784C and 785C Off-Highway Trucks Machine Systems Caterpillar

Assembly Procedure

Note: Cleanliness is an important factor. Before the assembly procedure, all parts should be thoroughly cleaned in cleaning fluid. Allow the parts to air dry. Wiping cloths or rags should not be used to dry parts. Lint may be deposited on the parts which may cause later trouble.

1. Check all of the O-ring seals and the components for wear or damage. Replace the components, if necessary.

2. Lubricate all of the O-ring seals lightly with the lubricant that is being sealed.
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   Illustration 1	g00530902

3. If two bearings (7) were removed, use a suitable press and Tooling (A) (not shown) in order to install two bearings (7) into body assembly (25).

   Note: The seams of two bearings (7) should be indexed closest to the center of body assembly (25).

   Note: The tops of bearings (7) should protrude between 5.588 mm (0.22 inch) and 5.842 mm (0.23 inch).

4. Use Tooling (C) (not shown) in order to install eight studs (24) into body assembly (25). Tighten eight studs (24) to a torque of 215 ± 40 N·m (158.6 ± 29.5 lb ft).
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   Illustration 2	g00530729

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   Illustration 3	g00532363

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   Illustration 4	g00530874

5. Coat the inside of body assembly (25) lightly with clean hydraulic oil.

6. Position bottom isolation plate (19), backup ring (12), O-ring seal (14) and ring retainer (15) in body assembly (25).

   Note: Install bottom isolation plate (19) with the rounded edge toward the bottom of the body assembly. Install bottom isolation plate (19) on the suction side of body assembly (25).

7. Install pressure plate (16) into body assembly (25).

   Note: Orient pressure plate (16) so that groove (A) is located on the outlet side of body assembly (25). Install pressure plate (16) with the bronze surface toward the top of the body assembly.

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   Illustration 5	g00530872

8. Coat drive shaft (27) and idler gear (17) lightly with clean hydraulic oil. Install drive shaft (27) and idler gear (17) into body assembly (25), as shown.

9. The rear set of gears must be positioned for proper timing with the front set of gears. In order to set the timing, rotate the gears until the point of a tooth on the drive gear is in line with the center of the nearest dowel hole in the body assembly. The rear set of gears must remain in this position until all of the remaining parts have been assembled.
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   Illustration 6	g00530729

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   Illustration 7	g00530678

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   Illustration 8	g00530864

10. Install pressure plate (16) into body assembly (25).

    Note: Orient pressure plate (16) so that groove (A) is located on the outlet side of body assembly (25). Install pressure plate (16) with the bronze surface toward the rear gear set.

11. Position top isolation plate (13), backup ring (12), O-ring seal (14) and ring retainer (15) on top of pressure plate (16).

    Note: Install top isolation plate (13) on the suction side of body assembly (25).

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    Illustration 9	g00530856

12. If two bearings (7) were removed, use a suitable press and Tooling (A) (not shown) in order to install two bearings (7) into plate assembly (20).

    Note: The seams of two bearings (7) should be indexed closest to the center of plate assembly (20).

    Note: The tops of bearings (7) should protrude between 5.59 mm (0.22 inch) and 5.84 mm (0.23 inch).

13. Install O-ring seal (9) into plate assembly (20).

14. If two dowels (5) were removed, install two dowels (5) onto plate assembly (20).
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    Illustration 10	g00530847

15. Install plate assembly (20) onto body assembly (25), as shown.

16. Install O-ring seal (9) onto plate assembly (20). Install eight O-ring seals (26) onto eight studs (24).
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    Illustration 11	g00530842

17. Use Tool (B) in order to install retaining ring (23) (not shown) into coupling (21).
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    Illustration 12	g00530792

18. If two dowels (5) were removed, install two dowels (5) onto plate assembly (20).

19. Install coupling (21) into plate assembly (20), as shown.
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    Illustration 13	g00530742

20. If two bearings (7) were removed, use a suitable press and Tooling (A) (not shown) in order to install two bearings (7) into body assembly (4).

