Often, fasteners used to assemble performance critical components are tightened to a specified torque level to introduce a “pretension” in the fastener. As torque is applied to the head of the fastener, beyond a certain level of torque the fastener begins to stretch. This stretch results in the pretension in the fastener which then holds the components together. A popular method of tightening these fasteners is to use a torque wrench. Accurate and reliable torque wrenches help insure the fasteners are tightened to the proper torque specifications.
Torque wrenches vary from simple mechanical types to sophisticated electronic types. Mechanical type torque wrenches are generally less expensive than electronic ones. There are two common types of mechanical torque wrenches, beam and clicker types. With a beam type torque wrench, a beam bends relative to a non-deflecting beam in response to the torque being applied with the wrench. The amount of deflection of the bending beam relative to the non-deflecting beam indicates the amount of torque applied to the fastener. Clicker type torque wrenches work by preloading a snap mechanism with a spring to release at a specified torque, thereby generating a click noise.
Electronic torque wrenches (ETWs) are typically more accurate than mechanical torque wrenches, but they tend to be more expensive than mechanical torque wrenches and less rugged in their construction. Typically, when applying torque to a fastener with an electronic torque wrench, the torque readings indicated on the display device of the electronic torque wrench are proportional to the pretension in the fastener due to the applied torque. Because the display devices on electronic torque wrenches often include liquid crystal displays, or similar devices, they are often the “weak link” of the torque wrenches construction.
Drawbacks present in prior art electronic torque wrenches may leave them susceptible to being easily damaged through normal usage and, subsequently, may lead to the over or under-torquing of fasteners, which can contribute to reduced performance, and eventual failure, of the fasteners.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.