What tool is primarily used for mechanics to tighten threaded connections?

The torque wrench is a specialized tool designed specifically for applying a predetermined amount of torque to a threaded fastener, like bolts or nuts. This is essential in mechanical applications where precise tension is critical for the integrity and safety of an assembly. The torque wrench ensures that the fastener is tightened to the manufacturer's specifications, which helps prevent issues such as stripping threads or under-tightening, which can lead to failure in machinery or equipment.

In various contexts, other wrenches may be used for tightening various fasteners, but they do not provide the same level of control over torque. For instance, while a socket wrench is effective for turning fasteners, it does not measure the amount of torque applied and can lead to improper tensioning if the user is not careful. Similarly, adjustable wrenches and box end wrenches allow for gripping and turning nuts and bolts but lack the precision measurement that a torque wrench offers. Thus, when it comes to ensuring threaded connections are tightened correctly, the torque wrench is the most appropriate tool for the job.