DIY Articulating hitch for cheap

[a1gemmel]

I'm building an offroad trailer, the thread is on another forum but I figured I'd double-post this part in case it can be of inspiration to anyone else here.

All the hardware was about $40 from Tractor Supply, all the dimensional steel and plastics are salvaged from my empire of dirt.



Made some parts:



All the parts for the vehicle side. The outer tube is 1 3/4" 0.120" wall DOM, the inner is something like 1.32" OD and 1" ID. Bushings are delrin turned on a lathe.



And the trailer side. This uses '95 pickup rear leaf spring bushings that fit inside 1 3/4" DOM after turning them down a tiny bit in the lathe.



The vehicle side gets assembled - the bolt clamps on the steel sleeve inside the bushing, so the bolt can be torqued down tight and all the swiveling happens with the bushings.



The longitudinal axis does rotate on the bolt, so the nut is welded on solid. That does make this part non-serviceable, but I can make another pretty quick if I need to replace it. There is a grease fitting to keep it lubricated. This uses the same 3" spacing as my ball hitch tongue, so it can be swapped in if needed.



The two assemblies are married with a removeable 7/8" pin. The vehicle side can be unbolted and placed on a different drop/rise hitch mount (or flipped upside down), and the trailer side can be flipped to ride under the tongue, with these options I can configure the trailer to tow level behind different vehicles.



How strong is this? I can start with estimating each axis, since I'm using standard fasteners and can look up their properties.

Horizontal axis: 1" Grade 8 bolt in single shear: 0.606in^2 * 150,000 psi * 60% = 54,450lbs

Vertical axis 7/8" SAE 1020 pin in double shear: 0.601in^2 * 55,100psi * 120% = 39,738lbs

Longitudinal Axis:1" Grade 8 bolt in tension: 0.606in^2 * 150,000 psi = 90,900lbs

In all reality, something else will fail before those numbers. I mean, a 2" hitch mount only uses a 5/8" pin so that's pretty much guaranteed to be the fuse before these fasteners. I suspect the weakest link is the trailer side of the vertical axis, with the tube welded to the bolt head. I did reinforce it with a second layer of steel and there's ~10" of blazing hot weld mating it all together so I'm pretty comfortable with it... I think it'll be fine unless I try to snatch a semi out a snowbank off the back of the trailer. Maybe I'll go hook it to a tree and see how much I can stretch my kinetic rope out as a proof test.

[OVRAROK]

I'm building an offroad trailer, the thread is on another forum but I figured I'd double-post this part in case it can be of inspiration to anyone else here.

All the hardware was about $40 from Tractor Supply, all the dimensional steel and plastics are salvaged from my empire of dirt.



Made some parts:



All the parts for the vehicle side. The outer tube is 1 3/4" 0.120" wall DOM, the inner is something like 1.32" OD and 1" ID. Bushings are delrin turned on a lathe.



And the trailer side. This uses '95 pickup rear leaf spring bushings that fit inside 1 3/4" DOM after turning them down a tiny bit in the lathe.



The vehicle side gets assembled - the bolt clamps on the steel sleeve inside the bushing, so the bolt can be torqued down tight and all the swiveling happens with the bushings.



The longitudinal axis does rotate on the bolt, so the nut is welded on solid. That does make this part non-serviceable, but I can make another pretty quick if I need to replace it. There is a grease fitting to keep it lubricated. This uses the same 3" spacing as my ball hitch tongue, so it can be swapped in if needed.



The two assemblies are married with a removeable 7/8" pin. The vehicle side can be unbolted and placed on a different drop/rise hitch mount (or flipped upside down), and the trailer side can be flipped to ride under the tongue, with these options I can configure the trailer to tow level behind different vehicles.



How strong is this? I can start with estimating each axis, since I'm using standard fasteners and can look up their properties.

