988G Wheel Loader Machine Systems Caterpillar

Assembly Procedure

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Illustration 1	g00670525

1. Use the proper equipment in order to handle bearing (54).

2. Heat bearing (54) to a maximum temperature of 121 °C (250 °F).

3. Install bearing (54) onto the shaft (49).
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   Illustration 2	g00670361

4. Use the proper equipment in order to handle the bearing cup.

5. Lower the temperature of bearing cup (53) and install the bearing cup in pump body (27).
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   Illustration 3	g00670360

6. Inspect the O-ring seals on plugs (52). Replace the O-ring seals, if necessary.

7. Install two plugs (52) in pump body (27).
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   Illustration 4	g00670531

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   Illustration 5	g00670532

8. Install snap ring (50).

9. Use Tooling (A) in order to install seal (51) (not shown).
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   Illustration 6	g00670298

10. Install shaft assembly (49).

11. Use the following steps in order to determine the proper preload on the bearings of the pump assembly.
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    Illustration 7	g00669728

    1. Use the proper equipment in order to handle the bearing cup. Lower the temperature of bearing cup (30) and install the bearing cup in head assembly (26).
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       Illustration 8	g00670604
       Typical Example

    2. Install adjustment shim (33) and bearing (32) onto shaft (49).
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       Illustration 9	g00670605

    3. Position head assembly (26) onto pump body (27).
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       Illustration 10	g00670624

    4. Use Tooling (C) in order to measure the distance between the head and the pump housing.

    5. Take measurements at three equal intervals on the surface between the head and the pump housing.

    6. The average of the three dimensions should be between zero and 0.05 mm (.002 inch).

    7. If necessary, grind adjustment shim (33) in order to obtain the correct dimension between the head and the pump housing. It may be necessary to replace the shim with a new part.
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       Illustration 11	g00670625

    8. Install four bolts (25) in the head and pump housing (27). Tighten bolts (25) to a torque of 100 ± 20 N·m (75 ± 15 lb ft).
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       Illustration 12	g00670626

    9. Use Tooling (D), (E), and (F) in order to check end play in shaft (49). If end play exists in the shaft assembly, repeat Step 11 until the correct dimension between the head and the pump housing is reached.

    10. Remove bolts (25) and head assembly (26) from pump body (27). Remove bearing (32) and adjustment shim (33) from shaft (49).

    11. Proceed with the assembly of the fan drive pump.
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    Illustration 13	g00670223

12. Install two swashplate bearings (48).
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    Illustration 14	g00670207

13. Install spring (47).
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    Illustration 15	g00670206

14. Install swashplate (46).
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    Illustration 16	g00670205

    Note: Note that there is a correct connection of the piston rod and the swashplate.

15. Install piston rod (45).
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    Illustration 17	g00670204

16. Install the control piston (44).
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    Illustration 18	g00669745

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    Illustration 19	g00669744

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    Improper assembly of parts that are spring loaded can cause bodily injury. To prevent possible injury, follow the established assembly procedure and wear protective equipment.

    Note: There is spring force against lock ring (43). When lock ring (43) is not seated properly, the spring force will be released. Installation of the internal components in barrel (38) should be performed in a press. This is done in order to retain spring (42) and lock ring (43).

17. Install pins (40), guide (41) and spring (42) in barrel (38).

18. Use a press and Tooling (A) in order to compress spring (42) in barrel assembly (38).

19. Use Tooling (B) in order to install retaining ring (43).

20. Slowly release compression on spring (42). Make sure that the retaining ring (43) is seated properly.
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    Illustration 20	g00669743

21. Install retaining ball (39) on barrel assembly (38).
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    Illustration 21	g00669741

22. Install piston assembly (37) in barrel assembly (38).
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    Illustration 22	g00669742

23. Install rotary group (36) onto the shaft. Make sure that the splines are aligned properly.
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    Illustration 23	g00669732

24. Inspect the O-ring seal on plug (34). Replace the O-ring seal, if necessary.

25. Install plug (34).
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    Illustration 24	g00669731

26. Install the adjustment shim (33).
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    Illustration 25	g00669730

27. Install bearing (32) on the shaft.
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    Illustration 26	g00669729

28. Install O-ring (31).
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    Illustration 27	g00669727

29. Install O-ring seal (28) and port plate (29) on head assembly (26).
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    Illustration 28	g00669722

30. Install head assembly (26) and four bolts (25). The torque for bolts (25) is 100 ± 20 N·m (75 ± 15 lb ft).
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    Illustration 29	g00670203

31. Install spool (23) in compensator valve (1).

32. Install spacer (24) onto plug (22).

33. Install plug (22) in compensator valve (1). The torque for plug (22) is 30.5 ± 1.5 N·m (23 ± 1 lb ft).
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    Illustration 30	g00670201

34. Install O-ring seal (17) to plug (16).

35. Install plate (18), spring (19), spring (20), and guide (21) in compensator valve (1).

36. Install plug (16) in compensator valve (1). The torque for plug (16) is 100 ± 5 N·m (75 ± 3 lb ft).
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    Illustration 31	g00670198

37. Install spool (14) in compensator valve (1).

38. Install spacer (15) on plug (13).

39. Install plug (13) in compensator valve (1). The torque for plug (13) is 30.5 ± 1.5 N·m (23 ± 1 lb ft).
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    Illustration 32	g00670195

40. Install O-ring seal (8) to plug (7).

41. Install plate (9), spring (10), spring (11), and guide (12) in compensator valve (1).

42. Install plug (7) in compensator valve (1). The torque for plug (7) is 80 ± 5 N·m (58 ± 3 lb ft).
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    Illustration 33	g00670190

43. Inspect the O-ring seals on plugs (5). Replace the O-ring seals, if necessary. Install two plugs (5) in compensator valve (1).
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    Illustration 34	g00670188

44. Inspect the O-ring seals (4) and replace the O-ring seals, if necessary. Install three O-ring seals (4) on compensator valve (1).
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    Illustration 35	g00669721

45. Install four bolts (2) and pressure and flow compensator valve (1) to fan drive pump (3). The torque for bolts (2) is 34 ± 3 N·m (25 ± 2 lb ft).

End By:

1. Install the fan drive pump. Refer to Disassembly and Assembly, "Piston Pump (Hydraulic Fan) - Install".