Safe to use recovery strap on hitch pin instead of shackle?

[Antichrist]

Here is why

1) A reciever shackle, like a lot of hunks of metal, is inordinately expensive for what it is. They seem to be around $75. My whole hitch costs only twice that. I just bought a 500gb hard drive, an extremely complex electronic and mechanical device, with millions of parts and a lot of engineering work to make it, that cost that much.

I don't know where you're looking, but they can be had for $40 or less.
As for comparing it to a hard drive, that's really sort of silly. How many hard drives do you think get made, compared to the number of receiver shackles?

2) It's another thing to carry

True, but it doesn't really take that much space.

3) Even if it's stronger, it does have a negative effect-- it pushes the attachment point of the strap further to the rear, changing the angles of forces and stress to the frame/unibody. If using a pin is OK, I'd rather do that since the point is much closer to the frame, and to the rear tires.

While technically true, it's a fairly minimal change. And as has happened to others, if you do bend the pin, or get the strap wedged in your receiver, or both, you're potentially screwed if you need the strap on the front of your vehicle, or need to hook up your trailer when you get back to camp.
I've never heard of anyone bending a receiver shackle or getting it all bound up. If done correctly.

 

[winkosmosis]

What about the aspect of a non-straight pull severely rubbing the strap on the inside edge of the reciever tube? Or the fact that a heavy pull is seemingly likely to bend the pin, jamming in the reciever tube, and leaving you with a recovery strap stuck in your hitch? The shackle mount is less likely to jam the pin, since it's a pure double shear force on the pin.

For me, using the strap on the pin is a contingency for if there are no other options. The

I would think sliding something over the strap to protect it would work. You could make a sheath from nylon or vinyl fabric and velcro.

Yeah the possibility of the pin bending because of different forces is why I made this thread. Most people seem to think it's unlikely though

 

[Antichrist]

Aluminum ones are available as well, to reduce weight.
http://www.okoffroad.com/stuff-smw-shackles.htm as an example.

 

[R_Lefebvre]

The weight issue really seems like much ado about nothing. So what, it's 5-10lbs? Not a big deal. Besides, I need extra weight on the back of my Disco anyway. And I carry it *in the receiver* so it takes no space. My HiLift and chain weigh much more, with much more dubious usefulness.

 

[BIGdaddy]

Aluminum ones are available as well, to reduce weight.
http://www.okoffroad.com/stuff-smw-shackles.htm as an example.

:drool: thats cool.

 

[ntsqd]

I pay attention to weight. I drive a 22R. I don't get anal about it, my tooth brush is fully handled and does not have any holes drilled in it, but I've found that just being cautious makes a large difference. Partly why I built my slider. I took weight out of it where it didn't need to be. That and I was a poor college student when I built it.

 

[winkosmosis]

The Marines use pins instead of shackle mounts?

 

[RobA]

To answer the original question yes you can if the pin is one that you use to secure the tow receiver and tow ball. At least it is in Australia. The reason is we have a standard that is required to be met before the item can be fitted to any vehicle so there is a guarantee of quality.

I have never seen a proper hitch pin bent in over 25 years of 4WD training and recovery. I probably average several hundred snatch recoveries and a couple of hundred winch recoveries every year during training and tours without equipment damage or breakage.

Over last weekend we were running mud and water training and I had to snatch recover a Patrol weighing over 3tonne using my Prado which weighs in at 2.5 tonne. Took three goes and we hooked up using the block hitch receivers on both vehicles and bow shackles. Both hitch receivers were held in with the standard towing retainer pin. Similiar situation with the ten winches I did. All used the same or similiar fixing points and pins.

But as usual with recovery if you don't know or are suspicious about the quality of any of the equipment then don't use it

One of the key areas of risk is ensuring that the sharp edges around the hitch receiver are filed smooth to prevent premature chafing and failure of the head of the strap as it rubs around the edges during recovery. To this end I always use the hitch receiver. We actually always carry a spare and two spare receivery pins as well

Regards

RobA

 

[emmodg]

When training the Marines they have more 3" straps then 2" straps. We have got the 3" straps in the 2" receivers, it is a pain and you have to work more at it. The G-wagons have 2" X 30' straps for the most part and the Hummers have the 3" X 30'.

