Trailer Tech: Leaf Springs

Welcome back to Trailer Tech!

Leaf springs which are commonly used in light to medium duty trailer applications generally fall into one of three categories. In this Trailer Tech, we'll take a quick look at them and discuss their applications.

Pictured above from back to front is the double eye spring, the slipper spring and the mono leaf spring commonly found on 2000lb-7000lb light to medium duty axles.

First up is the double eye spring. One of the more common leaf spring designs, it performs in partial to fully loaded applications. They are often found in both tandem axle and single axle orientation on recreational trailers, cargo trailers, utility trailers and some boat trailers. Because of their comparatively high complexity when mounting, this spring requires more maintenance in the shackle and bushing department. Also, due to the multi-leaf design, they may have to be repacked if the spring pack loosens and leaves begin to shift or be re-arched if the leaves begin to fatigue. The double eye spring can be tuned by adding, removing, rearranging or re-arching the leaves in the spring pack.

Next is the slipper spring. It's commonly found on dollies, carts, boat trailers and construction trailers where the trailer is either fully loaded or unloaded. Normally chosen for its high, fully-loaded durability, on-road characteristics when unloaded are normally poor. The simplicity in the slipper design results in a rugged, low maintenance spring but leaves more room for play when unloaded or fully loaded over rough terrain. Once again, due to the multi-leaf design, they may have to be repacked if the spring pack loosens and leaves begin to shift or be re-arched if the leaves begin to fatigue. Like the double eye spring, the slipper spring can be tuned by adding, removing, rearranging or re-arching the leaves in the spring pack.

Finally, we have the mono leaf spring. Due to their comparatively high complexity when mounting, this spring requires more maintenance in the shackle and bushing department. Commonly used in applications where the trailer is primarily stationary, they offer good long term rigidity and with no leaves, low maintenance but feature on-road characteristics similar to an oversprung or unloaded spring.

Thanks for reading.