7 Things You Need to Know About the Trailer Axle

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A trailer, even the custom-made ones, needs regular maintenance and care. You need to ensure that all its parts are in good working condition and well-maintained. However, among these parts, you must pay special attention to the axles.

Any wheeled vehicle with a problem with the axles will have difficulty moving. In turn, an unmoving trailer could mean a significant loss for your business, especially when the vehicle is loaded with cargo.

Axles serve as the central shafts connecting the trailer’s body to the wheels. Many of the problems with axles root from failing to keep them greased routinely.

With that said, here are the top 7 things you need to know about trailer axles and how to keep them in top shape.

trailer axle with spring


1. The Types of Trailer Axles

2. Single vs. Dual Trailer Axle

3. How to Determine Trailer Axle Rating?

4. How to Measure Trailer Axles?

5. How to Check Trailer Axle Alignment?

6. How to Repair or Correct a Bent Trailer Axle?

7. How to Install an Axle on the Trailer?


1. The Types of Trailer Axles

Trailer axles are typically categorized into two types – torsion axles and spring axles. These two types have similar jobs but differ in how they cushion and suspend the trailer load.

a. Torsion Trailer Axles

These axles do not rely on metal trailer springs. Instead, the torsion arms are secured to the inner core piece placed inside a square tube, containing a series of lengthy rubber cords.

The torsion axle also has a cross-section. Here, the torsion bars connect the inner square piece to each wheel, while the steel tubing comprising the outer square is attached to the frame.  

When the trailer wheels go on an uneven or bumpy road, the rubber cords get compressed by the inner bar throughout the bearing surface.

Torsion Trailer Axles

Some of the plus points of using torsion trailer axles include the following:

  • They have more extended warranties than leaf spring axles.
  • The construction made of a cross-bar style welded directly to the frame makes the material stiffer and more sturdy.
  • The torsion bars are adjustable, making it easier to change the ride height.
  • Trailers with this type of axle are quieter.
  • They provide independent wheel suspension.
  • There are no contact points done from metal to metal.
  • They are simple to maintain since the design is maintenance-free. You only need to grease the wheel bearings, and you’re good to go.

The downside of this type is that it’s designed to undergo a total overhaul. So, you will need to cut off the axle to have a major repair done. On the other hand, repairs seldom happen due to the axle’s simple construction.

b. Spring Trailer Axles

This type of trailer axle is more common and easily recognizable, especially to those who have been around motors for a long time. They are made from flat spring stock stacked according to the trailer’s load.

Unlike in a pickup truck where the spring is over the axle, the axle is suspended over the springs in trailers. As a result, the lower trailer gains more excellent load stability, and the trailer’s height decreases. This makes it easier to load and unload in the trailer.

Spring axles are easy to maintain and inexpensive – the top reasons they are among the popular choices in the suspension systems of a trailer. You can even have them shipped with pre-attached and ready-to-install curved spring plates.

They can also provide efficient applications, including most commercial trailers, dump trailers, and utility trailers.

Here are some of the benefits of using spring trailer axles:

  • You don’t have to repeat the welding process when replacing the entire trailer
  • Manufacturers will find them easy to install, plus they are inexpensive.
  • They offer tried and tested tire wear, especially on trailers that require multi-axles.
  • You can have the axles undergo extensive maintenance by changing the problematic parts and not the entire axle.

2. Single vs. Dual Trailer Axle

You need to look under the trailer to know if it is a single axle or double axle. If it has one set of wheels, it is a single axle trailer, and it is a double or tandem axle trailer if it has two sets of wheels.

Single Axle Trailers

They are easier to maneuver since they are smaller than tandem axle trailers. This type is best suited for those without sufficient parking space to allow the trailer to wiggle.

single trailer


It also consumes less fuel due to its size, making the trailer easier to tow with adjustable towing positions and lighter weight. A single trailer axle has fewer tires, meaning that you need to allot less for the cost of replacement and maintenance.

On the other hand, the small size of single axle trailers restricts their moving and storage abilities. Also, since only two tires handle the weight of the load, the tires can easily get worn out, especially if you often put heavy load and move a lot.

This type operates with a single axle connected to the wheel. It can be directly attached to the trailer bed using supporting hardware or clamps or attached via the springs.

