Torqueing knock sensor/crow's foot

[DePenning, Charles [EPM/MTN]]

Or just turn the crow's foot 90 degrees from having the open pointing 'out'
(along the axis of the torque wrench).  That way you don't have to calculate
or measure anything for a reasonably accurate torque measurement.  The
distance between where the 'new' center of rotation is (with the crow's foot
turned 90 degrees) and where it should be (with a normal socket on the
torque wrench) will be so minimal that the precision and accuracy errors of
the torque wrench will probably overshadow any inaccuracies due to that
distance.  Plus, trying to measure the distance from an imaginary center of
a crow's foot to an imaginary center of a square opening in the crow's foot
will be difficult at best and probably contribute to more errors. 

Charley, a.k.a. the mechanical engineer



Original:

Konstanin,

Buy a 15 mm "crow's foot" socket. It's essentially and open end wrench
end, but the shank
becomes an appropriate drive size (in this case, 3/8 drive) square
opening to which 
you can attach either a drive or, in this case, torque wrench. Now, bear
in mind, the
crow's foot will cause an "under-reading" of your set torque, as it
extends the length
of the torque wrench (okay, yes, I know, there was quite the thread on
this not too
long ago). First, for something like a knock sensor, a bending beam type
torque 
wrench is a more appropriate tool than a click type. It's generally more
controllable. 

Second: The simplest method of recalculating the torque is by proportions

        Say the crows foot adds center of 3/8 drive socket to center of
the 15mm opening 
                        for sake of argument, 20 mm.

        For sake of example, say the torque wrench measures from the
drive end center to
                        point of application at the handle, 400 mm. 

          For this example, let's say the required torque is 10 N-m,
which becomes 0.10 N-cm.

Set up the proportion:

        Torque SETTING/Standard wrench length = Torque Spec/Wrench with
Crow's Foot

        Torque ?/40.0 cm = 0.10 N-cm /42.0 cm


        If you did this correctly, you should find your wrench setting
should be 0.095 N-cm
                which is 95% of the original setting. 

NOTE: If you're not sure, remember the following. Your wrench setting
with a crow's foot
will ALWAYS be LESS than the original spec!

HTH!

LL - NY, a.k.a. the Physics Teacher