Actuator device (1, 2), or servomotor, for displacing a clamping piston in translation along a piston axis, said piston thus producing a clamping pressure, said device comprising or receiving a first drive and a second drive, in which the second drive is rotary and is driven by a second motor, and displaces said piston in translation by means of at least one transmission called locking transmission, which includes at least two toothings cooperating together in irreversible fashion, for directly or indirectly: - driving said piston in translation in the clamping direction during an actuation of said second motor, and - locking said piston in translation in clamping position when said second motor is deactivated, the first drive is rotary and is driven by a first motor, the device also comprises a transmission called main transmission, which receives the first rotary drive and which includes at least two toothings cooperating together in reversible fashion for producing, directly or indirectly, a drive of said piston in translation in the clamping direction during an activation of said first motor, said main transmission is arranged to operate in parallel with the locking transmission, and is arranged to be capable, on its own, of applying a clamping force, called nominal clamping force, on the piston, characterized in that the actuator is arranged to make it possible, after having produced abutment under a clamping force by actuating at least the main transmission, to maintain said clamping force by the irreversibility of the locking transmission while deactivating said main transmission. said device comprising or receiving a first drive and a second drive, in which the second drive is rotary and is driven by a second motor, and displaces said piston in translation by means of at least one transmission called locking transmission, which includes at least two toothings cooperating together in irreversible fashion, for directly or indirectly: - driving said piston in translation in the clamping direction during an actuation of said second motor, and - locking said piston in translation in clamping position when said second motor is deactivated, - driving said piston in translation in the clamping direction during an actuation of said second motor, and - locking said piston in translation in clamping position when said second motor is deactivated, the first drive is rotary and is driven by a first motor, the device also comprises a transmission called main transmission, which receives the first rotary drive and which includes at least two toothings cooperating together in reversible fashion for producing, directly or indirectly, a drive of said piston in translation in the clamping direction during an activation of said first motor, said main transmission is arranged to operate in parallel with the locking transmission, and is arranged to be capable, on its own, of applying a clamping force, called nominal clamping force, on the piston, characterized in that the actuator is arranged to make it possible, after having produced abutment under a clamping force by actuating at least the main transmission, to maintain said clamping force by the irreversibility of the locking transmission while deactivating said main transmission.