View Full Version : Trailer for long loads.

19th Jan 2010, 10:12 PM
Hello everybody. First time user, so here goes! I've been a hobby stick welder for about 20 years,and i tend to over engineer most things so would like a bit of advice for my trailer project. Basically i need a trailer to haul long materials like timber and steel 5 to 6 metres long and up to 1.2 metres wide. An example would be timber rafters, roofing iron and steel angles and RHS. Weight of these materials in one load would not be more than one ton at a time. I'm thinking of a tandem 4.5 by 1.5 metres and a drawbar 1.2 long. This will allow 900mm of load over the drawbar and 600 rear overhang for 6 metre long lengths. Most loads won't hang over the rear. I'm thinking of using 75x50x3 RHS for all the main frame and 100x50x5 RHS for the drawbar. What do you think of that size steel? Could I use 75x75x6 angle for the drawbar? There will be no front or rear walls and only an open side frame to support the mudguards. Floor would be treated timber planks spaced apart so i can tie the load down easily. (Rope over the load and under the floor). One ton axles and Ford bearings. Over-ride brakes (sorry) as i will no doubt find new 'friends' to borrow my trailer! Centre spring hanger is 200mm back from centre of load area. I hope I've done my homework there. I'm not worried about resale value, so I don't really care if the trailer just suits my needs only. I would greatly value your input in setting me straight or any idea's. Cheers.

19th Jan 2010, 10:42 PM
100x50x5 RHS for the drawbarThats pretty heavy. If it was me I wouldnt bother going over 3 mm wall for your intended purpose.

75x50x3 RHS for all the main frame Given the specs u have provided I wouldnt go over that

Remember its all weight at the end of the day. Before I even think about building anything I look around at what others have done before me.

Whow I think all those Bourbons I had just kicked in......the text is getting fuzzy .......... better stop now.:D

Have fun. Of course fotos are a must.

20th Jan 2010, 11:09 AM
Firstly, Welcome Buildspacetrain. Hopefully we can give you some assistance.

The size of the trailer is the first area I'd suggest a change. If you've got somewhere to store a trailer that size, then an extra 400mm shouldn't be an issue. To save yourself some cutting, flat floor sheet comes in 8'X5', and therefore if you make your chassis 16foot long (4880mm), then you wont have to cut anything, just buy two sheets. Similarly, if you design your cross rail spacing to match up with the join, you'll save yourself some headaches later. Also the extra length wont cost you extra in RHS either, because if you cut 4880mm off an 8 metre length, it leaves you 3120mm, or 2 x 1560, perfect for two cross rails. Bigger trailer, less waste, no extra expense. (More on that later)

I agree with Jatt that the size of steel you mentioned would be way overkill for the weight of the load you intend to carry. If you intend to have sides on this trailer, then this will be the area where the longitudinal strength lies and the chassis could even be made lighter/smaller again. But I too like over engineering, so here's what I would suggest;

2 x 8M lengths of 75x50x3mm RHS:
Each one Cut:
1 x 4780mm (Two main side chassis rails)
1 x 1425mm (Internal cross rails)
1 x left over 1795mm (Front and Rear cross rails)

1 x 8M length of 100x50x3mm RHS:
Cut to desired lengths for drawbar. You'd have more than enough to tie right back to the front spring hanger. But this is up to you.

For the rest of the internal cross rails and the four corner uprights I'd use 40x40x3mm RHS, but you could go 50x50x3mm.

I'm not too good at 'sketch-up' just yet so I'll describe what I'd do the main frame.
Laid out on the workshop floor (all measurements from front cross rail);
2 x side rails 5 foot apart
2 x front and rear rails either end
7 x internal cross-rails every 2 feet (this would place one in the middle for the sheet join, and evenly spacing the rest.) Where you place the two 75x50's is your choice, but I'd place one at 4' and one at 10'
Centre spring hanger should be at 8'8" (2640mm), and the rest of the hangers placed accordingly. (Yes you'd got your homework correct:2tsup:)
If you intend running the drawbar to the front hanger, then a straight line would make it quite narrow where it supports the front cross rail. I would mark a point on the side rails 3 foot from the front and run the draw bar to there, then continue along the chassis to the front hanger.

Once tacked, squared, checked three times, and then welded we can turn over.
I would place uprights at each corner, then one in the middle of the guard, one at 5' and another at 12' and then a rail on top of these front to back. To mount the gaurds, cut out the square bit in the middle for the upright, and tuck it up under the top rail and sit it against the chassis at the bottom. Another rail across the top at the front and we're pretty much done for the main frame. How you do light boxes, tie-down rails, tailgates, number plate, etc. is up to the individual.