    Note: The seam of two bearings (7) should be indexed closest to the center of body assembly (4).

    Note: The tops of bearings (7) should protrude between 5.59 mm (0.22 inch) and 5.84 mm (0.23 inch).

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    Illustration 14	g00530737

21. Install body assembly (4) onto plate assembly (20), as shown.
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    Illustration 15	g00530729

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    Illustration 16	g00532363

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    Illustration 17	g00530728

22. Coat the inside of body assembly (4) lightly with clean hydraulic oil.

23. Position bottom isolation plate (19), backup ring (12), O-ring seal (14) and ring retainer (15) in body assembly (4).

    Note: Install bottom isolation plate (19) with the rounded edge toward the bottom of the body assembly. Install bottom isolation plate (19) on the suction side of body assembly (4).

24. Install pressure plate (16) into body assembly (4).

    Note: Orient pressure plate (16) so that groove (A) is located on the outlet side of body assembly (4). Install pressure plate (16) with the bronze surface toward the top of the body assembly.

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    Illustration 18	g00530692

25. In Step 9, the rear set of gears were positioned for timing. The front drive gear must now be positioned for correct timing. The following procedure is used in order to correctly position drive shaft (18) into body assembly (4).

    1. Coat drive shaft (18) with clean hydraulic oil. Position drive shaft (18) on the top of the spline coupling.

    2. Before engaging the shaft spline into the coupling, rotate the drive shaft (18) until the valley between two gear teeth is lined up with the center of the nearest dowel hole in body assembly (4).

    3. Drive shaft (18) must engage the coupling. The valley cannot be off-center with the dowel hole. If the valley is off-center with the dowel hole, rotate drive shaft (18) to the next valley.

    4. Repeat Step 25.c until the combination of the valley and the spline will allow the valley to remain centered with the nearest dowel hole in body assembly (4).

26. Coat idler gear (17) lightly with clean hydraulic oil. Install idler gear (17) into body assembly (4).
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    Illustration 19	g00530729

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    Illustration 20	g00530678

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    Illustration 21	g00530670

27. Install pressure plate (16) into body assembly (4).

    Note: Orient pressure plate (16) so that groove (A) is located on the outlet side of body assembly (4). Install pressure plate (16) with the bronze surface toward the front gear set.

28. Position top isolation plate (13), backup ring (12), O-ring seal (14) and ring retainer (15) on top of pressure plate (16).

    Note: Install top isolation plate (13) on the suction side of body assembly (4).

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    Illustration 22	g00530543

29. If bearings (6) and (7) were removed, use a suitable press and Tooling (A) (not shown) in order to install bearings (6) and (7) into flange assembly (1).

    Note: The seams of bearings (6) and (7) should be indexed closest to the center of flange assembly (1).

    Note: The tops of bearings (6) and (7) should protrude between 5.588 mm (0.22 inch) and 5.84 mm (0.23 inch).

30. If two dowels (5) were removed, install two dowels (5) onto flange assembly (1).

31. Install O-ring seal (9) onto flange assembly (1).

32. Install plug (8) into flange assembly (1).
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    Illustration 23	g00532340

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    Illustration 24	g00532337

33. Use Tooling (A) in order to install lip seal (10) into flange assembly (1). Use Tool (B) (not shown) in order to install retaining ring (11). Use Tooling (A) in order to install lip seal (10) into flange assembly (1).
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    Illustration 25	g00530542

34. Position flange assembly (1) onto body assembly (4). Use eight nuts (3) in order to install flange assembly (1) to body assembly (4). Tighten eight nuts (3) evenly. Tighten each of the nuts by one revolution before proceeding to the next nut. Tighten eight nuts (3) to a torque of 238 ± 13 N·m (175.5 ± 9.6 lb ft).

35. Install O-ring seal (2) onto flange assembly (1).

End By:

1. Install the hoist and rear brake cooling gear pump. Refer to Disassembly and Assembly, "Gear Pump (Hoist and Rear Brake Cooling) - Install".