Simplex expanding wedge brake Assembly and Maintenance Instructions
Simplex expanding wedge brake Assembly and Maintenance Instructions Edition 1 This publication is not subject to any update service. You will find the latest version in INFORM www.wabco-auto.com 2010 The right of amendment is reserved. Version 1/01.2010(en) 815 010 155 3
Table of Contents 1 Important instructions and safety instructions 5 1.1 General Information 5 1.2 Safety instructions 5 1.3 Repair and maintenance instructions 6 2 Description and function 7 2.1 Simplex expanding wedge brake 7 2.2 Simplex expanding device 9 3 Checking the brake pad thickness 10 4 Removing and inspecting the brake 11 4.1 Releasing the automatic adjuster 11 4.2 Removing and inspecting the brake drum 11 4.3 Removing and inspecting the brake shoes 12 4.4 Checking other brake parts 13 5 Replacing the expander 14 5.1 Removing the expander 14 5.2 Checking the expander 14 5.3 Dismantling the expander assembly 14 5.4 Reassembling the expander assembly 16 5.5 Installing the expander assembly 19 6 Installing the brakes 20 6.1 Installing the brake shoes 20 6.2 Initial brake setting 22 6.3 Installing the brake drum 23 6.4 Functionality testing and breaking in 23 7 Replacing the brake cylinder 24 7.1 Removing the brake cylinder 24 7.2 Installing the brake cylinder 24 8 Procurement and disposal of spare parts 26 4
Important instructions and safety instructions 1 1 Important instructions and safety instructions 1.1 General Information 1.2 Safety instructions This documentation describes the maintenance and repairs for Simplex expanding wedge brakes of types, and with the required steps and work-procedures for replacing individual parts, utilising the available repair sets. Wheel brake product numbers Brake type Part number 10 410 777 10 410 849 10 500 729 10 500 770 10 500 775 10 500 779 10 500 789 10 500 728 10 500 769 10 500 771 10 500 774 10 500 780 10 500 783 This publication is directed at trained service technicians employed at workshops for commercial vehicles. Before you begin with maintenance, repair, replacing a part etc., carefully read all the safety instructions as well as the repair and maintenance instructions included this publication. These instructions must be observed to avoid personal injury or material loss. WABCO only guarantees the safety, reliability and performance of its products and systems if all instructions, notes and safety instructions are observed. Before you perform any work on the vehicle (repair, maintenance, replacing parts, etc.), you must ensure the following: Only trained and qualified personnel may perform repairs on the vehicle. Always follow specifications and instructions of vehicle manufacturer. Always comply with the company and national accident prevention guidelines and Health and Safety regulations. Wear any necessary protective clothing. The workplace has to be dry, as well as sufficiently lit and ventilated. WARNING WARNING WARNING CAUTION CAUTION Reduced braking effect or brake failure Regularly check the wear limits of brake linings and brake drums. Replace worn, scorched, glazed, or oily brake linings immediately. Immediately replace worn or damaged brake drums. Always replace all brake linings and brake drums axle by axle. Rolling vehicle Position the vehicle on an even surface and secure it against rolling away with brake wedges. Only use approved devices to jack up and secure the vehicle. Make sure that the gearbox is in neutral and the hand brake has been pulled. Rolling vehicle Make sure that the release screw of the spring brake cylinder is threaded completely in after completing the maintenance and installation work and check the functionality of the parking brake. Risk of injury due to hazardous dusts Do not clean any soiled areas of the brake with compressed air or other high-pressure devices. Risk of injury due to heavy load A second technician must assist during removal and installation of the brake. 5
1 Important instructions and safety instructions CAUTION CAUTION CAUTION Risk of injury due to brake action while working on the brake Attach a clearly marked note on the steering wheel saying that work is being performed on the vehicle and that the brake must not be touched. Danger of injury by the release springs rebounding Use suitable tools or brake spring pliers for installing the release springs. Risk of injury due to falling brake parts Use suitable equipment, such as a vice, to clamp the brake when performing repairs on the brake outside the vehicle. Only use original WABCO parts and brake linings approved by the vehicle manufacturer. Overdimensioned pads are not approved and are not to be used. Renolit LX PEP 2 or an equivalent grease is recommended as a lubricant. Do not use a silicone grease or sprays containing silicone. Make sure that the brake linings, brake hoses, and the friction surfaces of the drum brakes do not contact any grease or oil as this may cause the brake to fail. Perform the repair work using only the recommended tools. Do not use motor-driven screw tools. Only tighten bolts and nuts with the specified wrenches and to the specified torque. Perform a concluding roller test stand test having completed the repairs. Do not perform full braking, with the exception of emergency braking, during the first 500 kilometers after new brake linings have been fitted. Also avoid continuous braking over longer periods. Ensure that the driver of the vehicle is informed. 