TECHNICAL BULLETIN TP-96175 Issued 12-96 Servicing Rockwell s TB Series Trailer Axles with Unitized Hub Assemblies
TB Series Trailer Axles Introduction Rockwell s TB series trailer axle features a permanently sealed and lubricated unitized hub assembly designed to help reduce wheel-end maintenance. Removal of the long-life bearings, seals and lubricant from the hub assembly will void the warranty. Figure 2: Conventional Hub OUTER BEARING CUP INNER BEARING CUP INNER BEARING CONE LUBRICANT Lubricant Comparing a Unitized Wheel-End to a Conventional Wheel-End On a unitized wheel-end, you install the hub, seal, lubricant and bearings onto the axle spindle as an assembly. Figure 1. On a conventional wheel-end, you install the hub, seal, lubricant and bearings onto the axle spindle as separate components. Figure 2. For service and lubrication instructions for the TB trailer axle unitized hub assembly not covered in this bulletin, refer to Maintenance Manual No. 14, Trailer Axles; and Maintenance Manual No. 1, Lubrication. Call 800-535-5560 to order these publications. Figure 1: Unitized Hub AXLE SPINDLE UNITIZED HUB ASSEMBLY OUTER BEARING CONE HUB OIL SEAL AXLE SPINDLE Identifying a Trailer Axle with Unitized Wheel-Ends r The model number designation for the TB series is prefixed with TB; for example, TB-4670 or TB-8670. r The axle spindles are shorter with a single journal. r The hubs contain non-serviceable bearings, seals and lubricant. r The hub caps screw onto the hub and have no provision for adding lubricant. r The axle spindle retention hardware features a thicker inner nut and a bendable tab lockwasher. The inner nut is stamped TORQUE TO 700 LB-FT. DO NOT BACK OFF FOR TB AXLE ONLY. r Warranty information is stamped on each unitized hub cap: Important: Removal of long-life bearings, seals or lubricant from the Rockwell TB series trailer axle hub will void the warranty. Refer to Technical Bulletin TP-96175 or call 800-535-5560 for information. TP-9700 Page 2 Issued 12-96 16579/24240 TP-96175 Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 Printed in USA
Comparison Identification Unitized Hub Removal WARNING r To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. r Do not work under a vehicle that is supported only by jacks. Jacks can slip or fall over and cause serious personal injury. r Always support the vehicle with safety stands. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose longterm effects to health are unknown. You must use caution when you handle both asbestos and nonasbestos materials. For copies of the complete asbestos and nonasbestos warnings, refer to Maintenance Manual No. 14, Trailer Axles, or call 800-535-5560 and request TP-8712 and TP-88144. When to Remove the Unitized Hub Under normal operating conditions, you will not have to remove TB series trailer axle unitized hub assemblies from the axle spindle, because the hub assemblies are permanently sealed and lubricated to help reduce wheel-end maintenance. However, you will remove the hub assemblies under certain maintenance procedures. For example: Remove the unitized hub assembly from the axle when you replace stripped wheel studs. Removing the Unitized Hub Rockwell TB series trailer axles with unitized hub assemblies use conventional brakes, automatic slack adjusters and tire-wheel assemblies. Service brakes and automatic slack adjusters as specified in Rockwell s Maintenance Manual No. 4, Cam Brakes; and Maintenance Manual No. 4B, Automatic Slack Adjuster. Call 800-535-5560 to obtain copies of these publications. Refer to the wheel manufacturer s service procedures for tire-wheel assemblies. A unitized hub is permanently sealed and lubricated as an assembly. Do not attempt to remove the hub bearings, seals and lubricant. You cannot service or reinstall these components back into a unitized hub assembly. Damage to components can result. NOTE Removal of long-life bearings, seals and lubricant from the Rockwell TB series trailer axle hub assembly will void the warranty. 1. Raise the trailer until the tires are off the ground. 2. Put jack stands under the trailer frame or under each axle spring. Do not remove the tire-wheel assembly, hub and drum as a unit by removing the spindle nut. The bore clip can dislodge and the hub can disassemble. Damage to components can result. Remove the tire-wheel assembly by removing the wheel nuts. 3. Remove the tire-wheel assembly using procedures specified by wheel manufacturers. Figure 3. Figure 3 16579/24240 Issued 12-96 Page 3 Printed in USA Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 TP-96175
TB Series Trailer Axles 4. Disengage the brakes using procedures specified in Rockwell s Maintenance Manual No. 4. Remove the brake drum. 5. Remove the hub cap. Figure 4. When you bend the two opposing lockwasher tabs, be careful that the tool you use does not slip past the tabs and damage the hub outer seal. 6. Use a tool to straighten the two opposing flattened lockwasher tabs until they clear the outer nut. Figure 5. 7. Remove the outer nut, lockwasher and inner nut. Figure 6. Figure 4 COUNTERCLOCKWISE Figure 6 NUT LOCKWASHER WARNING INNER NUT When you remove the hub assembly from the axle spindle, carefully pull the hub off the spindle as straight as possible to avoid both dislodging the clip inside the hub bore, and damaging axle spindle threads. Figure 7. If the clip becomes dislodged, the hub will disassemble. Disassembly of the unitized hub will contaminate the lubricant and void the warranty. Do not attempt to rebuild the hub. You must install a new unitized hub assembly to avoid serious personal injury and damage to components. Figure 5 Figure 7 CLIP HUB BORE Page 4 Issued 12-96 16579/24240 TP-96175 Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 Printed in USA
