Torque wrenches are tools used for auto repair or maintenance to screw on nuts and bolts. A torque wrench is basically a socket wrench that measures torsion. Torque wrenches have an indicator that tells you how much torsion (force) you are applying.

There are several types of torque wrenches and, depending on the type and brand, there are different ways to determine whether you are applying proper torsion.

The most common varieties are the "clicker" and the "beam." Digital or electronic torque wrenches can be pricier. Hydraulic and pneumatic torque wrenches are primarily used by professionals in an industry setting.

A clicker torque wrench has a spring-loaded mechanism that releases when you reach the correct torsion.

After setting the torsion on the wrench, apply the head of the wrench to a nut or bolt. Pull up on the handle and listen for the "click" sound that will alert you that the correct amount of pressure has been applied. 

A beam torque wrench has a long rod called a "beam" that flexes slightly. Opposite this rod is a wide metric scale and a handle pivot. 

Position the handle pivot over a nut or bolt and apply force at the center of the handle. As the beam bends, the scale will show the amount of force applied.

A digital torque wrench allows you to set the torsion by entering the correct amount. These wrenches are battery-powered with an LCD screen. A "beep" alert will sound when the correct torsion is applied.

A hydraulic torque wrench (far left) is powered by fluid.  A pneumatic torque wrench (left) is powered by a compressed-air motor. Both are industrial strength, used to apply high torsion.

To keep your torque wrench working correctly, you should check its calibration before you use it, especially if the tool has been dropped. 

While you can calibrate it yourself at home, it is a complicated process. Having your torque wrench professionally calibrated may be a better recourse.