1.3 Repair and maintenance instructions For good handling and braking characteristics it is essential that the brake and the brake drum be in flawless technical condition. Check the brake at the time intervals specified by the vehicle manufacturer and replace the worn parts. Check the brakes every two years and replace the release springs and all rubber parts. Before opening the brake, release the service brakes and parking brakes and the bus-stop brake on buses. Spring brake cylinders are under tension from the spring. They are loosened by unscrewing the release screw on the spring brake cylinder of the parking brake before performing any maintenance and installation work If cast parts have been heavily damaged or are severely worn, (cracks for example), replace the entire brake following the instructions. Do not apply the brake when brake linings have been removed. Do not use compressed air or other high-pressure devices when cleaning the brake or the vehicle. This may result in the risk of personal injury or hazardous dusts. Rubber parts of the brake could also be damaged. 6
Description and function 2 2 Description and function 2.1 Simplex expanding wedge brake Description The Simplex brake consists of a brake calliper (1) in cast with an expander (2) bolted on and the cover plate (3) and the brake shoes (4, 5), which are connected with the brake calliper (1) and the expander (2) by means of the release springs (6). fig. 2-1: View of a drum brake 1 Brake anchor plate 2 Expander 3 Cover plate 4, 5 Brake shoe 6 Release springs 7
2 Description and function The braking effect is almost the same when traveling forward or backward. The cover plate protects the brake from the infiltration of splashed water and contamination. The brake lining wear is checked through the opening in the cover plate (3) after removing the sealing plug (8a). Function The actuation of the brake moves the expanding wedge (9) through the brake cylinder (compressed air diaphragm or spring brake cylinder or hydraulic cylinder) in the direction of the arrow (a). The rollers (12) located between the expanding wedge (9) and the piston (10) cause the piston (10) to move in the direction of the arrow (b). The pistons (10) then cause the brake shoes (4, 5) to press on the brake drum. As a result of the varying pad wear of the two brake shoes (4, 5), the expanding wedge (9) will be on a slant. After the braking procedure is ended, the brake shoes (4, 5) are pulled back into the original position by the release springs (6). The expanding wedge is moved back into its original position by the compression spring (11). Based on the Simplex principle, the brake shoe (4) has greater pad wear as a leading braking system than the trailing brake shoe (5). Brake shoes (4, 5) are designed as pivoted shoes. To correct the pad wear, integrated automatic readjustments are used in the expander. fig. 2-2: Cut-out view of the expander device 9 Wedge 10 Piston 11 Pressure spring 12 Rollers a Expander wedge direction of operation b Piston direction of operation 8
Description and function 2 2.2 Simplex expanding device Description The expander device mainly consists of the housing, an expander wedge, rollers and piston with integrated automatic readjustments. The spreader device is protected against the infiltration of sprayed water and dirt with a protective cap. Function The expander (2) has an automatic readjustment apparatus for each piston (10), which continually readjusts for pad wear, separately for each brake shoe (4, 5) and therefore always guarantees sufficient space between the brake drum and the brake pad. Operation: When actuated, the expander wedge (9) is pressed against the pre-tension of the compression spring (11) between the rollers (12), and the rollers (12) run down the slant of the wedge (9) and the piston (10). This causes both pistons (10) to be pressed outward with the adjuster ring (13) and the adjuster nut (14), which presses the brake shoes against the brake drum and introduces a braking procedure. At the completion of the braking process, the expander wedge (9) is pressed into its original position by the compression spring (11). Release springs (6) for brake shoes (4, 5) press the adjuster nut (14), the adjuster ring (13) and the piston (10) back into their original positions. If