Abstract: A microcomputer based system is designed to accurately detect the amount of previously applied torque to a fastener by way of a retorque test in which torque is subsequently applied to the fastener in the tightening direction until breakaway occurs. As torque is subsequently applied to the fastener a microprocessor operates to sample an analog torque input signal and convert it into discrete digital samples. These digital samples are stored in sequential memory locations during the tightening process. The microprocessor stops generating any further samples once a window containing the values of interest has been defined in memory. Then, the microprocessor examines the stored window samples in more detail to detect the sample value associated with the amount of torque previously applied to the fastener.

Abstract: The amount of previously applied torque to a fastener is measured by analyzing a series of digital torque values generated during a test of the fastener.

Abstract: Apparatus for measuring the amount of previously applied torque to a fastener. A transducer is utilized to sense the amount of a subsequently applied torque to the fastener and provides an output signal representative of the applied torque. The torque is applied until further motion or breakaway of the fastener is obtained. Typically, the signal from the transducer increases until breakaway of the fastener is obtained and then the signal decreases momentarily to a valley before it again increases with further applied torque. In those instances where the particular fastener does not exhibit a well-defined valley torque signal, provision is made for detecting the value of the transducer torque signal upon breakaway. Preferably, circuitry is provided for artificially creating the valley when there is a change of slope in the torque signal above a given threshold level.

Abstract: Apparatus for measuring the amount of previously applied torque to a fastener. A transducer is utilized to sense the amount of a subsequently applied torque to the fastener and provides an output signal representative of the applied torque. The torque is applied until further motion or breakaway of the fastener is obtained. Typically, the signal from the transducer increases until breakaway of the fastener is obtained and then the signal decreases momentarily to a valley before it again increases with further applied torque. A positive peak detector senses the maximum positive output of the transducer before the signal begins to decrease. A negative peak detector senses the minimum negative output of the transducer before the signal again increases. The negative peak detector is energized by a switching network upon detection of a negatively sloped signal from the transducer.