725C Articulated Truck Power Train Caterpillar

Assembly Procedure

1. Inspect all parts and clean all parts. If any parts are worn or damaged, use new Caterpillar parts for replacement.

2. Pay attention to all location marks on all housings and case assemblies for assembly purposes.
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   Illustration 1	g01430001
   Typical Example

3. Raise the temperature of bearing cone (58). Install bearing cone (58) on pinion shaft (33).

   Note: Reset bearing cone (58) with a suitable driver after the mating parts have reached a uniform temperature.

   Note: Bearing cone (58) may be pressed onto pinion shaft (33). The bearing cone does not need to be heated.

   Note: Bevel gear and pinions are sold in matched sets. The technician should use only matched sets when you are replacing the bevel gear and pinions.

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   Illustration 2	g01430003

4. Shims (56) are located under bearing cup (57). The thickness of the shim pack will not need to be changed if you are not changing the bevel gear and pinion or the carrier assembly. The shims are needed to set up the bevel gear and pinion properly. The initial thickness of the shim pack must be calculated. If you are installing a new bevel gear set into the existing carrier assembly, obtain the "HD" number from the end of the old pinion shaft. Obtain the "HD" number from the end of the new pinion shaft. Subtract the new "HD" from the old "HD". If the answer is negative, remove an equivalent thickness of shims from the existing shim pack. If the answer is positive, add an equivalent thickness of shims to the existing shim pack. If the answer is zero, reuse the existing shim pack.

5. If you are installing an old bevel gear set into a new carrier assembly, obtain the "DC" number from the new carrier assembly. The number (DC) is stamped under the bearing cap. Obtain the "DC" from the old carrier assembly. Subtract the new "DC" number from the old "DC" number. If the answer is negative, remove an equivalent thickness of shims. If the answer is positive, add an equivalent thickness of shims.

6. If you are replacing both the carrier assembly and the bevel gear set, use an initial shim pack of 1.5 mm (0.06 inch).

   Note: You may cool bearing cup (57). Seat the bearing cup with a suitable driver once the mating parts have reached a uniform temperature.

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   Illustration 3	g01431322

7. Lubricate bearing cone (58) with clean oil before you install pinion shaft (33). Install pinion shaft (33) in the differential and bevel gear assembly.

8. Install Tooling (E).

9. Install bearing caps (14). Install bolts (13) and the washers to hold Tooling (E) in place.

10. Tooling (E) has an adjustment screw (34) which should be adjusted to hold pinion shaft (33) in place. Rotate the differential and bevel gear assembly.
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    Illustration 4	g01429859

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    Illustration 5	g01429863

11. Lower the temperature of bearing cups (51) and (54). Install bearing cups (51) and (54) in bearing cage (45) and the differential and bevel gear assembly (2). The bearing cups are a press fit after the temperature of the bearing cups have reached room temperature. Lubricate the bearing cups with clean oil.

    Note: Reset the bearing cups with a suitable driver after the mating parts have reached a uniform temperature.

12. Raise the temperature of bearing cone (50) and (53). Install the bearing cones onto gear (52). Apply Tooling (T) to bearing cone (50) and (53) after installation. Reset the bearing cone with a suitable driver after the mating parts have reached a uniform temperature.

13. Raise the temperature of bearing cone (55) to install bearing cone (55) into bearing cage (45). Install bearing cone (55) in bearing cage (45).

14. Install gear (52) into the differential and bevel gear assembly (2).
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    Illustration 6	g03801643

15. Install spacer (49), gear (48), and retaining ring (47) onto pinion shaft (33).
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    Illustration 7	g01429849

16. Check the seal for the bearing cage. Replace the seal if the seal is damaged. Install bearing cage (45). Install bolts (44) and the washers to secure the bearing cage.
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    Illustration 8	g01429378

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    Illustration 9	g01192550

17. Install notched washer (43), and locknut (40) on pinion shaft (33). The chamfered side of locknut (40) should face toward notched washer (43). Use Tooling (F) to tighten locknut (40) until the play is out of the bearings of pinion shaft (33). Do not make the nut too tight. The pinion bearing preload must be set.

    Note: Do not install retaining ring (41) on locknut (40) at this point.

18. Install a suitable bolt into pinion shaft (33). Use Tooling (N) to tighten the bolt until pinion shaft (33) turns. Record the torque that is required to turn pinion shaft (33). The torque that is required to turn pinion shaft (33) should be 0.67 N to 1.35 N·m (5.93 lb in to 11.95 lb in). Adjust locknut (40) until the proper preload for the bearings is obtained.

