torquewrench

A torque wrench is a tool used to apply a specific torque to a fastener, such as a bolt or cap screw, ensuring joints are tightened to a precise specification. It differs from a standard ratchet by providing controlled twisting force rather than a rough estimate.

Torque wrenches come in several designs: beam, click, dial, digital, and hydraulic (or pneumatic) torque wrenches for high-torque applications. Beam wrenches measure deflection of a calibrated beam; click wrenches emit a physical click at the set torque; dial wrenches display the torque on a gauge; digital wrenches show the torque on an LCD; hydraulic models use pressure in a hydraulic circuit to control torque.

Units used include newton-metres (Nm) and pound-feet (lbf-ft). Common ranges: consumer models from 5 to 200 Nm; larger models for automotive or industrial use can exceed 1000 Nm. Most consumer wrenches are rated to about ±4% of the indicated setting.

How to use: select the required torque, attach to the fastener, ensure proper alignment, and apply force smoothly until the wrench signals (click or display reaches the setting). Do not continue to apply force after the signal; for many tools a brief recheck is recommended after loosening.

Calibration and maintenance: torque wrenches should be calibrated periodically, with intervals depending on use, typically 1 year for regular shop work or after a drop or suspicion of inaccuracy. Store at the lowest setting, keep clean and dry, avoid exposure to extreme heat, and protect the head from impacts.

Safety and notes: using incorrect torque can lead to fastener failure or joint damage. Always follow manufacturer specifications, use the correct type for the fastener, and verify calibration if accuracy is critical.