An autothrottle system for an aircraft, comprising: a motor configured to impart rotational movement to a shaft extending from the motor, the motor being mounted on a support; an actuator assembly operatively connected to the shaft and to an attachment end of a throttle lever, the throttle lever having a control end, opposite to the attachment end, for application of manual force; a position sensor operatively connected between the motor and a moving portion of the actuator assembly; and an electronic controller configured to control the motor so that the motor moves the actuator assembly to determined actuator positions based at least in part on position information received from the position sensor to cause movement of the throttle lever, wherein the actuator assembly comprises: a bearing assembly having a plurality of bearings configured to contact a surface of the shaft for converting rotational movement of the shaft into linear motion of the bearing assembly along the shaft; and a shuttle arm (34; 34') having a mounting surface at a first end configured to attach to the bearing assembly and at least one linkage arm (52; 52') at a second end of the shuttle arm (34; 34') which is operatively coupled to the attachment end of the lever, wherein the actuator assembly is configured so that manual movement of the control end of the throttle lever applies a thrust force to the distal end of the shaft relative to the bearing assembly; and when the thrust force exceeds a threshold, the bearing assembly is configured to slip along the shaft irrespective of any rotation that may be concurrently imparted to the shaft by the motor. a motor configured to impart rotational movement to a shaft extending from the motor, the motor being mounted on a support; an actuator assembly operatively connected to the shaft and to an attachment end of a throttle lever, the throttle lever having a control end, opposite to the attachment end, for application of manual force; a position sensor operatively connected between the motor and a moving portion of the actuator assembly; and an electronic controller configured to control the motor so that the motor moves the actuator assembly to determined actuator positions based at least in part on position information received from the position sensor to cause movement of the throttle lever, wherein the actuator assembly comprises: a bearing assembly having a plurality of bearings configured to contact a surface of the shaft for converting rotational movement of the shaft into linear motion of the bearing assembly along the shaft; and a shuttle arm (34; 34') having a mounting surface at a first end configured to attach to the bearing assembly and at least one linkage arm (52; 52') at a second end of the shuttle arm (34; 34') which is operatively coupled to the attachment end of the lever, a bearing assembly having a plurality of bearings configured to contact a surface of the shaft for converting rotational movement of the shaft into linear motion of the bearing assembly along the shaft; and a shuttle arm (34; 34') having a mounting surface at a first end configured to attach to the bearing assembly and at least one linkage arm (52; 52') at a second end of the shuttle arm (34; 34') which is operatively coupled to the attachment end of the lever, wherein the actuator assembly is configured so that manual movement of the control end of the throttle lever applies a thrust force to the distal end of the shaft relative to the bearing assembly; and when the thrust force exceeds a threshold, the bearing assembly is configured to slip along the shaft irrespective of any rotation that may be concurrently imparted to the shaft by the motor.