1929-01-01

A Cure for Shimmy and Wheel Kick 290005

BEGINNING with a review of the effects of the almost simultaneous adoption of balloon tires and front-wheel brakes, the authors outline the dynamic conditions of the front-axle system of the conventional car. They show that two types of vibration, otherwise independent of each other, are coupled together by gyroscopic forces when the wheels are rotating. The effect is greatly to lower the frequency, so it can come into synchronism within the speeds at which the car is driven.
Shackling the front springs at the front end reduces the error in steering geometry, but cannot always entirely eliminate shimmy and wheel kick. A solution was found by adding a cushioned bracket at the rear end of the left front spring. This introduces damping, because of a phase difference between the gyroscopic forces and the elastic and friction forces, thus eliminating shimmy and at the same time reducing the reaction at the steering-gear to an amount so small that no kick is felt at the steering-wheel rim.
Further analysis of shimmy is given in the discussion, and two speakers state that independent springing of the front wheels seems to be the only sure cure. Another speaker reports that independent springing has proved unpopular in Europe, where it has been most extensively tried.

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