Actuator for controlling an engine with a crank-bar mechanism

The actuator (60) has a crank (5) driven by a toothed sector (8) operatively connected to an electric motor (6), and a connecting rod (9) connected to the crank and to a control rod (10) to be moved in a translational direction (X). A guide roller (12) guides the connecting rod on a rolling track (13) fixed to a frame (100) and parallel to the translational direction of the control rod. The rolling track of the guide roller includes two surfaces (13.1, 13.2) extending on either side of the guide roller.