Thread: Sizes and other things

Wombat, is the trailer to be a tipper, how are you going to get the cars on and off, are the tailgates to be ramps, will you require a winch to assist loading, what is the tow vehicle? If a winch is required a longer drawbar will be needed. Min 8 feet long, going back about a third of trailer length,about 2'6"
Why not make the trailer a 9'X4'6'' that way the tailgate will help stop vehicle from rolling off unintentionally, the sides could be formed in 1 piece with a 3" lip at the bottom to give a 4'6" inside (no tight squeeze).
For the main frame I would use 50x50x2RHS front rear and sides, with 50X50X5 angle cross members, for the drawbar I would use 75X40 channel or 75X40X3 RHS connecting the drawbar to the spring hangers with 75X5 flat bar remembering to use 6mm plate for the coupling holder. I have a 6m trailer with this framing.
With this setup it could be turned into a tandem by replacing suspension and guards only. If you are going 8' try putting the numberplate on the tailgate by a hinge arrangement, so that if it is on the flat or an angle the number plate can still be seen.
Contact me for more details if required.
Kryn

Thanks Kryn -that gives me a starting point. I have folding aluminium ramps that I used to to get my current project onto a truck to move up from Brisbane - although not rated to the full weight of the car they are only 7 feet long so only half the weight was on them at any point in time. - I'll use those when needed.

The son's trailer has a hinged number plate holder - I was going to copy that.

I have a compact 12 volt winch that I'll work out some sort of removeable attachment for.

Tow vehicle with be a Toyota Land Cruiser

This might take a while... trying to describe this stuff without drawings is complicated.

Seeing as it's going to see occasional duty as a car carrier, I would make this trailer as a small, single axled car trailer, then clad it to be able to do double duty as a box trailer.
Starting with 1 x 8M length of 75 x 50 x 3.0 RHS (No idea where you'd find 75x40...), cut 2 x 3025mm for the drawbar, leaving a 1950mm peice for your rear cross rail. See if you can buy an off-cut (1 - 1.5M) of 75 x 50 x 4 or 5mm to use as a cross rail and upright half way along the drawbar as a winch post.

Attachment 171456

Next, an 8M legth of 75 x 50 x 2.5 cut to 2 x 2350mm for the chassis rails (this will give you a trailer 10mm longer than 8'), a 1425mm piece for the first centre cross rail, leaving an 1875mm piece fro the front cross rail. The rest of the cross rails would be fine in 50 x 50 x 3.0mm. 1 x 8M length would give you 3 x 1425mm pieces for this leaving 3725mm. I would run 10" (255mm) sides, giving you clearance to open most car doors, and filled dead level, 2450 x 1525 x 255 = 0.95M3. People will want to borrow the trailer, and you don't want to give them an opportunity to overfill it. So, 4 x 255mm uprights (one in each corner) and I'd also put a 1425mm cross rail between the two front uprights at 100mm off the floor to act as a wheel chock. The front tailgate can still open and close against it. The rest of the frame I'd do in 40 x 40 x 2.5mm. 2 x 215mm uprights halfway along the length, 2 x 2350mm between the front & rear uprights, welded on top of the centre uprights, and four diagonal braces, running from the top of the centre uprights, to the bottom of the front & rear uprights.

Rather than having to make the tailgate strong enough to drive over, simply put the hinges around the same way and have the tailgate removable. Put your hinged number plate mount and light under the rear cross rail.

Originally Posted by Yonnee

This might take a while... trying to describe this stuff without drawings is complicated.

Seeing as it's going to see occasional duty as a car carrier, I would make this trailer as a small, single axled car trailer, then clad it to be able to do double duty as a box trailer.
Starting with 1 x 8M length of 75 x 50 x 3.0 RHS (No idea where you'd find 75x40...), cut 2 x 3025mm for the drawbar, leaving a 1950mm peice for your rear cross rail. See if you can buy an off-cut (1 - 1.5M) of 75 x 50 x 4 or 5mm to use as a cross rail and upright half way along the drawbar as a winch post.

Attachment 171278

Next, an 8M legth of 75 x 50 x 2.5 cut to 2 x 2350mm for the chassis rails (this will give you a trailer 10mm longer than 8'), a 1425mm piece for the first centre cross rail, leaving an 1875mm piece fro the front cross rail. The rest of the cross rails would be fine in 50 x 50 x 3.0mm. 1 x 8M length would give you 3 x 1425mm pieces for this leaving 3725mm. I would run 10" (255mm) sides, giving you clearance to open most car doors, and filled dead level, 2450 x 1525 x 255 = 0.95M3. People will want to borrow the trailer, and you don't want to give them an opportunity to overfill it. So, 4 x 255mm uprights (one in each corner) and I'd also put a 1425mm cross rail between the two front uprights at 100mm off the floor to act as a wheel chock. The front tailgate can still open and close against it. The rest of the frame I'd do in 40 x 40 x 2.5mm. 2 x 215mm uprights halfway along the length, 2 x 2350mm between the front & rear uprights, welded on top of the centre uprights, and four diagonal braces, running from the top of the centre uprights, to the bottom of the front & rear uprights.

Rather than having to make the tailgate strong enough to drive over, simply put the hinges around the same way and have the tailgate removable. Put your hinged number plate mount and light under the rear cross rail.

Rather than having tail lights and number plate underneath I'd mount them on the sides and tailgate, if you've ever gone down a steep driveway onto the road you'll know what I mean.
Kryn

Thanks Yonnee - as usual your information is worth bottling !
What thickness floor(sides) would you recommend ? I'll go for smooth as it's hard shovelling sand/dirt/screenings out of checkerplate
Also I'll add to the wish list a removable cage and ladder racks for really long loads - am I reading right that the corner up rights are 50x50 while the rest of the frame is 40x40?

Originally Posted by Wombat2

Thanks Yonnee - as usual your information is worth bottling !

What thickness floor(sides) would you recommend ? I'll go for smooth as it's hard shovelling sand/dirt/screenings out of checkerplate.

I'd go a 2mm for the floor sheet, and there's no reason you can't run checkerplate, you just install it upsidedown. For the sides, you're only using it as cladding, so you could run 1.6mm, but 2.0mm takes a little longer to rust out.

Also I'll add to the wish list a removable cage and ladder racks for really long loads - am I reading right that the corner up rights are 50x50 while the rest of the frame is 40x40?

Yeah, 40 x 40 is fine for rest of the upper framework, the front to rear upper rails and the diagonals. The 50 sq for the six uprights are just off cuts from the rest of the centre cross rails and would be ideal for being the female receiver for both your ladder rack uprights. and your cage side uprights. Get enough 40mm sq. to use as your ladder rack uprights, cross-rails as well as the uprights for your cage sides.

**Tip***
Cut a 45deg. section off one corner of the bottom of your corner uprights... this way they won't fill up with water...

Is there a big difference in strength between 2.5mm and 3.0mm wall thickness?

Local steel yard has a sale on at the moment with gal seconds of 75x50x2.5 for $43.50 as opposed to $143 for 1st quality 3.0mm

Way back when, I worked at a furniture factory and we routinely bought seconds furniture tube in packs of 100 lengths.

We were paying about 60% less than retail for it but for each 6 metre length we probably averaged about 2 metres straight in the scrap bin, bad welds, no welds, improperly formed shape - and that was an average, some lengths we wouldn't get a metre of usable material.

It's seconds grade for a reason, and it may look fine but you can't check the integrity of the welds or the galvanising - personally I would not touch seconds for a trailer.

Good point - I'll save the seconds for the chook pens and the garden arches