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Jackstand failure testing

T

tomsmith

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Jul 12, 2009
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207
Hey,

I know there are a few horror stories out there regarding jack stand failure (the Porsche 914 is the scariest) but I wonder if anyone knows of any real testing?

I'm working on my Chevy Trailblazer and have it supported by 6 jack stands ,read here if you're interested:

http://forums.trailvoy.com/showthread.php?t=100600

However, I've never seen actual destructive testing of jack stands. Not only would it be cool to watch :thumbup: but it would actually be educational too.

It would be pretty easy to test with a hydraulic press I think? Put a 2-ton or 6-ton press in a press, start it and back away to a safe distance. A 20-ton press should have no problem causing a 6-ton jack stand to fail I think.

Would be interesting to see it happen with the jack stand extended and not extended.
 
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BJ42LX

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WNY
I would be interested in the test results as well.

Go ahead and do the tests and post up your results. Don't forget the videos!

:beer:
 
A

Air_Cooled_Nut

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Portland, Oregon
Remember that though they are rated at 2-tons, that is with a safety allowance so it would actually withstand double to triple that amount at least.
 
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rsanter

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I used to product testing and specifically load testing.
You need a load cell that can apply the force but you also need something that will Tess instanoius load so you can plot a graph
For critical items it is not testing to failure as you may expect. It is when the load it carries starts to drop off a little and you start to get movement in the head. In other words as soon as something starts to give I conceder that a failure even with no catastrophic damage
You would need to know what ther spec is

Bob
 
B

brownbagg

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Mar 20, 2006
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but with an hydraulic press you are measuring two different item, hydraulic is force, pound per square inch, jack stand is weight, dead load. the weight on a jack stand is nothing to steel, you get more into design than failure as in size of footprint.


let say you have a 8000 ls truck on 4 jackstands, 8000/4 is 2000 lbs per jacksatnd,

if the head of the jackstand is 4 sq inch, then that would be 2000/4 equal 500 lbs per square inch.

know these numbers are example and did not actual measure. on a small car say 3000 lb then it be 187 psi of dead weight. its more design than material
 
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retrobuilder

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Alpharetta GA
if the head of the jackstand is 4 sq inch, then that would be 2000/4 equal 500 lbs per square inch

The jack stand is under three types of loading-

Compression of the steel frame like a column

Shear load of the cast contact pads (bending or breaking the lugs)- my biggest concern.

Compression of the leg :"gear column:" as a loaded column.

The psi per inch stress is useful only for compression but discounts the height of the structure.

Your 500 psi is misleading relevant to both design and loading.
 
C

c39er

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Mar 23, 2008
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Seattle, Washington
I tested this jack stand I have had since high school and used under everything except a AC Dozer! It was in a set of four and I would repair /replace it except having a problem finding 2-1/2" tube. I do have better stands too.
 

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alan camby

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South of Indianapolis, Indiana
Mine took everything that my 20 ton press could put out.
BTW: I know that US jack tests stands at 200% for the military. They will do it for the ones they sell the public for a charge of $75, if i remember correctly.
testingstand001_zps0251f09a.jpg
 
H

Higgins

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Dec 25, 2009
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Shepheardsville, KY
From listening to those occasions that jacks have failed, collapsed there were issues with the vehicle may not have been level, the jack stands may have been on an uneven surface, or something on the car shifted causing the jack to move, fall or collapse.
 
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alan camby

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South of Indianapolis, Indiana
marlinspike said:
So, when are you going to start selling your extremely strong camera stands? :D
Click to expand...

I wish I could. My garage is so small and every time I start a project my entire floor space is at a premium.
All the steel for the stands was cut on the floor. Which was a big pain in the back and knees.

The materials were not cheap. Over $140 for 6 foot of 1.5" Acme, 4 nuts and shipping. Also had the DOM tubing and used about 16 foot of 1x2x.120".

If i were ever to build another set, I would have the feet cut out on a plasma table. This was a huge pain cutting them out with a hole saw.

It all boils down to having the proper shop setup. Even with that, would have to charge quite a bit just to break even.

The biggest problem is liability. What if someone were to ever get hurt:dunno:

Glad you liked them though. Had a lot of fun building them.
 
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alan camby

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Back to your regularly scheduled program.

I have spent hours and hours researching jack stands and failures. IMO, The failures I have seen are mostly due to a complete lack of common sense.

I have seen several of the ratchet pawl style stands fail. From what I can tell, The person setting up the stand either thought it was OK to place the load bar on top of the pawl or they accidentally placed the load bar on top.
Most of the Chinese stands have instructions that show or say, insert the load bar (ratchet bar or whatever you want to call it) into the frame and bend over a tab that prevents the bar from over extending. If you look at the pictures of a failed stand, everyone I have seen, has not had this tab bent. Pictures that show the inside of the frame have the pawl flipped 90 degrees past were it should be. I don't see how this could happen unless the load bar was placed on top of the pawl. This is just my opinion, take it for what it is worth.

