Abstract: Systems and methods are described for shoulders that can be implemented on shafts in gear systems, such as a drive train. The shoulders, in combination with other components like bearings, or nuts, can help restrict movement of the shaft within the drive train. Use of the shoulders in various embodiments can avoid the need for grind reliefs in corners. Grind reliefs can help in prior art systems where machining or grinding is used at surfaces where raceways of bearings border shoulders that are integrated with the shaft. Grind reliefs create tight spaces where edge breaks are difficult to create. Press-fit shoulders, such as described herein, allow machining and edge break creation on the shaft prior to installation of the shoulder.

Abstract: A planetary gear system is provided in one example embodiment and may include a planet gear further comprising a bearing system, the bearing system further comprising an inner bearing assembly comprising a spherical bearing and an outer race; an outer bearing assembly comprising a plurality of cylindrical roller bearings, an inner race, and an outer race; and a race element comprising an inner surface and an outer surface, wherein the outer surface of the race element is the inner race for the outer bearing assembly and the inner surface of the race element is associated with the outer race for the inner bearing assembly.

Abstract: Briefly, the disclosure relates to apparatuses and methods to form a gearbox enclosure comprising an external liner, an internal liner, and a variable porosity region disposed between the external liner and the internal liner. The variable porosity region may be configured to accommodate flow of the lubricant, thereby providing a capability to cool, for example, a lubricating fluid at an elevated temperature.

Abstract: In some examples, an aircraft gearbox comprises a plurality of gears and a hybrid lubrication system to lubricate the plurality of gears. The plurality of gears comprises a first gear and a second gear. The plurality of gears operable to rotate based on torque received from a driveshaft. The hybrid lubrication system comprises a pressurized lubrication system and a non-pressurized lubrication system. The pressurized lubrication system comprises a nozzle to spray a lubricant onto the first gear. The non-pressurized lubrication system comprises a reservoir to catch a portion of the lubricant from the pressurized lubrication system. The second gear is operable to disperse the lubricant across others of the plurality of gears based on the second gear rotating through the portion of the lubricant.

Abstract: In some examples, an aircraft gearbox comprises a housing, a barrier, a rotatable drive system component, a set of gears, and a lubrication system. The barrier separates a first compartment and a second compartment within the housing. Each of the rotatable drive system component and the set of gears operable to rotate based on torque received from an engine. The rotatable drive system component is located in the first compartment. The set of gears is located in the second compartment. The lubrication system comprises a first lubrication subsystem and a second lubrication subsystem, which are, at least in part, independent from one another. The first lubrication subsystem is operable to lubricate the rotatable drive system component in the first compartment. The second lubrication subsystem is operable to lubricate the set of gears in the second compartment. The barrier inhibits lubricant from passing between the first compartment and the second compartment.

Abstract: A planetary gear system is provided in one example embodiment and may include a planet gear further comprising a bearing system, the bearing system further comprising an inner bearing assembly comprising a spherical bearing and an outer race; an outer bearing assembly comprising a plurality of cylindrical roller bearings, an inner race, and an outer race; and a race element comprising an inner surface and an outer surface, wherein the outer surface of the race element is the inner race for the outer bearing assembly and the inner surface of the race element is associated with the outer race for the inner bearing assembly.

Abstract: A bearing system is provided in one example embodiment and may include an inner bearing assembly comprising a spherical bearing and an outer race; an outer bearing assembly comprising a plurality of cylindrical roller bearings, an inner race, and an outer race; and a race element comprising an inner surface and an outer surface, wherein the outer surface of the race element is the inner race for the outer bearing assembly and the inner surface of the race element is associated with the outer race for the inner bearing assembly. The inner bearing assembly allows tilting movements of the bearing system and the outer bearing assembly allows rotational movements and supports, at least in part, radial loads for the bearing system.

Abstract: A driveshaft includes a first end, a second end, and a length extending from the first end to the second end. The driveshaft includes an engagement section at the first end configured to cooperatively engage and transfer torque to a gearbox. The driveshaft also includes a compressible section configured to selectively decrease the length of the driveshaft. The driveshaft being configured to transition between an engaged configuration, wherein the engagement portion is engaged with the gearbox, and a disengaged configuration, wherein the compressible section is compressed, and the engagement portion is disengaged from the apparatus.

Abstract: A tiltrotor aircraft may be provided and may include a mast assembly, in which the mast assembly may include a mast; a bearing system; a housing; and a housing cap secured to the housing, wherein the bearing system is between the mast and the housing. The bearing system may further include a first bearing assembly including a first inner race, a first outer race, and a plurality of first tapered roller bearings; a second bearing assembly including a second inner race, a second outer race, and a plurality of second tapered roller bearings; an inner spacer and an outer spacer in which the inner and outer spacers are between the first and second bearing assemblies; and a retaining device in which the retaining device and the housing cap provide, at least in part, pre-loading for the first and second bearing assemblies.

Abstract: Systems and methods include providing an aircraft with a fuselage and a wing assembly rotatable relative to the fuselage about a stow axis between a flight position and a stowed position. The aircraft includes an engine reduction gearbox (“ERGB”) having a retractable driveshaft assembly with an actuation shaft and a first friction plate. Actuation of the retractable driveshaft assembly by the actuation shaft causes the first friction plate to selectively engage and disengage a second friction plate associated with a mid-wing gearbox (“MWGB”) via axially translatable motion of the retractable driveshaft assembly along its rotation axis. When the friction plates are engaged, rotation of the retractable driveshaft assembly imparts rotation to at least one rotor assembly. When the friction plates are disengaged, the wing assembly is capable of selectively rotation with respect to the fuselage about the stow axis between the flight position and the stowed position.

