Abstract: A sealing ring for a seal assembly is described that comprises: a main body rotating about an axis; and a first surface, which is defined by the main body, extends transversely to the axis and is suitable for abutting against a further sealing ring in a direction parallel to the axis; the first surface comprises a plurality of grooves forming respective hydropads; the grooves are delimited by a first edge and a second edge facing one another; the first edge and the second edge delimit the grooves in a circumferential direction to said axis; at least one of the first edge and the second edge is shaped like an elliptical arc, which has coincident or separate foci; comprises first grooves and second grooves alternating with one another in a circumferential direction to said axis and staggered from each other in a radial direction to said axis.

Abstract: A sealing ring for a seal assembly is described that comprises: a main body rotating about an axis; and a first surface, which is defined by the main body, extends transversely to the axis and is suitable for abutting against a further sealing ring in a direction parallel to the axis; the first surface comprises a plurality of grooves forming respective hydropads; the grooves are delimited by a first edge and a second edge facing one another; the first edge and the second edge delimit the grooves in a circumferential direction to said axis; at least one of the first edge and the second edge is shaped like an elliptical arc, which has coincident or separate foci; comprises first grooves and second grooves alternating with one another in a circumferential direction to said axis and staggered from each other in a radial direction to said axis.

Abstract: A hover-capable aircraft having propulsion means; at least one rotor; transmission means for transmitting power from the propulsion means to the rotor and lubricated with a lubricant; a heat exchanger, which receives the heated lubricant from the transmission means and feeds the cooled lubricant back to the transmission means; and a fan for producing airflow through the heat exchanger to cool the lubricant, and which has an impeller with blades, and an exhaust pipe for expelling the hot air produced by cooling the lubricant; at least one portion of the wall of the exhaust pipe has dissipating means designed to selectively absorb pressure waves in a given frequency band related to the rotation speed of the impeller and to the number of blades of the impeller.

Abstract: A lock ring for securing a threaded stud to a first member, the ring having a first surface defining the ring on the side facing a first axis of symmetry of the ring, and in which a toothed impression is formed when it is forced onto a toothed portion of the threaded stud; and a conical second surface defining the ring on the opposite side to the first axis, and which is forced inside the first member.

Abstract: A hover-capable aircraft having propulsion means; at least one rotor; transmission means for transmitting power from the propulsion means to the rotor and lubricated with a lubricant; a heat exchanger, which receives the heated lubricant from the transmission means and feeds the cooled lubricant back to the transmission means; and a fan for producing airflow through the heat exchanger to cool the lubricant, and which has an impeller with blades, and an exhaust pipe for expelling the hot air produced by cooling the lubricant; at least one portion of the wall of the exhaust pipe has dissipating means designed to selectively absorb pressure waves in a given frequency band related to the rotation speed of the impeller and to the number of blades of the impeller.

Abstract: A fastening assembly having a tubular first coupling member; a second coupling member insertable coaxially inside the first coupling member in a first direction; and releasable fastening means for locking the first and second coupling member to each other in a predetermined axial lock position. The fastening means include: first and second engaging means formed on the first and second coupling member, connectable to each other to define a foolproof angular insertion/release position, and releasable by positioning the second coupling member in a predetermined axial position inside the first coupling member; and third and fourth engaging means formed on the first and second coupling member and connectable to each other in a further angular position of the second coupling member, different from the angular insertion/release position, by moving the second coupling member axially, from the predetermined axial position, in a second direction opposite the first direction.

Abstract: An epicyclic gear train, for an aircraft capable of hovering, having a sun gear rotating about a first axis; a fixed ring gear positioned coaxially with the first axis and radially outwards with respect to the sun gear; a number of planet gears, which are interposed between and mesh with the sun gear and the ring gear, and rotate about respective second axes, in turn revolving about the first axis; and lubricant feed means; the feed means having a number of nozzles arranged about the first axis and the sun gear to produce an annular flow of lubricant.

Abstract: Described herein is a planetary gear train, comprising: a sun gear that can turn about an axis and comprises a plurality of first teeth; a fixed crown wheel comprising a plurality of second teeth; and two planetary gears, each comprising a plurality of third teeth, the planetary gears each meshing with the crown wheel and the sun gear and able to turn about second axes, which are in turn able to turn about the first axis; at least two third teeth simultaneously mesh with second teeth and further two third teeth simultaneously mesh with first teeth; the third teeth comprise a first and a second side, which have, respectively, a first and a second pressure angle different from one another; and the number of the third teeth is different from the absolute value of the semidifference between the number of the first teeth and of the second teeth.

Abstract: A non-rotating universal joint for a helicopter drive unit has a spider defined by a ring, which has four connecting portions spaced 90° apart and engaging respective forks defining the ends of respective arms of two connecting members which, in use, are fixed with respect to a casing of an engine and a casing of a reduction gear; each fork and the corresponding connecting portion have respective through holes coaxial with one another and engaged by a screw; and dampers are interposed between the connecting portions of the ring and the shanks of the screws, and between the connecting portions of the ring and the forks.

Abstract: A damping device for damping flexural vibration of a shaft rotating about a first axis, the device having: a supporting body; and a member, which defines an annular opening fitted through with the shaft, and is movable, with respect to the supporting body and radially with respect to the first axis, between a first and a second position when the shaft flexes radially with respect to the first axis. The member is set to the first position, and the opening is traversed loosely by the shaft when the rotation speed of the shaft is within a first range; the member is set to the second position, and the opening cooperates with the shaft, when the rotation speed of the shaft is within a second range differing from the first range and including at least one critical speed of the shaft; and the damping device has elastic means interposed between the supporting body and the member.