there is an increase in the space because of pad wear, the expander wedge (9) presses further down and the piston (10) is pressed further outward. As soon as the adjuster wheel (13) rotation is greater than the tooth distribution of the adjuster wheel teeth (18) - saw-teeth - between the adjuster ring (13) and the adjuster nut (14), the automatic adjustment is put into play. Here the teeth (18) are moved one tooth further by a flexible spring (19). Release: When the brake is released, the adjuster bolt (15), the adjuster nut (14), the adjuster wheel (13) and the piston (10) are pressed back inward by the release springs (6). Because of the lateral shift in the piston (10), the spring-loaded pin (16) is applied on the shoulders of the helical groove (17), so that the adjuster ring (13) can be turned based on the piston (10) stroke. Because the pin (16) is pressed against the shoulder of the helical groove (17), the adjuster nut (14) and the adjuster ring (13) wheel rotate by one tooth. The adjuster bolt (15) is turned outward in the threads of the adjuster nut (14), therefore evening out the pad wear. The adjuster bolt (15) is fastened in place by the flat retainer spring (32) on the brake shoes (4, 5). Because the distribution of the teeth in the wheel (18) is so fine, the adjustment is very small - almost stageless - and equally sized steps of 0.03 mm. 9
3 Checking the brake pad thickness 3 Checking the brake pad thickness CAUTION Risk of injury Observe all safety instructions, as well as all repair and maintenance instructions (see chapter 1 "Important instructions and safety instructions", page 5). These instructions must be observed to avoid personal injury or material loss. Always check the brake pad thickness of both brake shoes and especially the brake pad thickness on the brake shoe that is in the direction of travel when moving forward (leading shoe). Remove the seal plugs (8a) from the inspection openings in the cover plate (3). Check the pad thickness of the brake pads. Replace the pads if a pad thickness of 6 mm has been reached on the brake lining. Depending on the type of brake and the available repair kits, either new brake pads can be riveted onto the brake shoes or new brake shoes can be installed with brake pads. Use WABCO replacement parts only and pay attention to the installation instructions provided with the repair kit (see chapter 8 "Procurement and disposal of spare parts", page 26). Make sure to put the seal plugs (8a) back into the inspection openings of the cover plate (3) after checking the brake pads. If braking force is insufficient or noises or vibrations during braking require further inspection, the brake drum will have to be removed. 10
Removing and inspecting the brake 4 4 Removing and inspecting the brake CAUTION Risk of injury Observe all safety instructions, as well as all repair and maintenance instructions (see chapter 1 "Important instructions and safety instructions", page 5). These instructions must be observed to avoid personal injury or material loss. Reset the automatic adjuster by turning the gears back to the stop with a flat screwdriver. This is done by inserting the screwdriver through the opening in the cover plate. Be sure not to damage the protective caps with the screwdriver. The brakes must be checked at regular intervals, in relation to vehicle use, during maintenance intervals, as well as in the context of applicable local laws and regulations. Replacing the brake pads, brake shoes and brake drums must always be done per axle and only use the brake pads that are approved for the vehicle by the vehicle manufacturer. 4.1 Releasing the automatic adjuster Release the parking brake by completely unscrewing the release bolt on the spring brake cylinder assembly. Observe the instructions of the brake cylinder manufacturer in this regard. Check for whether the brake is released. Remove the seal plugs (8b) from the cover plate. Turn both gears clockwise to reset the adjuster mechanism. 4.2 Removing and inspecting the brake drum The steps for removing and installing the brake drum depend on the construction of the axle. Refer to the respective documentation from the axle manufacturer! Remove the brake drum from the brake. Remove any course dirt, debris and rust from the brake drum and the clean the brake drum with a non-regreasing solution (brake cleaner). Check the brake drum for wear, grooves, cracks and damage. Degree of wear to the brake drum Diameter Max. drum Wear limit machining dimensions Ø 410 mm Ø 411 mm Ø 412 mm Ø 500 mm Ø 501 mm Ø 502 mm Small cracks and/or grooves can be professionally machined to the maximum drum machining dimensions. Recommended surface finish: Rz = 12 30 µm 11
