What’s the purpose of directional switches on torque wrenches? I know it’s so you can change the direction of rotation of the ratcheting mechanism… but I also know that your not supposed to use a torque wrench as a regular ratchet, and should only use it to fasten fasteners to a torque specification, not to remove fasteners.
So is their any practical use for the directional switches on torque wrenches?
What about left handed threads?
While not super common, they exist and serve a purpose.
We use them on certain rotational assemblies at work.
The cam mechanism is not a huge cost to include it on every tool…
Most, if not all (I’m sure some aren’t and will be pointed out to me lol) ring and pinion, ring gear bolts are left handed threads… So yes, as Twin Turbo pointed out, it is used for left hand threaded bolts…
And before you ask, these can/are used for checking rotational torque, for setting the preload on a bearing such as a pinion bearing on a differential, as well as a general torque wrench… lol
With two adaptors! 1/4 to 3/8ths inch and 3/8 to 1/2 inch to the big socket needed for the pinion nut!
Do ‘click’ type wrenches work (signal the set torque with a click) in reverse? I never tried it.
I actually used a 1/4" Hex Shank Socket Driver with 1/2" driver and a 1/4" socket on the torque wrench… Didn’t feel like separating all the different adapters from each other, and these were in a closer tool box… 
Mine always have when torquing ring gear bolts, as long as it is directional…
I generally use the the type shown in post 3 above. I don’t recall ever using the other side (CCW rotation) of the scale, but I can envision it might come in handy for some applications, as already mentioned.
Torque wrenches aren’t just used in automotive repair/maintenance. They’re also used in other industries where left hand threads may be encountered.
Tester
If you work on old cars, many cars of the 50s and earlier had lefgt hand studs and lug nuts on the drivers side.My 52 and 54 P[ymouth had them as well as my 56 Desoto. My 56 Studebaker Commander had them but the 59 Lark did not.
I believe Chrysler used left handed wheel stud on one side up until the early 70’s on some vehicles, I know my 67 B body rear end still had left handed wheel studs in it when I got it, and I broke a few on some other late 60’s models before realizing they were lefty’s… lol
I think the rule is that you’re not supposed to break a nut with the torque wrench. Once the nut is broken, I don’t think there’s any harm in using the torque wrench to remove it if for some reason that’s more convenient.
Breakaway torque can exceed the tool working range. As long as you’re careful and don’t surpass that limit, no harm will be done. There are times where measuring breakaway torque is necessary and torque wrenches serve that purpose.
