It just got harder in Oz

[MickinOz]

Making your own chassis just got harder here in Oz.
You will have to specify and calculate the strength of the drawbar, or test it.
For example, a "very small trailer" is one that weighs max 750kg loaded and doesn't need brakes.
You will have to either calculate or prove empirically the draw bay will stand longitudinal tension and compression of 1.5 x 9.81 x 750 = 11 metric tonnes.
It will also have to withstand transverse, upwards and downwards thrust of 0.5 x 9.81 x 750 = 3.7 metric tonnes.

To put it in American/English terms, if you build a trailer that will max out (trailer plus load) at 1650 pounds, you will have to prove, by way of approved calculations or actual test work, that the drawbar does not stretch or bend under 24,200 lbs of longitudinal tension or compression, and under 8093 lbs of transverse or vertical up/down thrust.

 

[twisted lines]

I think I would stop building trailers and build a test stand, for hire!
Sounds easier.

 

[Ottsville]

I think I would stop building trailers and build a test stand, for hire!
Sounds easier.

Or market a drawbar kit with an engineer's stamp on the paperwork.

 

[Tony Latham]

Good grief.

I live in a large county with few folks. Three hours from the nearest box store. But it's DIY trailer rich and I have never seen a trailer beside the road that the tongue failed.

Tony

 

[bdosborn-SMB]

Just curious, is there a problem with trailers failing and causing damage to other motorists in Oz?

Bruce

 

[MickinOz]

Just curious, is there a problem with trailers failing and causing damage to other motorists in Oz?

Bruce

Good grief.

I live in a large county with few folks. Three hours from the nearest box store. But it's DIY trailer rich and I have never seen a trailer beside the road that the tongue failed.

Tony

I've never seen a trailer on the side of the road with a failed drawbar either. I have seen two red bolt together trailers that had drawbar issues, and one boat trailer where there was no anti crush tubes and through bolts holding the hitch on. That one finally pulled the short bolts through the top of the tube, since they were only going through the top plate.
Usual problem is failed wheel bearings - a straight out maintenance issue.
Just the usual Gummint BS. They say there are standard calcs you can use, but I haven't researched those yet. It's not very clear yet, but I say to people here in Oz who are building - get her done now.

 

[MickinOz]

BTW - Our European brothers have been dealing with a similar situation for years.
That is why so many of them look around for an old caravan chassis or similar, rather than build their own.

 

[bdosborn-SMB]

We're probably right behind you in regulating trailers. I bet California has or will have similar requirements soon.
Bruce

 

[twisted lines]

I actually Passed one that failed this summer.
Pickup bed trailer, with a very shiny harley & Ape hangers, Bike was tied tight.
Two guys standing their staring at it. I didn't stop to help

 

[kennyrayandersen]

Rules by folk who understand neither physics, nor engineering. A simple free body diagram (where loads and reactions are expressed) will reveal you can't even get all that load even if your trailer gets flung off the side of a bridge and it's hanging over the the water!