988G Wheel Loader Power Train Caterpillar

Assembly Procedure

1. Clean all the components of the differential and bevel gear group. Replace all seals and any damaged components with new parts for replacement.

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Illustration 1	g00685286

2. Heat bearing cone (43) to a maximum temperature of 135°C (275°F).

3. Use insulated gloves in order to install bearing cone (43) on differential case (37) .

   Note: Allow the bearing cone and the differential case to reach a uniform temperature.

4. Use a hammer and a punch in order to reset the bearing cone and the differential case around the inside race of the bearing. This will ensure that the bearing cone is seated correctly on the case.

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Illustration 2	g00685202

5. Install sleeve (40) , pinion gear (41) , and spacer (42) onto the spider assembly (36) . Repeat this procedure for the three remaining pinion gear assemblies.

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Illustration 3	g00685199

6. Place the bottom differential case on suitable wood blocks, as shown.

7. Install thrust washer (39) into the bottom differential case.

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Illustration 4	g00685197

8. Lubricate the thrust face of gear (38) with clean oil. Install gear (38) in differential case (37) .

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Illustration 5	g00685196

9. Attach a suitable hoist and lifting slings to the spider and pinion gear assemblies (36) , as shown.

10. Use the hoist in order to install the spider and the pinion gear assemblies in differential case (37) . The combined weight of the spider and of the pinion gear assemblies is 32 kg (70 lb).

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Illustration 6	g00685195

11. Install gear (35) on the pinion gear assemblies. Lubricate the thrust face of gear (35) with clean oil.

12. Install spacer (34) .

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Illustration 7	g00685294

13. Heat bearing cone (33) to a maximum temperature of 135°C (275°F).

14. Use insulated gloves in order to install bearing cone (33) on the top differential case (32) .

    Note: Allow the bearing cone and the differential to reach a uniform temperature.

15. Use a hammer and a punch in order to reset the bearing cone around the inside race of the bearing.

    Note: This will ensure that the bearing cone is seated against the shoulder of the differential.

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Illustration 8	g00685191

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Illustration 9	g00685192

16. Install Tooling (B) to the top differential case (32) .

17. Attach a suitable hoist and lifting slings to Tooling (B) .

18. Use the hoist in order to install the top differential case (32) onto the bottom differential case. The weight of the top differential case is 105 kg (230 lb).

19. Install two bolts (31) .

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Illustration 10	g00685189

20. Carefully invert the differential (29) .

21. Install bolts (31) . The torque for bolts (31) is 300 ± 30 N·m (220 ± 22 lb ft).

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Illustration 11	g00685149

22. Place bevel gear (30) on suitable wood blocks, as shown.

23. Install Tooling (B) to differential assembly (29) .

24. Attach a suitable hoist and lifting slings to Tooling (B) .

25. Use the hoist in order to install differential assembly (29) to bevel gear (30) .

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Illustration 12	g00685148

26. Remove Tooling (B) .

27. Install bolts (28) . Tighten bolts (28) to a torque of 130 ± 30 N·m (95 ± 22 lb ft) plus an additional 120 degrees ± 10 degrees.

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Illustration 13	g00686566

28. Heat bearing cone (13) to a maximum temperature of 135°C (275°F).

29. Use insulated gloves in order to install bearing (13) on pinion shaft (10) .

    Note: Allow the bearing cone and the pinion shaft to reach a uniform temperature.

30. Use a hammer and a punch in order to reset the bearing cone around the inside race of the bearing.

    Note: This will ensure that the bearing cone is seated against the shoulder of the pinion shaft.

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Illustration 14	g00685139

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Illustration 15	g00685137

31. Lower the temperature of bearing cups (14) and (15) .

32. Use insulated gloves in order to install bearing cup (15) in the pinion housing.

33. Rotate the pinion housing and install bearing cup (14) in the pinion housing.

    Note: Allow the bearing cups and the pinion housing to reach a uniform temperature.

34. Use Tooling (D) in order to reset the bearing cups.

    Note: This will ensure that the bearing cups are seated against the shoulders of the pinion housing.

35. Lubricate the bearing cups with clean oil.

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Illustration 16	g00685309

36. Lubricate bearing cone (13) with clean oil.

37. Install Tooling (B) , a suitable hoist and suitable lifting slings to the pinion housing.

38. Use the hoist in order to lower the pinion housing onto pinion shaft (10) . The weight of the pinion housing is 81 kg (180 lb).