Unitized Hub Removal NOTE Small amounts of grease may be visible at the hub s outer seal. This is a normal occurrence and does not indicate a seal leak. Figure 8. 8. Grasp the hub assembly with both hands. If the hub is free on the axle spindle, carefully pull the hub from the spindle as straight as possible. Figure 9. Figure 9 9. If the hub sticks to the axle spindle: a. Tap lightly on the axle with a hammer to help loosen the hub assembly for easier removal. Figure 10. Always use a metal plate at the end of the spindle when you use a puller to help remove a hub assembly to avoid damaging the spindle end plug. Figure 10 b. You can also use a puller to remove a hub assembly that is stuck to the axle spindle. Figure 8 1. Install a metal plate on the end of the spindle. 2. Use a puller to remove the hub. Figure 11. 3. Remove the hub as straight as possible from the axle spindle to avoid both dislodging the clip inside the hub bore and damaging axle spindle threads. GREASE Figure 11 METAL PLATE 16579/24240 Issued 12-96 Page 5 Printed in USA Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 TP-96175
TB Series Trailer Axles Removing and Replacing the Studs WARNING Observe all warnings and cautions for press operation provided by the press manufacturer to avoid serious personal injury and damage to components. Removing 1. Follow the instructions under Unitized Hub Removal in this bulletin. 2. Support the inboard side of the hub flange perpendicular to the press cylinder. 3. Use the press cylinder to push on the threaded end of the stud to force it out of the hub flange. Figure 12. Figure 12 Installing the Unitized Hub WARNING You must follow the installation procedures outlined below when you install a unitized hub. Wheel separation, damage to components and serious personal injury can result if you do not carefully follow these procedures. NOTE Do not install a hub onto the axle spindle when the brake drum and tire-wheel assembly are in place. 1. Clean the axle spindle by wiping it with a clean rag. Do not use solvents to clean the hub bore. Solvents can penetrate into the hub and contaminate the lubricant. Damage to components can result. 2. Clean the hub bore by wiping it with a clean rag. 3. Check the axle spindle and hub bore for scratches, nicks or marks. Repair them with a crocus or emery cloth. Figure 13. 4. Lubricate the hub bore and the entire axle spindle, including bearing journals and threads, with oil. Figure 14. Figure 13 Replacing 1. Turn the hub over. Support the outboard side of the hub flange perpendicular to the press cylinder. 2. Use the press cylinder to push on the stud head, applying no more than 10,000 lbs. (44 500 N) of force to seat the new stud. 3. Follow the instructions under Unitized Hub Installation in this bulletin to install the hub. Figure 14 CROCUS OR EMERY CLOTH Page 6 Issued 12-96 16579/24240 TP-96175 Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 Printed in USA
Stud Removal and Replacement Unitized Hub Installation Aligning the Hub Aligning the Hub WARNING You must align the bore straight onto the axle spindle to avoid both dislodging the clip inside the hub bore (Figure 15) and damaging spindle threads. If the clip becomes dislodged, the hub will disassemble. Disassembly of the unitized hub will contaminate the lubricant and void the warranty. Do not attempt to rebuild the hub. You must install a new unitized hub assembly to avoid serious personal injury and damage to components. Figure 15 CLIP Installing the Hub Do not force the hub assembly onto the axle spindle. Damage to the hub assembly will result. 1. Carefully slide the hub straight onto the axle spindle. Lightly tap on the rough part of the axle with a hammer to ease installation. Figure 10. The hub is aligned correctly when it rests against the spindle backup collar. Figure 16. Figure 16 SPINDLE BACKUP COLLAR HUB BORE Align the hub bore to the axle spindle by using one of the methods below: 1. Physically lift up the hub and align the bore to the axle spindle. 2. Support the hub with a sling and align the bore to the axle spindle. a. If the hub does not slide easily onto the axle spindle: Do not force the hub, or it can jam on the spindle. Tap on the hub to help align the hub. Figure 17. If this does not work, carefully remove the hub assembly so that you do not disassemble or loosen the inner bearing and seal or dislodge the clip located inside of the hub bore. b. Repeat Step 1. Figure 17 16579/24240 Issued 12-96 Page 7 Printed in USA Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 TP-96175
