Patent ID: 7413029

Claim:
A screw fastening machine comprising a drive shaft for engaging a screw component and screwing in the screw component to a work, a first driving means for applying driving force of high speed low torque to the drive shaft, and a second driving means for applying driving force of low speed high torque when the high speed low torque drive is finished; wherein a first pulley is fixed to a first output shaft of the first driving means, a second pulley is fixed in an integrally rotatable manner to a transmission shaft for connecting the drive shaft, and an endless belt is interposed between the pulleys to obtain a configuration for high speed low torque drive; the second driving means for performing low speed high torque drive is arranged on a back side on an extension of the transmission shaft until a final fastening torque is reached, a clutch member is interposed between a second output shaft of the second driving means and the transmission shaft, and the first and second driving means are electrically connected to a control unit having a configuration of performing a control such that the rotation drive changes from by the first driving means to by the second driving means so that the second driving means rotatably drives the transmission shaft until the final fastening torque is reached when the screw component is seated on the work by the high speed low torque screwing work by the first driving means and a stall state is achieved.