EngSplainin’ a pivot click torque wrench.

So you think you can reef on a one of these anywhere you like, good luck with that!

Your greasy mitt has to be on the handle IN THE RIGHT PLACE and here is why…

In the depiction below:

· Fb = the Bogun force (your greasy mitt and Fosters powered muscle),

· Fc = the “click” force of your calibrated torque wrench (constant),

· D1= distance from bolt center to your mitt,

· D2 = distance from pivot to clicker,

· D3 = distance from pivot to bolt center,

· Mega = a hell of a lot,

· SFA = Sweet F All or bugger all.

Assumptions:

1. Fc is calibrated and is CONSTANT. It cannot change and gives the same force every time it is actuated within variation of the mechanism (SFA),

2. STP standard temperature and pressure,

3. Standard gravity,

4. Standard laws of physics,

5. Above room temperature IQ, if you can read this you pass,

6. ONLY D1 is changed in any testing as an input.

Some of the forces detailed are reaction some are action this is very simplified but I hope will get the point across as to where this “magic” torque is coming from. It is the reaction on the pin equal to Fb - Fc

Now for the splainin’:

Bolt torque is (D1 x Fb) + ((Fb-Fc) x D3). If your mitt is in the right place it works.

If D1 gets VERY big, it affects the force needed and Fb becomes SFA to click the torque wrench but the second part of the torque formula gets very small and the ((Fb-Fc) x D3) component of APPLIED TOTAL Torque is low so if you put a cheater bar on the torque wrench you will UNDER torque the fastener.

Conversely if you “choke up” and D1 gets small, Fb becomes a Megaforce, you will be blowing chunks to get that wrench to click. ((Fb-Fc) x D3) becomes MUCH bigger and you will OVER torque the fastener.

The point that is missed is the fastener has TWO applied torques on these pin torch wrenches and the D1 length will directly affect the amount of force, and thereby magnitude of second torque that is applied to the fastener.

Please apply safe torques to your member and appropriate harmonic frequencies to ming moles.

There is even a Torque Wrench SIMULATOR.

Download the Excel sheet, see the formulas, prove to yourself it is a problem to choke up (over-torque) or cheater bar (under-torque).

TWS download