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STEERING GEAR ASSEMBLY
6-16. DESCRIPTION. (See Figure 6-4.)
6-17. The steering gear assembly consists of a worm shaft (20), ball nut (24), sector gear (8), and a pitman shaft (5). Two sets of worm balls (23) in the ball nut act as rolling threads between the ball nut and the worm shaft. Gear teeth on the ball nut mesh with the sector gear. The steering ratio between the worm shaft and the pitman shaft is approximately 28:1.
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6-18. When the steering wheel is turned, the steering column assembly rotates the worm shaft. This causes the ball nut to move up or down on the worm shaft. Movement of the ball nut causes the sector gear and pitman shaft to rotate forward or back, depending upon the direction of steering wheel rotation. A pitman arm is splined onto the pitman shaft to provide the steering gear assembly output. Clearance between the ball nut and sector gear is adjustable by a screw (12) located on the outside of the gear assembly. a. Place the steering gear worm shaft (20, Figure 6-4) flat on a workbench and slip the ball nut (24) over the worm shaft. The ball guide holes in the nut (24) must be up and the shallow end of the sector gear teeth toward the pitman arm end of the shaft. Align the grooves in the worm and ball nut by sighting through the guide holes. b. Drop the worm balls (23) into one of the guide holes while turning the worm gradually away from the hole. Continue turning until the ball circuit is full from the bottom of one guide hole to the bottom of the other guide hole (or until stopped by reaching the end of the worm).
6-19. REMOVAL. (See Figure 6-5.)
6-20. DISASSEMBLY. (See Figure 6-6.)
6-21. CLEANING.
6-22. Clean all parts of the steering gear assembly with cleaning solvent. Use compressed air to dry, then store in a clean area until reassembled.
6-23. INSPECTION. (Refer to Table 6-1.)
6-24. REASSEMBLY. (See Figures 6-4 and 6-6.)
NOTE If the balls are stopped by the end of the worm, hold down the balls already dropped into the ball nut with a blunt, clean rod and turn the worm in the reverse direction a few turns. The filling of the ball circuit can then be continued. It may be necessary to work the ball nut back and forth, holding the balls down first in one holethen the other.
