US Patent 9126321 Machine tool and control procedure

A machine tool has a tool retainer for retaining a tool, a motor and a drivetrain which couples the motor with the tool retainer for transmitting a torque. A system pushbutton is coupled with a motor control. When the system pushbutton is activated by a user, the motor control controls the motor in such a way that the motor turns in a first sense of rotation for a duration and then in a sense of rotation opposed to the first sense of rotation. The duration is shorter than 100 ms.