Over-ride brakes have their place, particularly if numerous different tow vehicles are in use. I would go 4 wheeled brakes, either Hydraulic or Mechanical drum brakes. In all cases if the budget is tight to start with, get the brake mounts added to both axles, even if you only start with one set. It makes the upgrade a 'bolt-on' application.

Ford "Slimline" bearings are 1.4 tonne axles, not 1 tonne, but I highly recommend using Slimline axles, just to have that capacity.

This should get you going for now. Good luck and have fun. Take lots of pics too!!

I see you're in Melbourne too. If you need a hand, or some advice in person, let me know.


20th Jan 2010, 11:35 AM
Firstly welcome.

This link will take you to what I made, it may help. The inside tray size is 3m x 1.5m, drawbar is 2m, the unit weighs 600kgs. I was an Owner Builder and the trailer worked a treat for me and still does.


20th Jan 2010, 08:31 PM
Wow, what can I say! Thanks for all your help and suggestions.
Firstly, Jatt - thanks for the steel size suggestion. I see your from Bendigo. I have property in Heathcote where I keep my 4 sheds, 3 wheel-barrows and 2 other trailers. Can a man have too many of these? Keep an eye out for the new trailer some time in the future in the streets of Bendigo.

Rod, nice trailer. HEAVY DUTY STUFF! Always get good ideas from photo's.

Yonnee, thanks for your time and effort to reply. It must have taken some time to figure it all out and put finger to keypad. I really appreciate it.

I'm much more confident now that the steel size will be ok and that I'm heading in the right direction. I will post some photo's of construction, but Im a slow worker. Might post a few photos (if your interested) of big new shed I'm building (over engineering) to house a model railway. (my future retirement hobby).
Again, many thanks. Cheers, Richard

20th Feb 2010, 10:11 PM
Hi Chaps, Just a few photo's and update of the trailer.
Construction is going well but slow due to time (not enough).
Spent a lot of time setting up for squareness prior to and during welding and has paid off with a nice square and level frame.
I am keeping track of material costs and weight which I will write up later as it might help another trailer builder later.

27th Feb 2010, 08:20 AM
Its not fair.

where do you guys get your nice clean workshops from!:weeping:

keep the photos coming.

27th Feb 2010, 09:52 AM
It's looking great BST. Look forward to seeing more as you progress. Also interested in how much it will end up costing you.

27th Feb 2010, 10:37 PM
Richard, Something to be aware of, when I welded my draw bar on to the front rail of the trailer body it pulled/bent the draw bar hence to mini truss on the underside of the draw bar.

Your's is looking good:2tsup:

28th Feb 2010, 09:24 AM
Another reason never to weld across the top of the drawbar where it meets the front cross rail.

28th Feb 2010, 08:56 PM
I just welded the drawbar and coupler plates on today, most pleased with the outcome, then read your comment 'rod 1949'. :doh: Bugger I was just enjoying a cupper too! So out I go back to the workshop, grab a straight edge and say a little prayer. The drawer bars are 100 X 50 x 3 and 2700 mm long and yes they have pulled about 4mm over the whole length, with I think is acceptable. I've taken Yonnee's advice and not welded across the top of the drawbar too. Hope to weld the hangers on tomorrow and turn her over.
Sorry Franklin, I'll do better and make the workshop a bit messy for the next photo's.
Cheers for now, Richard.

12th Apr 2010, 08:22 PM
Not much to show for the past few weeks, but the hard work on the frame is done. Drawbar and coupler is on and frame is nearly complete. That's it now for 6 weeks till I come back from holidays with the good wife. Will buy the mudguards and axles if i got any money left over!
Cheers for now.

8th Aug 2010, 11:08 AM
C'mon, youve got another thread where you're painting it, where's the updates??

8th Aug 2010, 11:03 PM
Not a lot has changed since the last photo apart from the addition of the mudguards. It took longer to paint than to weld it up!
Put the fancy white wheels on today but still have to wire it up and put the lights on, also still to do the brakes.
Sorry, Mr Yonnee, will take a few photos next weekend and list detailed prices and weights of individual components for future reference.

