SD-23-7541 ® Bendix® ADB22X™, ADB22X-V™ Air Disc Brakes SECTION ONE: AIR DISC BRAKE OVERVIEW 1.1 DESCRIPTION Bendix ® ADB22X ™ and ADB22X-V ™ Air Disc Brakes (ADB) 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.
SAFE MAINTENANCE PRACTICES 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: 1. 2. 3. 4. 5. 6. 7. 8. 9. 2 Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Always wear safety glasses.
1.3 Rotor identification 1.5 Operation See Figure 4 to help you identify which type of rotor is used on the axle being inspected. Note that the maintenance inspection procedure will depend on the type of rotor installed. Bendix air disc brakes convert air pressure into braking force. (See Figure 6.) When the vehicle brakes are applied, air enters the service brake chamber through the supply port, applying pressure within the diaphragm.
12 Pad 1 Assembly Caliper 9 22 58 Inner Boot 7 Inner Seal 5 Ring Brass Bushing Guide Pin 40 Caliper Bolt Top Sectional View 10 Cap 23 Adjuster Unit 161 Tappet Bushing 32 Chain Wheel 16 Threaded Tube 13 Tappet and Boot Assembly 61 Shear Adapter 45 Washer 26 Spring Clip 37 Adjuster Cap 44 Pad Retainer Pin 27 Spring 30 Chain 11 Pad Retainer 17 Bridge 33 Wear Sensor 22 Inner Seal 16 Threaded Tube 161 Tappet Bushing 13 Tappet and Boot Assembly 24 Turning Device 6 Guide Sleeve 2 Carrier 2 Carrie
Type A Type B (Wheel turns toward fixed pin side of ADB) 18/1 Spring Brake Actuator 44 Pad Retainer Pin (Fixed pin) 11 Pad Retainer 18/2 Service Actuator 26 Spring Clip 12/2 Pad Holder Spring 45 Washer Wheel Rotation (typically right hand) 12/1 Pad (Pad Assembly consists of 12/1 plus 12/2) 10 40 Cap 5 Caliper Guide Bolt Wheel Rotation (typically left hand) 7 Brass Bushing Pin 68 Cap 39 Caliper Bolt 22 Inner Seal Shield Kit (Drive or Steer) 161 Tappet Bushing 13 Tappet and Boot Assembly 4
SECTION TWO: PREVENTIVE MAINTENANCE SCHEDULE AND WHEEL-ON INSPECTIONS 2.0 PREVENTIVE MAINTENANCE Regular inspection and maintenance of air disc brake components is an important part of vehicle maintenance. The maintenance practices outlined here are recommended in addition to all standard industry practices (including daily pre-trip inspections.) Also, see the vehicle's manual for recommendations.
2.1 BRAKE PAD AND ROTOR INSPECTIONS Visual checks of the condition of the brake pad/rotor wear can be made without removing the wheels. Where dust guards are not used, the top of the pads and part of the rotor are visible through the opening at the top of the brake. Other visible portions of the rotor can be inspected at the same time. Wear Indicator Style A: Where both the carrier and caliper have an indicator notch. Compare the relative position of two notches cast into the carrier and caliper.
H F No action is needed for small cracks spread over the surface (e.g. Area F) Rotor Friction Surface Width “f” Area F • For standard Bendix rotors, cracks running in a radial direction — like spokes of a wheel (see Area H) — less than 0.06 in. (1.5 mm) deep or wide are acceptable if they do not reach either edge (see G). Cracks are only acceptable if the length of the crack is less than 75% of dimension “f” (the width of the rotor contact area).
SECTION THREE: TROUBLESHOOTING PROCEDURE FLOWCHART Air Disc Brake Inspection Follow safe maintenance practices, chock wheels. Engage spring brakes and cage spring. Release spring brakes and drain air from system. Raise axle, spin the wheel by hand. Does the wheel turn smoothly? YES NO Is the spring brake fully/ partially applied? Check running clearance (4.1) - OK? NO YES YES NO YES Check running clearance (4.1) - OK? Check adjuster (4.2) - OK? YES YES NO NO Drain air pressure from system.
