Torque Wrench Differences

Torque is energy or pressure exerted in a rotational direction. It is the force we use when tightening nuts and bolts or screwing the lid onto a jar. All wrenches apply torque. Torque wrenches not only apply torque, they measure torque. A number of different torque wrenches are available, ranging from simple to complex.

Beam

A beam torque wrench is the simplest form. It is a long, basic wrench--usually a foot or longer. The shaft is light enough that it bends when pressure is applied to a nut or bolt. A needle is mounted to the head of wrench, near the socket. The needle, unlike the shaft does not flex; it remains straight. A scale is mounted near the handle. The scale measures the amount of flex in the shaft. It is precisely calibrated, so a given amount of pressure (applied torque) is measured on the scale by measuring the amount of flex in the shaft.

Clutch

A clicking torque wrench is a more sophisticated tool. It works by way of a clutch. The clutch is designed to slip at a specific torque threshold. The reason it is more sophisticated tool is ability to set the desired torque. The user dials the amount of desired torque, then begins turning the wrench. The wrench turns the nut or bolt until enough force is applied to make the clutch slip. The clutch prevents over-tightening.

Dial Torque Wrenches

Dial torque wrenches are similar to another common machine shop tool: a micrometer or dial caliper. The dial torque wrench measures torque on a dial. A convenient feature--and an advantage over simple clutch torque wrenches--is a memory needle. Rather than look at the gauge continuously to observe the maximum torque exerted, the memory needle records the highest torque exerted, until you reset it.

Electronic Torque Wrench

Electronic torque wrenches convert torque pressure from a sensor into a digitized measurement. They have a digital display showing the user how much torque is being applied. Many electronic torque wrenches also measure the angle a nut or bolt is tightened to. This measurement is done with a gyroscope.