Here are the advantages of using single axle trailers:

  • Less expensive to buy
  • Require a set of brakes, bearings, and tires
  • Can park in a tight spot
  • Easier to control than a tandem trailer of the same size
  • More economical to tow since the trailers weigh less
  • More efficient for short distances and in towing light loads

Here are the disadvantages of using single axle trailers:

  • It won’t provide enough stability in riding, and you will find it hard to cushion the load if the trailer doesn’t have suspension.
  • The trailer will start wobbling once your tire gets flat while on the road and driving.
  • The tires will easily get worn out since they are carrying heavier loads.
  • They don’t require brakes to be installed on trailers below 750kg GTM. This is risky and makes the owner responsible for what to do to ensure the ride’s safety.
  • You cannot haul a bulky payload that you can put in a dual axle trailer, even when they are of the same size.

Dual Axle Trailers

Commonly referred to as a tandem axle trailer, this type uses two axles positioned near each other, ensuring the cargo’s weight load level distribution. Here, its two sets of axles are placed behind one another.

As a result, the trailer can move at high speeds with stability and carry more weight even when driven on highways due to the extra tires. This means you will have more room for the load you need to haul since the payload capacity is generally higher.

Tandem trailers are considered a good choice for expanding businesses since they can carry heavier loads. This will ensure that you can use the trailer for a long time, even as your business continues to grow.

2 axle trailer


It may be more expensive upfront, but since you can use it for a longer time, you can consider the initial costs you paid for the trailer as an investment you will benefit from in the long run.

However, tandem axle trailers require level towing, which isn’t necessary with single axle trailers. It would be best to level the load all the time because not doing so might take a toll on the tires as one set of axles can suffer from wear and tear.

Here are the advantages of using tandem axle trailers:

  • These are less prone to wobbling and will bounce less as long as the load is placed correctly.
  • These trailers are safer. Trailers with 2000 kg and above are required to have brakes on each axle, and the law also requires brakes to be installed by trailers of this type carrying 750 kg to 3000 kg.
  • You can easily change a flat tire without too much trouble and the need for a jack.
  • They have better suspension systems.
  • You can count on the trailer to move more stably, even along the highway.
  • This type ensures safety when towing over long distances.

Here are the disadvantages of using dual axle trailers:

  • They require more maintenance.
  • They need more fuel since they weigh heavier than a single axle trailer.
  • They can get challenging to maneuver, but this will depend on the brand of the trailer axle.
  • It is more expensive.

3. How to Determine Trailer Axle Rating?

The rated value of the load determines the rating of a trailer axle it can carry. This makes it easier for users to choose the more suitable trailer axle, depending on how they intend to use it. Different methods are being followed in assessing the trailer axle’s weighted grade.

Moreover, this rating pertains to the allowable weight you can place on each axle. So, the automaker of the trailer determines the weight limit and not any other governing bodies. This makes the manufacturer responsible for answering queries about the trailer axle weight rating.

The weights may not always be different, but the individual ratings depend on the rear and front axles. So, for example, if you are looking for a trailer capable of carrying 2550 pounds per axle, you have to look for a weight rating with one number listed, which is 2550 pounds.

trailer axle

You will often find the axle’s weight rating on the trailer’s primary identification sticker plate, located on the axle beam or a sticker plate. You will find the information valuable unless you have bought a second-hand trailer whose axles have already been replaced.

You can also get the rating by getting information about the axle diameter. Typically, a 6K or 7K weigh rating is given to an axle with a 3-inch diameter.

On the other hand, an 8K rating for an axle with a 3.5-inch diameter. There are also rare occasions when the 3.5-inch diameter is rated low at around 3500 pounds. However, the weight capacity of a trailer is more difficult to estimate. Trailer manufacturers differ in the safety margins they use in giving ratings to their trailers.

4. How to Measure Trailer Axles?

Measuring the trailer axles can come in handy when getting replacement parts. You need to know two vital measurements: the distance between the hub face or wheel hubs, tire centers, track width, and the measurement of the spring center.

If you get the measurements of the spring center right, you can quickly compute the measurement of the hub face. This will allow you to order a replacement for the damaged axle readily.

