Description & Operation
The 2 primary purposes of front suspension are to isolate driver from irregularities in road surface and to define vehicle ride and handling characteristics. The front suspension absorbs impact of tires travelling over irregular road surfaces and dissipates this energy throughout suspension system. This process isolates vehicle occupants from road surface. The rate at which suspension dissipates energy and amount of energy that is absorbed is how suspension defines vehicle ride characteristics. Ride characteristics are designed into suspension system and are not adjustable. The ride characteristics are mentioned in this description in order to aid in understanding of functions of suspension system. The suspension system must allow for vertical movement of tire and wheel assembly as vehicle travels over irregular road surfaces while maintaining tire's horizontal relationship to road.
This requires that steering knuckle be suspended between a lower control arm and a strut assembly. The lower control arm attaches from steering knuckle at outermost point of control arm. The attachment is through a ball and socket type joint. The innermost end of control arm attached at 2 points to vehicle frame through semi-rigid bushings. The upper portion of steering knuckle is attached to a strut assembly. The strut assembly then connects to vehicle body by way of an upper bearing. The steering knuckle is allowed to travel up and down independent of vehicle body structure and frame.
This up and down motion of steering knuckle as vehicle travels over bumps is absorbed predominantly by coil spring. This spring is retained under tension over strut assembly. A strut is used in conjunction with this system in order to dampen out oscillations of coil spring. A strut is a basic hydraulic cylinder. The strut is filled with oil and has a moveable shaft that connects to a piston inside strut. Valves inside shock absorber offer resistance to oil flow and consequently inhibit rapid movement of piston and shaft. Each end of shock absorber is connected in such a fashion to utilize this recoil action of a spring alone. Each end of strut is designed as connection point of suspension system to vehicle and acts as coil spring seat. This allows strut to utilize dampening action to reduce recoil of a spring alone. The lower control arm is allowed to pivot at vehicle frame in a vertical fashion. The ball joint allows steering knuckle to maintain perpendicular relationship to road surface.
Front suspensions systems utilize a stabilizer shaft. The stabilizer bar connects between left and right lower control arm assemblies through stabilizer link and stabilizer shaft insulators. This bar controls amount of independent movement of suspension when vehicle turns. Limiting independent movement defines vehicles handling characteristics on turns.