Figure 8-5. Checking backlash of bevel gears.

TM 9-2520-249-34&P

preload are properly adjusted, install shim pack Z (fig. 8-

pattern and compare it with the patterns shown in

2) (determined in para 8-5, above) and the bevel drive

gear assembly into the bevel gear housing. Tighten the

and Z (fig. 8-2), as required, to establish the proper

bolts which retain the assembly, Check the free rotation

pattern. Recheck the backlash. Figure 8-7 illustrates

of the bevel gears (para 8-11, step 8, below).

the proper gear tooth contact pattern under full load.

b. Check the backlash between the drive and

driven gear teeth by locking the drive gear with holder

assembly (15, table 3-1) (fig. 8-5). Install a dial indicator

against a tooth of the driven gear. Rock the driven gear

in both directions and note the backlash. It should be as

indicated by the etched dimension (BL) on the gear set.

NOTE

Backlash may be adjusted by changing shim

pack Z, or by moving shims from shim pack X

to shim pack Y or vice versa. However, any

change in shimming will affect the gear tooth

contact pattern and must be coordinated with

adjustments outlined in c, below.

Figure 8-6. Gear tooth contact pattern-no load.

Figure 8-5. Checking backlash of bevel gears.

c. Remove holder assembly (15, table 3-1) (fig. 8-

5). Coat several teeth of the bevel drive gear with a

Figure 8-7. Gear tooth contact pattern-full load.

fairly dry mixture of red lead and oil. Using wrench

assembly (30, table 3-1) (para 8-11, step 8, below), and

8-9.

Determining Nominal Shim Between Brake

a socket wrench drive, rotate the drive gear in a

Coolant Pump Body and Drive Gear Bearing

clockwise direction through several revolutions while

holding a light load against turning of the cross shaft

a. Measure and record width J (fig. 8-8), of

(para 8-11, step 8, below). Note the gear tooth contact

the pump drive gear bearing.

8-4