Torqued off

[Bernie Strub <bstrub@silverlink.net>]

DeWitt Harrison writes:
>>sneep<<
>Please consider the following experiment and then come to
>your own conclusions.  Connect a torque wrench adapter
>to a torque wrench keeping everything in a nice straight line.
>Now apply, for example, an effort of 100 lbs-force at a
>distance of 3 feet from the bolt.  I haven't told you any-
>thing about wrench or adapter lengths or what the torque
>wrench reads.  Questions:
>   a. How many foot-lb of torque moment does the bolt
>      experience?
>   b. Does the bolt care what the torque wrench reads?
>
Does the adapter care what the torque wrench reads?  Well, Mr. Bentley and
Mr. Audi seem to think so.  At this point, I think it appropriate to point
out that the spec calls for a certain torque, applied with whatever torque
wrench, at the input point of the adapter.  This will cause a fixed, orderly
amount of torque/force at the bolt, regardless of the length, breadth, or
price of torque wrench.  A properly designed wrench will display correctly
the amount of torque applied at the output point, regardless of hand
position, pipes stuck in the end, etc. (Been there, done & tested that - in
a torque calibration facility).  The sole exception to this is the
deflecting beam type, which has a pivoting hand hold, so that all of the
force is applied at one fixed distance from the output point.

Torque is not magic.  As you state, bolts don't care.  X force times Y
distance equals Z torque.  The problem comes in with some misconceptions
about adapters.  For a given length adapter, and a given torque at a certain
point on that adapter, the final torque at our uncaring, but
soon-to-be-tighter bolt will be the same.

BTW, if you really wanna get confused, think about the effects of
multipliers, and adapters/crow's feet at angles to the torque wrench...math
gets ugly quick...

>Now start changing the lengths of the wrench and adapter
>(using your infinite tool box)

Yup, need one of these...

Hope I haven't muddied the waters again...

>>>>>Bernie
87 4kcsq alpine white/light grey cloth
QCUSA #1765
Member #47 NW Region AQC