[TR] torque wrench question

Peter Ryner pryner at outlook.com
Sat Aug 11 09:31:29 MDT 2018


>From my jet engine mechanic days in the Air Force I offer the following.  You don't need to use the torque wrench in the computation as it is already calibrated for its length.  If you add any extension to the end of the torque wrench you have to adjust for the additional arm length.  Our tech orders had a formula to use which took into account the length of the extension including a crowfoot.  However, if the crowfoot was used at 90 degrees to the torque wrench no adjustment was required.  The calculation involved the angle and length of the extension, not the diameter.  Most of the time using a crowsfoot, especially for small torques there was very little difference of the torque wrench setting.  Since most specs are within a range, the calculated setting was still in the specified range.  You still had to do all of the calculations just to make sure.  
Pete

-----Original Message-----
From: Triumphs <triumphs-bounces at autox.team.net> On Behalf Of TERRY SMITH
Sent: Saturday, August 11, 2018 8:56 AM
To: Sujit Roy <triumphstag at gmail.com>; Randall <tr3driver at ca.rr.com>; triumphs at autox.team.net
Subject: Re: [TR] torque wrench question

LOL!  I'm just glad you science guys are out there!

> On August 11, 2018 at 5:51 AM Randall <tr3driver at ca.rr.com> wrote:
> 
> 
> > Uhm, that would be why English majors subscribe to this list....
> > 
> 
> Perhaps an example would help?
> 
> Let's say you want to torque your nut to 50 ftlb, your torque wrench 
> measures 26" overall and your crowfoot extension is 4" overall.
> 
> First we need the effective length of the torque wrench.  On mine, the 
> business end is about 1" diameter, while the hand grip extends about 2"
> beyond the center of my hand.  So we subtract half of the head 
> diameter
> (0.5") and the 2" for the hand grip to get 23.5" effective length.
> 
> Now the effective length of the torque wrench plus crowfoot extension.
> Assuming both ends of the crowfoot are around 1" diameter, it would 
> extend the center by about 3", or 26.5" overall.
> 
> Divide those two numbers to get the ratio.  23.5/26.5 = .89 (rounded 
> to 2
> digits)
> 
> Multiply the desired torque by the ratio. 50 * .89 = 44.5 ftlb.  Round 
> that to two digits, and set your wrench to 45 ftlb.
> 
> Hmm, well, perhaps not.  Reminds me of an old David Crosby line: "You 
> see just below the surface of the mud, there's more mud here."
> 
> -- Randall
>

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