On Fri, 11 Aug 2017 10:39:19 -0400, micky
wrote:
In alt.home.repair, on Fri, 11 Aug 2017 08:43:16 -0400, Ed Pawlowski
wrote:
On 8/10/2017 10:00 PM, DerbyDad03 wrote:
The angled and curved pieces are types of arches. The load is easily
transferred through those structures to the abutments resting on the
ground. As long as the welds are created properly (can be said about
everything which is welded), the structure of the jack stands appears
quite sound.
I understand how arches work/transfer the load. It's not the arch shape that
bothers me, it's the welds. Since I didn't do the welds, I'm not sure I
want to trust my life to them when a "straight down to the ground" option
exists.
I'm sure they're fine, I just don't want to be worrying about them while I'm
under the vehicle.
You trust your life to welds most every day crossing bridges, using
elevators. I don't crawl under a car unless it has two supports though.
I had a set of jackstands, maybe from Western Auto, and a friend who
didn't weigh more than 160 was sitting in the drivers seat with his legs
out of the car, a Chrysler K-car that didn't weigh more than 3000
pounds, and had 3 wheels on the ground so the stand was supporting only
a little more than a quarter of the car, and the jackstand collapsed on
him.
You can have 3 wheels "on the ground" and still have the jack stand
carrying half the weight of the car -
Not this brand but something like this:
https://www.amazon.com/Torin-T42002-...ds=jack+stands
A pair of 2000 lb stands can support 2000 lbs, not 4000. Stands are
solad AS A PAIR and the rating is FOR THE PAIR.. So, ONE stand is good
for 1000 lbs, not 2000 - and the curb weight of a K-Car is a minimum
of 2300 lbs. - so if ONE stand is supporting one side of the front of
the K-Car, it will be shifting the weight of the car to the opposite
rear wheel - taking load off both the opposite front and the same-side
rear wheel - so the stand is taking a load SUBSTANTIALLY over 1000
lbs.
If 2 stands are used under one side of a car, the car transfers weight
to the opposite side, and the 2 stands combined are holdinf
substantially UNDER half the weight of the car.
If the 2 stands are used under the front of the car, depending where
the stands are located they can either transfer load to the rear
wheels or take load off the rear wheels - so the stands can be taking
close to half the weight of the car, or substantially more. 2 to jack
stands are "light duty" stands. Knowing how to use them properly is
required to be safe.
This doesn't take into account the folly of using them on irregular or
soft surfaces, which can put over 30% more load on each of 3 legs
contacting the floor if one is not contacting the floor.
I took it back but didn't want to spend extra for bigger, so like an
idiot, I accepted another box of the same thing that failed once.
A few years later when I was changing the right half axle on my car and
the ball joint, I was so afraid another would collapse that I used both
stands, another one, and 2 floor jacks and a scissors jack all at the
same time so I wouldn't get crushed. It was hard to get it to rest on
all of these at the same time.