Three-legged jackstands

[Christopher Hoffman <imperial67@xxxxxxxxxxxxx>]

Title: Re: IML: Three-legged jackstands

It would seem the operative issues here are the "legspan" of a stand and the sturdiness with which it is built.

While many tripod stands are indeed garbage, tripods are by the laws of geometry (not physics, actually) more stable, because three points define a plane whereas four points can form an irregular surface. In other words, all three legs of a three-legged table or tripod or whatever always touch the ground when you set it down. It's why three-legged tables never wobble but four-legged ones can. And it's why photographers use tripods rather than, um, quadripods?

There have been three-wheeled cars in history, and while even tricycles can tip over, so can 4-wheeled cars and SUVs or 4-legged jackstands. Static (stationary) objects are affected by different laws of physics than moving objects, especially vehicles with steering and suspension. And perhaps cows and dogs and such have four legs so they can remain standing if they lift (or lose) one leg... the animal kingdom does not rigidly adhere to the laws of physics when it comes to the design department.

(As an aside, you can also remove one rear wheel from a Citroen DS and drive it around on three tires... Don't corner too fast because the tires are not symmetrically positioned under the car's center of gravity, but I've witnessed it being done and not just in a straight line!)

The real reason I bring this up is so people don't think just any four-legged jackstand is better than any three-legged stand. As Arran said, the spread of the legspan (especially in relation to their height) and sturdiness of their construction make a huge difference. Sturdiness, stability, and sensible placement on a hard and level surface (and under a suitable part of the car) are key. Placing a few steel wheels under the car so it can only drop so far if it falls might also be a good safety net (provided you're thinner than the wheels).

And always wear your cell phone where you can reach it in case you need to (and still can) call for help...

I wish you all years of safe hobbying, my friends... and I extend my belated condolences to Greg and Russell for the tragic loss of their friend (as well as my thanks for their willingness to share their pain for the good of others).

Chris in LA

A. Foster (monkeypuzzle1@xxxxxxx) wrote:

I disagree with one statement in this posting. Tripod jack, or axle stands, are cheap garbage, do not use them. Anytime that I have seen  stands fall over, or tip, it was always the three legged kind. Four legged ones always have a wider, more stable stance then three legged ones, it just plain physics. Its the same reason that you don't see three wheeled cars or three legged cows. I was loaned a pair or the tripod type and I threw them in the trunk and decided not to use them, they were just too tippy especially when they were extended.