Power Steering Gears - SAGINAW Rotary Valve: Description

Steering gear is a recirculating ball type, available in either a constant or a variable ratio design. Steel balls work as rolling thread between steering gear worm shaft and rack-piston nut. Worm shaft thrust is taken by a thrust bearing and two races at the lower end, and by a bearing in the adjuster plug at the upper end.

This design puts spring pressure on worm shaft to prevent loss of thrust bearing preload. The adjuster plug provides initial preload adjustment and service adjustment (when repairing gear). As worm shaft is turned right, the rack-piston is moved upward in gear. As worm shaft is turned left, the rack-piston is moved downward in gear.

The rack-piston teeth mesh with the sector, which is forged as part of the sector shaft. Rotating the worm shaft moves the sector shaft, which turns the wheels through mechanical linkage. See Figure.