Abstract: Described herein is a planetary gear train, comprising: a sun gear that can turn about an axis and comprises a plurality of first teeth; a fixed crown wheel comprising a plurality of second teeth; and two planetary gears, each comprising a plurality of third teeth, the planetary gears each meshing with the crown wheel and the sun gear and able to turn about second axes, which are in turn able to turn about the first axis; at least two third teeth simultaneously mesh with second teeth and further two third teeth simultaneously mesh with first teeth; the third teeth comprise a first a second side, which have, respectively, a first and a second pressure angle different from one another; and the number of the third teeth is different from the absolute value of the semidifference between the number of the first teeth and of the second teeth.

Abstract: A fastening assembly having a longitudinal axis; a tubular first coupling member; a second coupling member insertable coaxially inside the first coupling member in a first direction; and releasable fastening means for locking the first and second coupling member to each other in a predetermined axial lock position. The fastening means include first and second engaging means formed on the first and second coupling member, connectable to each other to define a foolproof angular insertion/release position, and releasable by positioning the second coupling member in a predetermined axial position inside the first coupling member; and third and fourth engaging means formed on the first and second coupling member and connectable to each other in a further angular position of the second coupling member, different from the angular insertion/release position, by moving the second coupling member axially, from the predetermined axial position, in a second direction opposite the first direction.

Abstract: A damping device for damping flexural vibration of a shaft rotating about a first axis, the device having: a supporting body; and a member, which defines an annular opening fitted through with the shaft, and is movable, with respect to the supporting body and radially with respect to the first axis, between a first and a second position when the shaft flexes radially with respect to the first axis. The member is set to the first position, and the opening is traversed loosely by the shaft when the rotation speed of the shaft is within a first range; the member is set to the second position, and the opening cooperates with the shaft, when the rotation speed of the shaft is within a second range differing from the first range and including at least one critical speed of the shaft; and the damping device has elastic means interposed between the supporting body and the member.

Abstract: A lubricating pump having a first stage and a second stage; the first stage in turn has an intake connectable hydraulically to a tank of lubricating fluid, and a delivery outlet connectable hydraulically to a lubricated member; the first stage compresses the lubricating fluid from the tank to a pressure for supply to the member; the second stage in turn has an inlet connectable hydraulically to a casing housing the member, and an outlet connectable hydraulically to the tank; the second stage feeds the lubricating fluid in the casing back into the tank; the second stage is a Roots type, and has a first and a second rotor rotating about respective axes to feed the lubricating fluid from the inlet to the outlet; and the first and second rotor are operated by the first stage.

Abstract: A non-rotating universal joint for a helicopter drive unit has a spider defined by a ring, which has four connecting portions spaced 90° apart and engaging respective forks defining the ends of respective arms of two connecting members which, in use, are fixed with respect to a casing of an engine and a casing of a reduction gear; each fork and the corresponding connecting portion have respective through holes coaxial with one another and engaged by a screw; and dampers are interposed between the connecting portions of the ring and the shanks of the screws, and between the connecting portions of the ring and the forks.

Abstract: A transmission joint for angularly connecting a first and a second member, and having a coupling member interposed functionally between the first and second member and extending about an axis; the coupling member has: a first portion connectable angularly to the first member, a second portion connectable angularly to the second member and located radially outwards of the first portion, and an intermediate portion interposed radially between the first and second portion and elongated in a direction crosswise to the axis; the intermediate portion of the coupling member has, from the first portion to the second portion, a first portion decreasing in thickness crosswise to the direction, and a second portion of constant thickness.

Abstract: There is described a transmission for a helicopter, the transmission having a movable transmission member; a casing housing the movable member; lubricated supporting means for supporting the movable member inside the casing and for rotation about an axis; and feed means for feeding a lubricating fluid to the supporting means; the transmission also has storage means permitting gradual release of the lubricating fluid, and which are connected fluidically to the feed means and to the supporting means to permit lubrication of the supporting means in the event of breakdown of the feed means; and the storage means are angularly integral with the movable member and located radially inwards of the supporting means to feed the lubricating fluid centrifugally to the supporting means.

Abstract: There is described a helicopter having a first member movable with respect to a second member; lubricated supporting means for supporting the first member with respect to the second member; and a primary lubricating circuit for lubricating the supporting means and in turn having primary storage means for accumulating a lubricating fluid, and primary fluid feed means for feeding the lubricating fluid to the supporting means; the helicopter also has an auxiliary lubricating circuit supplied continually by the primary storage means with a first lubricating fluid flow value, and itself continually supplying the supporting means with a second lubricating fluid flow value lower than the first value, so as to produce an auxiliary storage volume of lubricating fluid for use in the event of breakdown of the primary lubricating circuit.

Abstract: There is described a helicopter having a transmission for transmitting motion from a driving member to a driven member; the transmission has at least a first gear driven by the driving member, and a second gear meshing with the first gear and in turn driving the driven member; the first and second gear have teeth shaped so that the gears mesh with one another at at least two pairs of respective simultaneously meshing teeth; the teeth of at least one of the gears have a profile having an end portion relieved with respect to a starting theoretical involute; and the pattern of the distance between the points of the end portion and the starting involute along an axis of the tooth has at least a first and a second segment sloping with respect to each other.

Abstract: A lubricating pump having a first stage and a second stage; the first stage in turn has an intake connectable hydraulically to a tank of lubricating fluid, and a delivery outlet connectable hydraulically to a lubricated member; the first stage compresses the lubricating fluid from the tank to a pressure for supply to the member; the second stage in turn has an inlet connectable hydraulically to a casing housing the member, and an outlet connectable hydraulically to the tank; the second stage feeds the lubricating fluid in the casing back into the tank; the second stage is a Roots type, and has a first and a second rotor rotating about respective axes to feed the lubricating fluid from the inlet to the outlet; and the first and second rotor are operated by the first stage.