4 Quick Reasons on Why Shackle Suspension Is Better On Box Trailers

4 Quick Reasons on Why Shackle Suspension Is Better On Box Trailers

As manufacturers of Heavy Duty and Light Weight Box Trailers, we thought it was necessary to help clear the confusion between Shackle Suspension and Slipper Suspension.

Many people do not know that there are different types of suspension on the market. The two main types of suspension used on your common Box Trailers are Shackle Suspension and Slipper Suspension.

So what’s the difference between the two? Why is one better than the other? How do I know if a trailer I am looking at has Shackle or Slipper Springs? If you have just started researching trailers or you are in the last stages of making your decision about which trailer you are going to buy. Here is 5 main points of difference between the two and why we choose Shackle over Slipper. Let’s take a look at each one.

First, let’s take a look at the two different types of springs.

Shackle Springs (Eye to Eye)

What are they?

  • Eye to eye (shackle) springs. The traditional leaf spring, these have both ends coiled in an ‘eye’ into which a bush is placed. The front of the spring is held in a ‘hanger’ while the rear swings on shackle bolts and plates around a rear hanger.
    They’re common in a multi-axle configuration, since the load can be transferred when one axle is carrying more of the weight (such as crossing kerbs) so that it’s more evenly spread.
Trailer Guys Shackle Suspension

Trailer Guys Shackle Suspension


Slipper Springs

What are they?

  • Slipper springs. Simple and long wearing, slipper springs have an eye on one end, while at the other end the open leaves form a ‘tail’ that slides in a hanger welded to the trailer chassis. They’re a low-cost solution to multi-axle trailer suspension as they can be joined sequentially or attached as individual sets, but these do not transfer the load between axles and have a lower load rating.
Slipper Spring - Box Trailer

Slipper Spring – Box Trailer


Now that we know the difference of the two let’s get to the 5 quick tips on why Shackle Suspension is better than Slipper.

1) Noise

Shackle Suspension is quieter on the road:

Shackle suspension use nylon bushes in the Eyes of the spring to allow a greaseable bolt to be used when mounting. This allows grease to be applied which reduces friction and wear to a certain extent. This bush becomes the cushion between the bolt and metal spring which minimises any hard banging of steel on steel when you’re carrying your load.

These nylon bushes will need to be maintained and serviced, but a well maintained trailer will last for many more years then not.

2)Load Transfer

Shackle Springs assist the driver whilst carrying heavy loads:

The driver when towing any trailer is a very important factor when towing heavy loads! Shackle Springs do four main things:

  1. Resiliently support vehicle, protect driver and load from damage by road shock
  2. Resiliently control brake and torque applications
  3. Transfer load share between each other to ensure you and your load are safe
  4. Act as structural members to position axle, both lengthwise and crosswise, with regard to chassis frame

In easy terms the springs cushion brake and acceleration Torque Reactions.

3) Wear & Tear

Shackle Plates and Eye Bushes Save Your Chassis:

Yes, it may be cheaper to purchase a trailer with slipper springs, but…

if you think about the longevity of your box trailer, we are sure you will choose to replace Shackle Eye bushes and bolts. Rather than repairing the Steel on Steel wear and tear that a slipper spring can produce.

For example, when a Box Trailer is running Slipper Springs and has a load in it, that load compresses the springs and the ‘slipper’ part of the spring ends up constantly rubbing up hard against the chassis. Over long trips with heavy loads this causes the slipper spring and chassis rub together over long periods of time causing a lot of heat and friction in one small area. Eventually the spot where all of that constant friction has been. Will need to be repaired or replaced due to the friction of two metals rubbing together.

Shackle Suspension eliminates the Steel on Steel friction. By using the nylon eye bush and the small amount of movement that the Shackle Plates allow when a trailer is loaded.

4) Eliminate Springs Popping

Shackle Springs Will Not Dislocate

Shackle Springs eliminate the chance of a spring popping out of it location as it is attached to the chassis hanger by greaseable shackle bolts. This gives the Shackle Spring a ‘Positive Location’ to the Chassis and eliminates the spring from moving TOO much.

Slipper Springs on the other hand have the ability to float around in ‘No Mans Land’. They have no ‘Positive Location’ to the chassis. Yes they have a square locating hanger but they can move about freely. In some cases it is possible for the slipper springs to ‘Dislocate’ from its hanger!

If the trailer is hit from behind or reversed up a curb to fast. This jolt from behind will assist the Slipper spring to move too far forward and fall out of its locating hanger.  Leaving you in a spot of bother.

Shackle Suspension Is The Pick:

Trailer Guys Box Trailers are designed for the Tradesman and the Weekend Warrior. Both our Heavy Duty and Light Weight Hot Dipped Galvanised Box Trailers are built with ‘Shackle Suspension’.

A lot of buyers get overwhelmed with the amount of information that can be found on box trailers and suspension on the internet. As long as you know what information is important to your wants and needs. You will be on track to understanding and purchasing your box trailer.

Have you ever thought about what suspension you should have on your trailer? Has this impacted on your purchase decision?