Clutch with pressure sustaining system

An aircraft comprising:

• an airframe;
• a drive system supported by the airframe, wherein the drive system comprises:
• an output shaft;
• an input shaft having an internal reservoir;
• a balance pressure chamber having a first fluid inner radius which is fixed during operation;
• and
• a clutch adapted to selectively engage and couple the input shaft to the output shaft, the clutch comprising:
• an actuation pressure chamber that communicates with the reservoir of the input shaft, wherein the actuation pressure chamber has a second fluid inner radius which is variable during operation;
• and
• one or more passages that communicate fluid generally radially outward from the reservoir to the actuation pressure chamber, wherein the one or more passages include one or more axial bleed orifices connecting the one or more passages to a plenum axially overlapping with a plurality of clutch plates and radially between the clutch plates and the reservoir;
• and
• wherein in operation during an interruption of a fluid supply to the input shaft the second fluid inner radius is located radially inward of the first fluid inner radius such that during the interruption of the fluid supply to the input shaft a centrifugal head pressure of the actuation pressure chamber is greater than a centrifugal head pressure of the balance pressure chamber, and wherein the reservoir has a sufficient volume to maintain the second fluid inner radius radially inward of the first fluid inner radius such that the actuation pressure chamber is provided with a fluid pressure adequate to maintain engagement of the clutch during an interruption of a fluid supply to the input shaft.

An assembly comprising:

• an output shaft;
• an input shaft having an internal reservoir;
• a balance pressure chamber having a first fluid inner radius which is fixed during operation;
• and
• a clutch adapted to selectively engage and couple the input shaft to the output shaft, the clutch having an actuation pressure chamber that communicates with the reservoir of the input shaft via one or more passages, wherein the one or more passages include one or more axial bleed orifices in fluid communication with a plenum axially overlapping with a plurality of clutch plates and radially between the clutch plates and the reservoir, wherein the actuation pressure chamber has a second fluid inner radius which is variable during operation, wherein in operation during an interruption of a fluid supply to the input shaft the second fluid inner radius is located radially inward of the first fluid inner radius, and wherein the one or more bleed orifices and the reservoir of the shaft are sized to maintain the second fluid inner radius radially inward of the first fluid inner radius such that the actuation pressure chamber has a fluid pressure adequate to maintain engagement of the clutch during the interruption of a fluid supply to the input shaft and clutch.