IT28G Integrated Toolcarrier and 928G Wheel Loader Differential Backlash and Bearing Adjustment Caterpillar

Illustration 1	g02109738

Note: The same adjustments are used for both the front and the rear axles.

1. Assemble the differential group (17) .

2. Heat the bevel gear (16) to 95° ± 25°C (203° ± 45°F) for a maximum of four hours. Partially press the large diameter Connex pin (19) into the bevel gear. Press the smaller Connex pin (20) into the larger pin (19) with the serrations that have a 180° separation. Press both pins until the pins are flush with the surface of the bevel gear. Make sure that the bevel gear is seated on the shoulder of the differential group.

3. The bolt holes on the bevel gear must be aligned with the holes in the differential group. Put lubrication on the threads of the bolts (15) . Torque for 16 bolts 95 ± 10 N·m (70 ± 7 lb ft). Then turn bolts (15) by an additional 180 ± 5 degrees.

4. Press the bearing cone (4) and bearing cone (12) on differential group (17) . Check for full seating of the cones.

5. Remove intermediate housing (1) from the center housing (18) .

6. Install bearing cups (3) and bearing cups (11) . Install the bearing sleeves (6) and the bearing sleeves (14) . Install two pins (2) and two pins (10) . Lubricate the threads of the adjusting nuts (5) and (13) and install the adjusting nuts in intermediate housing (1) and center housing (18) .

7. Position the center housing (18) in a fixture for support that is appropriate with the open side facing upward. With a lifting device, lower the differential group (17) and the bevel gear into position in the center housing (18) .

8. Install intermediate housing (1) on the three dowels in the center housing (18) . Tighten four bolts.

9. Lubricate the seal and install the seal on the pinion housing (8) . Install the pinion housing (8) on center housing (18) . Torque eight bolts (21) and eight washers (22) to 300 ± 40 N·m (221 ± 30 lb ft). Use the original thickness of the shims (9) or a new shim pack that is the same thickness as the original pack. If the original shim pack is not available, use 70 percent of a new shim pack.

10. Reposition the center housing (18) in the fixture in order for the center housing (18) and pinion housing (8) to be horizontal. This is the same position which is in the machine.

11. Tighten the adjusting nuts (5) and (13) to a position that maintains gear backlash but not tight gear mesh and a slight bearing end play.

12. Measure the torque that is required to rotate the pinion shaft (7) . Record the measured torque.

13. Rotate the pinion shaft (7) back and forth and tighten the adjusting nut (13) to the zero backlash position. Then back off the adjusting nut (13) . Turn the nut by 20 degrees plus the increment to the nearest lock position.

14. Tighten the adjusting nut (5) while you rotate the pinion shaft (7) . Tighten the nut (5) until a torque increase of 0.2 to 0.6 N·m (2.0 to 5.0 lb in) over the amount that was measured is measured. This is the seated position.

15. Tighten the adjusting nut (5) to forty degrees plus the increment that is to the nearest lock position.

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Illustration 2	g00104810

16. Measure the backlash between the bevel gear (16) and the pinion shaft (7) . The specification for the backlash is 0.25 mm (.0098 inch) plus 0.1 mm (.0039 inch) and minus 0.08 mm (.0031 inch). Make the backlash measurements at the pinion shaft spline. Place a dial indicator tangent to the spline on a flat of a drive shaft yoke or a spline adapter. The yoke or the adapter should be tight to the spline in order to get an accurate measurement. If a yoke or an adapter is not available, a strip of steel may be attached to the spline.

    Use the following formula to determine the backlash measurement for the dial indicator.

    Maximum backlash is equal to dimension (A) times 0.006.

    Minimum backlash is equal to dimension (A) times 0.0035.

    Dimension (A) is equal to the distance of the dial indicator from the pinion centerline.

    Use the following procedure for the bevel gear backlash that does not meet the specification.

    Retract one adjusting nut for the same amount as the adjusting nut that is opposite is advanced in order to maintain the bearing preload.

17. Recheck the pinion preload adjustment by the following assembled specification.
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    Table 1

    Assembled Pinion Preload Adjustment
    Bearings	Actual Torque At The Pinion
    New Bearings	1.4 N·m (12.39 lb in) to 6.0 N·m (53 lb in)
    Used Bearings	0.7 N·m (6.20 lb in) to 3 N·m (26.6 lb in)