    Note: If the rolling torque exceeds the specification, back off locknut (40). Perform Step 18 again. Check the pinion. The pinion should have no end play.

    Note: The torques that are specified are for new bearings. For used bearings, limit the applied torque to one-half of the specified torque in Step 18.

    Note: Rotation of the pinion is critical. Rotate the pinion to seat the bearings.

19. When the correct torque is reached to rotate pinion shaft (34), install locking washer (42) and retaining ring (41). Install locking washer (42) onto locknut (40). Rotate the locking washer (42) until the grooves of locking washer (42) and notched washer (43) are aligned. Use Tooling (S) to install retaining ring (41).

    Note: If the locking washer (42) does not align with notched washer (43), position locking washer (42) on locknut (40). Tighten locknut (40) until the locking washer (42) aligns with notched washer (42). The locknut (40) cannot be tightened more than 1 degree.

    Note: If locknut (39) is loosened to install locking washer (41), the pinion, and the bearing will need to be reseated.

20. Use the following procedure to determine the end play on the differential input gear.
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    Illustration 10	g01430022

    1. Install cage (39), bolts (38), and the washers. By even amounts, tighten bolts (38) to a torque of 23 ± 1 N·m (17 ± 1 lb ft). Rotate gear (52) three times. Tighten bolts (38) again to 23 ± 1 N·m (17 ± 1 lb ft). Rotate the gear three times. Repeat this process until the bolts do not move on subsequent torquing.

    2. Remove bolts (38) with the washers. Install bolts (38) without the washers. By even amounts, tighten the bolts to a torque of 6 ± 1 N·m (53 ± 9 lb in). Rotate the gear three times.

    3. By even amounts, tighten four bolts (38) to a torque of 11.3 ± 0.5 N·m (100 ± 4.5 lb in). Rotate the gear three times. Repeat this process until the bolts do not move on subsequent torquing.

    4. Use a depth micrometer to measure the distance from cage (39) to bearing cage (45) at Points (AA) and (BB). Record the average measurement and call this Measurement (Y). Remove bolts (38) and cage (39).

    5. Use a micrometer to measure the thickness of cage (39) at Point (AA) and (BB). Record the average measurement and call this Measurement (X).

    6. Subtract Dimension (X) from Dimension (Y). Call this Measurement (Z). Measurement (Z) is the average gap.

    7. Add 0.30 mm (0.012 inch) to Measurement (Z). This new dimension is the target for the shim pack thickness. The shim pack thickness will give a cold bearing end play setting of 0.050 mm to 0.125 mm (0.002 inch to 0.005 inch).

    8. Install cage (39), the shims, bolts (38), and the washers.
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    Illustration 11	g01431333

21. Apply clean oil to the outside of seal (37) prior to installation. Install seal (37) in seal retainer (35). Use Tooling (J) for installation. Apply clean oil to the lips of seal (37).
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    Illustration 12	g01431288

22. Inspect the O-ring seal on the seal retainer. Replace the O-ring seal if the O-ring seal is damaged. Install seal retainer (35) with bolts (36) and the washers. Tighten bolts (36) to a torque of 60 ± 12 N·m (45 ± 9 lb ft).
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    Illustration 13	g01431271

23. Install yoke (1) and the brake disc onto the differential and bevel gear assembly (2). The weight of the yoke (1) and the brake disc is approximately 24 kg (53 lb). Install bolt (31) and washer (32) to secure the yoke (1) and brake disc on the differential and bevel gear assembly (2). Tighten bolt (31) to a torque of 900 ± 100 N·m (664 ± 74 lb ft).
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    Illustration 14	g00514952

24. Rotate the differential and bevel gear assembly (2). Remove the bolts and the washers to remove bearing caps (14). Remove Tooling (E).
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    Illustration 15	g01430648

25. Install thrust washer (30) on bevel gear (29). Apply a light coat of Tooling (K) to the thrust surface of the bevel gear before the thrust washer is installed.
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    Illustration 16	g01430646

26. Install bevel gear (29) into case assembly (20).

    Note: Line up the tabs which are on thrust washer (30) with the spaces within case assembly (20).

