Revery Hitch Pin

Hi all,

I have been doing a lot of research here and elsewhere on safe and effective recovery with a snatch strap. I did a search on my specific question and didn't find the answer I'm looking for.

I purchased a WARN recovery hitch, an ARB snatch strap rated to 17000 lbs. and a couple Van Beest shackles. The hitch did not come with a hitch pin, so I plan on using the hitch pin that will come on my new Tacoma (yet to be delivered). What I want to clarify is is the hitch pin that will come stock on the truck rated for the kind of pressure required in a recovery? I assume it is but would rather not find out the hard way with a bent pin that I have to cut out.

Thanks,

Tal

 

The hitch pin should work just fine.

 

Thanks BR,

Good to hear.

 

The pin will fail in double shear, not in bending...if you look at the design of the receiver hitch and the shackle insert, there is no place for it to bend.

IIRC, it is a 5/8" pin, assuming 80KSI shear strength, we have area (pi r^2) or 0.3068in^2, and area x strength = max allowable stress or 0.3068 x 80,000lbs (inches square cancel) or 24543 lbs force. Now DOUBLE that, since you have a double shear situation or roughly 50,000lb force prior to yield. Assume it goes plastic at about 1/2 that, and you have exceeded the strength of every other part of your recovery system. For a truck that weights 6k...fully loaded.

Note: this is an informal analysis and not to be quoted or used in design. This information in provided for entertainment use only.

 

Did you consider cyclic loading failure?

Kidding of course, you will be fine OP

 

Under 1000 lifetime cycles we ignore fatigue...

Howard

 

Wow. I'm not sure I understand any of that but somehow I still find it comforting. I will proceed with the stock pin with confidence.

Thanks.

 

Great helpful explanation Howard. Can you clarify on this part - 'Assume it goes plastic at about 1/2 that'. I wasn't sure what that part meant...

 

Plastic...stretch or bend to the point it won't return to the original shape, and we are going to select roughly HALF the ultimate yield point for that, since the actual steel used is unknown. Remember we "guessed" that the steel in the pin will have a yield (failure) point at 80ksi, or 80,000 pounds per square in, so the plastic point would be 40,000 PSI.

I got my first engineering degree before most of the kids on the forum were born...

Howard

 

My new 2014 Tacoma with the tow package did not come with a hitch pin.

 

Did your new '14 come with a ball hitch receiver? Most likely not.

You'll have to buy a hitch pin when you decide which size & application ball hitch or recovery shackle you buy. And you'll be lucky if one comes with one when you purchase it, because it's usually not the case...

 

Nope, I guess I misunderstood what a "tow package" was. I picked up a Reese hitch pin at my local Napa.

 

I've been encountering divergent views on whether it's safe to use a hitch pin as a recovery point. Some views express concern for the integrity of the pin, while others express concern over the strap. The respected engineer put the pin issue to rest. Also, ARB4x4 has a video on YouTube showing their recommended tips for recovery. The guy in the video uses just the hitch pin (no shackle/receiver combo). I can understand how this would be okay for straight pulls. However, given the depth of the pin inside the receiver, it would be very easy for that snatch strap to rub against the corners of the receiver tube and cause fraying and failure.

I'm debating whether to spend the extra $40 on a shackle mount and then just go cheap on the recovery strap (Smitty instead of the ARB). I fully plan on getting stuck during my first OHV outing in October.

 

Would a grade 8 bolt be stronger for this application?

 

Yes, a grade 8 bolt is stronger than mild steel...BUT the mild steel still shows adequate strength. Plus the threads of the bolt are a weak point, plus the bolt would need some torque to develop full strength.

 

Duly noted. Thank you.

I'm thinking the necessary torque would have to come from a nut on the side of the receiver tube opposite the bolt's entry point, and I doubt the receiver tube was designed to accomdate that.

Interesting discussing and useful info.

 

Torquing improve's the bolt's tensile fatigue strength. Not required if used as a shear pin.

I use one of these. Doesn't rust and doesn't require tools to take out: http://www.summitracing.com/int/parts/mlc-1465dat/overview/

 

Don't forget Mohr's Circle...even if the primary loading is in shear, we are in a combined stress environment.

Howard

 

I'm really questioning a recovery method that involves inserting the hitch pin through the end loop on a recovery strap. When the hitch pin is simply inserted through holes of the hitch receiver (member 1), the force or weight applied at the ends (at the holes) wouldn't be the problem. The force would be targeted at its most vulnerable point -- the very middle -- by the recovery strap. The formula provided by the engineer, if I understand it correctly, assumes use of a shackle mount receiver, which is why he calculated equal force only at the holes in the receiver, which is why he used a double shear formula. However, in a scenario in which no mount tube is inserted into the receiver, and the recovery strap is connected to the center of the hitch pin, that would be equivalent to standing on opposite ends of a stick, bending over and grabbing the stick in the middle, and pulling it up and breaking it. Double shear would be a situation in which a 2-inch shackle mount is slid into the two-inch receiver, with the two connected by the hitch pin. In that case, going back to the stick analogy, it would be like standing on opoosite ends of the stick and bending down and grabbing, with two hands, the stick on both ends right next to your feet, which would be much more difficult to break. Shackle mounts with 60,000-pound rated D-rings would be the way to go in my humble opinion. With that method, the hitch pin would be the least of your worries.