drawbar coupling

Looks like ive a few more questions in the transport section yet!!

so, getting the light trailer sorted for the inflatable (non rigid hull) and its got one of these...... i know its rated to 900kgs but it just doesn't install confidence

Attachment 219712

i would like something a little more substantial BUT........all the couplings that im looking at have width hole pattern of 36mm centre to centre, the width of the drawbar is 50mm.....

are there any other couplings that have an inline hole pattern for a draw bar this size or a more sturdy option?

I hope this makes sense

GET Local engineer to weld a plate flat on top of existing drawbar and predrill holes for new coupling????if its got a couple of inches of proper welding on each side....it will be very strong I would have thought,not sure if needs to be certified etc???

better still find another drawbar and sleave one inside the other,so can extend its length LOL.

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Originally Posted by Tertle

Looks like ive a few more questions in the transport section yet!!

so, getting the light trailer sorted for the inflatable (non rigid hull) and its got one of these...... i know its rated to 900kgs but it just doesn't install confidence

Attachment 219712

i would like something a little more substantial BUT........all the couplings that im looking at have width hole pattern of 36mm centre to centre, the width of the drawbar is 50mm.....

are there any other couplings that have an inline hole pattern for a draw bar this size or a more sturdy option?

I hope this makes sense

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As MD said, get 4 hole plate welded on top but use wider pattern to allow for bolts to pass beam. Standard Trojan will be too narrow.
No option for heavy duty version of what you have. Incidently, that current design is used in the US for up 6000lb towing, though heavier gauge of steel on a 2 & 5/16 ball.

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Originally Posted by Micky Duck

GET Local engineer to weld a plate flat on top of existing drawbar and predrill holes for new coupling????if its got a couple of inches of proper welding on each side....it will be very strong I would have thought,not sure if needs to be certified etc???

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i guess thats an option? ive a welder just need how to learn how to use it.........electricity is one thing that truely tightens the buggery out of me!

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Originally Posted by Mathias

As MD said, get 4 hole plate welded on top but use wider pattern to allow for bolts to pass beam. Standard Trojan will be too narrow.
No option for heavy duty version of what you have. Incidently, that current design is used in the US for up 6000lb towing, though heavier gauge of steel on a 2 & 5/16 ball.

Sent from my SM-S906E using Tapatalk

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6000lb wow! so weld top plate on that would allow wider pattern, then U bolts to also go under draw bar as well or just plate to the coupling? (again i hope that makes sense, off work today brain a little foggy :) )

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Originally Posted by Tertle

6000lb wow! so weld top plate on that would allow wider pattern, then U bolts to also go under draw bar as well or just plate to the coupling? (again i hope that makes sense, off work today brain a little foggy :) )

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If you take trailer to Briford, get Brian to weld plate & supply plunger coupling. No need for u bolts.

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either or both LOL

If its only going to pull 900 kg that coupling is probably fine as long as it isnt rusty inside.

And for your info the welding on a trailer under 2.5 ton doesn't have to be certified. It just has to be 'up to a reasonable visible standard'

I normally just make a longer plate with the bolt hole pattern for the coupling. Weld the plate to the drawbar. If you didn't want to bust the galv on your existing drawbar you could do plates at 90 degrees to the top plate and pick up those existing bolt holes and bolt it on.

Nothing wrong with those coupling as long as you are within the weight limits, I have its bigger brother on a 3000kg 5th wheeler

I think you can buy the pre drilled plates ready to weld on from repco or super cheap.

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Originally Posted by Savage1

I think you can buy the pre drilled plates ready to weld on from repco or super cheap.

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Yeah you can but they are only 8mm thick.

I always go for 12mm. They little extra it costs is worth it for piece of mind.

Piece of 12mm plate, cut to right size predrill holes and tip the trailer upside down. Clamp plate on in right place, with the trailer upside down you can get to it as a horizontal weld so no bullshit positional galv contaminated chicken turds... Pretty simple blaze job to be fair, then zinc it the hell outta dodge and go from there.

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Originally Posted by Tertle

i guess thats an option? ive a welder just need how to learn how to use it.........electricity is one thing that truely tightens the buggery out of me!

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wimp! :P

I would keep the existing coupler and just add a second safety chain. I have one of those couplers on a trailer I use on the 4 wheeler for feeding out etc, never had a problem and the great thing is that they are fast to use with no bits to loose

Yeah, weld 12mm plate to box section that’s possibly only 3.5-4mm thick and possibly create stress lines along welds if done wrong, really gives confidence. Some, just a bit cynical after some of the things I’ve seen when doing wofs in the past.

Who says that the box section here is 4mm 223?? where did you get that figure from because I cant see it anywhere on the original post.

In any case, welding 12 mm to 3 mm with a weld length of say 150 mm is not going to crack, as long as you are :

1) A competent welder, and understand the need for penetration and the avoidance of undercut.
2) You do the prep on the galv box section properly before you weld it

Ive done this heaps of times and never ever had one come back cracked. Remember its only towing 900 kg.

Not having a go at you, just saying

Was merely making an observation based on what I’ve seen as a past WOF issuer. And as you say weld strength is dependent on preparation and welding skills, speaking as someone who has worked on such projects as a certified welder. To get thread back on track I have used and seen many of these couplings on trailers over the years an never seen one give trouble when used within specs.

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Originally Posted by Savage1

I think you can buy the pre drilled plates ready to weld on from repco or super cheap.

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Or direct from Trojan

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Originally Posted by woods223

Was merely making an observation based on what I’ve seen as a past WOF issuer. And as you say weld strength is dependent on preparation and welding skills, speaking as someone who has worked on such projects as a certified welder. To get thread back on track I have used and seen many of these couplings on trailers over the years an never seen one give trouble when used within specs.

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Half of that is using a budget mig to do the job so the weld is barely lukewarm, without cleaning the metal and getting rid of the paint galv and crap, doing the job outside and in the overhead position... The other half is probably amateur hour weld as you learn techniques which is fine except when its a reasonably stressed weld that if it lets go is likely to result in some extreme stress at the very least!