Building a trailer coupler?

[choprboy]

Has anyone ever built a trailer coupler? Any suggestions for a design to go over a 2" ball?

I am rebuilding a towable engine hoist. Originally built for the rental industry I think, but I havn't been able to find a manufacturer or model number anywhere. It is built with all heavy 1/4" wall steel tube, but had a rather poor wheel and hydraulic cylinder setup. I cut off the mast and wheels, installed new spindles/hubs, reworked the mast and lifting arm arrangment with new material, and put on a new cylinder. It should now support up to 2 tons at a 4' reach and lift up to 8-1/2'.

But I've now come down to making a new coupler. The original was just a lathe-turned cup welded on the end of a 3"x1/2" strap that went over the 2" ball, stuck off the end of the mast. It had a piece of plate cut as a yoke that tightened against the ball neck with a wing-handle bolt to keep it from coming off.

I'd really like something built a bit better, perhaps with a spring loaded latch. But haven't been able to find anything online, everything is made to put on the end of a piece of 2-3" tubing or a-frame. Something like a bare weld-on gooseneck coupler would probably work well, but I can only find those for a 2-5/16" and 3" balls. Any suggestions?


Adrian

[stevec]

Adrian, I have one "on the shelf" it's for a 2" ball and fits a 2½" x whatever channel or sq./rect. tubing. It's a Reese#74042
No point in telling you where I bought it because I have no idea where you are.
It's a good idea to show your earthly whereabouts in your profile.

[Russ Hanscom]

Lots of replacement couplers available at dirt cheap prices, No need to build your own unless you really want to.

For starts, I know the local Lowes carries them as do most of the RV supply places.

Reese is a good name to start with. Look on Amazon or Ebay - there should be lots of choice there if not where you are located.

[scmods]

Adrian,

The couplers are readily available and so cheap that its hardly worth the trouble to make one. If there's no home center near you, an online choice is likely the next best idea.

As others read this too, I'll give a short safety message here. Any system that is capable of lifting 2 tons 8 feet in the air accumulates a significant amount of potential energy that can be released suddenly and dangerously. Take care to keep the center of gravity well within the footprint of the base. If this was from the rental industry, it should be relatively safe, but modifications like boom extensions, or reduced wheel track, etc. can introduce serious instabilities.

I personally don't care for these things, but I have other options, namely an overhead traveling hoist, and machinery. Any time I have to use one, I weight the legs with heavy scrap and cakes of lead. If the setup is getting "tippy" or otherwise weird, its way past safe. Sheer legs would be much safer, and can easily be set up.

Just be careful!

Bill Walck

[choprboy]

Yeah, I have a standard 2" coupler that attaches to a 2-1/2" channel/tube already, they are pretty cheap. The problem is that there really isn't anywhere to directly attach it and I'd rather not cludge it on. The mast is a piece of 4x4x1/4" tube about 5' long. The end of it has 3 pieces of 1/2" plate welded on to act as the hinge mount, forming 3 sides of the box and looking like a continuation of the tubing.

The original engine hoist looked like these. 2x4x1/4" legs with a 4x6x1/4" crossmember, 4x6x1/4" mast with an arm made from 1/4" plate bent into a piece of deep channel. I forgot to take a picture of mine before I started gutting it:


The wheels were is terrible shape, needed new tires and wheel bearings/seals.... but the rims were an all-in-one style that also served as the bearing hub. The spindles were non-standard and welded directly to the leg tube, making the wheels almost drag when rolling on the casters. I started by cutting off the old spindles, fashioned some new ears out of 1" plate to raise the wheel center line up and back from the original postion. Welded the ears in with new standard 1" spindles, new servicable wheel hubs and tires. Made it nice and road portable again, tracks very well and doesn't bounce alot.

