another DIY U-joint swiveling tongue coupler (1 Viewer)

[e9999]

Not my creation, got it with a trailer I just bought, but interesting I think in that the majority of it could be done easily enough by a DIY with access to a welder. Good potential for improvisation in other configs too and hopefully may give you some useful ideas.

Pros: easily built with a welder and (almost) all readily available bits and pieces. Not clanking like a lunette as there is no slop anywhere (and even has 2 bushings in the central "bone" u-joint for vibrations and stress reductions). Easily disassembled for anti-theft prevention (I replaced the bolts with hitch pins). As strong as you want to make it, just use bigger components, it can be easily scaled up.
The bent lunette stem allows for 2 set heights.
the whole assembly can be replaced by a regular military lunette ring coupler as needed since the female tapered coupler is built-in


Cons:
need to source a swiveling bent lunette and mating female receiver. Former relatively easy to get, latter less so.
more complicated than a regular lunette ring coupler



Description of DIY components from left to right:
- 2" tube to insert in truck receiver.
- DIY "bone" U-joint (a cute DIY part IMO)
- coupling welded on the stem of a military 105 ring coupler with lunette ring cut off
- female 105 (I think) receptacle welded to 2" tube
- 2" tube tongue

As mentioned the neat part is that it was made from readily available pieces (except for the lunette stem receiver):
the Us are made from 3-sided sections of a 2" ID square tube welded sideways to a 2" OD square tube.
The bone is made from 2 pieces of 2" OD circular tube (with poly bushings pressed inside) welded at 90deg on a 2" OD square tube.
the RHS U is similar to LHS but the 2" OD tube section is welded on the stem of a 105 ring coupler.

Pretty cleverly done in a DIY way I think.

 

[scrapdaddy]

Looks good and as I see it, if a guy had his tongue height set, with his truck, he wouldn't need the 105 lunette setup. Just straight into the tongue. how safe is that setup. do you think it would hold up?

 

[e9999]

Looks good and as I see it, if a guy had his tongue height set, with his truck, he wouldn't need the 105 lunette setup. Just straight into the tongue. how safe is that setup. do you think it would hold up?

Well you need the lunette stem part so it can swivel around the longitudinal axis. If there were only the bone Ujoint it'll bind for sure.

As it is now it's plenty strong for this very light and small trailer I'm sure. Admittedly, the 105 part is way overkill but the builder probably had that readily available I'm guessing.

 

[ntsqd]

It would be better if the two pivot points were closer together, less leverage on the pivot pins - the vertical one in particular.

 

[e9999]

It would be better if the two pivot points were closer together, less leverage on the pivot pins - the vertical one in particular.

true in principle, although I think it's plenty strong enough. Remember that the whole assembly is pretty much level (and free-rotating) and with very little tongue weight, so except for weird offroad articulation and attitudes -that are typically at very low speed- it's likely seeing very little torque on the center bone and pins. And those pins are ridiculously strong in shear.

But if that worries somebody, it'd be very easy to substitute a 1" hitch pin coupling like this
Clevis Trailer Pin Mount
for the LHS pin support, which isn't going anywhere with a light offroad trailer and would save some fabbing.

 

[ntsqd]

I'm thinking of situations like a 'break-over' where the weight of the trailer is pulling on the "bone" at an angle. The forces can get surprisingly large in such a situation. Add a stair-step or even a rock that a trailer tire has to be pulled over and the forces will skyrocket. Just going down the road would be no issue.

Having invested considerable time in CAD designing this type of coupler, the pitch and yaw pivots are not the difficult ones. The difficult pivot is the rotational pivot. I've yet to come up with or see a clean solution for this. The M416's is the best that I've seen, but it would be hard to replicate in the average garage.

 

[e9999]

I'm thinking of situations like a 'break-over' where the weight of the trailer is pulling on the "bone" at an angle. The forces can get surprisingly large in such a situation. Add a stair-step or even a rock that a trailer tire has to be pulled over and the forces will skyrocket. Just going down the road would be no issue.

Having invested considerable time in CAD designing this type of coupler, the pitch and yaw pivots are not the difficult ones. The difficult pivot is the rotational pivot. I've yet to come up with or see a clean solution for this. The M416's is the best that I've seen, but it would be hard to replicate in the average garage.

- point taken, I'll keep an eye on things but not worried for my exped uses.

- I'm going to experiment with that too. I got a lunette ring with a straight threaded shaft, the standard civilian thing. Basically just needs a big straight hole in a thick piece of metal as the female piece that is then welded to a tube or tongue. Just a matter of having the means to make a big hole, a big piece of metal, access to a welder. But yes, maybe not for the usual garage. The shank on mine is 1.5", that's a big hole in steel that should be at least 1" thick and preferably more I think.

