BAR 9U3837 - Caterpillar

Illustration 2 g00275111
Pinion shaft spline (backlash measurement) (B) Distance of dial indicator from the centerline of the pinion.
Table 3 that follows lists examples of backlash at the pinion shaft. Table 3 shows the different distances from the centerline of the pinion to the dial indicator.
Table 3
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)    
If backlash does not meet specifications, loosen one adjusting nut and tighten the opposite adjusting nut by the same amount to maintain the bearing preload.Pinion and Bevel Gear Tooth Contact Check
Illustration 3 g00103470
After differential backlash adjustments and pinion preload adjustments have been made, the tooth contact between pinion shaft (6) and bevel gear (16) must be checked. Perform the procedure that follows:
Apply a small amount of Prussian blue, red lead, or paint on three adjacent teeth or on four adjacent teeth of bevel gear (16) .
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.
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.
Illustration 4 g00103471
If, the tooth contact looks like the marks in Illustration 4 perform the procedure that follows:
Remove some of shims (28) .
From Specification, "Differential Backlash and Bearing Adjustment", perform Step 16, Step 17, and Step 18 again.
Perform Step 1 of "Pinion and Bevel Gear Tooth Contact Check" again.
Illustration 5 g00103472
If the tooth contact looks like the marks in Illustration 5, perform the procedure that follows:
Add some of shims (28) .
From Specification, "Differential Backlash and Bearing Adjustment", perform Step 16, Step 17, and Step 18 again.
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 require adjustment 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).
After adjustments are made, remove the Prussian blue, red lead or paint from the gears.
Install one bolt and lock (5) and (19) in each adjusting nut (4) and (20). Tighten both bolts and bend the locks.