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Illustration 17	g00685310

39. Heat bearing cone (12) to a maximum temperature of 135°C (275°F).

40. Use insulated gloves in order to install bearing cone (12) on pinion shaft (10) .

    Note: Do not reset bearing cone (12) at this time. Allow the bearing cone to cool. Refer to steps 41 through 46 for the procedure to set the bearing load.

41. Lubricate bearing cone (12) with clean oil.

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Illustration 18	g00667186

42. Install washer (11) on pinion shaft (10) .

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Illustration 19	g00685313

Note: Retaining nut (9) may be reused if the collar was not cracked during removal or during restaking. Otherwise, use a new part for replacement.

43. Install retaining nut (9) on pinion shaft (10) .

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Illustration 20	g00686567

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Illustration 21	g00686568

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Illustration 22	g00667185

44. Install Tooling (F) in order to the end of the pinion shaft.

45. Use Tooling (C) in order to slowly rotate pinion shaft (10) . Check the rolling torque. The proper rolling torque of new bearings is 1.0 N·m to 1.7 N·m (9 lb in to 15 lb in).

    Note: Reduce the rolling torque to 0.5 N·m to 0.85 N·m (4.5 lb in to 7.5 lb in) for machines with more than 100 hours of operation.

46. Continue to tighten retaining nut (9) until the proper rolling torque is achieved.

    Note: If the rolling torque exceeds the specifications, back off the retaining nut by 45 degrees. Reset the bearing in order to relieve the preload. Repeat Step 45 and Step 46 until the specified preload is achieved.

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Illustration 23	g00382081
Completed Stake (H) The spherical radius of the tool for peening must be 7.5 to 8.0 mm (0.295 to 0.315 inch). (J) The acceptable angle of the tool for peening is 20 ± 10 degrees. (K) The minimum length of the crimp is 4.7 mm (0.185 inch). (L) The minimum depth of the crimp is 2.5 mm (0.098 inch). (M) Top view

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Illustration 24	g00685314

47. Lock retaining nut (9) by peening the collar in the slot on pinion shaft (10) .

    Note: Before you stake the nut, make sure that the pinion shaft has zero end play.

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Illustration 25	g00667183

48. Use Tooling (D) in order to install lip seal (8) in retainer (6) .

    Note: The sealing lip must be facing the inside of retainer (6) .

49. Install O-ring seal (7) . Lubricate the O-ring seal with clean oil.

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Illustration 26	g00667182

50. Install retainer (6) on the pinion housing.

51. Install bolts (5) . The torque for the bolts is 55 ± 10 N·m (40 ± 7 lb ft).

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Illustration 27	g00685146

52. Use a suitable hoist and lifting slings in order to install the differential and bevel gear (26) in carrier (27) . The combined weight of the differential and of the bevel gear is 272 kg (600 lb).

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Illustration 28	g00685145

53. Lubricate bearing cup (25) with clean oil. Install bearing cup (25) in the carrier. Repeat this procedure for the opposite side.

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Illustration 29	g00685303

54. Install bearing cap (22) and adjustment nut (23) . Make sure that the adjustment nut can turn freely.

55. Install bolts (24) and tighten to a torque of 25 N·m (18 lb ft).

    Note: This will allow adjusting nut (23) to move freely.

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Illustration 30	g00685304

56. Install bearing cap (18) and adjustment nut (19) . Make sure that the adjusting nut turns freely.

57. Install bolts (24) . Tighten the bolts to a torque of 25 N·m (18 lb ft). This will allow adjusting nut (19) to move freely.

    Note: Adjust the bearing preload and the gear backlash after the pinion housing has been installed.

58. Use a suitable hoist and lifting slings in order to reposition the carrier on Tooling (A) . The weight of the carrier and of the differential assembly is 454 kg (1000 lb).

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Illustration 31	g00667179

Note: If the pinion housing or the carrier housing are being replaced, install 80 percent of a new shim pack as a starting point for the pinion depth adjustment.

