What are the Most Common Trailer Axles?
When it comes to towing, the axle is a critical component that significantly impacts a trailer’s performance, durability, and ride quality. Understanding the different types of trailer axles can help you make informed decisions when purchasing or upgrading your trailer. In this comprehensive guide, we’ll delve into three of the most common trailer axle types: straight spring axles, torsion axles, and drop spring axles.
Straight Spring Axles: A Classic Choice
Straight spring axles are one of the most traditional and widely used types of trailer axles. They feature a simple design with leaf springs attached directly to the axle housing. These springs absorb shock and vibration, providing a relatively smooth ride.
Spring axles involve many different variables, so each one remains unique to the trailer it’s on. For starters, a spring axle can feature three types of camber: full camber, half camber, or no camber at all. Most axles come with half camber as the standard option, while full camber and no camber depend on personal preference and the type of trailer. Trailers that carry consistent weight, such as wood chipper trailers, typically use full camber. On the other hand, light-duty trailers or those that don’t haul heavy loads often utilize axles without camber. Learn more about camber in our Axle Camber Blog.
The leaf spring setup further differentiates these axles. A standard spring axle includes spring perches or spring pads welded either to the top or bottom of the axle beam. When the spring perches attach to the top of the axle, the setup is called overslung, meaning the leaf spring sits on top of the axle. Conversely, when the spring perches attach to the bottom, the setup is referred to as underslung, which positions the spring underneath the axle. Both overslung and underslung suspension setups are common and serve specific purposes. An overslung suspension axle raises the trailer’s ride height, making it ideal for camper trailers that need extra ground clearance for grey water tanks, generators, and other components. An underslung axle lowers ground clearance by bringing the axle closer to the trailer frame, which makes it easier to load and unload utility trailers. Discover more on this topic in our Overslung vs. Underslung Axles Blog.
Key characteristics of straight spring axles:
- Simple design: Easy to maintain and repair.
- Durable: Can handle heavy loads and rough terrain.
- Affordable: Generally more budget-friendly compared to other axle types.
- Less precise handling: May exhibit some body roll and sway, especially on uneven surfaces.
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Torsion Axles: A Smoother Ride
Torsion axles have gained popularity due to their superior handling and smoother ride. They utilize rubber torsion bars instead of traditional leaf springs to absorb shock and vibration. The torsion bars twist and flex, providing a more controlled and stable ride.
Torsion axles have unique characteristics that make each one original. One key difference in torsion axles lies in the arm angle degree. The arm, or “dog bone” as we like to call it, sits at six different angles. These angles depend on the trailer’s desired ride height, the terrain it will travel on, and the weight it will haul. The available angles include 22.5 degrees up, 10 up, 0 degrees, 10 down, 22.5 down, and 45 down. To learn more about torsion arm angles and their role in your trailer’s performance, check out the diagram here.
The brackets on torsion axles vary as well. These brackets can be configured as either low-profile or high-profile. Low-profile brackets align flush with the axle tube, which means the trailer frame essentially rests on the axle. High-profile brackets create a 1-inch gap between the trailer frame and the axle, increasing the trailer’s ride height by 1 inch.
These brackets differ not only in height profiles but also in orientation. You can weld these brackets with the long leg facing inward or outward. The long leg refers to the part of the bracket that encases the axle tube. Whether the leg faces inward or outward is another critical detail to consider when ordering a new torsion axle.
To learn more about these differences found in trailer torsion axles view the diagrams here.
Key characteristics of torsion axles:
- Improved handling: Reduced body roll and sway.
- Smoother ride: Enhanced comfort for passengers and cargo.
- Lower maintenance: No lubrication or greasing required.
- Higher initial cost: Typically more expensive than straight spring axles.
Shop Torsion Axles Here
Drop Spring Axles: A Lower Profile
Drop spring axles are a variation of straight spring axles, designed to lower the trailer’s overall height. This can be beneficial for trailers that are loaded and unloaded often and need to have low ground clearance. The axle housing is lowered, and the leaf springs are attached to the frame at a lower point. Both camber and spring set-up variables discussed above also apply to drop axles as well.
Key characteristics of drop spring axles:
- Lower profile: Ideal for low-clearance applications.
- Similar to straight spring axle performance and maintenance.
- May require modifications to the trailer’s frame and suspension.
Shop Drop Spring Axles Here
Choosing the Right Axle for Your Needs
When selecting a trailer axle, consider the following factors:
- Trailer weight capacity: Ensure the axle can handle the maximum weight your trailer will carry.
- Terrain: If you’ll be towing on rough roads or off-road, a more durable axle like a straight spring axle may be suitable.
- Ride quality: For a smoother ride, a torsion axle is a good option.
- Budget: Straight spring axles are generally more affordable, while torsion axles tend to be more expensive.
- Trailer height: If you need a low-profile trailer, a drop spring axle may be necessary.
Additional Considerations:
- Brake System: Consider whether you need electric or hydraulic brakes, and the number of brakes per axle.
- Hub and Bearing Assembly: The hub and bearing assembly is a critical component of the axle, and it’s important to choose a high-quality assembly to ensure long-lasting performance.
- Tire Size and Load Rating: The tires on your trailer must be rated to handle the weight of your trailer and the load you plan to carry.
Beyond the Basics: Other Axle Types
While straight spring, torsion, and drop spring axles are the most common types, there are other options available, such as:
- Independent Suspension Axles: These axles provide superior handling and ride quality, but they are more complex and expensive.
- Air Ride Axles: These axles use air springs to provide a smooth ride and adjust the trailer’s height. They are often used on high-end trailers and RVs.
By understanding the different types of trailer axles and their characteristics, you can make an informed decision that will enhance your towing experience.