User manual BENDIX AIR DISC BRAKE-ADB22X-225-SN6-7-SK7

[. . . ] Bendix® ADB 22XTM, ADB 225TM, SN6TM, SN7TM, SK7TM Air Disc Brakes DESCRIPTION Bendix® Air Disc Brakes use a floating caliper design to provide foundation braking on all axles of heavy commercial vehicles, buses and trailers. Bendix Air Disc Brakes provide safety and performance, as well as ease of service. Available in models with or without a combination spring brake unit, these brakes may also include optional wear sensors and/or wear diagnostic equipment. OPERATION Bendix Air Disc Brakes convert air pressure into braking force. (See Figure 2. ) When the vehicle brakes are applied, air enters the service brake chamber through the supply port, applying pressure within the diaphragm. [. . . ] For a normally functioning Bendix air disc brake, the box-end wrench or socket should turn clockwise in small increments. NOTE: As the number of applications increases, the turning movement will decrease (as the brake reaches its normal calibration point). If the box-end wrench or socket does not: (a) turn at all, or (b) turns only with the first application, or (c) turns forward and backward with every application, the automatic adjuster has failed and the caliper/carrier assembly must be replaced. FIGURE 24 - COVER REMOVAL 61 37 12 Outboard Brake Pad 12 Inboard Brake Pad 37 Cap 23 Adjuster 61 Adapter Tab 37 Cap Tab FIGURE 26 - TAB POSITION FIGURE 25 - EXPLODED VIEW OF ADJUSTER AND ADAPTER FIGURE 27 - ADJUSTMENT MECHANISM TEST Bendix recommends installing a new adjuster cap (lightly greased using white lithium-based grease) when returning the air brake to service. Ensure that the tab is in the position shown in Figure 26. 15 GUIDE PINS CAUTION: Follow all standard safety procedures including, but not limited to, those on page 2 of this service manual. When working on foundation brakes, be sure that the vehicle is on level ground, that the vehicle is parked by other means than the foundation brakes, and that the wheels are chocked. Note: If the steps below lead the technician to a step where the wheel needs to be removed, inspect first to see that there is no contact between the caliper and axle, vehicle, chassis sections or carrier, etc. When removing wheels, refer to the vehicle manufacturer's recommendations. This guide pin inspection should be carried out if the result of the Caliper Movement Test (see Page 13) is that the technician cannot move the caliper. 13 Tappet and Boot 1 Assembly Caliper 5 Guide Pin 7 Brass Bushing 10 Cover LONG BEARING SIDE 23 Adjuster Unit 61 Shear Adapter 37 Adjuster Cap GUIDE PIN BEARING INSPECTION Use the following procedure to check caliper movement along the guide pins: Remove the Pads (see Page 18). One of the three different styles of guide pin (A, B, or C) may be present (See Figure 28). The bearings for styles A and B use a rubber bushing, and style C uses a guide sleeve. Using hand pressure only (no tools), the Caliper (1) should slide freely along the whole length of the Guide Pin arrangement. With the pads removed, this movement should be at least 0. 8 inch (20mm). If the movement is less than this amount, replace the caliper/carrier assembly. To measure the clearance from the rubber bushing (6a, 6b) or guide sleeve (6c) to the guide pin: See Figures 29 and 30. Attach a magnetic dial-gauge holder to the carrier (2) on the short bearing side of the caliper (1). Use the measuring point on the caliper (1) - see the arrow in Figure 28. Press the caliper in the direction of carrier (2) and set the dial-gauge to zero. screwdriver) between Carrier (2) and Caliper (1) forcing them in opposite directions, and read the maximum value on the dial-gauge. (2. 0 mm), or for style C guide pins, if the value is greater than 0. 039 in. (1. 0 mm), the caliper/carrier assembly must be replaced. 68a Cap SHORT BEARING SIDE Caliper Movement 39a 4a 6a (6a): Rubber Bushing (39a): Caliper Bolt (4a): Guide Pin (6b): Rubber Bushing (39b): Caliper Bolt (4b): Guide Pin 4b 6b 39b 6c Guide Sleeve 39c Caliper Bolt 4c Guide Pin 68c Cover FIGURE 28 - GUIDE PINS 12 Pad Assembly 1 Carrier 2 Caliper FIGURE 29 - MAGNETIC DIAL-GAUGE 16 GUIDE PIN SEAL INSPECTION Caliper Guide Pin Seals The long bearing side guide pin (5) is sealed with the cover (10) and with the inner boot (9). Note: It may be necessary to remove the pads to inspect the inner boots (9) if pad wear is minimal. The guide pin (4a, 4b, or 4c, depending on the style) is also sealed with an inner boot (9) and a cover (style C), or a flexible rubber wear indicator in the case of style A guide pins. [. . . ] When working on foundation brakes, be sure that the vehicle is on level ground, that the vehicle is parked by other means than the foundation brakes, and that the wheels are chocked. B A B 18/2 Brake Chamber or 18/1 Spring Brake Brake Chamber Removal With all air pressure drained from the air brake system, disconnect the air hose from the brake chamber (18/2). Remove and discard brake chamber mounting nuts (see Figure 50, arrows B). FIGURE 50 - ACTUATOR INSTALLATION Brake Chamber Installation Note: New brake chambers (18/2) have drain plugs installed (see Figure 50, arrows A). The drain hole must be aligned downwards (or within ±30°) when installed on the vehicle. Before installing the new brake chamber, the actuator flange (see Figure 51, arrow C) must be cleaned, and inspected. [. . . ]