What is torsion suspension

Torsion suspension is a suspension system in which the torsion shafts (torsions) act as the main working element. The word "torsion" of French origin also means twisting. Has a wide range of applications due to the simplicity of its design, manufacture and relative reliability. The principle of operation is simple. On the one hand, the torsion bar is fixed motionless, and on the other side the acting forces create a torque with the help of the fastening system. The rod resists torsion and, thus, damages the load. Apply rods, both round and square, made of hardened alloy steel. Doping is used such that increases the fatigue strength. The surface is shot blasted. To improve the performance of the torsion bar, a wax procedure is used. Twist the hot shaft to the limit and hold for a while, so that the upper layers are plastically deformed. Then, when the load is removed, the core will try to unwind, and the upper displaced layers will not let it. This creates internal stresses, and the rod will create a greater resistance to torque.

Torsion suspension is used mainly in automotive and tank production. On tanks, a torsion shaft of round or semicircular cross-section began to be used shortly before the outbreak of World War II. Reliability and maintainability of such a suspension system led to the fact that today all tank-building schools have switched to the use of such a design.

On cars, either a transverse torsion bar or longitudinal torsion bars are used. Longitudinal placement allows you to install longer rods and, accordingly, increase the softness of the suspension and the smoothness of the car.

Torsion suspension was first used on Citroën and Volkswagen cars. The famous Volkswagen Beetle opened the era of torsion in the German automotive industry. Its dawn, it survived in the 50's and was subsequently replaced by a multi-link system, but still finds use in low-cost cars with a small mass. Also, the torsion bars are used as stabilizers of the vehicle's lateral stability , which allows to significantly reduce rolls in bends and to achieve better handling of the vehicle.

The positive aspects of this design are as follows:

• Compactness. It takes up less space than a spring.
• Easy adjustment.
• Light weight.
• Reliability and durability.
• Easy maintenance and replacement.
• Simplicity of manufacture of a suspension bracket.

Possessing a number of advantages, the torsion suspension is still imperfect and has certain drawbacks. The simplicity of manufacturing is superimposed on the high cost of materials and the inability to dynamically change the elasticity. The load is limited by the strength of the applied welds, but not by the rod, although it also sometimes bursts. The size of the torsion bar is limited by the dimensions of the car, and the use of thicker rods increases the weight of the structure and negates the advantage of low weight. At the same time, there are no critical drawbacks, so this suspension is still used.