I have seen one Craftsman stand fail due the leg breaking. This was a angle iron legged stand that had braces connect the legs from bending out. The poor Chinese weld failed on the brace and allowed the leg to bend.


My advice for ratchet stands would be.
-Buy the kind with stamped legs, not welded angle.
-Always bend the tab over. Even if you know how to use them, someone you care about might borrow them and get hurt due to placing the load bar on top of the pawl.
-Last, Look for good welds and try to find USA made.
 
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LG63

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Sep 7, 2012
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I have some 6 ton import stands and I don't worry about the base as much as I do the ratchet bar. I assume it's cast iron which like concrete works great in simple compression but I have to wonder what would happen if the load were to shift. Granted it would take some significant side loading to cause a problem but then again cast iron is pretty brittle.
 
K

KMinAF

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Mar 5, 2011
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Fairview Utah
alan camby said:
I wish I could. My garage is so small and every time I start a project my entire floor space is at a premium.
All the steel for the stands was cut on the floor. Which was a big pain in the back and knees.

The materials were not cheap. Over $140 for 6 foot of 1.5" Acme, 4 nuts and shipping. Also had the DOM tubing and used about 16 foot of 1x2x.120".

If i were ever to build another set, I would have the feet cut out on a plasma table. This was a huge pain cutting them out with a hole saw.

It all boils down to having the proper shop setup. Even with that, would have to charge quite a bit just to break even.

The biggest problem is liability. What if someone were to ever get hurt:dunno:

Glad you liked them though. Had a lot of fun building them.
Click to expand...

+1
Somehow for me production takes the fun out of it
 
S

Shadowdog500

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Down the shore
I've been thinking about this a lot the last few days. I'm planning to service the wheel bearings on my Motorhome this spring and have been checking out 6 and 12 ton jackstands. The ones at HF have a little asterisk next to the rating. The asterisk indicates that the rated load must be distributed between two jackstands. The ones from Greg smith advertised rating is for one jackstand.

Hein-Werner are made in the USA and I would trust them more than offshore jackstands.
1027__(500_500).jpg


I would get these Heim-Werner forklift stands but they are $350 a pair.
2691__(500_500).jpg


The drop axle in my Motorhome is only 7" off the ground and the jack stands are around 19" minimum, so I'm actually planning to support the axle with at 10" using couple pieces of wood cribbing (The wood used to jack up houses). I understand cribbing is commonly used to support heavy equipment.

Chris
 
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1

#1SomeGuy

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Dec 4, 2012
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Canada
This is why I always try to give myself a backup if any part of my body is going under the vehicle...after putting the full weight of the vehicle on the primary jack stands, slide another pair under the vehicle somewhere that can handle a bit of load, or leave the floor jack snug (but not holding load) against the jack point if it's not in the way. This way if one were to break or slip out or whatever, it's going to come crashing down a fraction of an inch onto another set of stands/jack and who cares what is broken when that happens, as long as it's not me.

The other common thing to use if you don't have extra jack stands, is if the wheels are off is to throw them under the frame rails or somewhere not in the way of the job. Again, would rather wreck a set of wheels than me.

Last case, if the wheels are on, throw some blocks (concrete or wood, depending on height) under the wheels to give extra clearance if it comes down. Of course, works better on lower cars with less suspension travel than big trucks.
 
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alberto

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May 28, 2007
Messages
756
alan camby said:
Mine took everything that my 20 ton press could put out.
BTW: I know that US jack tests stands at 200% for the military. They will do it for the ones they sell the public for a charge of $75, if i remember correctly.
testingstand001_zps0251f09a.jpg
Click to expand...

Wow, those are great! I hear you about the liability etc., of making them for others, but if you ever do make them for sale, I'd be interested. The only thing I would change would be to add a rubber pad on top. Nicely done.
 
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brownbagg

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Mar 20, 2006
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5,208
i bought some at sear, and another day needed two more but sear was closed, harbor freight was across the parking lot. bought two at HF and they are identical to sears in every detail. except for color you can tell made at same place
 
S

Shadowdog500

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Dec 7, 2009
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Location
Down the shore
alan camby said:
Mine took everything that my 20 ton press could put out.
BTW: I know that US jack tests stands at 200% for the military. They will do it for the ones they sell the public for a charge of $75, if i remember correctly.
testingstand001_zps0251f09a.jpg
Click to expand...

I dont mean to derail this thread, but I have to ask.

Did you modify that bottle jack to work upside down, or did you buy the press that way?

Chris
 
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