Trailer Dimensioning

[Grahame Collins]

I should know this ,but hey its been 25 years but trailer dimensioning,it it done by inside dimension?

For instance is our Std 8' x 5' trailer inside measure.
The new boss hashad a a flash of brillance and decided that trailer building would be a good fab project for us as, well as makeit for the school to use and hire out.

I need to sit down and sketch up something.

He envisages making it as a 8' x 5' box caged unit with overhead carry racks to take steel from one school shop to another- about a kilometre- material weights on the rack probably not exceeding 120 kgs.

There will be a set of gas cylinder racks as we will often need cylinders to be picked up. the must be transported standing up. Freight costs for our school are a killer being 40kms away from Mackay.So we have to do more with less money.

I am thinking a cylinder axle that should not carry say more than 500 or 600 kgs total weight. I have looked at the ADRs (thanks Yonee) and got under .75 tonne ,ie light trailer - a single axle seems reasonable.
Does this sound Ok or have I missed something bigtime ?

Any opinions or comments or alarm bells ringing?

I would like to cover all contigencies as my name wioll be on the manufacture docs. If its a goer I will post pics of the build.

Thanks
Grahame

[Charleville]

I am no expert but I know from my own home made box trailer construction and my experience with my factory made boat trailer, that a long drawbar to give you a long wheelbase sure makes backing the trailer a lot easier than with the standard short drawbars that are usually to be found on commercially made trailers.

ie Give it a long drawbar. and you will not regret it.



.

[Grahame Collins]

Just some more random thoughts on this.

The quality of the welding will have to be excellent. Knowing some won't be up to scratch, those who shall be welding will be procedure tested before I permit them to strike an arc on the trailer.

Quality forms a big part of the competency units so quality control and methods of quality assurance will be applied and adhered to.

Part of the exercise is develop a plan for the task utilising every step from reading the blue prints to final assembly.

Grahame

[Bazzmate]

I should know this ,but hey its been 25 years but trailer dimensioning,it it done by inside dimension?
For instance is our Std 8' x 5' trailer inside measure. . . .

Inside or outside measure is all mind over matter . . . If you don't mind, it doesn't matter
Do whatever is the most economical (e.g. less wastage and the least labour intensive). It might be better to go 8'x5' (or metric equivalent) inside measurment but make it a couple of mm larger than a standard sheet of metal flooring so that you can just drop the floor in with little or no cutting? Accordingly, there would be miminal wastage on the sides and ends also.
That's my amatuer guess anyway as I only have experience from a non-standard size (1250mm Wide- inside) trailer build and the additional cost and time that an extra 50mm of width produces.
Cheers

PS - looking forward to the photos!

[ian]

The new boss hashad a a flash of brillance and decided that trailer building would be a good fab project for us as, well as makeit for the school to use and hire out.
He envisages making it as a 8' x 5' box caged unit with overhead carry racks to take steel from one school shop to another- about a kilometre- material weights on the rack probably not exceeding 120 kgs.

Graeme

some considerations for you

Trailer size -- for me the "critical" measure would be how easy is it to fit standard 8 x 4 sheet materials inside the tray

There will be a set of gas cylinder racks. They must be transported standing up. -- for me this says BRAKES

I have looked at the ADRs (thanks Yonee) and got under .75 tonne ,ie light trailer - a single axle seems reasonable.
Does this sound Ok or have I missed something bigtime ?
do you / will the school you have control over the towing vehicle?
do you / will the school have the knowledge to always load the trailer in a way that keeps the hitch load -- I hope that's the right term for the vertical weight on the towing point -- within the allowable range for the towing vehicle?
given my experience of school organisations and their often very limited knowledge of matters outside the curicullum, I'd opt for dual axles so the trailer is as far as possible "self balancing" with minimal load on the jockey wheel

[jatt]

"I'd opt for dual axles so the trailer is as far as possible "self balancing" with minimal load on the jockey wheel " Me too. It doesnt have to be built as heavy as a builders trailer. Personnally I recon u get less rocking effect on the trailer (and of course the tow vehicle when carrying lengths of stuff. Ok loaded up that will probably put u over 750 Kg, but I think its well worth it. Recon when empty the trailer would be able to be pushed around without the agro of digging the jockey wheel into the mud and giving u the sh*ts. Must admit I do like a trailer thats sheet floor is welded down the centre and folded up the side. Reason --- in the corners of the tub theres a 90 deg fold instead of a point where the water gets in and starts rusting the metal. If of course u have a sheet folder in the shop thats big enough to do this.

[Bushmiller]

Grahame

A trailer over 750kg aggregate weight requires a minimum of over ride brakes on at least one axle. (Over 2T agg weight it requires brakes on all axles and over ride is no longer sufficient.) Brakes add considerably to the expense. Probably double the cost.

I agree entirely with the long drawbar comments, but as the drawbar is extended it has to be correspondingly stronger, but not a big issue.

An 8 x 5 trailer I would expect to have a tarre weight of 250kg, which leaves 500kg for the load. A modest trailer load of sand or gravel probably weighs 2 tonnes An 8 x 5 tailer loaded up and struck (leveled) with 1.8 m3 of sand would weigh around 4 tonnes plus the weight of the trailer!

My point here is to consider what it will be used for and how easily it can be overloaded, particularly if it is to be used by all and sundry.

Regards
Paul

[Grahame Collins]

We have decided on a simple box with no cage and just some detachable steel racks.
It will be marked for max load.Definately not a loaner to say some teacher who is doing some concreting on the cheap.
The hire trailer the boss was talking about is a mobile BBQ trailer say for hire to Apex ,Lions and other service clubs, sporting clubs ,company xmas picnics that sort of thing

The boss wanted to cut costs by using crap from the wreckers.
If mt name is going on it i want new parts.

I reckon the steel will cost more than the hardware.

Grahame

[ian]

We have decided on a simple box with no cage and just some detachable steel racks.

Grahame
out of interest -- how will you carry the gas cyclinders in a simple box with no cage?

[Grahame Collins]

Easy.
Rings tacked on the floor to suit each diameter and an upright for each cyl, half ring on the top part of upright and chained for the rest of it., or similar on a headboard arrange ment

Cheers