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

[Bennyhana]

Am I going to have to start packing my scientific graphing calculator now?LOL..

 

[R_Lefebvre]

Does it matter whether the bolt bends at 6,200 or 8,200 lbf? Not really, because either way it's a much lower strength than you would get with a shackle mount inserted in your receiver instead. Even that 12K rated hook from Northern has a higher rated load. To get back to the original question of the topic, regarding whether or not it is safe to use the hitch pin instead of a shackle - yes, it is. Most recoveries take quite a bit less than 6,200 lbf, or even the 4,400 lbf you get from a Grade 5 bolt. However, no, the hitch pin will not provide the same capacity as the shackle insert. If given the choice, use the shackle insert, but the pin by itself will probably get you out of a pinch without hurting anyone.

I don't want to take this discussion too far, becaues I believe this paragraph is THE important take-away of the whole thread. Yes, a reciever bracket is better than using a pin, and I think that 10lbs and $40 is a pittance compared the annoyance of having to cut out a pin. Or during the same trip, needing the strap at the FRONT of your truck after it's now stuck in the back, due to a non-removable pin.

That being said, I believe the load would be evenly distributed on the pin along whatever length of pin is wrapped by the strap. This because of the simple fact that the stiffness of the pin is very much greater than the stiffness of the strap.

It should also be kept in mind that the failure mode here is likely to be non-injurious. If you go over the ultimate tensile of the pin, it will bend, it will not fracture. But that brings us back to the above point, is it worth 10lbs and $40 to suffer with a bent pin?

 

[winkosmosis]

Wait wait! Before you decide that even the small risk of the pin bending is worth avoiding by carrying a shackle mount, there is something else to consider. With anything other than a straight forward-backward pull, the pin method is going to put less force on the frame and hitch than a shackle mount.

 

[ntsqd]

If ultimately all of the pulling force goes through the pin then a slider won't offer any reduction in ultimate tensile loading of the hitch or the frame.

What will change is the leverage, so the torque on the hitch and the frame can vary, but as was previously discussed, pulling at angle with just the pin is very hard on the strap where it encounters the relatively sharp edge(s) of the socket.

I'm not ignoring any tractive force that might exist where the strap is 'bent' by the socket opening, but I am discounting it as insignificant. If it is not insignificant then it will be very short lived, and so will the strap.

 

[winkosmosis]

I'm talking about the leverage. Unless the strap is pressed against the side of the hole, the sideways force at the pin. If the strap is at a great enough angle to rest on the edge, the force is at that edge. Is that a big enough difference from the leverage gained with the shackle mount to matter?

 

[ntsqd]

No. There is a gain in length due to using a slider, but the edge will cut the strap (or try really hard to cut it) so the issue is moot. If the pull angle of a simply pinned strap causes the strap to even slightly bend around the edge of the socket opening it is time to re-rig the pull so that it does not make contact. At that point the leverage is so small that it is insignificant.


Re: A P.E. stamp, my discipline is a hybrid so there is no P.E. available. I didn't bother with taking the EIT either. That said, were I asked to put my stamp on something that was not formulaic, like this, I would require physical testing that supported the calculated results.
The exposure in posting on a public forum is nothing like issuing a P.E. stamp. It is incumbent on us that erroneous info not be posted, but excessively conservative info can be just as misleading as excessively liberal info. We are not contracted to render a design. We are offering an opinion without knowing how those in the future might apply that info. Since we have no control over this the info presented MUST be used as an opinion only. Anyone who stakes their life solely on an internet opinion must not know of Darwin.

 

[alexrex20]

lol all this talk of theory is a bit pointless. in the real world, we make do with what we got, and what we got is a receiver and a hitch pin.

personally, i've been yanked and have yanked on others with my strap through my receiver, and i've yet to see any fatigue in the receiver's eight grade-8 mount bolts, the receiver itself, or the grade-8 bolt which i use as the "hitch pin."

it's much safer to put the hitch pin through the strap than it is to put the strap over the ball, but let's keep crunching numbers and see what we can come up with.

until then, i'm going to continue putting my strap through my receiver and grade-8 hitch pin.

 

[youwillforget]

I have done both. My 06 GMC 2wd would not drive out unassisted = Stuck, however it was in a wet spot in a camp ground and I had simply lost traction so pin through strap worked. Buddy’s H2 SUT with 35"s in mud up to the diff = Stuck, shackle no question at all. Both times RV was the same Xterra. Use your brain stop and think about what is stuck and how it’s stuck if it is a lost traction or soft surface issue it’s going to take less effort or yanking than axels and frames making ground contact. An Escalade on 24’s wheels with 70 series tires slipped off and icy express way is going to take a lot less effort to recover than a Tahoe on 33’s sitting on its frame in a wet corn field. There is no magic recovery bullet "Situations dictate tactics, tactics dictate techniques"