Torsion springs, as an elastic component, are widely used in the suspension systems of modern cars, including sedans, trucks, and SUVs. Compared to leaf springs, torsion springs offer a range of advantages: they have a high energy storage capacity per unit mass, thus reducing the car's weight and saving materials. Additionally, since torsion springs are fixed to the vehicle frame, they decrease the unsprung mass, which is beneficial for improving the smoothness of the car's ride.

When applied to the front suspension of front-wheel drive vehicles, torsion bars can be arranged vertically, thereby providing space for the front drive axle's swinging half-shafts. However, the manufacturing cost of torsion bars is relatively high, and strict requirements are placed on materials and processes. Additionally, torsion bars can only act as elastic elements and must be accompanied by a guidance mechanism.

The torsion spring is made of chrome-vanadium alloy spring steel, with a highly polished surface after processing. It is essential to protect the torsion spring surface during use. Typically, a layer of epoxy resin is applied to the surface, followed by a layer of glass fiber cloth, another coat of epoxy resin, and then coated with asphalt and anti-rust paint to prevent collisions, scratches, and corrosion, thereby extending the service life of the torsion spring.

The扭杆弹簧 is essentially a torsion spring made from spring steel. The cross-section is typically circular, with some being tube-shaped or rectangular. The ends can be shaped into splines, squares, hexagons, or flat cylindrical shapes to allow one end to be fixed to the vehicle's chassis and the other to the suspension's arm, which is then connected to the wheel.

The torsion spring is connected and fixed at one end to the vehicle frame, while the other end is linked to the wheel via a lever arm. When the wheel encounters a ground obstacle and bounces upwards, it drives the lever arm to rotate around the torsion spring's axis by a certain angle, causing the torsion spring to deform elastically. Simultaneously, the stored elastic deformation energy from the torsion spring's deformation is released when the wheel leaves the obstacle, quickly returning the force transmission mechanism and the wheel to their original position.

During the manufacturing of torsion springs, a permanent twist deformation is initially applied to the torsion bar, endowing it with a certain pre-stress. The direction of the pre-torsion applied to the torsion bar is the same as the direction in which the torsion bar twists when installed on the vehicle, with the aim of reducing the actual stress during operation and extending the lifespan. Note that left and right torsion bars cannot be interchanged!