Overslung vs Underslung Axles - What's the Difference?

The world of trailers is filled with technical terminology, and sometimes it can get a little overwhelming to keep up with. Not to worry! The Trailer Parts Outlet is here to help you learn and understand everything you need to know about trailers. Let’s define some simple terms regarding axles, and then get into the difference between them. This is important information whether you are building a trailer from scratch, or repairing or updating the axles you have, this information is important for you. 

Overslung axles are fairly simple to understand, once you know what the term refers to. Overslung refers to a trailer part called a leaf spring. This is a springy piece of metal that helps absorb shock from a heavy trailer bed bouncing up and down. When this spring sits above the trailer’s axle, this is called overslung.

What are Underslung Axles?

Similar concert, but that shock absorbing leaf spring sits slung underneath the trailer’s axle. 

Check out the following diagram. 

What’s the difference? 

Frame height of your trailer

Obviously, if you have an overslung axle trailer, you have a taller frame height. That gives you a little more clearance, but remember, lower bases are very stable. 

Stability

While underslung axles offer lower clearance, they are a little more stable. 

So how do I choose between underslung or overslung?

Decide based on your terrain. If you go off roading on flat, chunky terrain to drop off hunting gear or ATVs, but you know you aren’t taking many sharp turns, overslung may be the way to go. But if you tend to twist and wind up developed roads that go over mountains, underslung might give you the stability you need. 

Contact The Trailer Parts Outlet with Axle Questions

We are always happy to talk shop and share our insights. If you need help deciding between underslung and overslung axles, give us a call any time.