A torque wrench is used to accurately apply torque. Torque refers to the force used to rotate any object on its axis, a fulcrum, or a pivot. In laymen’s terms, torque wrenches are used for measuring the resistance to any rotation when fastening nuts and bolts. In the field of mechanics, a torque will allow the manufacturer to ensure that the force or tension with which a nut or bolt is fastened is precise. There are many different kinds of torque wrenches in the market. The most common are beam-type torque wrenches, which are particularly meant for home use. However, the beam-type has a variant: the deflecting beam torque wrench. Given below is a description of beam-type torque wrenches and deflecting beam torque wrenches.
Beam-type Torque Wrench
Beam-type torque wrenches are the cheapest torque wrenches available, and for this reason, it has been criticized as being not good. However, being the oldest and the simplest type of torque wrench, it has been regarded by some as the most accurate. Beam-type torque wrenches were developed in the 1930s by Walter Percy Chrysler. However, it was Paul Allen Sturtevant who first patented the torque wrench in 1938, and made it commercially available. In fact, if used correctly, there is little room for error. The beam-type wrench comprises a lever arm and a smaller bar. The lever arm extends from the handle of the wrench to its head, and the smaller bar has a mechanical indicator on it; it is also attached to the wrench head. The handle of such torque wrenches have calibrated scales attached to them. When pressure is applied, the scale moves. On the indicator, you can see when the required toque has been reached.
Nowadays, a more advanced beam-type torque wrench is also available. These wrenches have a dial gauge indicator attached to the body. Beam-type indicators should not be dropped or roughly handled, as this may bend the arm, thereby providing incorrect reading. Although beam-type torque wrenches are known for their accuracy, readings can be incorrect if you view the indicator from any angle other than 90° angle. In other words, beam-type wrenches are prone to parallax error. Perhaps, the only disadvantage of a beam-type indicator is that is does not provide any visual or tactile signal when the required torque is obtained.
Deflecting Beam Torque Wrench
Patented by an Australian company, namely, Warren and Brown, in 1948, the deflecting beam torque wrench is also called the dual-signal deflecting beam torque wrench because it uses the dual-signal trip mechanism to read torque. When using a deflecting beam torque wrench, torque is applied to deflecting beams, as opposed to standard coil springs, and hence, the name “deflecting.” The deflecting beam torque wrench has a few advantages over a standard beam-type torque wrench. First, the former increases the lifespan of the wrench. Second, it is believed to give more accurate and consistent readings. Third, when the required torque is obtained, the dual-signal torque wrench provides audio-visual feedback, i.e., the signal is both heard and seen.