Utility trailer axles are normally divided into two different types: Spring axles and torsion axles. While these two types of axles perform the same basic job, the way they go about suspending and cushioning the trailer load is completely different.
Spring Utility Trailer Axles
This type of utility trailer axle will be immediately recognizable to nearly anybody who has been around motor vehicles for any length of time. Much like the name suggests, spring axles are constructed of stacked flat spring stock in proportion to the load.
But rather than having the spring over the axle (like on a pickup truck), trailers normally have the axle slung over the springs. This decreases the ride height of the trailer, which is important for many reasons. Load stability is greater on a lower trailer, and they’re easier to load and unload as well.
Spring axles are by far the most popular option when it comes to trailer suspension systems. They’re inexpensive and relatively easy to maintain. In fact, spring axles often ship with the curved spring plates pre-attached and ready to install. This helps reduce overall costs even more.
These parts are also an ideal choice for multi-axle trailers, because each tire has its own set of springs. If you have to store your trailer on uneven ground, this independent wheel suspension means the trailer will hold up better over the long run.
Benefits of the spring axle include:
- It’s possible to perform extensive maintenance. Unlike torsion axles (next section below), parts can be easily changed out.
- Spring axles provide the most dependable tire wear, especially on multi-axle trailers.
- They’re inexpensive and fairly easy for the manufacturer to install.
- Spring axles don’t require rewelding to replace an entire axle.
Spring axles excel in applications like:
- Utility trailers
- Dump trailers
- Basically any type of commercially available trailer, with a few special exceptions
Torsion Utility Trailer Axles
Rather than relying on the traditional tensioned and sprung flat steel plates of the spring axle, torsion utility trailer axles take a different approach entirely.
No metal springs of any type are used; rather, a series of long rubber cords are situated inside a square tube with an inner core piece that the torsion arms are secured to. This type of axle can be difficult to understand just by reading about them. In this case, a (moving) picture really is worth a thousand words:
As you can see, the above video shows the cross section of a torsion axle. The outer square steel tubing is the part that’s actually secured to the frame. The inner square piece is secured to the respective wheels via the torsion bars.
When the wheel moves up and down on bumpy or uneven ground, the inner bar compresses the rubber cords along the length of their bearing surface. The contact points are simply the corners and edges of the center support. Unbelievably simple!
Benefits of the torsion axle include:
- Maintenance free design. Lube your wheel bearings and that’s it!
- No metal-on-metal contact points
- Independent wheel suspension
- Quieter during travel
- Ride height can be easily changed via adjustable torsion bars.
- Cross-bar construction is directly welded to the frame, and adds stiffness
- Great corrosion resistance, as torsion axles are usually galvanized inside and out
- Warranty typically lasts longer than leaf spring axles
Half-torsion axles are also available, which means they come in two parts that don’t need to span the width of the trailer. These short units are perfect for specialized, custom applications.
Unfortunately, the attached design of torsion axles means that any major repairs are going to require the axle to be cut off. They really aren’t designed to be totally overhauled. But, their simplified construction usually means that repairs are seldom, if ever, needed.
Torsion axles excel in applications like:
- Boat trailer axles
- Salt water spray environments
- Windy environments
- Unusually bumpy or rough roads
- Conditions where a lower ride height is needed
- High vibration applications (like wood chippers)
Which Utility Trailer Axle is Best?
You might be asking “Which is better, torsion or spring axles?” That’s a complicated question. Torsion utility trailer axles offer a smoother ride and less maintenance. Leaf springs are more durable, less expensive and far easier to replace parts on.
Selecting the proper axle is as simple as determining your application, and figuring out the loads you need to carry. Whichever you choose, you’ll see the best results by properly loading your trailer with the aim of getting the most wear out of the system you pick.
Don’t Get Wrapped Around the Axle
Let’s face it: Without axles, we wouldn’t have trailers.
These humble parts may stay out of sight and out of mind most of the time, but they’re definitely not slacking around when it comes to keeping your load on the road. Reliable trailer axles are worth their weight in gold, especially if you make your living with your trailer.
Contact your local Lamar Trailers dealer today, and ask for help in choosing whether or not torsion or spring axles are the right choice for your application!