Thread: trailer design help

Hi andre,

More info needed. Is it to be registered for the road? What is it going to carry? How high do the sides need to be?

Drawbar should be 75 x 50 x 3 and chassis should be at least 50x50x2mm IMO.

cheers

the trailer is going to be road legal.it is going to carry my homebuilt tractor to take it to shows the tractor weights about 400-500kgs so i wanted the trailer to be light as possible to avoid the need for brakes . the sides are not a concern as all i need is a tie rail it need to be bigger than 8x5 because my tractor wont fit on 8x5 as it is 8x5 thus the reason for 6x10 i havent got any design yet just tossing around how to build it hopfully this year

all the best andre

If you check out this link of my trailer build;
https://www.woodworkforums.com/f184/p...-bobcat-72023/

The total weight for my tandem with brakes was 320kg.

You could easily build it using the above materials and still come in under 250kg easy. Dont forget that the weight transfer under emergency braking will go to the drawbar so it needs strength. You can save weight by using light material on the non chassis parts but IMO the sizes I have mentioned are the minimum for the chassis.

Yonnee will come along soon and give some advice as well.

For me, build it strong and put brakes on it....life is much nicer with brakes!

Hi Andre, and welcome to the trailer bit.

Firstly, your question of legality of size. Your size restrictions are 2500mm outside width, including mudguards, wheels and tyres... basically the outer-most part of the trailer, including the rope you tie to the rails cannot be more than 2500mm (8' 2-3/8" for those who work in old money) So, less standard guard width; 460mm (18"), your chassis can be up to 2040mm (6' 8")
Length... how's 12.5 metres grab you? Or 19 metres including your tow vehicle. Need I say more.

Next, the material. I don't particularly like angle iron or 'C' channel for large trailers. People use them with the justification that they're lighter weight material. However, the extra bracing required to stop them from flexing too much adds as much, if not more weight, than if you'd used RHS or SHS in the first place.

Originally Posted by welder

...so i don't need brakes...

Originally Posted by welder

...to avoid the need for brakes.

These very words will be reverberating around your head as you stand beside your car, its nose into an immovable object, and the trailer's drawbar on the back seat. And it wont be your fault... A down hill run, a sweeping bend that tightened quicker than expected, a fresh shower of rain, and last weeks diesel spill. But legally you'll be right, because your trailer and tractor only weigh 749Kg.

Just food for thought...

Having brakes on the trailer makes for much more peace of mind towing, particularly if the road conditions worsen, and gives you more scope for using the trailer in the future. I know I'd feel much better if one of my kids cars breaks down late at night, and I was able to go and fetch it, bringing it home safely rather than leaving it out all night, only to find a burnt shell in the morning. It's part of the reason for building my own car trailer in the near future.

Originally Posted by welder

the sides are not a concern as all i need is a tie rail...

This actually should be a concern, as it gives the trailer immence strength lengthwise. Example. Take a piece of 3" x 1" aluminium extrusion, 10 foot long, and sit each end up on a pair of saw horses. How much weight would you reckon it would take to bend it in the middle? Now sit your extension ladder on its side on the same saw horses. What weight do you suppose that will hold?
The trailer's sides dont need to be sheeted in, just the frame work will do... and it only needs to be as little as 8" high, and even better if one section is triangular.


I hope this hasn't scared you off. You'll have fun building it, almost as much as the tractor...

Speaking of which... let's see this tractor. C'mon... pics up.

Cheers,
Yonnee.

now some questions about brakes what do i need to set up electric brakes i am thinking of using override brakes also once the trailer is registered can i just re register it like a trailer without brakes.

thanks for the help Andre

If the trailer has brakes at first rego,then as far as I know it is registered as a braked trailer.

If your trailer falls under the weight requirement for brakes why put brakes on it .

Once its noted that there are brakes it needs to be inspected each year,where as an unbraked trailer dosent.

Also you will save yourself nearly $100 a year in rego costs.

Originally Posted by pipeclay

Also you will save yourself nearly $100 a year in rego costs.

