966M XE and 972M XE Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Caterpillar

Illustration 1	g03693008
Differential and Bevel Gear (1) Bearing sleeve (2) Bearing cup (3) Bearing cone (4) Adjusting nut (5) Bolt (6) Bevel pinion (7) Bearing cone (8) Bearing cup (9) Housing (10) Bearing cup (11) Bearing cone (12) Washer (13) Nut (14) Intermediate housing (15) Differential group (16) Bevel gear (17) Bolt (18) Bearing sleeve (19) Bolt (20) Adjusting nut (21) Differential case (22) Bearing cone (23) Bearing cup (24) Pins (25) Pin (26) Pin (27) Center housing (28) Shims (A) Bolt circle radius

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

1. Assemble differential group (15).

2. Heat bevel gear (16) to 135°C (275°F) for a maximum of 4 hours. Install the bevel gear on the differential group.

3. Install four large pins (25) partially into bevel gear (16). Install four small pins (26) into large pins (25). Make sure that the serrations of the small pins are 180 degrees from the serrations of the large pins. Press pins (25) and (26) so that the pins are flush with the surface of bevel gear (16). Torque the 20 9X-6494 Bolts (17) to 285 ± 40 N·m (210 ± 30 lb ft) and then turn the bolts for an additional 120 ± 5° turn. Make sure that the bevel gear is seated on the differential group shoulder.

   Note: Bolts (17) cannot be substituted with other bolts. If bolts (17) are replaced, new 9X-6494 Bolts must be installed.

4. Press bearing cone (3) and bearing cone (22) on differential case (21). Make sure that the bearing cones are fully seated.

   Note: If you freeze the bearing cups, allow the parts to reach a uniform temperature. Then use a driver or a press to reset the bearing cups. The limit for freezing the bearing cups is −29°C (−20°F). Remove any frost and wipe the bearing cups dry. Lubricate the bearing cups with SAE 30W gear oil in order to prevent rust on the bearing cups.

   Note: If you heat the bearing cones, allow the parts to reach a uniform temperature. Then use a driver or a press to reset the bearing cones. The limit for heating the bearing cones is a maximum of 135°C (275°F) for a maximum of 4 hours. Lubricate the bearing cones with SAE 30W gear oil after the bearing cones have cooled in order to prevent rust on the bearing cones.

5. Remove intermediate housing (14) from center housing (27).

6. Install bearing cups (2) and (23), bearing sleeves (1) and (18), and two pins (24). Lubricate the threads of adjusting nuts (4) and (20) and install the nuts in intermediate housing (14) and in center housing (27).

7. Position center housing (27) in an appropriate supporting fixture so that the open side faces upward. With a lifting device, lower differential group (15) and bevel gear into position on three dowels in center housing (27).

8. Install intermediate housing (14) on center housing (27). Apply 1U-8846 Liquid Gasket to the contacting surfaces prior to assembly. Torque the three bolts to 100 ± 20 N·m (75 ± 15 lb ft).

9. Lubricate the O-ring seal and install the O-ring seal on pinion housing (9). Install pinion housing (9) on center housing (27). To install the front differential, torque the ten bolts to 300 ± 40 N·m (220 ± 30 lb ft). To install the rear differential, torque the 12 bolts to 300 ± 40 N·m (220 ± 30 lb ft). Use the original thickness of shims (28) or use a new shim pack that is measured to the same thickness as the original pack. If the original shim pack is not available, use 70% of a new shim pack.

   Note: The needed thickness of the shim pack may change when the tooth contact pattern is adjusted.

10. Tighten adjusting nuts (4) and (20) to a position that maintains gear backlash and slight bearing end play. This position should not maintain tight gear mesh.

11. Reposition center housing (27) in the supporting fixture so that center housing (27) and pinion housing (9) are horizontal. The parts are horizontal when the parts are mounted in the machine.
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    Table 1

    Required Tools
    Part Number	Description	Quantity
    1U-6690	Socket Wrench Assembly	1

12. Measure the torque that is needed to rotate pinion shaft (6). Record this torque. For this measurement, use a 1U-6690 Socket Wrench Assembly on pinion shaft nut (13).

13. While you rotate pinion shaft (6) back and forth, tighten adjusting nut (20) to the zero backlash position. Then back off adjusting nut (20) by a value of 20° plus the increment to the nearest lock position.

