Patent ID: 8376094

Claim:
An electromechanical linear-motion actuator comprising a rotary shaft ( 14 ) driven by an electric motor ( 19 ) and having a radially outer surface, a stationary outer race member ( 15 ) provided around the rotary shaft ( 14 ) and having a radially inner surface, a plurality of planetary rollers ( 16 ) disposed between the radially outer surface of the rotary shaft ( 14 ) and the radially inner surface of the outer race member ( 15 ) so as to be rotated about their own axes while revolving about the axis of the rotary shaft ( 14 ) when the rotary shaft ( 14 ) rotates, wherein a helical rib ( 25 ) is provided on the radially inner surface of the outer race member ( 15 ) or the radially outer surface of the rotary shaft ( 14 ), and wherein a helical groove ( 26 ) or circumferential grooves are formed in a radially outer surface of each of the planetary rollers ( 16 ) in which the helical rib ( 25 ) is engaged, a planetary carrier ( 17 ) axially facing the planetary rollers ( 16 ), and thrust rolling bearings ( 27 ) disposed between the planetary carrier ( 17 ) and the respective planetary rollers ( 16 ) for preventing the rotation of the respective planetary rollers ( 16 ) from being transmitted to the planetary carrier ( 17 ), wherein each of said thrust rolling bearings ( 27 ) comprises a raceway ( 28 ) formed on an axial end surface of the corresponding planetary roller ( 16 ).