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    Illustration 17	g01431268

27. Install bearing (28) in gear (27). Repeat for the remaining gears (27) and bearings (28).
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    Illustration 18	g01431267

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    Illustration 19	g01431266

28. Install gears (27) onto spider (25). Install thrust washers (26) onto spider (25). Apply a light coat of Tooling (K) on the thrust surface of the pinion gears. Apply a light coat of Tooling (K) on the bore surface of the pinion gears.

29. Install spider (25), gears (27), and thrust washers (26) as a unit into case assembly (20).
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    Illustration 20	g00514937

30. Install bevel gear (24) into case assembly (20). Install thrust washer (23) onto bevel gear (24). Apply a light coat of Tooling (K) to the thrust surface of the bevel gear before the thrust washer is installed.

    Note: The tabs on thrust washer (23) must line up with the spaces that are provided in hub (22).

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    Illustration 21	g00514935

31. Install hub (22) onto case assembly (20). Rotate the differential assembly by 180 degrees. Install bolts (21) and the washers that secure case assembly (20) to hub (22) of the differential case. Tighten bolts (21) to a torque of 105 ± 20 N·m (77 ± 15 lb ft).
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    Illustration 22	g00518401

32. Raise the temperature of bearing cone (17). Install bearing cone (17) on differential assembly (15). Allow the bearing cone to cool before you rotate the housing.

    Note: Reset the bearing cone with a suitable driver after the mating parts have reached a uniform temperature.

33. Rotate differential assembly (15) by 180 degrees. Follow the procedure that is outlined in Step 32 to install the opposite bearing cone (17).
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    Illustration 23	g00518431

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    Illustration 24	g01440661

34. Perform the following to install bevel gear (19) to differential assembly (15).

    Note: New bolts and new hard washers should be installed to secure bevel gear (19).

    1. Raise the temperature of bevel gear (19) to install the bevel gear to housing (15).

    2. Install bevel gear (19) to differential assembly (15). Immediately install four bolts and hard washers into bevel gear (19). Install the bolts so that the bolts are spaced equally at 90 degrees. Install the hard washers with the flat face against the differential assembly. Tighten the bolts to a torque of 70 N·m (50 lb ft). Ensure that the bevel gear is properly sealed against the differential assembly.

    3. Loosely install the remaining bolts and hard washers for bevel gear (19). Ensure that the flat face of the hard washers is against differential assembly (15).

    4. Allow bevel gear (19) to cool to approximately 30 °C (86 °F). Tooling (P) may be used to check the temperature of the components. After the bevel gear has cooled to the required temperature, loosen the four bolts that were tightened earlier.

       Note: If the four initially tightened bolts are not loosened before the final torquing, the joint will not reach a full press fit.

    5. Tighten bolts (18) for bevel gear (19) in a star pattern. Mark each bolt after the bolt has been tightened. Tighten bolts (18) to a torque of 70 ± 15 N·m (52 ± 11 lb ft). Turn bolts (18) an additional 60° +10° / -0°.
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    Illustration 25	g00511445

35. Attach a suitable lifting device to differential assembly (15). The weight of the differential assembly (15) is approximately 89 kg (196 lb). Lubricate the rollers for the bearings with clean oil. Install bearing cages (16). Lower differential assembly (15) into the differential and bevel gear assembly. Hold bearing cages (16) in place. Lower the differential assembly (15) into position.

    Note: New bearing cups must be installed in bearing cages (16) if new bearing cones (17) have been installed.

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    Illustration 26	g01431347

36. Use four bolts (13) and the washers to install bearing caps (14). Tighten one bolt on each bearing cap to a torque of 70 ± 5 N·m (51 ± 4 lb ft). Tighten the bolts on the opposite side of the bearing cap to a torque of 5 N·m (4 lb ft).

37. The bearing caps have adjusting rings (64). Adjusting rings (64) are used for setting the bearing end play. The adjusting rings are used for setting the backlash of bevel gear. Remove two bolts and lock (63) on each of the adjusting rings.
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    Illustration 27	g01431350

38. Use Tooling (R) to advance adjusting rings (64) until bevel gear backlash is eliminated. Maintain slight bearing end play. Rotate the differential and bevel gear assembly by 90 degrees so that the pinion shaft is in a horizontal position. Install Tooling (N). Measure the torque that is required to rotate the pinion shaft. Record the measured torque.

