Usage:
789 (9ZC),
789B (7EK) Off-Highway Trucks
Description of Change: The new one-piece wheel with higher capacity bearings will provide improved service life.
Effective with: The new cast wheel and high capacity wheel bearings are effective with 789B (7EK660) Off-Highway Trucks. The 142-5946 Wheel (cast), 134-4149 Cone (Outer), 134-4146 Cone (Inner), and 134-4147 Cup are now available. The 142-5946 Wheel (cast) requires 143-2174 Demountable Rim Group (not serviced).
NOTE: The new cups and cones are wider than previous bearings and can only be used with the new 142-5946 Cast Wheel (refer to the following charts and illustrations).
Illustration 1.
Typical view of demountable rim group.
Wheel Bearing Adjustment Procedure For The Rear Wheels Of 789 And 789B Off-Highway Trucks
Illustration 2.
Typical cross-sectional view of partially assembled wheel group.
Illustration 3.
View X. Gap = (B-A)
The following procedure must be used to adjust wheel bearings in the 5T-4476, 143-2173 Rear Wheel Groups (groups are not serviced), and 129-1660, 106-2616, 115-1778, 144-3855, 0R-9040, 0R-9043, 0R-9034, 0R-4102, 0R-8285 Service Wheel Arrangement.
1. Thoroughly clean the tapped holes (6) in the end of the spindle to receive the retainer bolts (3).
2. With bearing assemblies (1) already in position, install retainer (2) using eight new 2H-3856 Retainer Bolts (3). Install the retainer bolts in equally spaced hole positions. Tighten in a crossing pattern to 200 N·m (150 lb ft).
3. Remove any lifting brackets or supports from under the wheel station.
4. Release the brakes. Refer to the "Towing" section in the Systems Operation, Testing and Adjusting (Air Systems and Brakes) module.
5. Turn the wheel two complete revolutions.
6. Retighten the retainer bolts (3) to 200 N·m (150 lb ft) using the same tightening sequence. Turn the wheel two complete revolutions.
7. Loosen all retainer bolts (3) in the same sequence by 120 degrees (two bolt head flats). Turn the wheel two complete revolutions.
8. Tighten retainer bolts (3) in a crossing pattern to 95 N·m (70 lb ft). Rotate the wheel two complete revolutions.
9. Repeat Step 8 until no further movement of the retainer bolts (3) occurs when a torque of 95 N·m (70 lb ft) is applied.
10. Use a depth micrometer to measure the distance from the outside face of the retainer (2) to the end of the spindle. Measure this distance at two holes directly opposite each other and average the measurements. Refer to Illustration 3. Record Dimension B. If the two measurements differ by more than 0.13 mm (.005 in), DO NOT CONTINUE restart adjustment procedure beginning with Step 2. If the two measurements again differ by more than 0.13 mm (.005 in), disassemble and check for any interference that would prevent correct seating of the wheel bearings.
NOTE: In addition to the hole pattern in the retaining plate for the retaining bolts, there are two holes which may be used to make the measurement indicated in Step 10.
11. Use an outside micrometer and measure the thickness of the retainer (2) at the bolt holes. Refer to Illustration 3. Record Dimension A.
12. Calculate the average gap between the end of the spindle and inside face of the retainer by subtracting dimension recorded in Step 11 from dimension recorded in Step 10. Record the average gap and remove the retainer (2). Refer to Illustration 3.
13. Select and install the required shim pack (4).
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Do not install or re-install the final drive screen assembly on trucks equipped with rear axle filtration.
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a. Shim pack required without screen assembly (5). To determine the required shim thickness, add 0.216 + 0.00/- 0.05 mm (.0085 + .00/- .002 in) to the average gap found in Step 12.
NOTE: Screen assembly may be installed on trucks NOT equipped with rear axle filtration.
b. Shim pack required with screen assembly (5). Determine the required shim thickness, add 0.216 + 0.00/- 0.05 mm (.0085 + .00/- .002 in) to the average gap found in Step 12 and subtract the screen assembly thickness. Install screen assembly with the outside of the screen assembly against the retainer.
14. Install retainer (2) with fifteen new 2H-3856 Bolts (3) and fifteen new 5P-8249 Washers (7). Tighten the bolts in a crossing pattern to a torque of 400 ± 50 N·m (295 ± 37 lb ft).
| NOTICE |
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Do not install bolts or washers which have been previously torqued to final assembly specifications. The eight new bolts used for wheel bearing adjustment may be used in the final assembly.
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15. Repeat the tightening procedure from Step 14 until no further movement of the retainer bolts occurs when a torque of 400 ± 50 N·m (295 ± 37 lb ft) is applied.
16. Tighten each bolt an additional 60 ± 5 degrees (one flat).