Abstract: A bearing carrier support for connecting a rotary shaft of a gas turbine engine to a static portion of the gas turbine engine. The bearing carrier support has: a bearing portion for supporting the rotary shaft; a flange portion for attaching the bearing carrier support to the static portion of the gas turbine engine; and a support portion that connects the flange portion and the bearing portion. The support portion has a plurality of circumferentially distributed struts that are axially aligned with respect to the rotary shaft. The number of struts is at least 500 and the diameter of each strut is no more than 3 mm.

Abstract: A gas turbine engine comprises a gearbox including a first epicyclic gearbox and a second epicyclic gearbox. The first epicyclic gearbox comprises a first sun gear meshing with the first planet gears and the first planet gears meshing with a first annulus gear. The second epicyclic gearbox comprises a second sun gear meshing with the second planet gears and the second planet gears meshing with a second annulus gear. An input shaft is arranged to drive the first sun gear and a first planet gear carrier is arranged to drive a propulsor. The first and second annulus gears are fixed to a static structure. A first clutch is arranged between the first planet gear carrier and the second planet gear carrier and a second clutch is arranged between the second sun gear and the input shaft. The gearbox is more efficient at cruise conditions.

Abstract: A gas turbine engine comprises a gearbox comprises a sun gear, an annulus gear, a plurality of planet gears and a carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. The planet gear carrier comprising a first ring, a second ring spaced axially from the first ring and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring. Each planet gear is rotatably mounted on a respective one of the axles and the axles are arranged at a first radius. At least one of the first ring and the second ring comprises a metal matrix composite material ring and the metal matrix composite ring comprises a ring of reinforcing fibres and the ring of reinforcing fibres having a second radius greater than the first radius.

Abstract: A planetary gear box assembly, comprises a sun gear and a plurality of planet gears in meshing engagement with the sun gear; the planet gears in meshing engagement with a ring gear which encircles the plurality of planet gears, each planet gear mounted for rotation in a planet carrier by means of a bearing pin wherein a bore in the planet carrier for receiving the bearing pin is parallel. The bearing pin includes a small axially tapered section adjacent one or both ends and the assembly further comprises a tapered sleeve configured to interference fit between a radially inner wall surface of the parallel bore and a radially outer surface of the or each axially tapered section.

Abstract: Described is a planet carrier rotatable about a carrier axis, comprising: a planet pin for receiving a planet gear, the planet pin having a body with an external surface for receiving a planet gear bearing or planet gear; a carrier having a first axial wall and a second axial wall with the planet pin extending there between along a planet pin axis, wherein each carrier wall includes a planet pin retention feature located on radially inwards of the planet pin axis and engaged with a portion of the planet pin.

Abstract: A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a carrier. The carrier comprises a primary structure and at least one reinforcing structure. The primary structure comprises a first material and the at least one reinforcing structure comprises a second material. The primary structure includes a first ring, a second ring spaced axially from the first ring and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring. Each planet gear is rotatably mounted on a respective one of the axles by a bearing. The reinforcing structure is secured to the primary structure and the reinforcing structure comprises a particulate reinforced material or a fiber reinforced material. The reinforcing structure increases the stiffness of the carrier and reduces the weight of the carrier.

Abstract: A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a planet gear carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. Each planet gear is rotatably mounted in the planet gear carrier. The planet gear carrier comprises a plurality of axles arranged parallel to the axis of the gearbox. The axially spaced ends of each axle are secured to the planet gear carrier. Each planet gear is rotatably mounted on a corresponding one of the axles by a bearing arrangement. Each bearing arrangement comprises a journal bearing and a rolling element bearing and each planet gear is rotatably mounted on a journal bearing and each journal bearing is rotatably mounted on an axle by at least one rolling element bearing.

Abstract: A gas turbine engine comprises a gearbox including a first epicyclic gearbox and a second epicyclic gearbox. The first epicyclic gearbox comprises a first sun gear meshing with the first planet gears and the first planet gears meshing with a first annulus gear. The second epicyclic gearbox comprises a second sun gear meshing with the second planet gears and the second planet gears meshing with a second annulus gear. An input shaft is arranged to drive the first sun gear and a first planet gear carrier is arranged to drive a propulsor. The first and second annulus gears are fixed to a static structure. A first clutch is arranged between the first planet gear carrier and the second planet gear carrier and a second clutch is arranged between the second sun gear and the input shaft. The gearbox is more efficient at cruise conditions.

Abstract: A transmission system for transmitting a change of speed between two rotating shafts, includes a planetary gear box having a sun gear arranged for rotation with a first shaft travelling at a first speed. Planet gears contained within a ring gear are arranged to orbit the sun gear when the sun gear rotates and the ring gear is in a fixed position. Each planet gear is mounted for rotation on a centrifugal carrier. An output carrier includes a body having arms and the arms are each aligned with an axis of rotation of a planet gear and held to the centrifugal carrier by one or more supports extending in a radial plane. An output shaft extends from the body in coaxial alignment with the input shaft. A connector which is stiff in a radial dimension but flexible under torsional load is arranged between the output carrier and the centrifugal carrier.