 

[ntsqd]

You got one similar to this?
Amazon.com: Tow Ready 63022 2-1/2" Diameter Lunette Ring: Automotive

I keep looking at it and thinking about how to use it. The simple way would be to let it rotate in the hole by not tightening it rock solid. That's not my way. It would work for a while, but I don't want to have to revisit it or worry about it. Build it once, and then use it without thought until I'm too old to care.

 

[e9999]

You got one similar to this?
Amazon.com: Tow Ready 63022 2-1/2" Diameter Lunette Ring: Automotive

I keep looking at it and thinking about how to use it. The simple way would be to let it rotate in the hole by not tightening it rock solid. That's not my way. It would work for a while, but I don't want to have to revisit it or worry about it. Build it once, and then use it without thought until I'm too old to care.

yup, similar thing. I'm thinking I'll washer it up, loctite it, cotter pin it, maybe double nut it, and it'll be good forever as a swiveling lunette ring. If you want it going for more than forever, drop a couple of beads of weld on the end where it can be ground off easily. I'm trying to figure out how much of a thickness of receiver plate I'd need for it. I was thinking 1" or more but it looks like the Lock and Roll is only 5/8"....

 

[ntsqd]

IF you can key the flat washers to the ring then some bronze thrust washers between they and the plate would be a very good thing.

I am convinced that the ring should not rotate easily, there should be enough friction in the assembly that you need a small bar to rotate the ring. Maybe even a big bar to rotate it. A pintle/lunette coupling has a fair amount of rotation available in the sloppy fit of the ring to the pintle, so what I'm after in a rotating ring are just the extremes and to keep the trailer's flopping from trying to flop the rig too.

 

[scrapdaddy]

I've got swiveling lunettes, on both my military trucks, that rotate easy. You can't spin them, but can move by hand. How about a bushing, in the hole with a zerk fitting.

 

[Tobiasinla]

Hey e9999,

Any chance of getting another picture without the wiring being draped over it?

I am still internet surfing for M105 pictures, but I cannot see the "mating female receiver" coming from a style of M105 like scrapdaddy posted in the other thread. Maybe it was an early model 105 part?

 

[e9999]

IF you can key the flat washers to the ring then some bronze thrust washers between they and the plate would be a very good thing.

I am convinced that the ring should not rotate easily, there should be enough friction in the assembly that you need a small bar to rotate the ring. Maybe even a big bar to rotate it. A pintle/lunette coupling has a fair amount of rotation available in the sloppy fit of the ring to the pintle, so what I'm after in a rotating ring are just the extremes and to keep the trailer's flopping from trying to flop the rig too.

Sure, thrust washes would be good but I'm not that worried about this that I'd feel the need to have them, frankly. If there is a 1" steel plate that the lunette shank goes through, and I pull the trailer a few times a year, it'll likely last 500 years before anything is worn and I have to redo anything, which would be easy and cheap.

Obviously, you would not want slop which would create additional wear on misaligned contact points, so it should be pretty tight, but other than that, I don't see that having a lot of friction would be much better. The trailer lunette will still need to swivel when on uneven ground probably some of the time (depending on degree of play between pintle and lunette) and the only thing high friction would accomplish is to increase wear on the rotating parts, which will probably mean less friction before too long. OTOH it's probably true that additional friction may help prevent a flopover under dynamic conditions but again at the expense of added stress on the components.

I think it's all good.

 

[e9999]

I've got swiveling lunettes, on both my military trucks, that rotate easy. You can't spin them, but can move by hand. How about a bushing, in the hole with a zerk fitting.

I thought about that, but a 1 1/2" hole is already pretty big in solid steel, with bushing it'd be even bigger. I have to figure out what tools I can find to use. Or I may go EDM, then the sky is the limit.

 

[e9999]

Hey e9999,

Any chance of getting another picture without the wiring being draped over it?

I am still internet surfing for M105 pictures, but I cannot see the "mating female receiver" coming from a style of M105 like scrapdaddy posted in the other thread. Maybe it was an early model 105 part?

it does look a bit different, it's missing the "ridges" at both ends. I did check the fit though and the lunette shank fits very well with no play and it appears to have the correct taper. But could be from some commercial heavy equipment unit that has the same specs as the 105.

 

[crossy]

ahhh, but what about backing up?? that's the first i have seen one like that. that looks like something the military would have used. just my .02, crossy

 

[e9999]

ahhh, but what about backing up?? that's the first i have seen one like that. that looks like something the military would have used. just my .02, crossy

backs up just fine of course, just like a ball tongue. it doesn't go accordion-like if that's what you were wondering, it can't.

 

[GILBERTO PEREZ]

Check this one

Home made axis coupler