After a few of lifts, were it would barely pickup my 650lb transmission, the hydraulic jack seal failed, wouldn't hold a load any longer. The setup was rather poor anyways, they mounted a ~8-10 ton jack about 5" from the fulcrum, the lifting point is about 53" out, giving a more than 10-1 ratio. Like the wheels, the hinge was also not servicable and had egged out its mounting holes on either side. So I cut it all off, built a new mast out of 4x4x1/4" that is sloped back. The arm is 2x4x1/4" about 5' long with an 8 ton jack 14" out from the fulcrum. It will now lift 2 tons from 2-1/2' to 8-1/2' under the hook, reaching out up to 4' over a low bumper (about 45" in front of the jack):


The new mast/hinge are all made from 1/4-1/2" material. The hinge pins are notched to lock into the side of the frame, so the large bearing surface will slide on the pin, not the pin sliding on the frame wall. Still need to do final trim up and drill for grease nipples, pins will be held in with hitch pins.




The original mast was welded vertically to the backside of the crossmember. The new mast is welded both on the back and top, thanks to the back tilt design. Has an extra 1/4" plate stiffener to make sure it dosn't try to punch thru the 4x6" crossmember.


The arm is a bit longer than the original and now has a chain attachment and pipe setup, like the original, and a 1" plate ear drilled to take 5/8" shackle for heavy lifting.


So I've spent quite a bit of time rebuilding it to be better than new, I'd like to find/design some sort of locking cup to go on the end of the mast, not just weld on an ill-fitting standard coupler. I was thinking something like a goosneck cup, but for a 2" ball which I haven't been able to find:

[Russ Hanscom]

Nice looking welding.

[choprboy]

Eh... thanks... Im slowly teaching myself to weld. Sometimes it looks like I know what I am doing... Sometimes I completely forget what I am doing, grind out and repeat... This was all done with stick, 1/8" 7018 mostly. The major connections have a 6010 root with 2-3 passes of 7018 on top. It's my second project, the first being a new bumper for my Unimog. The next up is a transmission mount for the same, but I need the engine hoist functional first...

[scmods]

Nice job! Well finished and neat.

IF..this were my project, I would install two triangular gussets at the bottom of the mast to transfer the compressive stress from the center of the base tube to the outside edge, where the vertical wall of the base tube provides better support. Just the way I think.

I would address the hitch issue by placing the hitch at the top of the mast so the unit could be tipped over backwards and coupled. You are not carrying cargo, just the hoist, so the loading on the weldment would be minimal.

Bill Walck

[choprboy]

For those that care... this project sat in my side yard the last few months, too much work and not enough play time. I had given up finding something stock and had started machining my own self-latching coupler design. Probably way over designed and to complicated to be useful... Then I just happened to be reading an article on restoring WW2 Bantam trailers and saw them using the Fulton model 308 coupler.


Unlike most couplers, the Fulton 308 is a bottom-mount coupler made from folded steel that can easily be cut and bent to other forms. I chopped off the head, cut a 3/8" plate tapered from 4" (the mast width) to match the coupler head. Large chamfer on the plate, filled with tig welding all around. Then stick welded the assembly to the end of the mast with a 6010 root and 7018 fill from both sides.




Added safety chains, lifting chain, and paint. I still have to replace the casters, but its mostly complete. Need to figure out some sort of handle to help in maneuvering.



Finally had a chance to test it out today getting a 600lb transmission out of my storage unit to start fitting it. Takes a lot of pumps of the handle to go from the ground to max height, but that is more the fault of the hydraulic jack. The mast is suprisingly bouncy... found a mistake on my part. The mast was actually 3/16" tube, not 1/4" like the rest, so I may have to derate a bit. But it lifted like the load was barely there. Playing around, thanks to the new lifting height I could lift the transmission out of my truck with almost 18" of clearance over the upright tailgate.

[redneckalbertan]

That looks real nice. I don't know if you have looked into trailer laws where you are at, but you may want to add marker and signal lights. My first thought was a rubber grommet mounted light cut into the bottom side of the leg. I don't know if this would reduce the strength of the leg too much or not.

[choprboy]

I have. Lightweight purpose-built towables, which do not carry a load, like cement mixers/etc. do not require lights or registration. I put a couple red reflectors on the legs for goo measure though.

[redneckalbertan]

I noticed them, and that's what got me thinking about the rubber grommet mounted lights. Up here reflectors like that don't last very long, I think it has to do with harsh winters, but I don't know. If you have issues with them you may want to consider DOT conspicuity tape. It shows up amazingly well and sticks like a sun of a gun.