[Spridgets] Jackstands

[Dan Dwelley]

When you load points V think about this! VV is only 16" long and uprights A,b,
and c support VV thus making V only about 7" each...Keep in mind that VV is
equally loaded. unless you load V with a sharp edge thus creating a point load
which will place V in tension creating deflection.

(Do you see where I'm
going here? )

Thanks for listening.

Dan



----- Original Message ----
From:
Tim Collins <thcollin at mtu.edu>
To: Dan Dwelley <maine2me at yahoo.com>; David
Ramsey <dwramsey at att.net>
Cc: spridgets at autox.team.net
Sent: Mon, January 11,
2010 11:16:07 AM
Subject: Re: [Spridgets] Jackstands

When you load a concrete
block at points "v" in this diagram, the underside (points a & b) are in
tension. Sprong goes the block, down goes the car.

        v              v
|--------------|-------------|
|      a        |    b        |
|             
  |              |
|--------------|-------------|



At 10:19 AM 1/11/2010,
Dan Dwelley wrote:
> "Concrete is very weak in tension"    Um....the load
would be compression not tension. and concrete blocks generally are about 15
PSI compression.. (This is not to say they should be used as jack
stands...cracks and damage can cause week spots and when concrete fails under
load, it's not graceful!) The face of the block has a center supporting
perpendicular.... it is weaker than the adjacent face but ... Just palying
devil's advocate... :o) Dan ----- Original Message ---- From: David Ramsey
<dwramsey at att.net> To: Tim Collins <thcollin at mtu.edu> Cc:
spridgets at autox.team.net Sent: Sun, January 10, 2010 4:55:51 PM Subject: Re:
[Spridgets] Jackstands Who cares by the time the cinder blocks fail, you're
down the road with your new set of wheels and tires.        Crash Finally,
don't ever use a concrete block as a jack stand. Concrete is very weak in
tension and will fail suddenly under a relatively small load. When loaded on
the face of the block the
 concrete is in tension. Tim Collins
http://www.flickr.com/photos/12702006@N07/
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Tim Collins
http://www.flickr.com/photos/12702006@N07/