Control Arm refers to a link that connects the front wheels to the vehicle.
In a double-wishbone system, The control arm pivots the vehicle body on the vehicle body or frame. The upper end of the coil spring rests in a pocket in the frame. The lower end rests on the lower control arm. As the wheel moves up and down the control arms pivot and the spring shortens or lengthens. Both control arms look like a wishbone or the letter A. They have a single ball joint in the outer ends and two attachment points on the inner ends.
The inner ends are supported by rubber bushings. These allow the control arms to move up and down with little resistance. Rubber bumpers attached to the frame or control arm prevent metal-to-metal contact when full spring compression occurs. The shock absorber is the center in the spring.
The upper end of the spring seats in a spring tower that is part of the body sheet metal. As the wheel moves up and down, the control arms also move up and down.