Trailer hitch pin rigging?

#1
I have read about people using a trailer hitch to directly to rig recovery gear so I thought I would investigate a bit.
The first thing I discovered is that NO manufactures that I could find would give a meaningful strength rating, only what class hitch the pin was made for. So I chose to use a 5/8" grade 8 bolt with a long enough shaft that no threads would be inside the receiver. Since grade 8 is too hard to drill I ground a grove for a retaining hair pin.
The next concern was the edges of the hitch receiver. Mine had very sharp edges so I ground, filed and sanded a nice radius on all four edges.
A 3/4" Buba rope just barely fits with enough room for the pin. 7/16" soft shackles fit with room to spare.
I do like the idea of using fewer parts on rigging

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#2
Even with the Grade 8 bolt this is not recommended. When using a hitch link device from Factor 55 (or similar), since that is a solid piece of metal (steel or aluminum) it is in contact with your pin/bolt over the whole width of the inner diameter and spreads that load across. If you just using a rope or soft shackle that concentrates the load on that one point and can lead to deformation.
 
#3
There will always be naysayers.
A grade 8 hitch pin has the tensile strength (over 55,000 lbs) to withstand way more than any rigging without deforming that will fit into a 4" receiver.
 
#4
Search for ppp-94 on the web, way more info than you will ever need to know about hitch pins. From Purdue University extension.
The pdf is too big to attach here.
 

smlobx

Adventurist
#5
I have often wondered about this as well and have heard about point loading and not spreading the load across the bolt/pin. Couldn’t you use a short 2” wide strap if you were concerned about this?

I have yet to find any studies done where a rope run through the hitch like the OP posted would result in any issues...maybe one of the million of Utubers out there aught to crank one out...
 

Andy

Adventurist
Moderator
Founding Member
#9
You are loading that bolt in shear and not in tension so the ratings on the bolt grade are not correct. Using this calculator you can enter your bolt size and see that the maximum estimated shear load (21,599lbf) is much less then the tensile strength . You are also loading a hardened bolt which can cause it to fail by cracking or breaking instead of bending. The estimated load in the calculator also assumes that you are loading it while supported while in this example we are loading the center of a bolt with around one inch of space before the shear surface on either side further reducing the shear strength. You should be able to use this method but it won't replace an actual rated recovery point.
 

Dean

Adventurist
Founding Member
#10
You are loading that bolt in shear and not in tension
Key important factor here. Even with a hitch-insert you're loading that pin in a double-shear fashion.

My current rule of thumb with using a hitch-insert for recovery is I do not load it to anything higher than the maximum load the equipment is rated to tow. So my hitch and gear is all Class III rated to 8,000#. So that's my basic working load limit. Which, given a modified Jeep Wrangler Unlimited, isn't hard to exceed even in a basic recovery scenario... so I always exercise caution when using a hitch insert and I make sure to do some mental math before committing to it.

If the recovery I'm doing is something simple (i.e. straight line extraction of a vehicle that still has power: i.e. high centered, or can't get traction due to crossed-axles and open-diff, or it's just stupid-stuck on a diff or suspension bracket) I'll give a nice controller gentle pull off a hitch insert. If it's anything more than that (vehicle is disabled, buried in a mud hole, or down in a ditch) I'll go with a different option (winch, k-rope to stronger recovery point, etc).
 
#11
A hitch pin is $4-7, and purpose built and endorsed recovery gear is much, much more. Anyone who is endorsed (the experts) will not support it’s use, and anyone who does will be ridiculed. -Cynic

I don’t believe there is anyway it is the best tool for the job, but would use it and not be concerned. Much better than a tow ball!
 

Dean

Adventurist
Founding Member
#12
A hitch pin is $4-7, and purpose built and endorsed recovery gear is much, much more.
Hitch pins are purpose built and they are rated for specific loads (at least the good ones are). I wouldn't used a Class II pin in a Class IV receiver. And if I was using a Class II pin in a recovery scenario (with or without a hitch shackle insert) I'd make sure my recovery loads weren't going to be more than 3500#. That's the main reason I put a Class III rated hitch on my Jeep and use Class III pins is so I know I can use for 8,000#. So, while it's not the "best tool for the job", it is a tool none-the-less.
 
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