply the parking brakes and drain all the vehicle reservoirs. Remove the two mounting nuts that secure the valve to the frame rail and remove the valve. VALVE INSTALLATION 1. [. . . ]