Torque Limiting Bar - How does this work?

[Chris Lovell]

I purchased a set of these torque limiting bars from HF. The reason is for getting these is that my son is a bit wild with the air impact wrench. So, I use the 90 foot lb torque limiting extension on the impact wrench and it seems to work almost perfectly. Can someone tell me how it works?
Thanks.

[Oh Haha]

Great question, Chris. I was just thinking about asking the same last week.

[Jeff Alton]

They are pretty, but I have no clue how they work

I only use air tools as a last resort when taking something apart, otherwise I might be like your son.........

Cheers

[Jim Sims]

They work by being a resonant torsional spring; when the rated torque level is reached they get "in sync" with the impact hammer blows, bouncing or twisting back before the next hammer blow hits. They must be matched to the air impact wrench and it's air settings. They do not work with hand wrenches or just any impact wrenches; I believe the electric impact wrenches are too fast (too many blows per minute) although I suspect that a set could be made (tuned) for an electric impact wrench.

http://www.procutinternational.com/html/torqstik/how_torqstiks.html

[Bill Verburg]

I use them myself, but for a wheel I would use the 80# stick, then a torque wrench for final snug.

[Chris Lovell]

Thanks all.
Great explanation Jim, and I was not aware they only work with impact wrenches but that makes great sense.
And Bill, another good bit of advice. I should always torque the last 1/4 turn, but this torque bar thing, based on my testing of and 80# bar and then manually torquing the final 1/8 turn to 96, seemed to be dead on 80#. I will try to keep laziness at bay and continue to the final torque manual.