13-07-2013, 12:00 PM
SHOCK ABSORBERS
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ABSTRACT
Springs alone cannot provide a satisfactorily smooth ride. Therefore an additional device called a “shock absorber” is used with each spring. Consider the action of a coil spring. The spring is under an initial load provided by the weight of the vehicle. This gives the spring an original amount of compression. When the wheel passes over a bump, the spring becomes further compressed. After the bump is passed the spring attempts to return to its original position. However it over rides its original position and expands too much. This behaviour causes the vehicle frame to be thrown upward. Having expanded too much, the spring attempts to compress that it will return to its original position; but in compressing it again overrides. In doing this the wheel may be raised clear of the road and the frame consequently drops. The result is an oscillating motion of the spring that causes the wheel to rebound or bounce up and down several times, after a bump is encountered. If, in the mean time, another bump is encountered, a second series of rebounding will be started. On a bumpy road, and particularly in rounding a curve, the oscillations might be so serious as to cause the driver to lose control of the vehicle.
A shock absorber is basically a hydraulic damping mechanism for controlling spring vibrations. It controls spring movements in both directions: when the spring is compressed and when it is extended, the amount of resistance needed in each direction is determined by the type of vehicle, the type of suspension, the location of the shock absorber in the suspension system and the position in which it is mounted. Shock absorbers are a critical product that determines an automobile’s character not only by improving ride quality but also by functioning to control the attitude and stability of the automobile body