Measuring the Hub Face

Measuring the Hub Face

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  1. To reach the hubs, you need to remove the wheels and tires from the trailer axle. Lift the trailer axle using a jack and loosen the nuts using a socket wrench.
  2. Ensure that the metal end of the tape measure is hooked at one of the trailer hub’s outside faces. It is better if you have someone to assist you. Ask them to hold the end of the tape measure while standing at the end of the axle.
  3. While standing at the opposite hub, carefully pull the tape measure through the axles towards your direction. Hold the tape measure in place once you reach the hub’s outside face. It is vital that the tape measure is not positioned at an angle or twisted. It must run straight throughout the axle to get the correct measurement.
  4. Once it gets to the edge of the hub’s outside face, the number on the tape measure pertains to the hub face measurement.

Trailer axles usually use inches as a unit of measurement. Use the number you’ve gotten in buying a replacement axle.

Measuring the Spring Center

  1. Find the edge of one of the springs nearest the hub’s end and place your tape measure’s metal hook on that spot.
  2. Position yourself at the other side of the leaf spring as you pull the tape measure in your direction until it reaches the opposite spring’s inner edge.
  3. The spring center measurement is the number indicated on the tape measure where it touches the inner part of the spring where you are positioned.

Measuring the Broken Axle

  1. Take the measurement beginning at the middle of one spring to the middle of the other spring. Ask an assistant’s help to get this done right. Get the measurements of the hub face of the broken axle and take note of the number.
  2. Hold the tape measure’s end in the spring’s center on the part of the axle that is not broken. Pull the tape measure out to the good hub’s outside face and take note of the number.
  3. Double the measurement you’ve got for the spring center and add it to the spring center measurement. The result corresponds to the measurement of the hub face.

5. How to Check Trailer Axle Alignment?

The trailer’s axle may get misaligned or damaged due to many factors. You will notice the problem when the wheels get scrapped and dragged to the ground when moving. To prevent any mishaps from happening, it is best to check the trailer axle alignment regularly.

The first thing you need to do is to check the suspension. To do this, make sure to look for holes that have become bigger, causing things to move in the wrong direction.

To check the axle alignment, measure one of the wheels’ centers to the coupler’s back’s center. Then, measure the center of the other wheel. If the results are not the same or seem off, you can make the suspension loose so that you can straighten the axle.

6. How to Repair or Correct a Bent Trailer Axle?

You can repair a bent axle as long as you have welding skills by doing the following:

  1. Use a jack to lift the trailer and remove the tires. Use a socket wrench in making the U-bolts loose. Once the shackle springs no longer hold the axle, you can lower and support the axle using more jack stands.
  2. Check where the impact happened indicated by an indent after lying an 8-foot level on the axle. Spin the axle several times as you take an accurate reading using the level. Mark the point of impact with chalk and ensure that you have the right spot.
  3. Rotate the axle in the opposite direction to get the impact spot marked. Cut into the bend’s bulging side halfway around the axle using a grinder with a thin metal blade. Place a hardwood block on the cut’s side and drive it close using a heavy hammer. Make sure the axle remains straight using the level.
  4. Use a wire-feed welder on several spots of the closed cut. Once cool, use the level again to ensure that the axle is straight. Modify the repair as needed.
  5. Make the metal smooth by grinding before spraying it with long-lasting black paint to prevent the formation of rust.

7. How to Install an Axle on the Trailer?

Follow these steps to install the axle on the trailer:

Install an Axle on the Trailer

  1. Lift the trailer using a jack and put the axle and frame on jack stands.
  2. Use a tire iron to remove the tires and place them on the side.
  3. Loosen the U-bolts.
  4. Use a brake line wrench to disconnect the brake line from the axle.
  5. Remove the bolts of the forward mount.
  6. Take out the axle from the trailer. Ask someone’s help since the axle is heavy.
  7. With the help of your assistant, slide the replacement axle in the same spot where you removed the old one. Lift and support the new axle as you make things tighter.
  8. Secure the leaf spring back to the mount of stock.
  9. Position the axle to the leaf spring, make sure everything is aligned, and tighten all the U-bolts.
  10. Use a brake line wrench to tighten the brake line of the trailer.
  11. Use a tire iron in reinstalling the tires. Remove the jack and the stands once done.


Having the basic knowledge about trailer axles, including measurement, maintenance, and replacement, will save you money in the long run. You only have to make sure that you have the tools and equipment to get things done.