4 Removing and inspecting the brake Replace the brake drum, if: the wear limit has been reached, cracks and grooves are still evident after machining to the maximum permitted drum machining dimensions, heat markings can be seen on the friction surface of the brake drum. Unhook the release springs (6) from the brake shoes (4, 5) using brake spring pliers or a suitable tool. Make sure that the inner diameters of the brake drums are the same on an axle when reinstalling the brake drums. Always replace both brake drums on an axle. 4.3 Removing and inspecting the brake shoes Burned, glazed or oil contaminated brake linings must be replaced immediately. Check the release springs for damages from corrosion or over-tensioning and replace damaged release springs. Remove both brake shoes (4, 5) from the brake. To avoid damaging the brake drum replace the brake linings no later than at the point when they reach the wear limit at their weakest spot. Only with brakes type : Unhook the springs from the lower release spring and remove the spring hook from the calliper. Check the brake shoes for wear, damage and corrosion. Danger of injury from release springs under tension! Use the respective installation/removal tool (figure) or brake spring pliers for unhooking the release springs. Replace the brake shoes, if: the contact surfaces on the web plate for the expander show signs of wear or are worn out, the contact surfaces of the brake shoe supports to the calliper show signs of wear or are worn out, the brake shoes show signs of corrosion damage, the brake shoes are deformed. Check the brake linings (pads) Replace the brake pads if the remaining pad thickness reaches 6 mm on the brake lining or if 12
Removing and inspecting the brake 4 the brake pads are burned, glazed or if they have been contaminated with oil. Depending on the type of brake and the available repair kits, either new brake pads can be riveted onto the brake shoes or new brake shoes can be installed with brake pads. Use WABCO replacement parts only and pay attention to the installation instructions provided with the repair kit (see chapter 8 "Procurement and disposal of spare parts", page 26). 4.4 Checking other brake parts Check all rubber parts of the brake for damages and replace any damaged rubber parts. Avoid damaging the protective caps while servicing or cleaning. Check the brake calliper (1) for damages, cracking, corrosion and wear. Clean the cotter pins and the mounts for the brake shoes on the brake calliper (1) and check them for wear and damage. Replace the brake callipers, if: the brake callipers show signs of cracking, corrosion damage or wear, the cotter pins or the mounts on the brake calliper for the brake shoes show signs of wear or damage. 13
5 Replacing the expander 5 Replacing the expander CAUTION Risk of injury Observe all safety instructions, as well as all repair and maintenance instructions (see chapter 1 "Important instructions and safety instructions", page 5). These instructions must be observed to avoid personal injury or material loss. 5.1 Removing the expander Remove the brake cylinder from the brake (see chapter 7.1 "Removing the brake cylinder", page 24). Pull the expander wedge out of the housing of the spreader if necessary. Reset the automatic adjuster mechanism (see chapter 4.1 "Releasing the automatic adjuster", page 11). Remove the brake drum (see chapter 4.2 "Removing and inspecting the brake drum", page 11). Remove the brake shoes (see chapter 4.3 "Removing and inspecting the brake shoes", page 12). Unscrew the four fastening bolts for the expander (2) using a ring spanner (SW 19) and remove the expander (2) from the brake calliper. 5.2 Checking the expander Replace the complete expander assembly if the expanding wedge actuation fails or if the automatic readjustment fails. Indication of a defective expander could also be excessive brake cylinder stroke distance or onesided brake pad wear. Check the protective caps (30) on the expander for damage and replace any damaged protective caps. Check the flat retainer springs (32) on the expander for damage and replace any damaged springs. Check the housing of the expander for damage or cracking. Replace the entire expander assembly if the housing is damaged or if there are signs of cracking. 5.3 Dismantling the expander assembly Pull out the entire expander actuation, consisting of the expander wedge (9), roller (12), roller cage (21), compression spring (11), snap ring (22) and double-sided spring plates from the housing (2) of the expander. 14
Replacing the expander 5 Pull the protection cap (30) out of the groove (arrow) of the housing (2). Release the protective cap (30) from the ring groove of the adjuster bolt (15) and remove the protective cap. Pull the complete units out of the pistons (10) of the expander assembly. Check the adjuster bolt (15) for damages to the flat retainer spring (32) or the adjuster bolt (15) with integrated toothed adjuster wheel (31) and replace any damaged parts. Unscrew the adjuster nut (14) from the adjuster bolt (15). 15