Are you serious

It cost me $36.70 for my last renewal on my 10' x 5' fully braked tandem axle trailer down here in Victoria.

Interesting point. I can only confirm here in Victoria, once a trailer is registered, then no further inspections are required. It continues to amaze me why residents of NSW put up with being continually robbed by the RTA with both their Rego for vehicles and trailers.

Now, if you decide that you might require brakes on your trailer, it's much easier to first present the trailer complete with brakes fitted and working. If you register the trailer without brakes, and then add brakes later and want to increase the registered carrying capacity, then you'll probably be asked to obtain an engineers report to do so.

Other than the brakes on the axle, all that's required for Electric brakes on the tow vehicle is the controller.

well i talked to my dad and he doesn't want to pay extra money to register a trailer with brakes so i will build an 8x5 another question can i build the tray over the top of the wheels or does the tray have to sit in between the wheels

all the best andre

put brakes on it....life is much nicer with brakes!

I'm with Dazzler here. Bummer about your rego issues with a trailer. Aint complaining about paying my $36 bucks a year on the tandem.

Electric brakes --- on the trailer side of things, couldnt be easier. Dont think one has to worry about polarity issues when connecting up. When I hooked up a set I had 2 x green wires to contend with, if there is I must have fluked it cause they work.

Originally Posted by welder

well i talked to my dad and he doesn't want to pay extra money to register a trailer with brakes so i will build an 8x5 another question can i build the tray over the top of the wheels or does the tray have to sit in between the wheels

all the best andre

Andre
I'm sitting here gob smacked.

you want
to carry a 500kg load on a trailer that is as light as possible, but you don't want to fit brakes to the trailer because registration will cost a few extra dollars per year.

and now you want to mount the load as far above the gound as possible by constructing the load floor above the wheels -- what size wheels and tyres were you planning on using? those that match your towing vehicle (so you only have to carry one spare) or rims and tyres suitable for a small boat trailer that's only towed a few kms each week?

BTW
What is your towing vehicle?

Yes, I'm a little angry.
Your stated locaton is Nowra -- that means you're driving up and down the Princes Highway, which is not particularly flat or straight, and up and down the escarpment crossings (Kangaroo Valley, Macquarie Pass, Mount Ousley) often on a wet road. You may not have noticed, but the flatest grade on the escarpment is about 9% (1 in 11), most of the crossings have grades steeper than 12% (1 in 8). A heavy unbraked trailer in the wet, with the centre of gravity sitting at chest height, will be real fun to control down Camberwarah Mountain.


Before you get too advanced with your trailer, I suggest you find out what the insurance requirements are for your home built tractor.
Don't be surprised if it has to be registered before you can take it to a show -- just so you have third party injury insurance -- and also don't be surprised if you need public liability insurance as well.
Both of these insurances will likely cost a whole lot more than the little extra required to register a braked trailer.

Yeh... thank you Ian... was wondering when someone would actually add that expert advice... I'm glad I don't travel those roads... I wouldn't like to meet the vehicle when fully loaded if/or when a mishap were to happen.... my thoughts are always with being OVER safe.... with it comes respect for equipment & an incident free life of traveling....

yes i though of all those problems but i decided that if i need a trailer to move my tractor i will borrow my friends truck. but i am still not even close to starting the project i haven't even thought of what material will be needed so i got tons of time to change my mind.

OK, I've done a bit of investigation on trailer fees for NSW. Registration fees
The RTA charge you for the Tare weight of the trailer, not whether it's got brakes. If you can keep your trailer under 255Kg... even if you put brakes on it and register it to carry more than 750Kg.
If your trailer is between 255Kg and 764Kg empty, then you will pay the higher fee (3 times the price), irrespective of whether you have brakes on it or not.

So, it's really not going to make a difference to the price of your rego if you do have brakes on it, and legally you are required to have brakes if the trailer and the load you're carrying weigh anything over 750Kg, not only for insurance purposes, but the safety of other road users.