Ever wondered how your torque wrench ‘clicked’ when you reached the torque goal? This video will not only discuss how to use a torque wrench (properly), but we also disassemble a perfectly good torque wrench to see what makes it “click.” You may be surprised at how simple the mechanism really is.

How To Use a Torque Wrench Properly

Before digging into the internals, we wanted to take a moment to discuss the essentials of using a torque wrench. In our case, we were using the torque wrench that’s included with the Sonic Tools 958-piece Mechanics Toolbox that we reviewed a few weeks ago. This is a 1/2″-drive torque wrench that has an operating range of 80Nm to 400Nm (60 – 250 ft-lbs). First, we unlocked the handle, then turned the handle to find the 140 ft-lb mark in through the magnified window on the torque wrench.

Now, we want to use a smooth pull or push to achieve the needed torque, and don’t rush this. You can easily surpass your torque measurement if you’re jerking or not paying attention. As soon as you hear and feel the click, stop. Just because it clicks doesn’t mean that it stops tightening.

What Makes It Click?

Now that we’ve covered how to use a torque wrench, let’s look at what makes that clicking sound. I’ve been using click-stop torque wrenches most of my life, and I never exactly knew how it all worked. Taking one apart, it’s very elementary. Basically, a large spring is compressed against a key, when the force applied to the handle overcomes that force and friction on the key, then Click! The internal conical shaped shaft slaps the side of the handle and the key rolls 90-degrees to the next side. See the video for much more detail.

Click the link for more information on Sonic Tools USA.