Abstract: A compact actuator (20) is arranged to selectively move an airfoil surface (27) relative to a support (27) relative to a support (21). The actuator includes a gear reduction unit (24) mounted on the support. The gear reduction unit has a ring gear (25) adapted to be rotated about a longitudinal axis (x—x), and a pinion (26) mounted on the ring gear. All bearings for the pinion gear are physically located within the gear reduction unit. The pinion gear engages a rack (23) attached to the airfoil surface such that rotation of the pinion gear will move the airfoil surface relative to the support.

Abstract: A compound differential planetary gear assembly (50) includes a sun gear (52), a plurality of planet gears (53) engaging the sun gear, a plurality of first ring gears (54), and a plurality of second ring gears (55). Each of the second ring gears has a number of teeth that is different from the number of teeth of the first ring gears. The first and second ring gears are arranged alternately in an axial stack. Each planet gear has a constant gear-tooth cross-section along the length of the stack, with its gear teeth in meshing engagement with the teeth of the first and second ring gears. Loads transmitted between the first and second ring gears and the planets act in alternate directions along the length of the stack.

Abstract: A compound differential planetary gear assembly (50) includes a sun gear (52), a plurality of planet gears (53) engaging the sun gear, a plurality of first ring gears (54), and a plurality of second ring gears (55). Each of the second ring gears has a number of teeth that is different from the number of teeth of the first ring gears. The first and second ring gears are arranged alternately in an axial stack. Each planet gear has a constant gear-tooth cross-section along the length of the stack, with its gear teeth in meshing engagement with the teeth of the first and second ring gears. Loads transmitted between the first and second ring gears and the planets act in alternate directions along the length of the stack.

Abstract: A differential coupling (20) has a body (21), a rotary input member (22), and two rotary output shafts (23, 24). The algebraic sum of the angular displacements of the output shafts is proportional to the rotation of the input member. The improvement includes mechanical means (39), such as a planetary gear (42), for sensing a torque differential between the output shafts, and a brake (38) mounted on the body and operatively arranged to selectively brake rotation of the input member, or both output members, when the difference between the torques on the outputs exceeds a predetermined first value.

Abstract: A differential coupling (20) has a body (21), a rotary input member (22), and two rotary output shafts (23, 24). The algebraic sum of the angular displacements of the output shafts is proportional to the rotation of the input member. The improvement includes mechanical means (39), such as a planetary gear (42), for sensing a torque differential between the output shafts, and a brake (38) mounted on the body and operatively arranged to selectively brake rotation of the input member, or both output members, when the difference between the torques on the outputs exceeds a predetermined first value.