615C Wheel Tractor-Scraper Wheel Tractor-Scraper Power Train Caterpillar

Illustration 1	g00886112
Differential and Bevel Gear (1) Cap (2) Adjustment ring (3) Bolts (4) Carrier (5) Shim pack (6) Bolts (7) Bearing cup (8) Pinion housing (9) Bevel pinion (10) Bearing cup (11) Washer (12) Nut (13) Bearing cone (14) Bearing cone (15) Adjustment ring (16) Differential lock assembly (17) Cap (18) Bevel gear (19) Bolts

Note: Differential lock assembly (16) must be removed before the differential and bevel gear is adjusted.

Preload Adjustment for Pinion

1. Install bearing cups (7) and (10) in pinion housing (8). Bearing cups (7) and (10) must be against the shoulders in pinion housing (8) .

2. Install bearing cone (14) next to the pinion teeth on bevel pinion (9). Bearing cone (14) must be against the shoulder on bevel pinion (9) .

3. Lubricate the bearing and install bevel pinion (9) in pinion housing (8). Lubricate bearing cone (13) and install bearing cone (13) .

4. Position the assembly in a soft jawed vise. Tighten the vise against the teeth on bevel pinion (9). Install washer (11) and nut (12). While you are turning pinion housing (8), tighten nut (12). Tighten nut (12) until the specified torque that is needed to turn bevel pinion (9) is reached.

   New bearings ... 1 ± 0.5 N·m (9 ± 3.5 lb in)

   Used bearings ... 0.5 ± 0.3 N·m (4.5 ± 2.2 lb in)

   Check bevel pinion (9) in order to ensure that there is zero end play.

5. If the bearing preload exceeds the specified torque, loosen nut (12) by 1/8 of a turn. Reseat bearing cone (13) .

   Repeat Step 4.

6. When the torque that is needed to turn bevel pinion (9) is correct, stake nut (12). Stake nut (12) by peening the collar on the nut (12) into the key slot in bevel pinion (9). Refer to Illustration (2) for the correct tooling and the correct dimensions.

Illustration 2	g00610384
(A) 8.0 ± .50 mm (0.32 ± 0.02 inch) (B) Spherical radius (C) 10° to 30° (D) 4.7 mm (0.19 inch) (E) 2.5 mm (0.10 inch)

Note: The nut may be reused if the collar is not cracked during removal or restaking.

Differential Backlash and Bearing Adjustment

Note: The following procedure controls backlash and bearing preload. This procedure gives the same results for used bearings and for new bearings.

1. Fasten pinion housing (8) to carrier (4). If the original gears, the carrier assembly and the housing are used again, use the original thickness of shim pack (5). If any of these parts are replaced, install a shim pack thickness of 80% of a new full shim pack.

   Note: When you adjust the tooth contact pattern, make sure that there is a change in the thickness of shim pack (5) .

2. Tighten eight bolts (6) to a torque of 270 ± 25 N·m (199 ± 18 lb ft).

3. When pinion housing (8) is fastened to carrier (4), position bevel pinion (9) in a downward vertical position.

4. Lubricate bearings and install bearing cups on the differential bearings in order to protect the bearings.

5. With a lifting device, lower the differential into carrier (4) with bevel gear (18) on the side that is opposite the pin hole.

6. Install caps (1) and (17) and adjustment rings (2) and (15). Adjustment rings (2) and (15) must turn freely.

7. Tighten one bolt (19) on caps (1) and (17) to a torque of 70 N·m (52 lb ft). Tighten the other bolt (19) on caps (1) and (17) to a torque of 5 N·m (44 lb in).

8. Tighten adjustment rings (2) and (15) until there is a small amount of backlash and zero preload on differential bearings.

9. Reposition the assembly so that bevel pinion (9) is in the horizontal position. Measure the torque that is required to rotate bevel pinion (9). Record this measurement.

10. While you turn the bevel gear, tighten adjustment ring (15) until the pinion backlash is zero.

11. Loosen adjustment ring (15) to the nearest lock position.

12. Tighten adjustment ring (2) until the torque that is required to rotate bevel pinion (9) increases 20% over the torque reading in Step 9.

13. Put a mark on cap (1). Put a mark on adjustment ring (2) that is three lugs from the first mark. Tighten adjustment ring (2) until the second mark is in alignment with the first mark.

14. If the lock can not be installed, tighten adjustment ring (2) until the lock can be installed.

15. Measure the backlash between the bevel gear (18) and bevel pinion (9). The backlash must be 0.36 ± 0.12 mm (0.014 ± 0.005 inch).

16. If there is too much backlash, loosen adjustment ring (2) and tighten adjustment ring (15) to the same amount.

17. If there is not enough backlash, loosen adjustment ring (15) and tighten adjustment ring (2) to the same amount.

    Note: The differential preload will be kept only if one adjustment ring is loosened and the other adjustment ring is tightened to the same amount.

18. Tighten bolts (19) in caps (1) and (17) to a torque of 475 ± 50 N·m (350 ± 37 lb ft).

Checking the Pinion and Ring Gear Tooth Contact

Illustration 3	g00578231

After the backlash and preload adjustments have been made, the tooth contact between bevel pinion (9) and bevel gear (18) must be checked. Do the following procedure.

1. Put a small amount of paint pigment and oil on the teeth of bevel gear (18) .

2. Turn bevel pinion (9) in both directions.

3. The correct area of tooth contact is located equally on both sides. The area starts near the inside end of the teeth of bevel gear (18). Refer to Illustration (3) for an example of the correct area of tooth contact.

Illustration 4	g00578253

If the marks that are made on the teeth of bevel gear (18) look like the marks in Illustration (4), do the following procedures.

1. Add some of shim pack (5) .

2. Loosen bolts (19) to the torque that is indicated in Step 7.

3. Repeat Steps 15 through 18.

Illustration 5	g00578254

If the marks that are made on the teeth of bevel gear (18) look like the marks in Illustration (5), do the following procedures.

1. Remove some of shim pack (5) .

2. Loosen bolts (19) to the torque that is indicated in Step 7.

3. Repeat Steps 15 through 18.

   Note: Always make sure that the backlash adjustment is correct before an adjustment is made to the area of tooth contact. Several adjustments to the backlash and tooth contact may be necessary to get the correct adjustments.

After adjustments are made, remove the paint from the gears. Install the locks and bolts on caps (1) and (17).