5 Replacing the expander Unscrew the shoulder bolts (28) with a ring spanner (SW 19) and screw them out of the housing (2). Dismantle the individual parts of the shoulder bolt (28): short and long compression springs (26, 27) with pin (16). Replace damaged or worn parts using WABCO repair kits (see chapter 8 "Procurement and disposal of spare parts", page 26). 5.4 Reassembling the expander assembly Grease a new flexible spring (19) and insert it into the piston (10) so that the ends of the spring (19) face the bottom of the piston and are across from the oblong slot in the piston (10). Grease a new disc (20) and the adjuster wheel (13). Insert the disc (20) and the adjuster wheel (13) into the piston (10) so that the helical groove (17) of the adjuster wheel (13) faces the oblong hole in the piston (10). Pull the piston (10) out of the housing (2). Grease the piston (10) and insert it into the housing (2) so that the oblong hole (arrow) of the piston (10) faces the threaded hole in of the shoulder bolt (28). Remove the adjuster wheel (13), disc (20) and flexible spring (19) from the piston (10). Grease the shoulder bolt (28), the short and long compression springs (26, 27) and the pin (16). Insert the short and long compression springs (26, 27) and the pin (16) into the shoulder bolt (28). Clean all parts and the housing of the expander and check all parts for damage or wear. 16
Replacing the expander 5 Insert the complete shoulder bolt (28) into the threaded hole in the housing (2) so that the shoulder bolt (28) reaches into the oblong hole of the piston (10) and the pin (16) in the helical groove (17) of the adjuster wheel (13). Thread on the adjuster nut (14) to the stop on the adjuster bolt (15) and make sure that the adjuster nut (14) does not counter against the stop. Grease the teeth of the adjuster nut (14). Insert the entire unit into the piston (10). Thread the shoulder bolt (28) into the housing (2) and tighten the shoulder bolt (28) with a spanner (SW 19) (tightening torque 60 + 10 Nm). Grease the groove and threads of the adjuster bolt (15). Insert a new protective cap (30) onto the adjuster bolt (15) so that it is seated completely in the groove of the adjuster bolt (15). Grease the groove (arrow) of the housing (2). Insert the protective cap (30) on the housing (2) so that it is seated in the groove (arrow) all the way around the housing (2). Grease the inside of the housing (2). This is done by filling the inner space in the base of the housing (2) between the pistons (10) with approximately 20 25 cm³ grease. 17
5 Replacing the expander Grease the parts of the expander actuation: Expander wedge (9), rollers (12), roller cage (21), compression spring (11), snap ring (22) and double-sided spring plate. Put the parts of the expander actuation together. Make sure that when installing the expander wedge actuator, the rollers (12) face toward the piston (10) and the roller cage (21) is not seated on the guide in the side of the housing (2). Make sure that the expander wedge actuation assembly is positioned correctly. This is done by using your hand to put light pressure on the expander wedge (9) and turn it in a circle. Align the expander wedge (9) centred with the housing neck axis (A) and insert the complete expander actuation assembly into the housing (2). If the expander wedge slips back by moving downward, the initial position of the rollers (12) between the pistons (10) is not correct. Realign the expander wedge in this case. Make sure that the expander wedge actuation remains in its initial position when installing the brake cylinder. Avoid putting the expander wedge (9) into the housing (2) at an angle. This could cause the expander wedge actuator to slip out of its original position and the rollers (12) would not go between the pistons (10). 18
Replacing the expander 5 Setting the expander assembly Screw in the adjuster bolts (15) under pressure until the wheel teeth (18) of the adjuster wheel (13) and the adjuster nut (14) slide audibly against one another. Screw each of the adjuster bolts (15) out two full turns. Make sure that both adjuster bolts are turned out the same amount. Insert the expander assembly (2) into the locator hole of the brake calliper (1). Screw the expander assembly (2) onto the brake calliper (1) with four new fastening bolts (SW 19). Tighten the fastening bolts, alternating in a crisscross fashion, to a tightening torque of 210 ± 15 Nm. By screwing the two adjuster bolts out, the functionality of the automatic adjuster is guaranteed! 5.5 Installing the expander assembly Clean the locating hole and the mounting surface for the expander assembly on the brake calliper (1). Grease the locator hole (arrow) for the expander assembly (2) on the brake calliper (1) with ANTI- SEIZE or an equivalent grease. The mounting surfaces must be free of grease. With brakes type, the four fastening bolts must also be secured with Loctite 270. Make sure that the threads in the housing and on the fastening bolts are free of grease. Install the brake (see chapter 6 "Installing the brakes", page 20). Install the actuation cylinder (see chapter 7.2 "Installing the brake cylinder", page 24). Perform a function and effectiveness test of the brake (see chapter 6.4 "Functionality testing and breaking in", page 23). 19
