Actuating device having: - an electric motor, - a body having a recess for receiving the electric motor, - a retaining plate designed to retain the electric motor in the recess without axial play, - a first fastening means extending along an axis and interacting with a first bearing surface of the retaining plate, the first bearing surface is comprised in an angular sector with a vertex located on the axis of the first fastening means and with an angular value less than 180°, the recess for receiving the electric motor extending along an axis parallel to the axis of the first fastening means and parallel to the axis of the second fastening means, the first and the second bearing surface being located radially, in relation to the axis of the receiving recess, between the axis (D1, D3) of the respective fastening means and the axis of the receiving recess, the retaining plate having a tab protruding radially in relation to the axis of the receiving recess, the first bearing surface of the retaining plate being comprised on the tab, the retaining plate having a second retaining tab protruding radially in relation to the axis of the receiving recess, the second retaining tab having a second bearing surface interacting with a second fastening means extending along an axis, the second bearing surface being comprised in an angular sector with a vertex located on the axis of the second fastening means and with an angular value less than 180°, characterized in that said tabs of the retaining plate have a U shape, the arms of the U pointing towards the axis of the recess and the first and the second bearing surface being comprised on the base of the respective U, the first fastening means is a shouldered screw, the shoulder of the screw being designed to bear solely against the first bearing surface of the retaining plate, and the second fastening means is a shouldered screw, the shoulder of the screw being designed to bear solely against the second bearing surface of the retaining plate. - an electric motor, - a body having a recess for receiving the electric motor, - a retaining plate designed to retain the electric motor in the recess without axial play, - a first fastening means extending along an axis and interacting with a first bearing surface of the retaining plate, the first bearing surface is comprised in an angular sector with a vertex located on the axis of the first fastening means and with an angular value less than 180°, the recess for receiving the electric motor extending along an axis parallel to the axis of the first fastening means and parallel to the axis of the second fastening means, the first and the second bearing surface being located radially, in relation to the axis of the receiving recess, between the axis (D1, D3) of the respective fastening means and the axis of the receiving recess, the retaining plate having a tab protruding radially in relation to the axis of the receiving recess, the first bearing surface of the retaining plate being comprised on the tab, the retaining plate having a second retaining tab protruding radially in relation to the axis of the receiving recess, the second retaining tab having a second bearing surface interacting with a second fastening means extending along an axis, the second bearing surface being comprised in an angular sector with a vertex located on the axis of the second fastening means and with an angular value less than 180°, characterized in that said tabs of the retaining plate have a U shape, the arms of the U pointing towards the axis of the recess and the first and the second bearing surface being comprised on the base of the respective U, the first fastening means is a shouldered screw, the shoulder of the screw being designed to bear solely against the first bearing surface of the retaining plate, and the second fastening means is a shouldered screw, the shoulder of the screw being designed to bear solely against the second bearing surface of the retaining plate.