18th Nov 2010, 08:45 PM
After 9 months the trailer is finished and ready to haul all my corrugated iron, timber and steel for the new hobby shed and house extension. The deck is treated pine screwed down to the frame (separated by rubber strip) and will make tying down the load soooo much easier.
I already have another trailer for loose material like sand and dirt which is why I built the deck this way. Total cost for all new materials was $2650 and weighed in at 600kg on the weigh bridge. It is 6 metres long and 2.1 metres wide.
Here's a few photos. Thanks for all your input during this project.

18th Nov 2010, 08:59 PM
Looks pretty shmicko:2tsup:

18th Nov 2010, 09:34 PM
That's a superb bit of work. I'll bet you're gonna discover a whole bunch of friends you never realised you had :)

24th Nov 2010, 05:41 PM
I'll bet you're gonna discover a whole bunch of friends you never realised you had :)

+1 :rolleyes:

28th Dec 2010, 10:39 PM
Centre spring hanger should be at 8'8" (2640mm), and the rest of the hangers placed accordingly.

How did you come up with this figure?
Congratulations on your very informative post.

29th Dec 2010, 09:00 AM
Welcome R W, good to have you on board.

The calculation is an industry standard that's used by most trailer manufacturers for most trailers. It's by no means the be all and end all as certain trailer configurations require the axle placement to be adjusted accordingly to get them to tow well. (Horse floats and boat trailers for example.)

Generally, the rule of thumb is the axle or axle group is placed 1/2" to the rear of centre for every foot of body of trailer, excluding the drawbar. So, the case with this trailer, with a 16' body, the centre hanger being the middle of the axle group for a tandem, is placed 8" rearward of centre, or 8'8" from the front cross rail.

However, once you go over 8.077M (26.5') in trailer length, your axle group can be no further forward than 3.7M from the rear cross rail.

29th Dec 2010, 08:17 PM
Thanks for your reply, That is a good one to remember, in fact I've written it down next to one I read
on a US forum, they worked on a 60/40 basis. (Length of trailer excluding drawbar).
Your method seems to work out around 54/46 and is very easy to calculate.

29th Dec 2010, 09:22 PM

Only just seen this thread. Really nice trailer. Interestingly I had the same challenge a few years back and built a trailer to haul some demolition materials I had acquired. It was timber up to 5m long, but I wanted it able to carry 6m at a push.

I had a long drawbar and allowed for up to 1m overhang at the rear. The trailer body is 3.6m long. I purposely left it without a floor initially, which produced an outcry at the inspection. The authorised inspector screamed,

"It's got no floor."

I had to explain that I made it to secure lengths of timber with chains and dogs, which I wanted to loop around the chassis rails. He was alright with that.

Subsequently I made few alterations. I put an additional second set of springs under the axle as I had seriously misjudged the first springs. I now have removable frontgate and tailgate and a removeable plywood floor so I can transport other materials too. I also moved the spare wheel ahead of the rear axle for better weight distribution when empty.

Lastly, I think you mentioned one of your proposed materials was corrugated iron. Quite a difficult commodity to tie down. Not if you sandwich it between two battens (75 x 38, 100 x 50 or similar) Bolts or even better suitable threaded rod clamp the boards jsut outside the sheets and across the width of the iron. One set of boards at the front of the trailer and one at the back will probably suffice but more can be used if you wish.

This gives something that you can really tie down on and prevent from moving forward as you like me do not have a headboard. If the iron is new the bolts won't have to be very long, but second hand iron tends not to sit snugly and depending on quantities you may need 200mm rods or longer. This is where the threaded rod is more versatile.

Anyhow, congratulations on the trailer. It is a superb job.


1st Jan 2011, 06:07 PM
Thanks Paul, It might have been easier to put a solid floor in it, cause now I have to explain to all and sundry why it hasn't! Yes, I too have used the batten method of tying down corry and also large flat cement sheets. It also prevents damage to the edges of the sheet. My other trailer has many holes in the floor where I have past the threaded rod through the batten and then the floor. The only thing I've ever lost off a trailer is a red tail flag! This trailer will make loading and securing super easy now.

1st Jan 2011, 07:09 PM

Looks like we are of one accord here.:).


12th Dec 2011, 05:29 PM
You don't see to many photo's of home built trailers after we start using them, so here is a few of my 'trailer for long loads' project doing what I designed and built it for! With thanks to this forums contributors.

13th Dec 2011, 08:30 AM
Looks very smart. Purpose built. Like it. Thanks for posting the pix. Some brief specs on dimensions, wheels etc would be good too.