6 Installing the brakes 6 Installing the brakes CAUTION Risk of injury Observe all safety instructions, as well as all repair and maintenance instructions (see chapter 1 "Important instructions and safety instructions", page 5). These instructions must be observed to avoid personal injury or material loss. Insert the brake shoes into the mounts (b, d) on the brake calliper (1) and into the slots (a, c) of the adjuster bolt (15) for the expander assembly. Set the expander assembly before installing the brake (see page 19). 6.1 Installing the brake shoes Grease the contact surfaces (arrows) of the adjuster bolts (15) in the expander assembly (2). Grease the surfaces (arrows) of the brake shoe mounts on the brake calliper (1). Notes: The brake shoes are symmetric/identical and do not correspond specifically with the main direction of rotation of the brake. Exception In the case of type brakes, the two brake shoes (4, 5) differ in the design of the holes for hooking the release springs (6) in place: The holes with bevels (arrows) must face mounts (b) and (c). 20
Installing the brakes 6 The centring pin of the brake calliper (1) must insert into the centring groove on the brake shoe (4, 5). Installing the release springs Danger of injury from release springs under tension! Use the respective installation/removal tool (figure) or brake spring pliers for hooking the release springs in place. Always use new release springs to install brake shoes. The web plate of the brake shoes (4, 5) must be in the gap in the brake calliper (1). Insert the new release springs (6) into the correct mounting position. The brake shoe must be in the groove of the adjuster bolt (15) and the gap of the flat retainer spring. Install a new spring hook (a) as well with type brakes. Insert the angled end of the release spring into the hole in the brake shoe. (This hole is not bevelled on type brakes.) 21
6 Installing the brakes Hook the hook-formed end of the release spring into the hole in the brake shoe with brake spring pliers or a suitable tool. (This hole is bevelled on type brakes.) Check the release springs for correct mounting position based on the picture. Make absolutely sure to also hook a new spring hook (a) into the release spring (6) on the shoe support side with type brakes to prevent the release spring from coming into contact with the wheel hub. Insert the angled end of the spring hook (a) into the hole in the brake calliper (1). 6.2 Initial brake setting Every brake must be set up individually to the respective brake drum dimension. Determine the inner diameter of the brake drum in the middle of the contact surface. Determine the outer diameter of the brake shoe with a calliper gauge. Set the brake shoes to the diameter of the brake drum by turning the adjuster bolt (15) evenly out or in. Setting dimensions: Diameter of brake shoe = diameter of brake drum minus 1.5 mm. Hook the release spring into the hook-formed end of the spring hook (a). Check the concentricity of the brake shoes using a gauge. This is done by using magnetic stands to mount the gauge on the wheel hub. Both brake shoes 22
Installing the brakes 6 must be measured in the middle (in the pad split groove area) and must show the same value. 6.4 Functionality testing and breaking in WARNING Rolling vehicle Make sure that the release screw of the spring brake cylinder is threaded completely in after completing the maintenance and installation work and check the functionality of the parking brake. Perform a concluding roller test stand test having completed the repairs. An incorrect adjustment will lead to damages to the brake pads and the brake drum. If necessary, correct the concentricity of the brake shoes by screwing the adjuster bolts (15) in or out. Check the setting dimensions with a calliper gauge. After completing the service and adjustment work, insert the seal plugs (8a, 8b) into the openings in the cover plate. 