Types of Steering Boxesby April Kohl
The steering box is a method of steering cars at high speeds, where accuracy is of paramount importance. It is a method of preventing the turning of the steering wheel from having a direct effect on the direction of the wheels, allowing for a more forgiving driving experience than direct access. A gear system is placed between the shaft of the steering wheel and the wheel axle, refining the controls and making driving safer.
Worm and Sector
The worm and sector steering box was one of the first steering box designs. It comprises a steering wheel shaft with a "worm" screw on the end, and a section gear that is moved up and down as the steering wheel turns. The movement of the section gear causes a pitman arm (a rod of metal attached to the track rod) to lever up and down, turning the wheels.
Worm and Roller
The worm and roller steering box was introduced in 1926 to combat friction and is still used today. It works on a similar principle to the worm and sector box, with section gear replaced by a roller attached to a cross shaft. As the steering wheel turns, the worm rotates and causes the roller to turn. This causes the cross shaft to twist, moving the pitman arm and forcing the wheels to change direction. According to carbibles.com, the worm gear is typically an hourglass shape, designed to be wider at the ends.
Cam and Lever
Introduced in 1923 as a means of reducing wear and friction, the cam and lever design is very similar to the worm and roller. As the worm turns on the steering shaft, the cam moves up and down the worm, forcing the pitman arm to move up and down along with it, causing the wheels to change direction. In this design, according to carbibles.com, the cross shaft is turned 90 degrees to the normal, causing it to exit through the side of the steering box instead of the bottom.
- photo_camera steering wheel image by Jeff Clarke from Fotolia.com