Re: Torsion Axle
Tandem torsion axles have one major drawback over a tandem leaf spring suspension. With a tandem leaf spring suspension, any wheel can "step" over an uneven surface without transferring load to any other wheel. This is because of the walking beam design. On the other hand, any single wheel on a torsion axle will transfer "additional" load to itself when stepping over a raised object, and transfer "additional" load to the other three wheels when any wheel drops into a depression. These trailers also require that they be towed perfectly level. The reason for that is with the tongue high, the front axle is supporting less weight than the rear axle. Therefore, if the trailer is loaded to anywhere near the maximum capacity, the rear axle and/or tires can be easily overloaded and damaged. Conversely, if towed tongue low, the opposite situation exists. This same principle applies to the single wheel over a bump (overloads that wheel) or stepping into a depression (transfers load to the other three). This does not occur with a leaf spring/walking beam design since the entire load is placed on the center of the walking beam which allows individual wheel movement without loading shifts and tongue high or tongue low makes no difference in tire loading characteristics. Now then -- torsion axles are fine, they ride well, and are used on many trailer designs. But be aware of the loading issues. If you ever see an empty boat, atv, or snowmobile trailer negotiating an uneven surface, you will at some point see the wheels on either the front or rear axle off the ground. That means one axle or the other is supporting the entire load. That can happen when loaded as well but less often. I use that example only to illustrate the load shift concept.
