Patent ID: 6968908

Claim:
A power tool adapted to tighten a fastener, comprising: a motor, means for generating an elevated torque, wherein the elevated torque generating means is coupled to the motor and has output shaft, wherein if a load acting on the output shaft is less than a predetermined value, rotating torque generated by the motor is directly transmitted to the output shaft and if a load acting on the output shaft exceeds the predetermined value, an elevated torque is generated by the elevated torque generating means and applied to the output shaft, a load shaft connected to the output shaft, means for detecting change in rotational angle of either the output shaft or the load shaft and the direction of rotation thereof, a memory for storing a state of either output shaft or the load shaft detected by the detecting means, and a processor in communication with the motor, the detecting means and the memory, the detecting means communicating signals corresponding to the state of either the output shaft or the load shaft to the processor, wherein the processor stores the state of either the output shaft or the load shaft in the memory at predetermined interval, and wherein the processor determines, based upon the stored state of either the output shaft or the load shaft, when the elevated torque generating means generates the elevated torque.