6.3 Installing the brake drum The steps for removing and installing the brake drum depend on the construction of the axle. Refer to the respective documentation from the axle manufacturer! Make sure that the parking brake is released, by completely unscrewing the release bolt on the spring brake cylinder assembly. Observe the instructions of the brake cylinder manufacturer in this regard. Install the brake drum on the axle. Breaking in specifications Every new brake pad must be broken in to achieve optimal braking performance and to prevent later damage to the brake pad, the brake drum and the expander. Breaking in is done with interval braking procedures in the lower to mid-speed range of the vehicle. The break-in distance must be at least 500 kilometers. During the break-in phase, the brake drum temperature must not exceed 200 C. Do not perform full braking, with the exception of emergency braking, after new brake linings have been fitted. Also avoid continuous braking over longer periods. Check braking performance on a rolling test stand after the brakes have cooled. Repeat the break-in process until the specified braking performance has been achieved. While breaking the new brake pads in (at least 500 km), the brake does not achieve full braking performance. With machined brake drums, the break-in time to achieving full braking performance is extended. Ensure that the driver of the vehicle is informed. 23
7 Replacing the brake cylinder 7 Replacing the brake cylinder CAUTION Risk of injury Observe all safety instructions, as well as all repair and maintenance instructions (see chapter 1 "Important instructions and safety instructions", page 5). These instructions must be observed to avoid personal injury or material loss. Loosen the counter nut of the actuation cylinder on the expander. Unscrew the brake cylinder out of the expander. Only use brake cylinders as specified by the vehicle manufacturer. These instructions for breaking the brake cylinder in are for general information. Pay attention to the installation specifications and the test and installation instructions of the manufacturer of the brake cylinder and adhere to them. Ensure that no dirt or moisture enters the expander when removing the brake cylinder. 7.1 Removing the brake cylinder Release the parking brake, by completely unscrewing the release bolt on the spring brake cylinder assembly. Observe the instructions of the brake cylinder manufacturer in this regard. 7.2 Installing the brake cylinder Before connecting the air lines to the brake cylinder and screwing the release bolt in again, the brake drum must be mounted. Clean the outer threads of the brake cylinder. Thread the counternut onto the brake cylinder until 27 mm of thread is protruding. Seal the outer thread (arrow) of the brake cylinder against water infiltration by applying sealant on the outer threads. Recommended sealant: Teroson-Atmosit. Mark the compressed air lines so that they cannot be switched when installing again. Unscrew the air lines from the brake cylinder. Ensure that the air connections of the brake cylinder are not pressurised. Thread the brake cylinder into the housing neck of the expander until it is stopped solidly. Release the brake cylinder again until the bleed vent faces upward with the hydraulic cylinder or 24
Replacing the brake cylinder 7 the required setting is achieved for the compressed air connection with a pneumatic cylinder. Tighten the counternut on the brake cylinder with the brake actuated. Tightening torque: 160 ± 20 Nm. Check the air connections for tightness. Perform a function and effectiveness test of the brake (see chapter 6.4 "Functionality testing and breaking in", page 23). Make sure that the expander wedge actuation is in the initial position when mounting the actuation cylinder. Make sure that the brake lines are not under the brake cylinder and that one of the drainage openings (e) faces down, vertically. The drainage openings (e) at the bottom must be open. The remaining openings on the brake cylinder must be plugged off. Screw the compressed air lines onto the brake cylinder. Thread the release bolt (arrow) for the spring brake cylinder completely in so that the brake is actuated. Observe the instructions of the brake cylinder manufacturer in this regard. 25
8 Procurement and disposal of spare parts 8 Procurement and disposal of spare parts Procurement of spare parts Identify the brake by means of the WABCO part number. Disposing of the brake components Dispose of used and replaced parts in accordance with the national and regional regulations regarding environmental protection. Generally brake components can be scrapped. fig. 8-1: WABCO type plate A Vehicle manufacturer part number B Production date C Assembly number D WABCO part number Open INFORM at www.wabco-auto.com Enter the WABCO part number of the brake calliper. Click "Repair". Open the spare part sheet. 26
WABCO Vehicle Control Systems (NYSE: WBC) is a leading supplier of safety and control systems for commercial vehicles. For over 140 years, WABCO has pioneered breakthrough electronic, mechanical and mechatronic technologies for braking, stability, and transmission automation systems supplied to the world s leading commercial truck, trailer, and bus manufacturers. WABCO is headquartered in Brussels, Belgium. For more information, visit www.wabco-auto.com 2010 WABCO All rights reserved. 815 010 155 3/01.2010