User manual BENDIX M-30 ANTILOCK MODULATOR ASSY

[. . . ] Identification 1, SUP 2, DEL 3, EXH Air Line Connection Supply Delivery (air delivery to service actuators) Exhaust exhaust diaphragm. Air pressure, along with spring force, seats the exhaust diaphragm on the exhaust passage, thus preventing the escape of service air. Simultaneously, application air flows to the supply diaphragm and forces it away from its seat. Air flows past the open supply port and out the modulator delivery port to the service brake chambers. (incoming air from foot, relay or quick release valve) NON ANTILOCK HOLD (FIGURE 6) When the desired air pressure is attained in the service brake chambers, the brake system is in the Holding position. [. . . ] When a solenoid coil is energized, and depending whether the exhaust or hold solenoid is energized, it either opens or closes, thereby causing the exhaust or reapplication of air pressure to the brake actuator. The solenoids in the modulator are controlled independently by the antilock controller. By opening and closing the solenoid 4 EXHAUST DIAPHRAGM EXHAUST VALVE EXHAUST PORT BRAKE VALVE SPRING BIAS VALVE BRAKE CHAMBER SUPPLY OR HOLD DIAPHRAGM HOLD VALVE FIGURE 8: M-30TM MODULATOR NON ANTILOCK EXHAUST OF SERVICE BRAKES (RAPID) EXHAUST DIAPHRAGM EXHAUST VALVE EXHAUST PORT BRAKE VALVE SPRING BIAS VALVE SUPPLY OR HOLD DIAPHRAGM HOLD VALVE BRAKE CHAMBER FIGURE 9: M-30TM MODULATOR ANTILOCK EXHAUST OF BRAKES ANTILOCK HOLD (FIGURE 10) The antilock controller will place the modulator in the hold position when it senses that the correct wheel speed (braking force) has been attained. The antilock controller will also place the modulator in the hold position, prior to entering the reapply, when it detects recovery from a locked wheel condition. In this mode of operation, the modulator supply/ hold solenoid remains energized while the exhaust solenoid is de-energized. De-energizing the exhaust solenoid allows 5 EXHAUST DIAPHRAGM EXHAUST VALVE EXHAUST PORT BRAKE VALVE SPRING BRAKE CHAMBER HOLD VALVE SUPPLY OR HOLD DIAPHRAGM BIAS VALVE FIGURE 10: M-30TM ANTILOCK APPLICATION HELD POSITION application air to flow to the control side of the exhaust diaphragm, which then seals the exhaust passage. With the exhaust diaphragm seated, further exhaust of brake chamber air pressure is prevented. Because the supply solenoid remains energized, the supply diaphragm remains seated, thus preventing application air from flowing to the delivery port and out to the brake chamber. The modulator can enter the antilock exhaust or reapply mode from the antilock hold mode. ANTILOCK REAPPLY If the antilock controller senses that wheel speed has increased sufficiently enough to require re-application of braking pressure, it deenergizes the supply and exhaust solenoids. With both solenoids de-energized, the modulator re-applies air to the brakes in the same manner it did during a non-antilock event. VEHICLE PREPARATION 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. 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. 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. [. . . ] Install all air line fittings and plugs, making certain thread sealing material does not enter the valve. Install the assembled valve on the vehicle. Reconnect both air lines to the valve using the identification made during VALVE REMOVAL step 5. Reconnect the electrical connector to the modulator. [. . . ]