Abstract: A tiltrotor aircraft may be provided and may include a mast assembly, in which the mast assembly may include a mast; a bearing system; a housing; and a housing cap secured to the housing, wherein the bearing system is between the mast and the housing. The bearing system may further include a first bearing assembly including a first inner race, a first outer race, and a plurality of first tapered roller bearings; a second bearing assembly including a second inner race, a second outer race, and a plurality of second tapered roller bearings; an inner spacer and an outer spacer in which the inner and outer spacers are between the first and second bearing assemblies; and a retaining device in which the retaining device and the housing cap provide, at least in part, pre-loading for the first and second bearing assemblies.

Abstract: Briefly, the disclosure relates to apparatuses and methods to form a gearbox enclosure comprising an external liner, an internal liner, and a variable porosity region disposed between the external liner and the internal liner. The variable porosity region may be configured to accommodate flow of the lubricant, thereby providing a capability to cool, for example, a lubricating fluid at an elevated temperature.

Abstract: A tiltrotor aircraft may be provided and may include a mast assembly, in which the mast assembly may include a mast; a bearing system; a housing; and a housing cap secured to the housing, wherein the bearing system is between the mast and the housing. The bearing system may further include a first bearing assembly including a first inner race, a first outer race, and a plurality of first tapered roller bearings; a second bearing assembly including a second inner race, a second outer race, and a plurality of second tapered roller bearings; an inner spacer and an outer spacer in which the inner and outer spacers are between the first and second bearing assemblies; and a retaining device in which the retaining device and the housing cap provide, at least in part, pre-loading for the first and second bearing assemblies.

Abstract: In some examples, an aircraft gearbox comprises a housing, a barrier, a rotatable drive system component, a set of gears, and a lubrication system. The barrier separates a first compartment and a second compartment within the housing. Each of the rotatable drive system component and the set of gears operable to rotate based on torque received from an engine. The rotatable drive system component is located in the first compartment. The set of gears is located in the second compartment. The lubrication system comprises a first lubrication subsystem and a second lubrication subsystem, which are, at least in part, independent from one another. The first lubrication subsystem is operable to lubricate the rotatable drive system component in the first compartment. The second lubrication subsystem is operable to lubricate the set of gears in the second compartment. The barrier inhibits lubricant from passing between the first compartment and the second compartment.

Abstract: In some examples, an aircraft gearbox comprises a plurality of gears and a hybrid lubrication system to lubricate the plurality of gears. The plurality of gears comprises a first gear and a second gear. The plurality of gears operable to rotate based on torque received from a driveshaft. The hybrid lubrication system comprises a pressurized lubrication system and a non-pressurized lubrication system. The pressurized lubrication system comprises a nozzle to spray a lubricant onto the first gear. The non-pressurized lubrication system comprises a reservoir to catch a portion of the lubricant from the pressurized lubrication system. The second gear is operable to disperse the lubricant across others of the plurality of gears based on the second gear rotating through the portion of the lubricant.

Abstract: A tiltrotor aircraft may be provided and may include a mast assembly, in which the mast assembly may include a mast; a bearing system; a housing; and a housing cap secured to the housing, wherein the bearing system is between the mast and the housing. The bearing system may further include a first bearing assembly including a first inner race, a first outer race, and a plurality of first tapered roller bearings; a second bearing assembly including a second inner race, a second outer race, and a plurality of second tapered roller bearings; an inner spacer and an outer spacer in which the inner and outer spacers are between the first and second bearing assemblies; and a retaining device in which the retaining device and the housing cap provide, at least in part, pre-loading for the first and second bearing assemblies.

Abstract: A bearing system is provided in one example embodiment and may include an inner bearing assembly comprising a spherical bearing and an outer race; an outer bearing assembly comprising a plurality of cylindrical roller bearings, an inner race, and an outer race; and a race element comprising an inner surface and an outer surface, wherein the outer surface of the race element is the inner race for the outer bearing assembly and the inner surface of the race element is associated with the outer race for the inner bearing assembly. The inner bearing assembly allows tilting movements of the bearing system and the outer bearing assembly allows rotational movements and supports, at least in part, radial loads for the bearing system.

Abstract: A driveshaft includes a first end, a second end, and a length extending from the first end to the second end. The driveshaft includes an engagement section at the first end configured to cooperatively engage and transfer torque to a gearbox. The driveshaft also includes a compressible section configured to selectively decrease the length of the driveshaft. The driveshaft being configured to transition between an engaged configuration, wherein the engagement portion is engaged with the gearbox, and a disengaged configuration, wherein the compressible section is compressed, and the engagement portion is disengaged from the apparatus.

Abstract: Systems and methods include providing an aircraft with a fuselage and a wing assembly rotatable relative to the fuselage about a stow axis between a flight position and a stowed position The aircraft includes an engine reduction gearbox (“ERGB”) having a retractable driveshaft assembly with an actuation shaft and a first friction plate. Actuation of the retractable driveshaft assembly by the actuation shaft causes the first friction plate to selectively engage and disengage a second friction plate associated with a mid-wing gearbox (“MWGB”) via axially translatable motion of the retractable driveshaft assembly along its rotation axis. When the friction plates are engaged, rotation of the retractable driveshaft assembly imparts rotation to at least one rotor assembly. When the friction plates are disengaged, the wing assembly is capable of selectively rotation with respect to the fuselage about the stow axis between the flight position and the stowed position.

Abstract: A drive coupling has first and second coaxial end adapters. A first set of at least two coaxial helical elements has a first end of each element attached to the first end adapter, and a second end of each element is coupled to the second end adapter. At least one biasing device biases the end adapters relative to each other. Torque applied to one of the end adapters is transferred through the first set of helical elements to the other end adapter, the helical elements allowing for misalignment of the end adapters during operation.