Power Steering - SAGINAW Rotary Valve: Description
Gear is variable ratio recirculating ball type. Steel balls work as a rolling thread between steering gear worm shaft and rack-piston nut. Wormshaft is supported by a thrust preload bearing and two conical thrust races at lower end, and a bearing assembly in adjuster plug at upper end. This design provides continual spring loaded pressure on wormshaft to prevent loss of thrust bearing preload for life of gear. Adjuster plug provides initial preload adjustment and service adjustment when servicing gear. As wormshaft is turned right, rack-piston moves upward in gear; turning wormshaft left moves rack-piston downward in gear. Rack-piston teeth mesh with sector which is forged as part of pitman shaft. Turning wormshaft turns pitman shaft which turns wheels through mechanical linkage.
- Small gear has a round side cover held in place by a retaining ring while large gear has a rectangular side cover held in place with 4 bolts.
- The worm and rack are directly mated rather than separated by recirculating balls as in the large gear.
- Thrust bearing adjustment is at lower end of gear by hex-driver instead of at stub shaft end with spanner.