An automotive vehicle steering system has an actuator (12) for steering a
wheel (10). A shaft (28) passes axially through the interior of a housing
(14) of the actuator and through a rotor tube (56) journaled for rotation
within the housing. On the exterior of the housing one end of the shaft
is coupled to the wheel. An electric motor (52) within the interior of
the housing rotates the rotor tube when the wheel is steered by a
steering wheel. An internal screw thread (68) on the rotor tube and an
external screw thread (70) on the shaft are operatively coupled by a set
(74) of transmission rollers (76) to provide for bi-directional
transmission of motion between the rotor tube and the shaft such that
rotation of the rotor tube causes the shaft to move axially of the
housing to steer the vehicle wheel and axial motion of the shaft due to
wheel recovery from a turn rotates the rotor tube.