Abstract: Machines and methods capable of evaluating torque-tension and prevailing torque performance of prevailing-torque threaded fasteners. Such a machine may include one or more of the following features: a coordinated drive unit for achieving relative linear and rotational movement of a nut and bolt of a nut-bolt assembly; a sensor unit with multiple reaction torque sensors in series, wherein a lower-range torque sensor is protected from being overstressed while torque is transferred therethrough to a higher-range torque sensor; an optical temperature measurement unit oriented to detect a temperature at a thread interface of a nut and bolt through an opening in a device adapted to rotate the nut; and a bolt recess measurement unit that determines a bolt-through condition of a nut-bolt assembly by detecting a bolt recess of the nut-bolt assembly that has been assembled such that a prevailing torque feature thereof has been encountered.

Abstract: Machines and methods capable of evaluating torque-tension and prevailing torque performance of prevailing-torque threaded fasteners. Such a machine may include one or more of the following features: a coordinated drive unit for achieving relative linear and rotational movement of a nut and bolt of a nut-bolt assembly; a sensor unit with multiple reaction torque sensors in series, wherein a lower-range torque sensor is protected from being overstressed while torque is transferred therethrough to a higher-range torque sensor; an optical temperature measurement unit oriented to detect a temperature at a thread interface of a nut and bolt through an opening in a device adapted to rotate the nut; and a bolt recess measurement unit that determines a bolt-through condition of a nut-bolt assembly by detecting a bolt recess of the nut-bolt assembly that has been assembled such that a prevailing torque feature thereof has been encountered.