You're training Marines in Hummers? Why not HMVEE's (1151 or 1152's)

We've never trained a Marine in a Hummer.

1151's and 1152's are equipped with 60k straps - 2 3" straps bar-stitched back to back; however, the ends are still "single layer". THIS is where we break them A LOT! These straps are limited in their use on dynamic pulls of 14-15k lb trucks. Especially scary when training the hasty recovery!

 

[Taz]

My take on this has always been, if the receiver pin fails you were NOT doing your recovery in a proper manor. This takes into account that first your hitch pin was the correct size for the receiver. Second that it was a "real" hitch pin not some POS. Third that you used a 3" strap not a 2". Note: They are wide so I really do not understand the "shear point" being in the center. I have yet to have a hitch pin fail or a strap damaged by doing a recovery off a hitch pin.

 

[I Leak Oil]

The strap is not a rigid object, like a receiver shackle, so it will tend to transfer more of it's load to the center of the pin, assuming a straight pull. Notice I said more of it not all of it.

I think this thread needs an official "beat a dead horse" emocon....

 

[michaelgroves]

1151's and 1152's are equipped with 60k straps - 2 3" straps bar-stitched back to back; however, the ends are still "single layer". THIS is where we break them A LOT! These straps are limited in their use on dynamic pulls of 14-15k lb trucks. Especially scary when training the hasty recovery!

The strap breaking is the least dangerous "bad" outcome. (Though, in a military context, maybe not!!!)

 

[Antichrist]

To answer the original question yes you can if the pin is one that you use to secure the tow receiver and tow ball.

I'm not clear if you really are answering the original question or not. The OP was about using the pin only, which loads it differently than if you're using a receiver shackle. There's isn't any way to connect a shackle, which you say you're using, to the hitch pin. Also, it seems to me that it would be a royal PITA to get a 3" wide strap in to a 2" receiver opening.

 

[ntsqd]

Since we're flogging, I thought that I'd take another look at the shear and the bending of the hitch pin. There appears to be agreement that a 2" strap is the widest that will reasonably fit inside of a receiver hitch. A quick survey of 4 Wheel Parts' page showed that 20,000lbs is the upper limit in 2" strap strength and 30,000 lbs is the upper limit in 3" strap strength.

Since most straps are folded over on themselves within the end loops to make fitting a shackle easier I made the assumption that the strap is 1.0" wide where it pulls on the pin or the shackle, and initially that the loop is centered on the pin.

As Dave noted a 5/8" pin (or shoulder of a bolt) has 0.307 square inches in cross sectional area.

Using these two pages:
http://www.aboutcivil.com/wiki/index.php/Image:Sfd-bmd-simp-udl-mid.JPG
http://www.aboutcivil.com/wiki/index.php/Image:Simply-supported-udl-mid-formulas.JPG
with the above numbers and assumptions and if the strap is used to it's limit then I get Shear stress on the pin at each of the receiver walls of 32,595 psi and a Bending stress at the middle of the pin of 24,446 psi.

Where things get interesting is if/when the strap slips off to one side. The Bending stress drops from 24,446 psi to 18,335 psi since the leverage was reduced, but the Shear stress grows significantly from 32,595 to 48,892 psi.

If a 3" strap is used then the loads start to get up there where the pin may be in jeopardy. Substituting 30,000 lbs pushes the max Shear to 73,339 psi and the max Bending to 36,669 psi.

My math could be off, feel free to check it.

Does anyone have exact info on the alloy used in these pins?

 

[michaelgroves]

Just a thought, but how much do we care if the pin breaks? It's not going to fly out, is it? Sounds to me like a benign (and unlikely) breakage. The main issue would be that it would be a PITA to get the broken/bent pin out.

Besides, tell me again why we're not using a receiver shackle, if we're using the receiver mount?