front suspension and steering 3D model

The most common coil-spring front suspension uses two control arms (also called A-arms because of their shape) per side, mounted to the frame, and a coil spring between them that exerts force on only one arm. As shown in the illustration, the top control arm is mounted to the frame, but the spring doesn't touch it. The spring sits in a frame pocket just under the upper arm and exerts downward force on the lower arm. The upper arm basically serves as a locating device. The control arms are connected at their outer ends by the spindle, so when the spring pushes down on the lower arm, the whole control-arm/spindle assembly moves with it. When a car is sitting still (static), the spring is slightly compressed, supporting the weight of the car. As the tire goes over a bump, the weight of the car overcomes the pressure of the spring and compresses it, allowing the wheel to follow the bump without forcing the entire body of the car to move.