Usage:
Start By:
a. remove main hydraulic pump and pump drive coupling
Fluid Spillage Containment
Care must be taken to ensure that the fluids are contained during performance of the inspection, the maintenance, the testing, the adjusting and the repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to the "Tools And Shop Products Guide, NENG2500" the tools and the supplies suitable to collect and contain any of the fluids in Caterpillar machines. Dispose of the fluids according to local regulations and mandates.
| NOTICE |
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During the disassembly of the main hydraulic pump, mark all of the components so they can be reinstalled in their original locations. Mixing the components will shorten the service life of the pump. |
1. Thoroughly clean the outside of the main hydraulic pump prior to disassembly.
2. Remove drain plug (1) and drain the oil from the main hydraulic pump in a suitable container for disposal.
3. Fasten the main hydraulic pump to Tooling (A) as shown.
4. Remove the four socket head bolts that hold plate (2) in position. Remove plate (2) and the O-ring seal from the main pump housing.
5. Remove 12 socket head bolts (3) that hold the head group in position.
6. Fasten Tooling (B) and a hoist to head group (4) as shown. Remove the head group from the main hydraulic pump. The weight of the head group is 43 kg (95 lb).
7. Remove two dowels (5) from the main pump housing.
8. Remove port plate (6) from each of the pump rotating groups.
9. Remove eight socket head bolts (7) that hold pump control head groups (8) in position. Remove the pump control head groups from the housing.
10. Disassemble both pump control head groups.
a. Remove O-ring seals (17) and (18) from housing (11).
b. Remove piston (14), bushing (13) and piston (12) from housing (11).
c. Remove cover (9), seats (16) and spring (10) from housing (11).
d. Remove O-ring seal (15) from cover (9).
11. Remove pins (21), spools (20) and springs (19) from the housing.
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There are two compressed springs behind housing assembly (23). When six socket head bolts (22) are removed, the spring force will be released. To prevent possible personal injury, slowly and evenly loosen the socket head bolts while retaining the housing assembly. |
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12. While retaining housing assembly (23), slowly and evenly loosen six socket head bolts (22) to release the spring force.
13. Remove housing assembly (23) from the head.
14. Disassemble housing assembly (23).
a. Remove six O-ring seals (28) and two O-ring seals (29) from housing assembly (23).
b. Remove two springs (24), two springs (25) and two spacers (26) from the housing assembly.
c. Remove two sheets (27) from the housing assembly.
15. Remove three plugs (30) from the housing assembly.
16. Remove O-ring seal (31) from each plug (30).
17. Remove three bushings (32), the three valves and the three seats from the housing assembly.
18. Remove two guides (35), two springs (34) and two spacers (33).
19. Turn the head around. Remove eight socket head bolts (36) and two cover groups (37) from the head.
20. Remove O-ring seals (39) and from each cover (38).
21. Remove two bolts (42), and two pistons (41) from the head. Remove ring (40) from each piston.
22. Using the appropriate size Allen wrench, loosen socket head screw (43) in each large piston in the head. The socket head screws Do Not have to be completely removed.
23. Mark the positions of rods (44) prior to removing them from the large pistons in the head. The rods can only fit the piston one way because of the locking setscrews.
24. Remove rods (44) from the large pistons. This will permit the removal of the pistons from the head.
25. Remove pistons (45) from the head.
26. Remove guides (46) from the head.
27. Remove O-ring seals (47) and (49), packing (48) and back-up ring (50) from each guide (46).
28. Remove cylinder (51) from each rotating group.
29. Remove spacer (52), and four bevel spring washers (53) from the center bore of each cylinder (51).
30. Remove 14 socket head screws (54) from each retaining plate (55).
31. Remove centering pin (56) and retaining plate (55) for each rotating group.
32. Remove seven pistons (57) for each rotating group.
33. Remove two rings (58) from each piston (57).
34. Remove the main pump housing from Tooling (A) and turn it over. Refasten the main pump housing to Tooling (A).
35. Remove four bolts (59) and pilot pump (60) from the main pump housing.
36. Remove two O-ring seals (61) from the pilot pump housing.
37. Thoroughly clean the outside of pilot pump (60).
38. Remove bearing (62) from the main pump housing. The bearing is a slip fit.
39. Use Tool (C) to remove retaining ring (63). Remove cover (64).
40. Remove lip seal (65) from cover (64).
41. Remove O-ring seal (66) from the main pump housing.
42. Install suitable size bolt (67) in the end of pump rotating group (68). Hit the end of the upper pump rotating group with a hammer to remove it from the main pump housing.
