A torsion bar is a type of suspension system that is typically used in wheeled vehicles such as cars, vans and trucks. A suspension system is an important and critical element of a vehicle’s design. Regardless of the design, all suspension systems perform the same important functions. They keep the tires in contact with the surface of the road, support the weight of a vehicle and absorb the forces generated by the movement and motion of the vehicle.
Torsion bars are essentially metal bars that function as a spring. At one end, the bar is fixed firmly in place to the chassis or frame of a vehicle. The other end of the bar may be attached to the axle, suspension arm, or a spindle, depending on the specifics of a vehicle’s design. As a vehicle moves along the road, the forces generated by the motion of the vehicle create torque on the bar, which twists it along its axis.
Counteracting the torque is the fact that the torsion bar naturally wants to resist the twisting effect and return to its normal state. In doing so, the suspension provides a level of resistance to the forces generated by the movement of the vehicle. This resistance is the key principle behind a torsion bar suspension system.
There are several key advantages of this system. The design of the torsion bar suspension takes up less space than other suspension systems. This can allow vehicle designers to create a more spacious passenger compartment. The height of the bars can also be adjusted more easily than other suspension systems. They are also extremely durable and traditionally have a long service life.
There are also several disadvantages of torsion bar suspensions. The first is that these bars generally do not offer what is known as a progressive spring rate. In suspensions with a progressive spring, the coils of the spring are spaced at different distances from each other. This allows the suspension system to enable firm steering, braking and handling, while also providing for a smooth and comfortable ride. Vehicles with torsion bars are often tuned to either provide a more firm driving experience at the expense of ride smoothness, or a smoother ride at the expense of the vehicle’s handling quality.
Torsion bar suspension systems were once relatively common in passenger vehicles, but today are used primarily for the suspension systems of trucks and sport utility vehicles (SUVs). Some notable automobiles that used this type of suspension were the original Volkswagen Beetle, Porsche 356, Porsche 911 models that utilized an air-cooled engine, and much of the Chrysler line-up of cars from the late 1950s through the late 1980s.