User manual BENDIX A2LS HYD DRUM BRAKES W-PARKING

[. . . ] ® Bendix® A2LSTM Hydraulic Drum Brakes w/Parking DIRT SHIELD CROSS-OVER PIPE RETAINING SPRING CROSS-OVER PIPE WHEEL CYLINDER END SHOE RETURN SPRING CAP SCREWS EXPANDER END SHOE RETURN SPRING WHEEL CYLINDER GASKET GROMMETS SHOE HOLD-DOWN CLIP (NOT FITTED TO EARLY BRAKES) EXPANDER FIGURE 1 - A2LSTM AUTOMATIC ADJUSTING TWO LEADING SHOE DRUM BRAKE DESCRIPTION The A2LSTM drum brake is a hydraulically operated duo-duplex brake with an automatic adjustment and parking brake feature. The A2LSTM drum brake (automatic adjust, two leading shoes) provides two leading shoes in either direction of drum rotation and an automatic adjustment of the brake shoes to compensate for lining wear. Both the wheel cylinder unit and expander unit have cast integral brake mounting lugs, each taking the brake torque load. The wheel cylinder unit contains two single acting hydraulic cylinders with automatic adjusters. [. . . ] Note: To avoid locking the auto-adjuster mechanism in the fully un-adjusted position, wind out each wheel cylinder piston one complete turn after fully un-adjusting the pistons. DUST BOOT MANUAL OVERRIDE WHEEL PISTON SEAL ADJUSTER SHAFT ASSEMBLY SPRING & LOCATOR ASSEMBLY GASKET FIGURE 15 - WHEEL CYLINDER 7 DISASSEMBLY PIN BRAKE SHOES Bendix brake shoes and linings are available as sets with new factory lining installed. If the brake shoes are in good condition, neither worn nor bent, new lining may be installed on the old brake shoes. For lining installation procedures, and brake shoe inspection procedures, refer to Bendix publication; The Brake Block Manual Part 11, Form No. BW-1257R. SPRING FERRULE WHEEL CYLINDER DISASSEMBLY Before proceeding, clean the exterior of the wheel cylinder and make sure the work area, tools, and hands are clean. Clamp the wheel cylinder unit in a bench vise with padded jaws. FIGURE 16 - REMOVAL OF PIN FROM WEDGE DUST BOOT INPUT TAPPET/ PISTON SPRING & LOCATOR PIN HYDRAULIC SEALS RETURN SPRING FERRULE ROLLER TAPPET/ PISTON WASHER BLEED SCREW CIRCLIP (SNAP RING) WEDGE SEAL- & RETAINING RING ASSEMBLY WEDGE ASSEMBLY TAPPET SEAL HOUSING STOP PIN GASKET ABUTMENT TAPPET DUST BOOT FIGURE 17 - EXPANDER UNIT 8 2. Remove the tappet head and manual override assembly from the wheel cylinder body, Figure 15. Using a blunt screwdriver, pry the dust boots from the housing and discard. Carefully blow out both piston assemblies from the cylinder housing using low pressure shop air. Using a small screwdriver, with the end rounded and polished, pry the seal from the piston, taking care not to score the seal groove or piston surface. Clean all rubber parts that are to be reused with clean DOT 4 heavy duty brake fluid. Check the seal ring and o-ring grooves for any nicks, burrs, or corrosion. Smooth with a fine emery cloth or clean as required. EXPANDER DISASSEMBLY Before proceeding, clean the exterior of the expander unit and make sure the work area, tools, and hands are clean. Slowly release the spring pressure and remove spring along with the ferrule. Use snap ring pliers to compress and remove the circlip (snap ring), Figure 17. Remove the dust boots from both ends of the expander housing and discard. Remove the abutment tappet, input tappet/ piston and stop pin from the housing. Remove the wedge assembly, wedge seal, retaining ring assembly and washer. Push the roller tappet/piston from the housing in the direction of the input tappet/piston, Figure 17. Using a small screwdriver, with the end rounded and polished, pry the seals and o-ring from the input and roller tappet/piston taking care not to score the seal grooves or piston surface. DOT 4 FLUID DOT 4 FLUID DOT 4 FLUID GREASE GREASE CLEANING AND INSPECTION Discard all of the old parts that are to be replaced with parts furnished in the repairs kits. Clean all of the metal parts with unused DOT 4 brake fluid or suitable solvent. Do not use gasoline or hot water solution on metal parts. GREASE FIGURE 18 - EXPANDER LUBRICATION POINTS 9 TAPPETS LOCATED OVER WEDGE, CAGE & ROLLER ASSY. 7. Clean the backing plate with a damp cloth and wire brush to remove any dirt or corrosion from the surface of the backing plate. IMPORTANT!PLEASE READ: Do not use an air hose to blow dust out of the backing plate (dirtshield). [. . . ] Depress the brake pedal several times to seat the brake shoes against the drums. Check the brake pedal travel by pushing the brake pedal as far down as possible. If the brake pedal free play exceeds recommended dimensions, or brake warning light is lit, refer to the vehicle service manual. With the vehicle on a level surface in a parking or service area, start the engine and apply the parking brake; test for operation. [. . . ]