TB Series Trailer Axles NOTE Use a torque wrench to install a unitized hub. Because of the relatively high torque values required, a torque multiplier will also be helpful. Figure 18. Figure 18 TORQUE WRENCH When you use a tool to bend the two opposing lockwasher tabs, keep the tool securely on the tabs. If the tool slips off the tabs, you can damage the hub s outer seal. Figure 20. 5. Bend two tabs of lockwasher over opposite flats of outer nut. Use care to ensure that tool used to bend tabs does not slip past tabs and damage the hub s outer seal. Figure 20. Figure 20 HUB OUTER SEAL TORQUE MULTIPLIER Tighten the nuts to the specified torque. If the nuts are not tightened to the specified torque, the parts will be damaged. 2. Install the inner nut (thick nut). Use a torque wrench to tighten the inner nut to a torque of 700 to 750 lb-ft (952-1020 N m) while rotating the hub in both directions. Figure 19. Figure 19 6. Apply a light coating of NLGI 1 or 2 grease to the axle spindle nuts to protect against corrosion. 7. Install the hub cap. Tighten it to a torque of 50 to 75 lb-ft (68-102 N m). 8. Install the brake equipment and the tire-wheel assembly. 3. Install lockwasher, making sure that washer tab is properly inserted into the spindle keyway. 4. Install the outer nut (thin nut). Use a torque wrench to tighten the outer nut to a torque of 250 to 300 lb-ft (340-408 N m). Page 8 Issued 12-96 16579/24240 TP-96175 Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 Printed in USA
Hubodometer Installation Servicing Brakes Installing the Hubodometer NOTE The plastic unitized bearing hub cap incorporates a pilot and boss for the installation of the hubodometer. Early models are equipped with a metal hub cap. 1. Remove the hub cap. 2. Using the pilot in the center of the hub cap, drill a 9/16-inch hole. Figure 21. Remove any drilling residue from the hub cap. 3. Install the hubodometer stud into the hole. Tighten the stud to the manufacturer s recommended torque. 4. Reinstall the hub cap and tighten it to a torque of 50 to 75 lb-ft (68-102 N m). Servicing Brakes Without Removing the Unitized Hub NOTE All TB series axles built with cam brakes feature outboard-mounted drums and bolt-on bushings, which allow you to remove the brake shoes, camshaft and bushings without removing the hub. Figure 22. 1. Remove the brake drum, slack adjuster and brake shoes using procedures outlined in Maintenance Manual No. 14, Trailer Axles, Section 2, Disassemble. 2. Use snap-ring pliers to remove the snap ring at the inboard side of the bolt-on bushing. Figure 23. 3. Remove the four capscrews from the bolt-on bushing. Figure 23. Figure 21 Figure 22 AXLE AND HUB ASSEMBLY BRAKE DRUM WHEEL STUD NUT Figure 23 BOLT-ON BUSHING ASSEMBLY SNAP RING CAPSCREW (4) 16579/24240 Issued 12-96 Page 9 Printed in USA Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 TP-96175
TB Series Trailer Axles 4. Use a screwdriver to pry the bolt-on bushing out of the spider retainer hole. Figure 24. 5. Move the camshaft head away from the center line of the axle, so that the head clears the hub flange. Figure 25. 6. Pull the camshaft from the bushing. 7. Install the new bolt-on bushing by aligning the four bushing holes with the four matching spider holes. 8. Press a new bushing into the spider with a C-clamp until the bushing is completely seated. Figure 26. 9. Install the new brake components. Figure 24 Figure 25 SCREWDRIVER Figure 26 Page 10 Issued 12-96 16579/24240 TP-96175 Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 Printed in USA
Hub Inspection Inspecting the Hub Figure 27 Rockwell recommends you inspect the unitized hub for smooth rotation and proper end play at a service schedule of 2-1/2 years or 250,000 miles (402,000 km), whichever comes first. Rockwell further recommends you inspect the unitized hub for smooth rotation at each brake reline. Smooth Rotation Check 1. Rotate hub in both directions. 2. If the bearing feels rough or sounds noisy, replace the hub. Figure 28 End Play Check 1. Attach the magnetic base of a dial indicator to the hub. Figure 27. 2. Touch the dial indicator stem against the axle spindle. 3. Slightly rotate the hub in both directions while pushing the hub inward until the dial indicator does not change. Set the dial indicator to zero. Figure 28. 4. Slightly rotate the hub in both directions while pulling outward until the dial indicator does not change. Figure 29. 5. The difference between the two is end play. 6. If end play exceeds 0.003 inch (0.0762 mm), use a torque wrench to tighten the inner nut to a torque of 700 to 750 lb-ft (952-1020 N m). 7. Replace the hub if end play exceeds 0.012 inch (0.3048 mm) after you tighten the inner nut to a torque of 700 to 750 lb-ft (952-1020 N m). Figure 29 16579/24240 Issued 12-96 Page 11 Printed in USA Copyright Rockwell Heavy Vehicle Systems, Inc., 1996 TP-96175
Automotive Rockwell Heavy Vehicle Systems, Inc. 2135 West Maple Road Troy, MI 48084 U.S.A. 800-535-5560 http://www.heavyvehicle.rockwell.com Information contained in this publication was in effect at the time the publication was approved for printing and is subject to change without notice or liability. Rockwell Heavy Vehicle Systems, Inc., reserves the right to revise the information presented or discontinue the production of parts described at any time. Copyright 1996 Rockwell Heavy Vehicle Systems, Inc. All Rights Reserved Printed in the U.S.A. Please Recycle TP-96175 Issued 12/96 16579/24240