All Aluminium large trailers

VBRAB
"Surprisingly the engineer advised not to fully weld, but to weld along edges, but not across the flanges. "
This is not surprising at all, welding across the flanges will induce failure quicker than you can blink.
Aluminium is very very very flexible unlike steel which is only very flexible. The trouble is Aluminium work hardens as it flexes. Hardening is compounded by the Heat Affected Zone of welds. If you weld across the flange at the transition those welds will crack quickly. By extending the decking 700mm onto the a frame you will be helping move the transition from a location of beam junctions to mid span of beams. Ensure that the front storage box is tied back rigidly to the main box.

Although you have lengths running from hitch to rear, there will still be a transition between the boxed section of trailer (very rigid due to triangulation of box) and the 180mm high chassis rail.
I can see that the A-frame and chassis are one unit but that does not preclude the differential in flexing between boxed in main section and drawbar section.
I would think you will find that transition your weakpoint and that the use of trussing may be advised.

If you use a 50mm hitch at a height of 450-460mm the trailer will not meet Australian Design Standards VSB1. They stipulate a hitch height of 270mm to 350mm for 50mm ball couplings. So either alter the height or DONT use a 50mm ball coupling.

S

Figured that welding on the flanges would weaken the profile, but I wouldn't have thought of that myself (having only previously built in steel), so at least somebody knew what they were doing.
I expect the welder would have known also, as he didn't query it.
We were looking to integrate the draw bar box into the main structure, but at this stage we are finding time against us to complete, so looks like the floor will be run through, and that will be welded to the front wall of main box and the draw bar.
Time permitting, the front wall and the floor would have been the floor and back wall of the box.
Looks like it is going to be there to be done "later", as at this stage we need a working van to move things outback by a certain date.
Have been looking to see if there is any benefits in more gussets across some of the intersections of main bearers, definitely keen to rigid it up as much as possible.

Honestly mate I would run the tension band steel truss past the guys
Two lengths of 75x5mm FMS tie it from the leading axle mount to the hitch along each a frame section - you can then apply tension as needed

S

Will definitely bring that option up when I get to town after next week.

I now have the word from the engineer on trailer ball heights

VSB1, 16.4.1 – 50mm Ball Couplings:
Ball couplings on towbars are required to be installed so that the height of the centre of the body of
the ball coupling is between 350mm and 420mm from the ground when laden (Refer to ADR 62/01).
Alternatively, if complying with the requirements of ADR 62/02 the maximum height of the centre of
the body of the ball coupling may be increased to 460mm. However, the ball may be installed at
any other height, provided it is also capable of being adjusted to at least one height within the 350-
460mm range.

He suggests changing to a swivel pin hitch on to the trailer which I hadn't seen, but which appears to get around the issue of ball heights, as well as giving more control and evidently being easier on the trailer.
Attachment 133251 Sorry small pic, but sure others will know of these.
So maybe that is a solution. (more $'s.)

My reading of VSB1 is that the quoted legislation is specific to 50mm ball couplings
Hence my suggestion to simply run a 70mm coupling?????

Rated to 6T that will give you plenty of headspace still in the same general format of a ball
coupling. Hell you could also run a pintle setup and keep it Landy-esque !!!!


https://infrastructure.gov.au/roads/...B1_JUN2009.pdf

Page 29 - 16:4:1


Kind regards

While the thought of a bigger ball getting around the strict requirements appeals, I am keen on anything that might also improve the tow and reduce stress on trailer frame (if one can believe all the sales hype).
I also like the swivel hitch as it has 6 bolt holes, and as bolting to Ali am happier for spreading the strain through more holes.
And if the changed coupling means no argument about where the tow height is, that sounds like it would work to allow placing the hitch at strongest point regardless of height.

Quote:

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Originally Posted by roverrescue

My reading of VSB1 is that the quoted legislation is specific to 50mm ball couplings
Hence my suggestion to simply run a 70mm coupling?????

Rated to 6T that will give you plenty of headspace still in the same general format of a ball
coupling. Hell you could also run a pintle setup and keep it Landy-esque !!!!


https://infrastructure.gov.au/roads/...B1_JUN2009.pdf

Page 29 - 16:4:1


Kind regards

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Sounds like a valid argument.
Good luck with the project!
Im sure you will get it all to work well!
S

Quote:

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Originally Posted by roverrescue

Sounds like a valid argument.
Good luck with the project!
Im sure you will get it all to work well!
S

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Seems like I got the holes wrong and it is just 4 holes, so just a standard mount pattern, but builder feels that because he doesn't have to make placement of hitch fit to AD requirements that might leave him a bit more leeway where to place the hitch and enable better options to gusset in the mounting plate. We are going for strength/bracing over style or aesthetics.
Managed to get the hitch (Hitchmaster DO35 V3) with brake handle, and delivered for $475 in Perth, and reports reckon they are a good thing, so I hope it adds to the towing comfort.

Quote:

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Originally Posted by vbrab

Seems like I got the holes wrong and it is just 4 holes, so just a standard mount pattern, but builder feels that because he doesn't have to make placement of hitch fit to AD requirements that might leave him a bit more leeway where to place the hitch and enable better options to gusset in the mounting plate. We are going for strength/bracing over style or aesthetics.
Managed to get the hitch (Hitchmaster DO35 V3) with brake handle, and delivered for $475 in Perth, and reports reckon they are a good thing, so I hope it adds to the towing comfort.

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Nice hitch......

I also had elec over hydraulic brakes however Disco 1 calipers don’t have the provision for cable hand brake, I’m assuming the alco calipers do??

I installed a inline Ball valve and a button to activate the hydraulic pump on the draw bar as my handbrake. Same setup as Kimberly Kampers use. Had wheel chock’s just incase but the hand brakes never really lost pressure.

Either way I believe handbrakes are only recommended I.e. not mandatory.