SECTION FOUR: WHEEL-OFF MAINTENANCE INSPECTIONS 4.1 CALIPER MOVEMENT TEST Section Four Section Page 4.0 4.1 4.2 4.3-4.4 4.3 4.4 4.4.3 4.5 4.6 Wheel-Off Inspections . . . . . . 10 Caliper Movement Test . . . . . . 10 Adjuster Mechanism Inspection . . . 11 Brake Pads and Rotors . . . . . 12-14 Inspect the Brake Pads . . . . . . 12 Inspect the Rotor . . . . . . . 13-14 Machining (Grinding or Turning) Rotors 14 Guide Pin Bearing Inspection . . . 14-15 Tappet & Boot Assembly Inspection . .
4.2 ADJUSTER MECHANISM INSPECTION CAUTION: Follow all safe maintenance practices. Aside from the normal maintenance schedule, the adjuster mechanism inspection that follows is also carried out when the Caliper Movement Test (4.1) finds that the running clearance is too small or too large. 4.2.1 With the spring brake released (or caged), remove the adjuster cap (37) using the tab, taking care not to move the shear adapter (61).
4.3- 4.4 BRAKE PADS AND ROTORS 4.3 INSPECT THE BRAKE PADS CAUTION: Follow all safe maintenance practices. Regular inspection of the brake pads (even for vehicles that use an electronic wear indicator) is an important part of vehicle maintenance. If electronic wear sensors are present, see Section 5.2. If dust covers are present, see Section 5.1. See Figure 23. While pressing down against the pad retaining bar (11), remove and retain the clip (26), washer (45) and pin (44).
4.4 INSPECT THE ROTOR Bendix air disc brakes are precision-engineered braking mechanisms. The “friction couple” braking characteristics have been carefully optimized — and the rotor design and materials have been matched with special formulation brake pads for optimal performance. In all cases, use brake pads with the type of backing plate and lining material originally supplied by the vehicle manufacturer. Identify if the rotor is a Bendix ® Splined Disc ® , or conventional rotor (See Section 1.03).
4.4.3 Machining (Grinding or Turning) Rotors Bendix rotors are normally service-free. In the case of severe grooving of the entire friction surface, however, CONVENTIONAL ROTORS may be turned when changing pads, to increase the load-bearing surface. 1 Caliper 5 9 Inner Boot Guide Pin 7 Brass Bushing 10 Cap MACHINING OF BENDIX® SPLINED DISC® ROTORS IS NOT PERMITTED. LONG BEARING SIDE CAUTION: Always maintain air disc brake pads and rotors within specifications.
4.5.2 Place a suitable tool (e.g. a large flat-blade screwdriver) between carrier (2) and caliper (1) forcing them in opposite directions, and read the maximum value on the dial-gauge. See Figure 27. If the value is greater than 0.078 in. (2.0 mm), replace the guide pin bushings (See Section 5.6) OR replace the caliper/carrier assembly (See Section 5.3). Measure the range of travel along the guide pin bearings: 4.5.3 Remove the Pads (See Section 4.3).
SECTION FIVE: MAINTENANCE KITS AND PROCEDURES Section Five Section 5.0 5.1 5.2 5.3 Page Maintenance Kits . . . . . . Air Disc Brake Shield Kit . . . Pad Replacement . . . . . Caliper/Carrier/Actuator Assembly Type A (Fixed pin) . 16-17 . . 19 . . 20 . 22-23 (Wheel turns toward fixed pin side of Type B ADB) Section Page 5.4 5.5 5.6 5.7 Spring/Service Brake. . . . . . . 24 Tappet & Boot, and Tappet Inner Seal 25-28 Guide Pin and Boot Assemblies . . 29-34 Bendix® Splined Disc® Hub Rotor . .
5.0 MAINTENANCE KITS Below is a list of some of the available kits. See Figure 30 for an exploded view showing the components listed. Kit See Section Dust Shields Section 5.1 Piece Number Components Included in Kit 803129 Trailer Axle Pad & Rotor Shield Kit 803130 Drive Axle Pad & Rotor Shield Kit 802948 Steer Axle Pad Shield Kit Pad Kit (axle set) Section 5.
5.0.1 GENERAL INFORMATION ABOUT BENDIX® AIR DISC BRAKE MAINTENANCE • When replacing bearings — or for any other maintenance procedure where the technician needs to remove the caliper/carrier assembly from the vehicle to perform the maintenance — replacement caliper/ carrier bolts will be required. Please note that due to the high torque required, the original bolts cannot be reused. The bolts are available from the vehicle manufacturer.
