> Elle wrote:
> >
[quoted text clipped - 69 lines]
> tool. the holes only resist rotation as "support" of the load is via
> the socket on the bolt.
I can't figure out what you're trying to say. Yours is
horrible writing. It wastes a lot of time. Tack on that I
sense you have never had a course in statics, much less
strength of materials, or you didn't understand the material
well if you did take these courses, and we have a nuclear
holocaust in communications.
Which "load"? The socket has a force being applied to it
from the wrench, but then the bolt itself is also applying a
force in the opposite direction to the socket.
Here's what is happening:
The commercial tool has a prong that goes through one of the
pulley holes. The commercial tool, like the homemade one,
must be supported against something, such as the ground or
maybe the body of the car. In both instances, the holes in
the pulley are pushing against the prong or the bolt in the
same manner.
> with your tool they resist both rotation /and/
> the leverage of non-radial loading - there is no "support".
>
> go to a junk yard some time. pulleys that have been broken using your
> kind of tool are very common. always two adjacent holes
My tool doesn't insert into two adjacent holes, for one
thing. For another, of course any breakage, with the
commercial tool or a homemade one, is going to be at two
holes, because of the way the forces are applied during
rotation.
> and extensive
> collateral damage. i'll take may camera to the junk yard some time if
> you want confirmation.
I suspect what you're seeing explains why the hole design is
no longer used. The flaw in the hole design of pulley would
be an argument against both the commercial tool and the
homemade tool. You want to make that argument, that's fine.
It is speculation but absolutely worthwhile speculation. IF
there are as many pulleys out there with busted holes as you
say.
I have yet to see a report, from anyone other than you, of
breaking the pulley as you describe. I'm not saying it
doesn't happen. I'm saying you're over-reacting. Again.
Just like you experienced yesterday, all tools should be
used with care. Hurting one's self as badly you did tells me
this was as much operator error as it was any problem with
the tool. You're applying a high enough amount of force to
cause something to go flying (your body? or the socket?),
without anticipating something suddenly loosening, after how
many years of experience? Phew...
jim beam - 02 Jan 2006 03:15 GMT
<snip unfocused sniping>
let's get to the point:
http://www.flickr.com/photos/38636024@N00/80617642/
examine this pic.
now, draw a line from the center of the pulley to one hole - that's a
radial line for the pulley. any force exerted between the center, a
hole and the exertion point must by definition be tangential to the
circle formed by the holes. with the correct tool, any twisting of the
holding dowel at the hole is mitigated by having a large stiff pivot
mounted at the bolt [via the driving socket] and by having a bolt head
with an extended hex [which it does].
/these/ holes on the other hand, as would be expected from drawing a
straight line between the two broken holes and the exertion point, do
NOT evidence force wholly applied tangential to the hole circle. this
leaves the web having to handle a mix of radial /and/ tangential loads,
AND the full twisting loads of the dowels used. the results of all 3
loading modes we see here.
Burt S. - 03 Jan 2006 15:17 GMT
> examine this pic.
> http://www.flickr.com/photos/38636024@N00/80617642/
> http://img468.imageshack.us/img468/5861/80617642ef047fce92m1ru.jpg
Looks like someone had used excessive force or forgot to remove
some form of a pulley holder before cranking the starter.