Thread: Stub axles and using RHS for the axle

On lite trailers used 4 mm RHS for axle. The weld inside 5mm makes it harder to fit

Spent more time making sure the stub was lined up than actually welding it. Wrapped a damp cloth around the threadded end. Recon a bit of preheat where its gunna be welded would be a goer due to the thickness of the bar.

Legal? Assume so.

On bigger/heavy duty trailers solid axles would be better.

Do the axles actually take any load or are they just there? ie, if you have a stub welded into the RHS, then the spring gets bolted to the area where the stub fits into the RHS then the load is transferred from the wheel to the stub to the spring to the frame, the axle tube doesn't do anything except maintain the straight up and down motion in the spring system? If you know what I mean?

I am sure that there are states that this is illegal. But for the life of me I cant recall which ones. Before you do it definitely call your local rego people to check as it will get knocked back at rego if its not legal.

The other thing is why bother. Just work out your length and get one from the trailer people.

It's quite legal, and is in fact how some axles are still made today. A QLD based company actually make some of their heavier axles this way, and they're an ADR approved manufacturer for over 4500Kg. The trick is to have the stub axle inserted far enough into the tubing so as not to crush the tube with the U-bolts. Also, the stub axle needs to be a pretty neat fit into the tube, again so as not to crush the tube. Once you put a kink into the outer tube, it will dramatically reduce its strength, so it's critical that the correct sized U-bolts, tube and stubs are used.

What about welding the stub to the outside of the shs to make a drop axle . As thinking of building a 4x4 trailer , have the wheels and lowering the load - tractor . For stability off road can i do this? Thanks bob

Hey Bob.
While it's quite acceptable to have an Overlay axle (stub welded on top of the main beam) or a Drop axle (solid piece welded between beam and stub, usually either 2.5" or 4" centres), it's not something I've seen or would recommend to be done using SHS as the axle beam.

The main issue I can see here is ensuring the integrity of the job.

A manufactuer with access to an engineer, testing facilities and certified welders...... no problem at all.

But a back yard fabrication...or even an uncertified workshop fabrication and I would have serious reservations.

Remember you the manufactuer of that trailer are responsible for the life of the trailer.

Unless you have " significant engineering resources" I don't think it could be recommended.

Then there is the big question...WHY.

Axles are reasonably cheap and easy to just go and buy.....even if it is weird....most places will supply to order.
And yess overlay axles are easily available straight off the shelf.

cheers

While it pains me to agree with the above, I only do in part.

There is no requirement for any trailer manufacturer to have an engineer, testing facilities or certified welders.

Some "backyard" facilities have better qualified people and better equipped workshops than some commercial businesses.

"WHY?"
Because some of us can!

there may be no legal requirement but if things get to court and there has been a component failure.

Having proper facilities will be assumed as part of a duty of care, and from an informed insurers point of view.....you would be hesitant to underwrite someone without proper facilities.

Of course there will be those of us, well resourced and skilled in certain areas........but this would be the extreeme minority.



But again it comes down to.....WHY would you.

cheers