Spring vs. Torsion Trailer Axles:
There are two main types of axles in the trailer industry: Spring axles and torsion axles. At Real Industries we often get asked which is better. Below we discuss both axle styles and the pros and cons of both.
Spring axles are generally the most common axles used in trailers due to their cheaper costs and proven design. They rely of leafs (flat arc shaped spring steel stacked on top of each other) to provide cushioning for the trailer frame as it travels down the road. Higher weight rating axles require bigger and stiffer leafs. Typically trailer springs are underslung (mounted below the axle); this allows the trailer frame height to be lower.
The two main mounting styles for spring axles are double eye (cheaper, more wearing parts, quitter, suitable for lighter duty axles) and slipper (more expensive, louder, less maintenance, suitable for heavier duty axles). Both styles require the axles to be attached the trailer in a way that allows them to pivot and slide as the spring compresses and expands. This requires bolts and bushings to be used on each axle, and requires regular maintenance.
On multi axle trailers the axles are connect with a walking beam, the walking beam allows the springs to flex and helps distribute the load between the two axles.
|Lots of wearing parts
|Parts are readily available
Torsion Trailer Axles:
Torsion axles on the other hand use long rubber cords inside a square tube with an inner piece that is attached to the torsion arms. When the wheel moves up and down on bumpy or uneven ground, the inner piece compresses the rubber cords which provide the cushioned ride. The weight rating of the axle dictates the size of the square tube and the size of the rubber cords. Because all of the components are integral to the axle all that is required to mount the axles to the frame is a bracket and bolts. This makes for a smooth, quite ride with no maintenance.
The design of the torsion axles also allows a wider range of trailer heights, the pitch (angle of the torsion bar) can be adjusted in relation to the beam to raise or lower the trailer height. By design the torsion axles provide a true independent wheel suspension as there is no walking beam to connect multiple axles together.
While both styles have their advantages and disadvantages, Real Industries believes that in most applications torsion axles are the superior choice. The zero maintance and quite/smooth ride make them an ideal axle for livestock and flat deck trailers.