HF jackstand failure experiment

While there may not be any fun in it, it would be valuable to know how much force is actually required to shear the pin. The fact that the pin didn't shear and possibly might not shear even if the jack is used at 100% of its rating (which is foolhardy in and of itself in my opinion) doesn't make me super nervous about it since you'd need to be doing something kind of dumb to cause the non-failure of the pin. It would be nicer, though, if the pin actually did its job. I assume all jackstands with that lever work the same way, so do other brands have shear pins that work or is this an oversight that they've all made?

It would figure, of course, that the one sturdy and overbuilt thing that you can buy at Ye Olde Hammer Shoppe is the freaking shear pin...

Kylini wrote: Anyone else notice that even after this "failure", the jack stand will still be in place, just at minimum length? That shouldn't be an issue if you're using more than one stand other than the pucker moment. Worst case, you should get stuck but not crushed.

Worst case would be that the sudden downward movement followed by the sudden stop could topple the stand or move the car in such a way that it would cause the other jackstand(s) to fail or be relocated causing the car to fall and to then trap or crush you.

I mean, the lesson is still don't stick a lever into the handle of the jackstand and pry on it with all your might. But once the car starts falling, the number of potential landing zones expands rapidly.

Blaise wrote: I guess now I'm not that weird for leaving the jack under the car too after letting it settle. Can't be too safe.

i do this as well, i'll releive the pressure of the floor jack so that the weight is on the jackstands then i'll jack it back up so that it is just touching. half so that if anything happens there is something else trying to catch the car and the other half is so that i dont have to get down to see where the lift pad is to get it back off the jackstands.

In reply to wae:

So how much force do you think it should take to shear than pin? 10lbf? 20lbf? 100lbf?

In order to lift that handle unintentionally and not realize you are doing it, it probably should shear well under 40 lbf. I would say you will be shearing pins left and right while moving the jackstand around. Drop it and it will be gone.

I agree with the poster above who said that pin might no be a safety device.

BTW, I am all for jackstand safety. I had a friend who passed away while changing his S2000 differential. He was alone and accidentaly pushed it out of the way.

In reply to Slippery:

Yeah all the ones I have look to be a steel roll pin. Those will take considerable load to shear. Maybe they are not safety devices. It would need to be quite light to be a safety device. release.

Sorry to hear about your friend. Thats terrible.

BrokenYugo wrote: I saw that a couple days ago, I think the guy's hypothesis is flawed. If that pin was meant to be a shear pin it wouldn't be a hardened steel roll pin, it'd be something soft, a piece of some sort of wire. He's testing a nonexistent safety.

Indeed. I usually replace those pins with bolts!

Slippery wrote: In reply to wae: So how much force do you think it should take to shear than pin? 10lbf? 20lbf? 100lbf? In order to lift that handle unintentionally and not realize you are doing it, it probably should shear well under 40 lbf. I would say you will be shearing pins left and right while moving the jackstand around. Drop it and it will be gone. I agree with the poster above who said that pin might no be a safety device.

IF it's a safety device, then I would think 250-500 pounds is probably a good target.

If it isn't a safety device, though, then it should probably not shear until over 12,000 pounds (or whatever the rating of the jackstand is).

While I also am all for under-car safety, if that is intended as a safety device it seems pretty pointless even if it did shear off at less force. If you're bound and determined to lever that handle up with a prybar, I'm not sure there's much we can do to save you...

Look at how long the lever he used with steady force was to pop that. It looks easy because it's 3' long. It took a strong direct upward hit with a 5lb hammer, or an even pull of over 100 ft/lbs of leverage to cause that failure. He should have used a torque wrench to measure it if he wasn't trying to be deliberately dramatic.

If you bring one of these down on yourself it should be considered a suicide attempt or atleast a cry for help.

Huckleberry wrote: Look at how long the lever he used with steady force was to pop that. It looks easy because it's 3' long. It took a strong direct upward hit with a 5lb hammer, or an even pull of over 100 ft/lbs of leverage to cause that failure. He should have used a torque wrench to measure it if he wasn't trying to being deliberately dramatic. If you bring one of these down on yourself it should be considered a Darwin Award application.

I want my 12 minutes back.

jk, I fast forwarded most of it. Nothing earth-shattering here.

Interesting. I just looked at the manual for the Pittsburg 3 ton aluminum racing stands sold by Harbor Freight and they are, in fact calling that a shear pin.

From the manual

"Do not move the Handle when the Jack Stands are supporting a vehicle. The shear pin is designed to shear in the event the user attempts to move the Handle while supporting weight"

I never knew that. Assuming that the stands tested in it are the same, that makes the video a little less irrelevant. I still think it's ill advised to be whacking at that handle regardless of jack stand manufacturer.

In reply to APEowner:

Interesting, the manual for the steel ones also calls it a shear pin. I've never seen a shear pin in a jack stand though, a little hardened roll pin is what keeps popping in my head. Translation error? Factory got a better deal on roll pins than aluminum pins?

This Craftsman manual just calls it a pin and makes no mention of it being a safety device.

BrokenYugo wrote: In reply to APEowner: Interesting, the manual for the steel ones also calls it a shear pin. I've never seen a shear pin in a jack stand though, a little hardened roll pin is what keeps popping in my head. Translation error? Factory got a better deal on roll pins than aluminum pins? This Craftsman manual just calls it a pin and makes no mention of it being a safety device.

Marketing?

wae wrote: If it isn't a safety device, though, then it should probably not shear until over 12,000 pounds (or whatever the rating of the jackstand is).

The rating of the jackstand is irrelevant, because all the pin does is to lock the handle to the pawl. The handle isn't involved in holding the weight of the car, so the most load that pin is expected to see is that of the jackstand itself (when you pick it up by the handle) times a few gees (say you're swinging it up to put it in the back of the truck).

Huckleberry wrote: Was anyone else annoyed that he could figure all that out but used the channel locks backwards when loosening fittings?

those were not channel locks. They are knipex. consider them more like a C-wrench than pliers

Trans_Maro wrote: Tools don't have a brain, you'll have to use yours.

I think I'll be hanging a sign in my shop that says this.

mad_machine wrote:

Huckleberry wrote: Was anyone else annoyed that he could figure all that out but used the channel locks backwards when loosening fittings?

those were not channel locks. They are knipex. consider them more like a C-wrench than pliers

Still used them backwards.

Ummm, my jack stands have a safety pin. This was not an accident.

Marginally related: bend that tab in, and the two parts won't separate when you chuck them around.

In reply to wheelsmithy:

I like those, redundancy aside. My primary reason for the use of ratcheting stands is for adjustability. The pin types usually have 2-3 inches between holes and generally find me between too low, and not enough jack.

In reply to Kylini:

I could totally see a car come off a jack stand if the other violently failed or slipped. It's not like all cars mate up to the jack stands ends equally as well either

In reply to Crackers:

Definitely not arguing, but mine have what appear to be 1" between clicks. Cheap at Northern, too. Admittedly, I also have some that were my grandfathers, and are made of little more than sheet metal, and have pins only. Their range may be closer to 2" per slot. I still use them for light duty stuff.

I agree with the statement from earlier. (paraphrased?). "Tools don't have brains, you have to use yours."

I think the solution is might be to replace the roll pin with an appropriately sized wooden toothpick. I don't use those release bars except as handles when carrying the things around anyway.

He used math to figure the pressure/force applied to the jack stand.

He should have figure the amount of force that bar applied to the handle.

Hard to figure the force of a hammer.

I'm guessing that the person who had the car come down on their face didn't have the car level on all four jackstands. Weird, dangerous things can happen if your load isn't evenly distributed.