Abstract: A bearing arrangement comprises a rolling element bearing assembly including a bearing cage. The bearing cage comprises an annular cage body having an inner surface defining a coaxial bore. The bearing cage has a plurality of circumferentially spaced pockets and each pocket houses a rotatable rolling element. A first annular skirt extends axially from a radially inner end of a first axial end of the cage body and at least one first support member extends radially and axially from the remote axial end of the first annular skirt to the radially outer end of annular cage body. The bearing cage is hollow and has a high stiffness to weight ratio. The bearing arrangement is particularly suitable for use for a planet gear of a planetary gearbox. The planetary gearbox may be for a gas turbine engine.

Abstract: A planetary gear box assembly, comprises a sun gear and a plurality of planet gears in meshing engagement with the sun gear; the planet gears in meshing engagement with a ring gear which encircles the plurality of planet gears, each planet gear mounted for rotation in a planet carrier by means of a bearing pin wherein a bore in the planet carrier for receiving the bearing pin is parallel. The bearing pin includes a small axially tapered section adjacent one or both ends and the assembly further comprises a tapered sleeve configured to interference fit between a radially inner wall surface of the parallel bore and a radially outer surface of the or each axially tapered section.

Abstract: Described is a planet carrier rotatable about a carrier axis, comprising: a planet pin for receiving a planet gear, the planet pin having a body with an external surface for receiving a planet gear bearing or planet gear; a carrier having a first axial wall and a second axial wall with the planet pin extending there between along a planet pin axis, wherein each carrier wall includes a planet pin retention feature located on radially inwards of the planet pin axis and engaged with a portion of the planet pin.

Abstract: A gas turbine engine comprises a gearbox comprises a sun gear, an annulus gear, a plurality of planet gears and a carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. The planet gear carrier comprising a first ring, a second ring spaced axially from the first ring and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring. Each planet gear is rotatably mounted on a respective one of the axles and the axles are arranged at a first radius. At least one of the first ring and the second ring comprises a metal matrix composite material ring and the metal matrix composite ring comprises a ring of reinforcing fibres and the ring of reinforcing fibres having a second radius greater than the first radius.

Abstract: A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a carrier. The carrier comprises a primary structure and at least one reinforcing structure. The primary structure comprises a first material and the at least one reinforcing structure comprises a second material. The primary structure includes a first ring, a second ring spaced axially from the first ring and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring. Each planet gear is rotatably mounted on a respective one of the axles by a bearing. The reinforcing structure is secured to the primary structure and the reinforcing structure comprises a particulate reinforced material or a fibre reinforced material. The reinforcing structure increases the stiffness of the carrier and reduces the weight of the carrier.

Abstract: A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a planet gear carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. Each planet gear is rotatably mounted in the planet gear carrier. The planet gear carrier comprises a plurality of axles arranged parallel to the axis of the gearbox. The axially spaced ends of each axle are secured to the planet gear carrier. Each planet gear is rotatably mounted on a corresponding one of the axles by a bearing arrangement. Each bearing arrangement comprises a journal bearing and a rolling element bearing and each planet gear is rotatably mounted on a journal bearing and each journal bearing is rotatably mounted on an axle by at least one rolling element bearing.

Abstract: A transmission system for transmitting a change of speed between two rotating shafts, includes a planetary gear box having a sun gear arranged for rotation with a first shaft travelling at a first speed. Planet gears contained within a ring gear are arranged to orbit the sun gear when the sun gear rotates and the ring gear is in a fixed position. Each planet gear is mounted for rotation on a centrifugal carrier. An output carrier includes a body having arms and the arms are each aligned with an axis of rotation of a planet gear and held to the centrifugal carrier by one or more supports extending in a radial plane. An output shaft extends from the body in coaxial alignment with the input shaft. A connector which is stiff in a radial dimension but flexible under torsional load is arranged between the output carrier and the centrifugal carrier.

Abstract: A bearing arrangement comprises a rolling element bearing assembly including a bearing cage. The bearing cage comprises an annular cage body having an inner surface defining a coaxial bore. The bearing cage has a plurality of circumferentially spaced pockets and each pocket houses a rotatable rolling element. A first annular skirt extends axially from a radially inner end of a first axial end of the cage body and at least one first support member extends radially and axially from the remote axial end of the first annular skirt to the radially outer end of annular cage body. The bearing cage is hollow and has a high stiffness to weight ratio. The bearing arrangement is particularly suitable for use for a planet gear of a planetary gearbox. The planetary gearbox may be for a gas turbine engine.