• The mechanism that converts the steering wheel's rotational movement to the linear left-right movement required to steer a car is called a rack-and-pinion. Though some vehicles use other means to accomplish this end, rack-and-pinion systems remain by far the most common.

    Basic Geometry

    A rack-and-pinion system uses a stationary round gear to move a bar with matching teeth side to side.


    The rack-and-pinion principle can be demonstrated by rotating a pencil with the eraser resting on a piece of paper. The pencil is the rotating steering shaft, and the paper is the laterally moving rack.


    The rack can be placed either ahead of or behind the steering wheel centerline, depending on clearance.


    This system's main advantage is its direct engagement, linear feel and directional feedback. Racing applications employ rack-and-pinions almost exclusively for this reason.

    Variable Steering

    Street and stock cars usually use a variable-ratio steering rack. By varying the size and spacing of the rack gear teeth, manufacturers can tune the steering so it has adequate feedback just off-center but travels easily to its extremes for parking.



    Patent Storm


    Rack and Pinion Demonstration Model (Video)

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