What is the principle of a torque wrench?
2 Answers
The principle of a torque wrench is based on the bending principle of beams, the bending principle of torsion bars, and the compression principle of helical springs, allowing it to measure the torque applied to a nut. A torque wrench, also known as a moment wrench, torque adjustable wrench, is a type of wrench generally categorized into three types: manual torque wrenches, pneumatic torque wrenches, and electric torque wrenches. The torque wrench has a long elastic rod, with a handle at one end and a square or hexagonal head at the other end. A replaceable socket is fitted over the square or hexagonal head and secured with a steel ball. A long pointer is also mounted at the top. The scale plate is fixed on the handle base, with each division representing 1 Newton.
The principle of a torque wrench is actually quite simple - it uses leverage to control the tightening force on bolts. I use this tool frequently for car repairs. Essentially, it's a calibrated wrench where the lever amplifies torque when you apply force by turning the handle. The internal spring or mechanism provides feedback based on preset values. For example, when set to 100 N·m, once that torque level is reached, the wrench will click or the indicator will jump to signal you to stop. This prevents both under-tightening (which could cause bolts to loosen) and over-tightening (which might strip threads or damage components). The key is to properly align the scale with zero position and regularly calibrate the wrench's accuracy. When I change wheels, I rely on it to ensure even bolt tension - uneven tightening could create safety hazards at high speeds.