59. Install original shim pack (3) between the carrier and the pinion housing.

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Illustration 32	g00685316

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Illustration 33	g00667181

60. Install Tooling (B) to pinion housing (1) .

61. Install O-ring seal (4) in the groove of pinion housing (1) . Lubricate the O-ring seal with clean oil.

62. Use a suitable hoist and lifting slings in order to install pinion housing (6) on the carrier, as shown. The weight of pinion housing (1) is 132 kg (290 lb).

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Illustration 34	g00667174

63. Make sure that backlash is present before you secure pinion housing (1) to the carrier. Install bolts (2) . The torque for the bolts is 210 ± 40 N·m (155 ± 30 lb ft) plus an additional 120 degrees ± 10 degrees.

    Note: Steps 64 through 74 are for setting the backlash and the pinion depth.

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Illustration 35	g01365183

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Illustration 36	g01365190

64. Move adjustment nuts (19) and (23) on the carrier to a position that maintains gear backlash and slight bearing end play.

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Illustration 37	g00686436

65. Install Tooling (F) on the yoke assembly, as shown. Use a torque wrench in order to slowly turn pinion shaft (10) . Check the overall rolling torque with no load on the carrier bearings. Record the measured torque.

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Illustration 38	g01365861

66. Oscillate the bevel gear and advance adjustment nut (19) . Continue to advance the adjustment nut until there is no backlash. Back off the adjustment nut by 1/2 turn.

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Illustration 39	g01365183

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Illustration 40	g00686436

67. Advance nut (23) and check the rolling torque on pinion shaft (10) . Continue to advance adjustment nut (23) until the rolling torque increases by 20 percent over the rolling torque that was measured in Step 65. This is the seated position.

68. Advance adjustment nut (23) while you are rotating pinion shaft (10) . Advance adjustment nut (23) until an overall rolling torque of 4.5 - 6.7 N·m (40 - 59 lb in) is achieved.

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Illustration 41	g00383278
Typical Example

69. Mount Tooling (E) on the carrier, as shown. Measure the backlash at four places on the bevel gear at 90 degree intervals. Compare the lowest reading to the specifications. The proper backlash setting is 0.40 ± 0.12 mm (0.016 ± 0.005 inch).

70. If the backlash is not within the specification, retract one adjustment nut and advance the opposite adjustment nut equally. This will maintain the bearing preload.

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Illustration 42	g00686436

71. Use a torque wrench and Tooling (F) in order to measure the overall rolling torque at the pinion shaft. The rolling torque must be 4.5 N·m to 6.7 N·m (40 lb in to 59 lb in).

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Illustration 43	g00315875

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Illustration 44	g00315877

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Illustration 45	g00315878

72. After the backlash adjustment and the preload adjustment have been made, the tooth contact between the pinion shaft and the ring gear must be checked. Use the following procedure:

    1. Put a small amount of Prussian blue, red lead or paint on the teeth of the ring gear.

    2. Rotate the pinion in both directions.

    3. The correct area of tooth contact starts near the inside end of the teeth. The contact area should extend to a maximum of 50 percent of the length of the teeth. See Illustration 43 for the correct area of tooth contact.

73. If the area of tooth contact looks like Illustration 44, use the following procedure:

    1. Remove some of shims (8) under the pinion housing.

    2. Perform Steps 69 through 71 again.

    3. Perform Step 72 again in order to check the area of tooth contact.

74. If the area of tooth contact looks like Illustration 45, use the following procedure:

    1. Add some shims (8) under the pinion housing.

    2. Perform Steps 69 through 71 again.

    3. Perform Step 72 again in order to check the area of the tooth contact.

       Note: Make sure that the backlash adjustment is correct before you adjust the area of the tooth contact. Several adjustments of the backlash and of the tooth contact may be necessary in order to achieve the correct adjustments.

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Illustration 46	g00685321

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Illustration 47	g00685322

75. Install locks (17) and (21) . Secure the locks to the bearing caps with bolts (16) and (20) . The torque for bolts (16) and (20) is 55 ± 10 N·m (41 ± 7.4 lb ft).

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Illustration 48	g01365235

76. Tighten bolts (24) to a final torque of 1800 ± 200 N·m (1330 ± 150 lb ft).

End By: Install the differential and bevel gear. Refer to Disassembly and Assembly, "Differential and Bevel Gear - Install" for the machine that is being serviced.