What is the purpose of a torque wrench and how should it be calibrated?

• A. To apply accurate torque to fasteners; calibrate regularly with traceable standards and verify torque at the tool handle
• B. To measure vibration
• C. To tighten bolts loosely
• D. To measure RPM

Answer: (A)

The main idea is that a torque wrench is used to apply a precise, repeatable amount of torque to fasteners, and keeping that accuracy requires regular calibration. When you tighten a bolt, you want the exact torque specified by the design or maintenance procedure. If the wrench is off, you can over-tighten and strip threads or snap bolts, or under-tighten and risk a fastener loosening in service. Calibration aligns the wrench’s reading with a known reference so the indicated torque corresponds to the true torque applied.

Calibration is done with traceable standards, meaning the reference values come from calibrated equipment that is tied to recognized standards. This creates a documented link back to a standard of measurement, ensuring the readings are credible and comparable over time. Verifying torque at the tool handle means checking that the display or pointer on the wrench actually represents the torque being delivered, often by testing against a torque transducer or calibrated tester. Regular checks account for wear, temperature, and use that can drift the tool’s accuracy.

In practice, this careful calibration and verification ensure fasteners are tightened correctly every time, which is essential for reliability and safety. The other choices describe different measurements—vibration, speed, or simply tightening loosely—which do not pertain to the purpose or calibration of a torque wrench.