Horizontal axis: 1" Grade 8 bolt in single shear: 0.606in^2 * 150,000 psi * 60% = 54,450lbs

Vertical axis 7/8" SAE 1020 pin in double shear: 0.601in^2 * 55,100psi * 120% = 39,738lbs

Longitudinal Axis:1" Grade 8 bolt in tension: 0.606in^2 * 150,000 psi = 90,900lbs

In all reality, something else will fail before those numbers. I mean, a 2" hitch mount only uses a 5/8" pin so that's pretty much guaranteed to be the fuse before these fasteners. I suspect the weakest link is the trailer side of the vertical axis, with the tube welded to the bolt head. I did reinforce it with a second layer of steel and there's ~10" of blazing hot weld mating it all together so I'm pretty comfortable with it... I think it'll be fine unless I try to snatch a semi out a snowbank off the back of the trailer. Maybe I'll go hook it to a tree and see how much I can stretch my kinetic rope out as a proof test.

Beautiful...

[Gnarly4X]

"I think I'll be fine unless I try to snatch a semi out a snowbank off the back of the trailer.
Maybe I'll go hook it to a tree and see how much I can stretch my kinetic rope out as a proof test."

Wow!!... nice fabricating. 

As you know, articulating hitches have been around for a while.

Your comment above triggered a flashback to a 4x4 club trip to Mexico back about 20+ years ago.

The wind during the night had drifted sand under and around a 32-foot motorhome of one of the members.

3 guys decided to snatch it loose. 

They hooked up their snatch straps and backed up enough to get a snap on the straps.

Having attached tow hooks to my Toy pickups in the past, I was always a little concerned that those bolts on the hooks
mounted to the thin metal on the bumper would not hold under a powerful snap.

Well... the first big tug of the 3 vehicles didn't move the motorhome. So they backed up and gave the straps more slack.

There were probably 30 of us standing and watching this.

When the straps went tight, one of the tow hooks under the rear bumper of one of vehicles tore loose and sling shotted through the back of the motor home.

I sounded like a canon going off.  The tow hook went through the rear exterior wall, through the bedroom wall and into the kitchen.

Luckily, no one was in the motorhome and no one was touched by the strap.

This could have easily killed someone in the path of the tow hook.

Looking at the bumper and the mount, you could see where the bolts simply pulled right through the thin metal bumper.

After that eye-opening event, I beefed up the mounts on all 4 of my tow hooks on my pickup with 3/8" metal bar stock.

Gnarls.

[a1gemmel]

You know I had to do it...

[a1gemmel]

Full trailer build is here, by the way: https://www.frontrange4x4.com/forums/showthread.php?29755-a1gemmel-builds-an-offroad-trailer-from-scratch
The gentlemen here will be pleased to note that the suspension concept is literally just a toyota pickup rear leaf spring assembly.

[OVRAROK]

Gathering parts...

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[OVRAROK]

Almost there. Couple holes for hitch pins and zerk fittings. Little bit of cutting on a few things.

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[OVRAROK]

Couple pics of the finished product. Works great. So quiet..

Sent from my SM-S928U using Tapatalk

[a1gemmel]

Yeah that's definitely the biggest upside, let alone the angle capability!

I just took my trailer out for a 1000 mile break-in trip, it tows like a dream with this style hitch. Zero rattling or push/pull like you get from a typical ball hitch. If not for the crippling lack of power on the inclines you'd never even know the trailer was back there.

[Gnarly4X]

Mr. DIY Fabrinator!!

Can you patent it?
Call it an "Articulator".

Gnarls.

[a1gemmel]

I'll admit... I stole the initial concept from some older webpage I can't seem to find again. They did have some component rotating on a nut and bolt that was unsafe in my eyes.

Basically, I saw $450 for a lock'n'roll hitch and said "no f#$%ing way!"

[Gnarly4X]

With 5 Classes and 6 ratings for trailer hitches, is there any way you can determine what Class it might pass for?

Gnarls.

[a1gemmel]

Nice try officer, this hitch is for offroad use only. I would never dream of operating with this unrated homemade equipment on public roadways.

[Gnarly4X]

Nice try officer, this hitch is for offroad use only. I would never dream of operating with this unrated homemade equipment on public roadways.

Was your 1,000 mile break-in trip strictly ALL off-highway??

Gnarls.