You should know the basics about suspension since its what keeps your car from shaking or twisting itself apart.
Without a suspension to smooth the ride and control body motion, even the smoothest road would place unbearable stresses and forces on the frame of your vehicle. The key parts of a suspension are springs, shock absorbers and the links that tie all the parts together. A suspension works in concert with parts called torsion bars, sway bars and control arms to deal with the forces created by tons of metal in motion. There are many types of suspension, but all have the same objective: to resolve the long-standing conflict between cabin comfort and optimum handling.
Springs control up and down motions. There are three types of springs: coil springs, leaf springs and torsion bars. Coil springs and torsion bars are generally used in the front whereas leaf springs are generally used in the rear. Typically,coil springs are mounted between the upper and lower control arms, and the shock absorber sits inside the spring. There are varying "rates" of coil springs designed to achieve the desired road feel of the vehicle.
Another type of spring is the leaf spring, which is composed of layers of steel that are bolted together. The spring is attached in the middle to the axle using U-bolts. There are shackles as both ends of the leaf spring that attach to the body of the vehicle and allow it to flex.
Then there are torsion bars that mount to the frame and the lower control arm. As the torsion bar twists, it provides resistance, or spring. Each front wheel has one torsion bar.
The sway bar is essentially a brace. It’s used to fight the tendency of vehicles to lean excessively when cornering. In a turn as a vehicle leans, the upward push on one wheel is transferred as a downward force on the other. This works to keep the vehicle more level.
Finally, there are the control arms. The work of the control arm is to control the action of the suspension in relation to the movement of the body.a
Shock absorbers (shocks) do precisely that. Links tie the springs and shocks to the frame and chassis. Springs and shocks always work as a team. If your car only had springs, it would bounce and wallow along the road until you got physically sick and had to get out. Shock absorbers control and damp the motion of the springs. They absorb the “shock” of hitting a bump and prevent it from being transmitted to the car chassis. Shocks are filled with oil and a piston. The faster the inner piston moves, the more resistance there is to that movement, as the piston attempts to compress the oil. The damping effect eliminates the bouncing and wallowing of an uncontrolled spring. Most shocks are “double-acting” with damping in both directions. Shock absorbers literally keep your wheels planted on the road. And you thought all shocks did was leak oil!
In the early automotive days, the shock absorbers worked alone. Today, most cars have sophisticated, multi-link suspension “systems.” One of the most common is the MacPherson strut, essentially a shock absorber surrounded by a coil spring. MacPherson struts also keep the front end of the vehicle properly aligned, so your vehicle tracks straight and tires wear evenly. The strut itself is the load-bearing member in this assembly with the spring and shock absorber merely performing their duty, as opposed to actually holding the car up. MacPherson struts are good for more miles than simpler shock setups. Still, they will eventually start to leak at which time you should replace them.
Modern vehicle suspension is both a science and an art. Since there is so many forces at play in the suspension, you should be aware of any problems that may crop up. Have your systems checked regularly for maximum safe handling.