Converts torque units from/to [N·m], [kg·m] and [lb·ft] When you use a wrench, you apply a force to the handle. This force creates a torque on the lug nut. Torque is important in the design of machines such as engines. The measurement of torque is also important in automotive engineering, being concerned with the transmission of power from the engine through the drive train to the wheels of a vehicle. A torque wrench is used where the tightness of screws and bolts is crucial.