39. Advance the adjusting ring that is next to the bevel gear. Oscillate the bevel gear. Find a zero backlash position. Then back off the adjusting ring to the nearest lock position. Only back off one lug on the adjusting ring. Notice that there are two lock positions that are available on each adjusting ring (64).

40. Advance the adjusting ring opposite the bevel gear. Monitor the torque that is required to rotate the pinion shaft. Look for a torque increase that is over the torque that is measured in Step 38. Tighten the adjusting ring which is opposite the bevel gear. Tighten the adjusting ring until the lock can be installed. Do not install lock (63) until you have finished all adjustments.

    Note: Rotation of the bevel gear is critical to get the proper seating of all components.

41. Measure the rolling torque at the pinion shaft to verify the correct preload. The rolling torque should be 1.2 N to 2.5 N·m (10.6 lb in to 22.0 lb in). This reading is above the reading that is found in Step 18.
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    Illustration 28	g01431360

42. Install Tooling (Q). Measure the backlash of bevel gear (19). The backlash should be 0.30 ± 0.10 mm (0.012 ± 0.004 inch). Assume that the measurement does not meet the specification. Retract one adjusting ring. Advance the other adjusting. Maintain bearing preload.

43. Remeasure the rolling torque at the pinion shaft to verify the correct preload after setting the backlash. The rolling torque should be 1.2 N to 2.5 N·m (10.6 lb in to 22.0 lb in). This reading is above the reading that is found in Step 18.
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    Illustration 29	g00521367
    Illustration A

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    Illustration 30	g00521369
    Illustration B

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    Illustration 31	g00521370
    Illustration C

44. The tooth contact between the bevel pinion and gear must be checked. Coat some of the bevel gear teeth with a rouge compound. Turn the bevel pinion shaft in both directions. The correct area of tooth contact starts near the inside of the teeth of the bevel gear. See Illustration (A). If the tooth contact looks like Illustration (B), some shims will need to be removed. Recheck the tooth contact. If the tooth contact looks like Illustration (C), some shims will need to be added. Recheck the tooth contact. If the shim pack has been changed, the backlash will need to be rechecked. See Step 40.

    Note: If the shim pack needs to be adjusted, refer to Step 4.

45. Install lock (63) and the bolts. Apply Tooling (L) to the bolts of lock (63) before installation. Refer to Step 40.

46. After the proper backlash has been obtained, tighten the bearing cap bolts to a torque of 530 ± 70 N·m (390 ± 52 lb ft).
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    Illustration 32	g00511386

47. Rotate the differential and bevel gear assembly by 90 degrees. Position plate (11) and install four screws (12).
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    Illustration 33	g00511378

48. Install bearing (10). Lubricate the bearing assembly with clean oil.
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    Illustration 34	g00511131

    Note: Install the plate and the screws onto hub (9) prior to installation of hub (9).

49. Install hub (9).

    Note: Three coil springs are loosely attached to hub (9). The coil springs do not need to be removed. The coil springs should be inspected for damage. Replace all three of the coil springs if any of the springs are damaged.

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    Illustration 35	g00511109

50. Install gear (8).
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    Illustration 36	g00511092

51. Install discs and plates (7) onto the differential lock. Maintain the order of the disc and the plates.

    Note: Lubricate both sides of the discs and plates with the lubricant that is being sealed.

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    Illustration 37	g00511036

52. Install clutch plate (6).
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    Illustration 38	g00511032

53. Lubricate bearing (5) with lubricant being sealed. Install bearing (5).
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    Illustration 39	g01429868

54. Lubricate the O-ring seals for the piston with Tooling (M) before you install the O-ring seals. Install O-ring seal (61) onto piston (60). Install O-ring seal (62) onto piston (60).
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    Illustration 40	g01430036

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    Illustration 41	g01429867

55. Lubricate the piston (60) and the housing (4) with clean oil before you install piston (60). Install piston (60) into housing (4).

56. Install bolts (59), the washers, and the spacers which hold piston (60) in housing (4).
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    Illustration 42	g00511027

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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.

57. Install housing (4). Install bolts (3) that hold the housing in place. Tighten bolts (3) to a torque of 105 ± 20 N·m (77 ± 15 lb ft).
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    Illustration 43	g01196303

58. Install Tooling (C) and a suitable lifting device onto yoke (1).

59. Carefully remove the differential and bevel gear assembly (2) from Tooling (A). The weight of differential and bevel gear assembly (2) is approximately 385 kg (850 lb).

End By:

1. Install the center differential assembly.