43. Remove plug (69) from the main pump housing. Install a suitable size bolt in threaded hole for plug (69). Tighten the bolt to remove the lower pump rotating group from the main pump housing.
44. Disassemble the upper pump rotating group.
a. Remove spanner nut (70).
b. Remove bearing (71), shims (72), bearing (73), spacer (74) and bearing (75) from the shaft.
45. Disassemble the lower pump rotating group.
a. Remove spanner nut (76).
b. Remove bearing (77), shims (78), bearing (79), spacer (80) and bearing (81) from the shaft/gear.
46. Fasten Tool (D) to the shaft in the main pump housing using a suitable size bolt and washer. Use Tool (D) to remove shaft (82) (not shown) from the main pump housing.
47. Remove gear (83) from the main pump housing. Sliding the gear to the center of the housing, and remove it out the top.
48. Remove race (84) and bearing (85) from the main pump housing. The race and bearing are slip fits.
NOTE: The following steps are for the assembly of the main hydraulic pump.
49. Make sure all the components of the main hydraulic pump are thoroughly clean and free of dirt and debris. Check the condition of all of the components. If any of the components are worn or damaged, use new parts for replacement. Put clean hydraulic oil on all of the parts during assembly.
50. Install bearing (85) in its original position in the main pump housing. The bearing is a slip fit. Install race (84) in bearing (85).
51. Heat gear (83) to a maximum temperature of 85 °C (185 °F). Lower the temperature of shaft (82) to -40 °C (-40 °F). Place the preheated gear in the main pump housing, above the bearing. Install the cooled shaft, with the attached race, through the gear and into the lower bearing. Note that the shaft has a woodruff key and the gear has a corresponding slot. Install the upper bearing on the shaft. It is a slip fit.
NOTE: Prior to assembling the remainder of the main hydraulic pump, the Main Pump Rotating Group Adjustment, Displacement Angle Adjustment, Bearing Preload Adjustment and Lift-Off Limitation Adjustment must be performed. Use the procedures which follows.
Main Pump Rotating Group Adjustment
Cross Section Of Pump Rotating Group
NOTE: Each of the two pump rotating groups are divided into two groups. The mechanical drive group consists of shaft/gear (68) and bearing assemblies (71), (73) and (75).
8T-7773 Measuring Kit (Partial Consist)
Cross Section Of Pump Rotating Group
NOTE: Preload (K) between spacer (52) and centering pin (56), in combination with bevel spring washers (53), maintain the correct limit of separation between cylinder (51) and port plate (6) (lift-off limitation). This limits leakage during heavy, transient loading of the pump. When servicing the hydraulic group, there are two critical dimensions. Dimension (I) is determined by one of several sizes of spacer (52). Dimension (J) is determined by one thickness of shim.
Displacement Angle & Bearing Preload
52. Place 8T-7774 Support (86) on a surface plate. Position gauge blocks (92) from Tooling (E) on the support to obtain dimension (I) of 76.00 mm (2.992 in). Position Tooling (F) over the gauge blocks, and zero the indicator.
53. Place bearing (75), spacer (74), bearing (73) and shim (72) on 8T-7774 Support (86). Slide the bearing assembly under Tooling (F). Add shims (72) to obtain the correct dimension (J). Dimension (J) must be 0.00 and -0.05 mm (.000 and -.002 in).
Thickness of shims (72):
- 9T-3376 - 2.70 mm (.106 in).
- 9T-3377 - 2.80 mm (.110 in).
- 9T-3378 - 2.90 mm (.114 in).
- 9T-3379 - 3.00 mm (.118 in).
- 8T-3380 - 3.10 mm (.122 in).
- 9T-3377 - 2.80 mm (.110 in).
