The system comprises a roller screw mechanism 12 which is provided with a screw 16 which comprises at least a first outer threaded portion 18, a nut 20 and a plurality of rollers 24 which cooperate with the first outer portion 18 and an inner thread of the nut. The system further comprises a roller thrust bearing 14 which is mounted on a second outer portion 52 of the screw and which is provided with a bushing 50 and a plurality of rollers 56 which comprise flanks which cooperate with flanks of the second outer portion 52 of the screw and the bushing 50. The flanks of the screw, the bushing and the rollers are configured so that, during a rotation of the screw, the rollers 56 are fixed axially relative to the screw 16 and relative to the bushing 50.