A power wrench with a torque sensing unit includes a housing, a motor, an output shaft, and a planetary reduction gearing connecting the motor to the output shaft and including a stationary ring gear supported in the housing, wherein the torque sensing unit includes a torque transferring element with a single radially extending reaction arm arranged to transfer reaction torque from the ring gear to the housing and carrying strain measuring sensors for generating signals in response to the transferred reaction torque. The torque transferring element includes an annular body with two weak portions to be elastically deformed during torque transfer and having flat surfaces for carrying the strain measuring sensors.
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