Stub Shaft Group
NOTE: The following procedure for the bearing preload applies only to new bearings with manufacturer's lubricant.
Locally fabricated tools.
NOTE: Rotating group holding tool (97) and bearing support (96) will be required when setting the bearing preload of the rotating group. These tools must be fabricated.
To fabricate rotating group holding tool (97), use a 13 mm (.5 in) thick steel plate that is approximately 19 mm (.75 in) wider than the outside diameter of retaining plate (55). Using retaining plate (55) as a template, transfer the outer bolt circle of the retaining plate to the steel plate, and drill the holes. Drill an additional hole in the center of the steel plate, and install a bolt through the center hole. Secure the bolt with a nut. This bolt will be used to rotate the rotating group during the bearing preload adjustment. Attach rotating group holding tool (97) to the bottom of the shaft/gear with the appropriate size bolts.
To fabricate bearing support (96), cut a 90 degree vee approximately 150 mm (5.9 in) wide [dimension (H)] in a block of wood. This wood block will be used to hold the rotating group while the drive shaft is rotated.
54. Install bearing (79), spacer (80) and bearing (81) with shims (78) determined in Step 53 on shaft (95). Install bearing assembly (77). Apply 9S-3263 Thread Lock on the threads of spanner nut (76). Place the rotating group holding tool (97) in a vise. Use Tool (H) to tighten spanner nut (76).
Lift-Off Limitation Adjustment
(Cylinder Barrel To Port Plate Maximum Separation)
Setup Of Dial Indicator Group [Tooling (F)]
55. Position 8T-7774 Support (86) on a surface plate. Position gauge blocks (94) from Tooling (E) on the support to obtain dimension (I) of 127 mm (5.0 in). Position Tooling (F) over Tooling (E), and zero the indicator.
Installing Spacer
56. Using a piece of wire (98), guide spacer (52) (minimum thickness) into center pin cylinder (99) of cylinder (51). Place spacer (88) and centering pin (56) in the cylinder. Position 8T-7775 Cylinder (87) over the 8T-7774 Support (86), and lay the cylinder on its side. Carefully install the centering pin cylinder and the cylinder into the pump cylinder, and return the unit to a vertical position. Align port plate (6) over cylinder (51). Install 8T-7777 Plate (90). Position 8T-7776 Centering Pin (89), with the two lifting bolts, over 8T-7777 Plate (90).
Positioning Of Cylinder Assembly In Cylinder
Measurement For Spacer Thickness
57. Slide the above assembly under Tooling (F). The dial indicator must read between +0.05 to -0.10 mm (+.002 to -.004 in). There are several different sizes of spacers (52) to choose from to obtain the correct lift-off limitation. There is a minimum spacer size. Each succeeding size of spacer is 0.10 mm (.004 in) thicker. Depending on the dial indicator reading, the correct size spacer can be selected. For example, the dial indicator has a reading of -0.50 mm (-.020 in). To obtain the 127 +0.05 -0.10 mm (5.0 +.002 -.004 in) dimension, remove the spacer with the minimum thickness. Replace it with a spacer which is 0.40 mm (.016 in) thicker than the minimum. The tolerance should now be -0.10 mm (-.004 in).
Measurement For Spacer Thickness
Installation Of Bevel Spring Washers
58. Once the correct size spacer has been determined, the 8T-7777 Plate and 8T-9302 Spacer can be removed. The four bevel spring washers (53) can be installed using wire (98) as a guide.
59. Assemble both of the pump rotating groups for the main hydraulic pump as follows:
a. Heat bearing (81), spacer (80) and bearing (79) to a maximum temperature of 100 °C (212 °F). Install the bearings and the spacer on the shaft as shown.
b. Install shims (78) making sure the distance between the top of the shim pack to the bottom of the lower bearing [dimension (X)] is 76 + 0 - 0.05 mm (2.99 + 0 -.002 in).
c. Heat bearing (77) to a maximum temperature of 100 °C (212 °F). Install the bearing on the shaft as shown.
d. Apply 9S-3263 Thread Lock on the threads of the shaft of the pump rotating group. Install spanner nut (76). For the correct bearing preload, turn the pump rotating group while tightening spanner nut (76). The shaft running torque must be 1 to 2 N*m (1 to 1.4 lb ft).
