For what purpose is a torque wrench used?

A torque wrench is specifically designed to apply a precise amount of torque to a fastener, such as a bolt or nut. This tool is essential in applications where the integrity of a connection depends on achieving a specific tension, as improper torque can lead to over-tightening or under-tightening, both of which can cause mechanical failure.

The functionality of a torque wrench is crucial in various mechanical and engineering tasks, as it helps ensure that fasteners are secured safely and effectively according to manufacturers' specifications or engineering requirements. This capability is vital in industries such as automotive, aerospace, and construction, where safety and performance are paramount.

In contrast, the other options do not accurately reflect the function of a torque wrench. Tightening bolts without measuring does not ensure accuracy, loosening stuck fasteners typically requires different tools like breaker bars or penetrating oils, and a torque wrench does not measure weight but torque, which is a measure of rotational force.