[Elarson]

Originally Posted by Mr Anonymous

For the nerdy:

When the pin is holding the hitch together, is it one case of double shear, or two cases of single shear? Can see it both ways.

It's one case of double shear; with a little bit of bending mixed in because of the side clearance between parts. Running a few numbers:

double shear area of 5/8" pin = .613 in2
Assuming 1018 mild steel cold drawn, the ultimate tensile strength = 63,800 psi
Shear strength is around 57% of ultimate so it's about 36,000 psi.
So the pin should break at about 22,000 lbs.
A wise traveler should have a safety factor of at least 2 or 3.
So the allowable load would be 7000-11,000 lbs.

Better pin material (like an alloy steel) would bump those numbers up a lot.

Eric

[Sirrotica]

Originally Posted by Elarson

It's one case of double shear; with a little bit of bending mixed in because of the side clearance between parts. Running a few numbers:

double shear area of 5/8" pin = .613 in2
Assuming 1018 mild steel cold drawn, the ultimate tensile strength = 63,800 psi
Shear strength is around 57% of ultimate so it's about 36,000 psi.
So the pin should break at about 22,000 lbs.
A wise traveler should have a safety factor of at least 2 or 3.
So the allowable load would be 7000-11,000 lbs.

Better pin material (like an alloy steel) would bump those numbers up a lot.

Eric

I guess E Trailer had some bad information on their site. Your calculations are a long way from the "90.000 Lbs" they have posted on their site. They are off 3 times too high on their guess............LOL

Looking further on some other sites I find specs of 21,000 lbs for 5/8 inch hitch pins.

I've had to do some jacking on my 1900 built farm house and using a 20 ton hydraulic bottle jack, using a floor jack post, the adjustable pin started to deform the tubing before the pin sheared. From that example I'd surmise the mild steel would start to tear at the holes before the pin shears on a receiver hitch. Just an experiment I've run across in jacking my home up to where it was before everything sagged and settled in the last 123 years.

The floor jack posts are rated at 18,000 lbs, much closer to Eric's calculations

Bob, my apologies for citing the wrong information from E Trailer.com..... You'd think a business that specializes in trailer towing equipment would strive to have more accurate information on their website.

Eric, thanks for some better calculations than E Trailer has posted....