5.1 AIR DISC BRAKE SHIELD KIT 5.1.1 CAUTION: Follow all safe maintenance practices, including those listed on page two of this document. Park the vehicle (by other means than the foundation brakes) on level ground and chock the wheels. Note: Most torque plates manufactured after January 1, 2007 have the required torque plate tabs to permit these shields to be mounted. 5.1.2 Remove and discard the spring clip and washer from the pad retainer pin. Remove and retain the retainer bar and retainer pin.
5.2 PAD REPLACEMENT 5.2.1 CAUTION: Follow all safe maintenance practices, including those listed on page two of this document. Park the vehicle (by other means than the foundation brakes) on level ground and chock the wheels. The Bendix DVD (BW7356) shows this procedure. Important: If the vehicle is equipped with spring brakes, cage the spring brakes on all axles to be worked on. Consult the vehicle manufacturer’s instructions as necessary.
CAUTION: Never turn the adjuster (23) without the shear adapter (61) installed. The shear adapter is a safety feature and is designed to prevent too much torque being applied. The shear adapter will fail (by breaking) if too much torque is used. Note: Always double-check that the spring brake is released (where applicable) if a shear adapter fails; if this step was missed, the shear adapter will break off, and it may incorrectly that the caliper is seized.
5.3 CALIPER/CARRIER/ACTUATOR ASSEMBLY 5.3.1 CAUTION: Follow all safe maintenance practices, including those listed on page two of this document. Park the vehicle (by other means than the foundation brakes) on level ground and chock the wheels. 5.2.19 Move the caliper to the full outboard position. The brake pads must be removed (See Section 5.2.0) and actuator disconnected (and caged if a spring brake), see Section 5.4.0. 5.2.20 Using a 10 mm.
5.3.4 If the brake assembly does not separate from the anchor plate it may be helpful to install an M16X2.0 screw longer than 120 mm at the bushing locations and tap the end of the bolt with a hammer to free the brake assembly. Remove the assembly. Caliper/Carrier Assembly (Actuator not shown) Axial Mounting Bolt Style Mounting Bolts and Washers (6 sets total) 5.3.5 Disconnect the air hose(s) to the brake chamber. See Figure 42.
5.4 SPRING OR SERVICE BRAKE 5.4.1 CAUTION: Follow all safe maintenance practices, including those listed on page two of this document. Park the vehicle (by other means than the foundation brakes) on level ground and chock the wheels. 5.4.6 The seal, as well as the push rod area, must be clean and dry. 5.4.2 Use the spring brake manufacturer’s recommended safety practices in all cases. Some spring brake and vehicle manufacturers permit caging the spring brake while the spring brake is engaged.
5.5 TAPPET & BOOT ASSEMBLIES, AND TAPPET INNER SEAL REPLACEMENT 22 Inner Seal 11 Pad Retainer 5.5.1 CAUTION: Follow all safe maintenance practices, including those listed on page two of this document. Park the vehicle (by other means than the foundation brakes) on level ground and chock the wheels. 13 Tappet and Boot Assy In some cases, the technician will need to remove the caliper carrier assembly from the vehicle. (See Section 5.3.
Figure 47 inset) should be used to move the boot and allow the wedge fork (“A” in Figure 48) to be inserted. CAUTION: Do not insert the screw driver more than ¼ inch. Take care not to damage the inner sealing face (see arrow “X” in Figure 49). Gouges or grooves will prevent a good seal and will require that the caliper be replaced.
To install inner seals where the caliper is on the vehicle: 5.5.12 Position the replacement inner seal (22) over the threaded tube (16). See Figures 52 and 53 for the tools and installation arrangement used. Position the L1 (T3 + T9) with the short spacer (T3) in position as shown in Figure 53. Guide the tool over the end of the threaded tube (16). Install the new inner seal (22) into position by rotating the adjuster nut on the T3 portion of the tool, using an open-ended wrench.
