Power Steering Gears - (SAGINAW) Rotary Valve Power Steering: Description

Both constant ratio and variable ratio, recirculating ball type gears are used on Chevrolet and GMC vehicles. Steel balls work as a rolling thread between steering gear worm shaft and rack-piston nut. Worm shaft thrust is supported by a thrust bearing and two thrust races at lower end, and by a bearing in the adjuster plug at the upper end. This design provides continual spring loaded pressure on worm shaft to prevent loss of thrust bearing preload for life of the gear. Adjuster plug provides initial preload adjustment, and service adjustment when repairing gear. As worm shaft is turned right, rack-piston moves upward in gear; turning worm shaft left moves rack-piston downward in gear. Rack-piston teeth mesh with sector, which is forged as part of the sector shaft. Turning worm shaft turns sector shaft, which turns wheels through mechanical linkage.