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A trailer torsion axle is a type of axle that uses no spring or shock absorber to cushion the ride of the trailer. Made of a spring-type steel tube within a tube, the trailer torsion axle flexes and rebounds by twisting the wheel hub assembly on a torsion tube mounted inside of a hollow axle tube. This style of axle does not require any space inside of the trailer to be used to house the suspension. The trailer torsion axle also allows the trailer to be towed close to the ground. This is because all of the trailer axle and suspension movement occurs outside of the trailer's cargo space.
A torsion bar is a steel bar that flexes to absorb energy, such as bumps and bounces. Used in place of a conventional spring, the torsion bar has been used on automobiles and light-duty trucks for decades without failure. The trailer torsion axle applies the torsion bar technology to a trailer axle, thus allowing the trailer to ride smoothly without the aid of conventional spring and shock absorber packages. Another benefit of using the trailer torsion axle is that the main center section of the axle can be used to support the trailer floor. This is possible because the only part of the trailer torsion axle that moves is the small section of axle attached to the wheel hub at the outside end of the axle.
If ever a problem presents itself requiring the trailer torsion axle to be replaced, only the torsion bar end of the axle will need to be changed. This component simply unbolts from the end of the axle tube and the replacement part is slid into place and tightened down. The ability to operate a trailer with very little ground clearance makes the torsion axle a perfect choice for livestock trailers, such as those used to haul cattle, hogs and horses. The animals do not need a ramp to step into the very low-slung trailer, in most cases.
Application of the trailer torsion axle on other types of trailers, such as auto transports and camping trailers, allows for more usable space between the tires of the trailer. Without springs and shock absorbers taking up valuable space between the trailer tires, more room can be devoted to the loading deck and the passenger compartment. The trailer torsion axle is available in various spring rates to compensate for heavy loads.