FIGURE 56 - ON VEHICLE TAPPET AND BOOT INSTALLATION TOOL (B1 - WITH T24 INSTALLED, B2) 13 FIGURE 59 - OFF VEHICLE TAPPET BOOT INSTALLATION TOOL (B3, WITH T24 INSTALLED, B4) B1 B3 161 13 FIGURE 57 - ON VEHICLE TAPPET BOOT INSTALLATION B2 13 FIGURE 60 - OFF VEHICLE TAPPET BOOT INSTALLATION 13 FIGURE 58 - ON VEHICLE TAPPET INSTALLATION To install tappet and boot assemblies where the caliper is removed from the vehicle: 5.5.18 See Figures 59, 60 and 61.
5.6 GUIDE PIN AND BOOT ASSEMBLIES Vertical Bolt Style (with bushing). Bushing (1) Guide Pin (2) Caliper Bolt (3) Cap (4) Inner Boot (8) Ring (7) Horizontal Mounting Bolt Style Shown: See Inset Above for Vertical Bolt Style (with bushing). Shear Adapter (5) Adjuster Cap (Two alternate caps supplied in kit) (6) Ring (7) Inner Boot (8) Guide Pin (9) KIT CONTENTS Item Guide Bushing (10) Caliper Bolt (11) Cap (12) 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10. 11. 12. . . . . . . . . . . . . Description . .
Bendix Number/ Ken-Tool Number Description 1-3/8 in. diameter disc T14 / KT14 Brass nut T06 / KT06 1-1/2 in. diameter disc T16 / KT16 Dimpling tool T07 / KT07 2 in. diameter sleeve T20 / KT20 8 in. bolt T08 / KT08 2-1/8 in. diameter disc T21 / KT21 Half Sleeve T10 / KT10 8 in. bolt T26 / KT26 Cap installation tool T12 / KT12 3-7/8 in. long sleeve T27 / KT27 Cap installation tool T13 / KT13 10 in.
5.6.8 Using a 14 mm hex bit socket, remove and discard the two caliper bolts (3) and (11). See Figure 67. By hand, retract both guide pins slightly and then remove the caliper from the carrier. 5.6.13 Turning the nut at the top, draw the brass nut up, bring the brass bushing up and out of the channel. Discard the bushing. FIGURE 67 - REMOVE THE CALIPER BOLTS The guide pins are now only held by the retaining rings (7). 5.6.9 Remove the boot retaining rings (7) and the guide pins (2) and (9).
5.6.15 Use the tool combination shown in Figure 75 (comprising T14, T20, T21, and a washer) to remove the bushing (1). Screw nut (T14) onto the assembly by hand, then tighten the bolt (T20) using a box end wrench to draw out the bushing. Discard the removed bushing, and verify that the bore is clean by wiping with a shop cloth. T20 5.6.18 Place the washer and thread the brass nut (T14) on to the bolt (T13) followed by the flange (T08). 5.6.
5.6.25 Place the new bushing (1) in position so that when drawn into position, the tab will align with the slot in the casting. With the tab aligned, place tool (T14) over the bushing and tap lightly. To position the bushing, see Figure 78.
(9), begin to tighten the bolts. With the caliper/carrier in a vice, continue installing the bolts to a torque of 133 ft. lbs. (180 N·m) . Finally tighten each bolt an additional 90º (ninety degrees). Installation of the Guide Pin Caps 5.6.37 See Figure 84. Place the caliper/carrier assembly on a bench so that the inner boots are fully compressed, check that the bores are clean and dry (e.g. free from lubrication). BOOT COMPRESSED 5.6.41 Install the caliper/carrier (See Section 5.3). 5.6.
5.
5.7.6 Following industry standards, clean and inspect the hub before installing the rotor. Look for corrosion and/or damage to the hub and inspect the wheel speed tone ring. Where necessary, consult the hub manufacturer's guidelines for more details.
5.7.9 Re-install the air disc brake (See Section 5.3). Supporting the air disc brake by all necessary means, attach the brake to the anchor plate using six bolts and washers as required (Bendix recommends the original bolts not be re-used). Torque to vehicle manufacturer's specifications. If torque values and bolts are not specified by the vehicle manufacturer, then torque according to the chart below.
SERVICE DATA INDEX Section One: Air Disc Brake Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Safe Maintenance Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Section Two: Preventive Maintenance Schedule and Wheel-On Inspections .6 2.0 Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 2.1 Brake Pad And Rotor Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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