Torsion axles are a type of axle suspension used on trailers.
Image: Diagram of a torsion axle, shown as a cross-section
Torsion Axle Construction
The torsion axle design features a hollow round-cornered square tube bolted directly onto the trailer frame. There is a square metal bar made of solid, high-tensile steel in both ends of the tube.
This bar is inserted at a 90-degree rotation from the alignment of the square outer tube. Four rubber cords are then placed in the tube, one in each corner, to keep the bar in place. The torsion arm is then attached to the inner bar, which connects to the hub assembly.
Torsion suspension provides cushion by resisting the twisting force (known as torsion) placed on the inner bar through the torsion arm. The rubber cords compress to counteract the force, thus smoothly cushioning the trailer.
What Defines Axle Capacity?
The axle’s capacity is defined by the size and durometer (stiffness) of the rubber cords. Torsion axles offer a multitude of benefits found in the article.