A device which shows the force of torque with which a screw or nut is being tightened. It allows one to set screws exactly at a predetermined torque without any effort. A wide range of models from different manufacturers are available. The most common models are listed below. Bolt Tension Machine: Used for measuring the axile force of bolts by oil pressure. Use this machine to determine whether the bolt is good or not as well as whether the tightening torque of the bolt is adequate or not by tightening the bolt with the torque wrench. Accuracy : ± 3%.