Leaf Springs vs. Torsion

This post was written by ghoj on January 31, 2014
Posted Under: Trailer Axles, Hubs & Springs

The two most common forms of suspension on general duty trailer axles (1,500 lbs – 5,200 lbs) are going to be leaf sprung or torsion. Leaf Sprung axles can be visually identified by the fact that they will sit either on top of or below a set of leaf springs.  A torsion axle will mount directly to the frame and has giant rubber cords in the axle tubing that resist torsion and create suspension.  Torsion axles will have torsion arms on both sides of the axle coming down to the spindle.  We are going to discuss the Pros and Cons of both suspension systems and a few things to consider.

Leaf Spring Suspension:

Pros: One of the major benefits of a trailer leaf spring suspension is found on a tandem axle application.  In a tandem axle application the leaf springs on each side are connected with an “Equalizer Bar”.  The Equalizer bar is designed to equally distribute force between both axles.  This will limit any damage caused by curbs, potholes, etc.  Another positive with leaf spring suspensions is that many of the components are fairly easy and inexpensive to replace in the event of something needing replaced.

Cons: On the other end of the things, because there are a lot of components, there are a lot of components that can break.  Another con to leaf spring suspensions is that leaf springs work on the premise of flexing metal.  This can sometimes make for a bit of a bumpy ride.

Torsion Suspension:

Pros:  Torsion suspension works on the premise of flexing rubber, which will create a smoother ride with less vibration.  Another Pro of torsion axles is that, although expensive, they are relatively easy to replace.  There is no welding required because they bolt directly to the frame.  A torsion axle is a self-contained suspension unit, which eliminates many of the smaller components and moving parts that are found on leaf sprung suspensions.

Cons:  Due to the fact that torsion axles are independent from each other, there is no transfer of impact.  This means that in the event that a pothole or curb is hit, the full force of that impact will be on that one wheel creating more chance for damage.  Secondly, it can be difficult and in many cases impossible to repair a torsion axle.  The rubber inside the axle tubing makes welding out of the question, which also means in the event of catastrophic damage, the entire axle would more than likely need to be replaced.

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