Electro-mechanical torque control-acceleration of return motion

A method of controlling an electro-mechanical axial setting device wherein the axial setting device comprises:

• two setting rings (23, 26) centered on a common axis, one of which is axially held, with the other one being axially displaceably mounted, and one of which is rotationally fixedly held in a housing, with the other one being rotatingly drivable,
• the two setting rings (23, 26), on their respective end faces facing one another, each comprise an identical plurality of circumferentially extending grooves (41, 44),
• the grooves (41, 44), in a plan view of the end faces, comprise depths which rise in the same circumferential direction, and form pairs of grooves (41, 44) in the two setting rings (23,26) each pair accommodating a ball (29),
• wherein the rotatingly drivable setting ring (23) is connected to an electric motor (11), and the axially displaceable setting ring (26) is loaded by pressure springs (37) towards the axially held setting ring (23),
• the method comprising:
• applying a positive voltage to the electric motor (11), to move the axial setting device into an advanced position;
• and
• for returning purposes, first applying a negative voltage to the electric motor (11), and when the electric motor (11) has reached its idling speed, disconnecting the motor from the negative voltage.