C'mon. You know you only clicked on this thread because of the title.

There really doesn't seem to be a better place to put this on DF, so I'll just leave it here where I hang out. This came out as a passing thought a few weeks ago and I thought I'd post it for disucssion.

When towing, "everything is big". The hitch ***** are 1-7/8", 2" or 2-5/16". The ball shanks are 3/4", 1" or 1-1/4". 2" square tubing for the reciever. 3/4" steel plate for the stinger, 2" solid steel for a weight-distributing hitch. Everything is huge...

Except for that little-bitty 1/2" or 5/8" pin the holds everything together on the hitch.

I'm sure that pin is designed to withstand a tremendous amount of shear strength but, when you think about it... It's one little pin keeping your truck and your trailer tied to each other. I wonder why there isn't a backup pin.

 

the ball is in bending/single shear.
the hitch is also set up in double shear/bending, but the moment arm is a lot bigger since load point and mount point are farther away.

that pin is in double shear over less than 2 inches, no bending. no bending=happy

 

I'm sure the force needed to sheer a solid metal pin is huge...more than you can get froming towing with a standard hitch. Now if you're towing 10k pounds on a trailer that doesn't have wheels...yea you'll have more than the pin breaking. Hopefully someone that knows a lot about physics will chime in....or freejay

 

I've done a lot of searching and can't find anything on shear strength for the pins. Since Class-IV uses the same receiver and pin, I'd expect it to need to withstand something like 2x or 3x that to be considered safe. There are two sets of 1/4" shear surface between the receiver/hitch/pin. "It just doesn't feel right"

 

If the pin breaks isn't that what the safety chains are for? They would still hold the trailer and give you time to stop. This is one of those things that if it worries you too much, just try not to think about it.

 

I've got chains, break-away brakes, etc. I was just doing a little bit of this-n-that when I realized how small that pin was. I "know" it has to be safe, otherwise DOT wouldn't allow it. It just seems strange, and now my curiousity bump wants to know what those pins are actually rated for.

 

I think if you could put enough pressure on the tow hitch to try and break it, you wouldn't break the pin. I think you'd pull the box section through the pin and leave the pin in place. The shear force to pull and break it would be huge. You'd snap the ball off first.

 

i love how the 'or feejay' is not edited in

and spell it right next time ****er

 

did some quick math.
at 1/2" that pin can take up to 22klbs,
at 5/8" it can take up to 35klbs.

this is assuming perfect loading and stuff, but it's still WAY over anything you're every going to do to it. of course if it rusts half way through, or gets a sharp groove in there somehow, game over.

 

Mind "shearing" the math with us?