Abstract: An electric motor device for powering a tool clamp, for example a resistance welding clamp, of the type comprising a casing of an electric motor 4 the shaft of which is connected to the clamp, to control the electrodes for opening, closing and clamping them onto a metal sheet, by a system of the through-the-motor type which converts the rotary motion of the shaft into translational motion of a mechanism 5 operating the clamp, this motor being linked to a control variator and a slaving device 10 coupled to the rotor of the motor.