14. Tighten adjusting nut (4) on the bevel gear group while you are rotating the pinion shaft. Tighten nut (4) until the overall preload rolling torque that is measured at the pinion shaft is 4.5 N·m to 6.8 N·m (40 lb in to 60 lb in).

    Note: When you check for correct assembly and for correct adjustment, measure the rolling torque of the bevel gear group at the shaft of the pinion. For new bearings, the rolling torque should be 4.5 to 6.8 N·m (40 to 60 lb in). For used bearings, the rolling torque should be 2.25 to 3.4 N·m (20 to 30 lb in).

15. Measure the backlash between bevel gear (16) and pinion shaft (6). Measure the backlash at the heel of the bevel gear. The backlash must be 0.30 + 0.12 − 0.10 mm (0.012 + 0.005 − 0.004 inch). To measure the backlash, place a dial indicator tangent to the spline. Refer to Illustration 2 for an example. Make sure that the yoke or the spline adapter is tight to the spline.
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    Illustration 2	g00275111
    Pinion Shaft Spline (backlash measurement) (B) Distance of dial indicator from the centerline of the pinion.

16. Table 2 that follows lists examples of backlash at the pinion shaft. Table 2 shows the different distances from the centerline of the pinion to the dial indicator.
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    Table 2

    Examples of Backlash at Pinion Shaft
    Dimension (B)	Nominal Backlash	Maximum Backlash	Minimum Backlash
    50 mm (2 inch)	0.28 mm (.011 inch)	0.40 mm (.016 inch)	0.18 mm (.007 inch)
    100 mm (4 inch)	0.57 mm (.022 inch)	0.80 mm (.032 inch)	0.35 mm (.014 inch)
    150 mm (6 inch)	0.86 mm (.034 inch)	1.20 mm (.047 inch)	0.53 mm (.021 inch)
    200 mm (8 inch)	1.15 mm (.045 inch)	1.60 mm (.063 inch)	0.70 mm (.028 inch)

17. If the backlash does not meet specifications, loosen one adjusting nut and tighten the opposite adjusting nut by the same amount. This procedure will maintain the bearing preload.

Pinion and Bevel Gear Tooth Contact Check

Illustration 3	g00103470

1. After the differential backlash adjustments and pinion preload adjustments have been made, tooth contact between pinion shaft (6) and bevel gear (16) must be checked. Perform the procedure that follows:

   1. Apply small amount of Prussian blue, of red lead, or of paint on three adjacent teeth or on four adjacent teeth of bevel gear (16).

   2. Rotate pinion shaft (6) for several revolutions in one direction. Then rotate pinion shaft (6) for several revolutions in the opposite direction. Then turn the pinion shaft in one direction until the marked teeth can be viewed.

   3. The correct area of tooth contact begins near the inside end of the teeth of bevel gear (16). The correct area reaches a maximum of 50 percent of the tooth length. See Illustration 3 for an example of the correct area of tooth contact.
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   Illustration 4	g00103471

2. If the tooth contact looks like the marks in Illustration 4, perform the procedure that follows:

   1. Remove some of shims (28).

   2. From Testing and Adjusting, "Differential Backlash and Bearing - Adjust", perform Step 15, Step 16, and Step 17 again.

   3. Perform Step 1 of "Pinion and Bevel Gear Tooth Contact Check" again.
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   Illustration 5	g00103472

3. If the tooth contact looks like the marks in Illustration 5, perform the procedure that follows:

   1. Add some of shims (28).

   2. From Testing and Adjusting, "Differential Backlash and Bearing - Adjust", perform Step 15, Step 16, and Step 17 again.

   3. Perform Step 1 of "Pinion and Bevel Gear Tooth Contact Check" again.

   Note: Always make sure that the backlash adjustment is correct before an adjustment is made to the area of tooth contact. To get the correct adjustments, the backlash and tooth contact may need adjusted several times. Always remember that a change to gear clearance (backlash) will also change the gear contact. A change in gear contact will also change gear clearance (backlash).

4. After adjustments are made, remove the Prussian blue, red lead or paint from the gears.

5. Install one bolt and lock (5) and (19) in each adjusting nut (4) and (20). Tighten both bolts and bend the locks.