60. Lower the temperature of the upper and lower pump rotating groups to a temperature of -40 °C (-40 °F). Install the upper and the lower rotating pump groups in their original locations in the main pump housing. Make sure the timing marks on each of the pump rotating groups are in alignment with each other as shown.
61. Install O-ring seal (66) in the main pump housing.
62. Install lip seal (65) in cover (64). Install the seal with the lip so it will be facing toward the inside of the main pump housing and until it makes contact with the counterbore in the cover.
63. Install cover (64) in its original position in the main pump housing.
64. Use Tool (C) to install retaining ring (63) to hold cover (64) in position in the pump housing.
65. Install two O-ring seals (61) on pilot pump (60).
66. Put pilot pump (60) in position in the main pump housing. Install four bolts (59) that hold the pilot pump in position.
67. Turn the main pump housing over.
68. Install two rings (58) on each piston (57).
69. Install 14 pistons (57) in their original locations in the pump rotating groups.
70. Install retaining plates (55) and centering pins (56) in their original positions over pistons (57). Make sure the screw holes in the retaining plates are in alignment with the screw holes in the pump rotating groups.
71. Apply 9S-3263 Thread Lock on the threads of 14 socket head screws (54). Install the 14 socket head screws to hold retaining plates (55) to the pump rotating groups. Tighten the socket head screws evenly.
| NOTICE |
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Bevel spring washers (53) are not flat. These washers should be installed so they provide the maximum amount of height. |
72. Install spacer (52) and four bevel spring washers (53) in each cylinder (51). Install the bevel spring washers so they provide the maximum amount of height.
73. Install two cylinders (51) in their original locations on the pump rotating groups.
74. Reinstall two dowels (5) in the main pump housing as shown.
75. Reinstall two port plates (6) in their original positions on cylinders (51).
76. Assemble both of the pump control head groups. Install back-up ring (50), packing (48) and O-ring seals (47) and (49) on each guide (46).
77. Install guides (46) in the head.
78. Install pistons (45) in the head.
79. Reinstall rods (44) in the large pistons in the head. Install the rods in their original positions. The rods will fit only one way.
80. Tighten socket head screw (43) in each large piston in the head.
81. Install a ring (40) on each piston (41). Install piston (41) and bolt (42) in each large piston.
82. Install O-ring seal (39) on each cover (38).
83. Put two cover groups (37) in position on the head. Install eight socket head bolts (36) that hold the cover groups in position.
84. Install two spacers (33), two springs (34) and two guides (35) in the head.
85. Install the three seats, three valves and three bushings (32) in the housing assembly.
86. Install an O-ring seal (31) on each plug (30). Install three plugs (30) in the housing assembly.
87. Assemble housing assembly (23).
a. Install two sheets (27) in housing assembly (23).
b. Install two spacers (26), two springs (25), and two springs (24) in the housing assembly.
c. Install two O-ring seals (29) and six O-ring seals (28) in housing assembly (23).
88. Put housing assembly (23) in position on the head. Slowly and evenly tighten six socket head bolts (22) to compress the springs in the housing assembly.
89. Install two springs (19), two spools (20) and two pins (21) in the housing assembly.
90. Assemble both of the pump control head groups.
a. Install O-ring seal (15) on cover (9).
b. Install spring (10), seats (16) and cover (9) in housing (11).
c. Install piston (12), bushing (13) and piston (14) in housing (11).
d. Install O-ring seals (17) and (18) in housing (11).
91. Put both pump control head groups (8) in position on the housing. Install eight socket head bolts (7) that hold the pump control head groups in position.
92. Fasten Tooling (B) and a hoist to head group (4) as shown. Put the head group in position on the main hydraulic pump.
93. Install 12 socket head bolts (3) that hold the head group to the main hydraulic pump.
94. Install the O-ring seal and plate (2) on the main pump housing. Install the four socket head bolts that hold the plate in position.
95. Make sure drain plug (1) is tight.
End By:
a. install main hydraulic pump and pump drive coupling