The present disclosure is directed to a turbine engine (10) defining an axial direction and a radial direction. The turbine engine includes a fan or propeller assembly (14) comprising a gearbox; an engine core (20) comprising one or more rotors, wherein at least one of the rotors defines an axially extended annular hub; and a flexible coupling shaft (100) defining a first end and a second end along the axial direction, wherein the first end is connected to the engine core and the second end is connected to the gearbox, and further wherein the flexible coupling shaft extends from the one or more rotors to the gearbox in the axial direction and inward of the hub in the radial direction.

The present disclosure is directed to a turbine engine (10) defining an axial direction and a radial direction. The turbine engine includes a fan or propeller assembly (14) comprising a gearbox; an engine core (20) comprising one or more rotors, wherein at least one of the rotors defines an axially extended annular hub; and a flexible coupling shaft (100) defining a first end and a second end along the axial direction, wherein the first end is connected to the engine core and the second end is connected to the gearbox, and further wherein the flexible coupling shaft extends from the one or more rotors to the gearbox in the axial direction and inward of the hub in the radial direction.

An actuation system includes a power drive unit that drives a plurality of drive shafts that each has a first end individually connected to the power drive unit. The power drive unit includes a geartrain including a plurality of individual gears that are offset relative to each other along the gearbox, and a motor-driven rotation of one of the plurality of individual gears drives rotation of the other individual gears, and each of the plurality of individual gears rotates to drive rotation of a respective one of the plurality of drive shafts. A plurality of torque brakes is mounted to the gearbox, the torque brakes being mechanically coupled to respective individual gears and drive shafts. When the torque being passed through is above a predetermined threshold value, a locking of one of the torque brakes stops rotation of all gears simultaneously to maintain positional symmetry in the actuation system.

An actuation system includes a power drive unit that drives a plurality of drive shafts that each has a first end individually connected to the power drive unit. The power drive unit includes a geartrain including a plurality of individual gears that are offset relative to each other along the gearbox, and a motor-driven rotation of one of the plurality of individual gears drives rotation of the other individual gears, and each of the plurality of individual gears rotates to drive rotation of a respective one of the plurality of drive shafts. A plurality of torque brakes is mounted to the gearbox, the torque brakes being mechanically coupled to respective individual gears and drive shafts. When the torque being passed through is above a predetermined threshold value, a locking of one of the torque brakes stops rotation of all gears simultaneously to maintain positional symmetry in the actuation system.

This disclosure generally relates to a headrest assembly, seat, and a method of use. In the disclosure, a head restraint is moveable from an upright position to a folded position by movement of either the push-button or a lever. The disclosed arrangement provides two ways to fold a head restraint, and can further be integrated with another assembly, such as a seat back folding assembly. The disclosed arrangement is further configured to resist vibration, leading to a tighter, more stable design, which provides increased customer satisfaction.

In accordance with at least one aspect of this disclosure, a drive shaft includes, a first tube body having one or more first body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

In accordance with at least one aspect of this disclosure, a drive shaft includes, a first tube body having one or more first body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

An input shaft includes an annular main shaft extending along a longitudinal axis with an internal bore configured for fluid flow through the annular main shaft. A generator spline is included on an exterior surface of a first end of the main shaft. A gearbox spline is included on an exterior surface of a second end of the main shaft opposite the first end. At least one orifice is defined through the main shaft from the internal bore to the exterior surface of the second end of the main shaft for flow of fluid from the internal bore to the exterior surface for cooling and lubrication.

An input shaft includes an annular main shaft extending along a longitudinal axis with an internal bore configured for fluid flow through the annular main shaft. A generator spline is included on an exterior surface of a first end of the main shaft. A gearbox spline is included on an exterior surface of a second end of the main shaft opposite the first end. At least one orifice is defined through the main shaft from the internal bore to the exterior surface of the second end of the main shaft for flow of fluid from the internal bore to the exterior surface for cooling and lubrication.

A flexible composite torsion shaft for attachment to a drive shaft includes an elongated core element having a circular cross section. A reinforcement comprising at least one polymer layer and multiple layers of reinforcing-fiber wound around the core element inside the at least one polymer layer. Each reinforcing-fiber layer is wound around the core element at a winding angle in a range of 40° to the hoop winding angle, depending on a width of a reinforcing-fiber being wound, relative to a longitudinal direction of the core element. At least one reinforcing-fiber-layer is wound at an opposite angle from another reinforcing-fiber layer inside the at least one polymer layer. The winding angle increases as an average layer diameter of reinforcing-fiber insider the at least one polymer layer increases.