User manual BENDIX PIGGYBACK SPRING BRAKE

[. . . ] ® Bendix Piggyback Spring Brake SERVICE PUSH-ROD SERVICE CHAMBER SERVICE DIAPHRAGM PIGGYBACK CHAMBER FIGURE 1 - BENDIX PIGGYBACK SPRING BRAKE DESCRIPTION The Bendix Piggyback Spring Brake is made up of a conventional brake chamber and an emergency or parking spring mechanism for use on vehicles equipped with cam foundation brakes. The Spring Brake Actuator provides: (1) Service Braking, (2) Parking and (3) Emergency Braking. The actuator can be piped with various system arrangements to be automatically or manually applied under emergency braking conditions. The spring brake is a diaphragm type actuator which converts the energy of air pressure into mechanical force. [. . . ] When the service chamber is used to actuate cam type brake foundation assemblies, the yoke (which is threaded on the push rod) is connected to a slack adjuster, which in turn is connected to the brake cam shaft. This forward motion of the push rod rotates the slack adjuster, cam shaft and cam applying the vehicle brakes. The greater air pressure admitted to the service chamber, the greater the force applied by the push rod and, conversely, the less pressure applied to the service chamber the less force applied by the push rod. Push rod force is determined by multiplying the delivered air pressure by the effective diaphragm area. is admitted to a type 30 service chamber, the lineal force on the end of the push rod is approximately 1, 800 lbs. When air pressure is released from the brake chamber, the push rod return spring in combination with the brake shoe return spring returns the diaphragm, push plate and rod assembly, slack adjuster and brake cam to their released positions releasing the brakes. When the driver operates the parking brake, air is exhausted from the piggyback chamber. The main spring is allowed to extend, which forces the push rod and the emergency diaphragm forward. This forces the service diaphragm and service push rod forward which applies the brakes. When the air pressure in the piggyback chamber drops to below 78 p. s. i. , the main spring overcomes chamber pressure and forces the push rod and emergency diaphragm forward. EMERGENCY PORT DIAPHRAGM RELEASE TOOL SIDE POCKET NON-PRESSURE HOUSING PUSH ROD FIGURE 3 - PIGGYBACK SPRING BRAKE CUT-AWAY VIEW 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. WARNING! · Piggyback Spring Brake Chambers contain a loaded compression spring. Property damage, serious injury or death may occur if instructions are not followed completely. When replacing the piggyback spring brake, make sure to block the wheels to prevent vehicle rollaway. · 3 SERVICE RETURN SPRING ADAPTER RETURN SPRING MAIN SPRING LOCKNUT YOKE RELEASE TOOL SERVICE DIAPHRAGM PRESSURE PLATE EMERGENCY DIAPHRAGM FIGURE 4 - CAGING THE PIGGYBACK · DO NOT service a piggyback spring brake chamber if it has structural damage of any kind. [. . . ] Remove the vise grips from the service push rod. Ensure that the piggyback spring brake chamber is caged. To cage the piggyback spring brake chamber, perform the steps outlined in either "Mechanical Release of the Bendix Piggyback Spring Brake" or "Mechanical Release of the Piggyback Spring Brake to be Replaced". Mark the service clamp ring and non-pressure plate to ensure proper alignment of parts during reassembly. SERVICE CLAMP RING PIGGYBACK CHAMBER 4. [. . . ]