A coupling (1,2) has an inner member (111) and an outer annular member (131) and an intermediate annular member (121) which when aligned share a common axis and have a common centre on the common axis. The inner and the intermediate annular member are constrained to rotate, one with respect to the other about a second axis perpendicular to the common axis. The intermediate annular member and the outer annular member are constrained to rotate, one with respect to the other about a third axis (Z) perpendicular to the common axis (X) and the second axis (Y). The members are spaced apart to leave a gap (103) between each of the members.

A coupling (1,2) has an inner member (111) and an outer annular member (131) and an intermediate annular member (121) which when aligned share a common axis and have a common centre on the common axis. The inner and the intermediate annular member are constrained to rotate, one with respect to the other about a second axis perpendicular to the common axis. The intermediate annular member and the outer annular member are constrained to rotate, one with respect to the other about a third axis (Z) perpendicular to the common axis (X) and the second axis (Y). The members are spaced apart to leave a gap (103) between each of the members.

A constant velocity joint comprising two concentric couplings, a first coupling comprising an inner member, an intermediate annular member and an outer annular member, the members being concentric. The inner member of the second coupling is common to the outer member of the first coupling. The members of the couplings are constrained to rotate one with respect to another and the outer member of the second coupling is constrained to rotate angularly in respect of the common member in a way that is the mirror image of the rotation of the inner member with respect to the common member.

A joint assembly having a first shaft having an end and extending along a first axis and a second shaft having an end and extending along a second axis is provided. A first inner ring coupled to the first shaft, a second inner ring coupled to the second shaft, and a sleeve coupled to the first and second inner rings are also provided. The first and second inner rings are disposed within the sleeve and a centering device engages the ends of the first and second shafts. The centering device is configured to maintain the angular positions of the first and second shafts relative to the sleeve. The centering device is substantially fixed from rotation during rotation of the first and second shafts and the centering device includes a receiving socket defining a socket path, the socket path having a different orientation than the second axis.

A joint assembly having a first shaft having an end and extending along a first axis and a second shaft having an end and extending along a second axis is provided. A first inner ring coupled to the first shaft, a second inner ring coupled to the second shaft, and a sleeve coupled to the first and second inner rings are also provided. The first and second inner rings are disposed within the sleeve and a centering device engages the ends of the first and second shafts. The centering device is configured to maintain the angular positions of the first and second shafts relative to the sleeve. The centering device is substantially fixed from rotation during rotation of the first and second shafts and the centering device includes a receiving socket defining a socket path, the socket path having a different orientation than the second axis.

A universal joint comprises an input shaft comprising at one end thereof a first pair of arms and an output shaft comprising at one end thereof a second pair of arms. Respective opposed first pivot pins are provided on the distal ends of the first pair of arms and aligned along a first axis (P.sub.1). Respective opposed second pivot pins are provided on the distal ends of the second pair of opposed arms and aligned along a second axis (P.sub.2), the second axis (P.sub.2) being perpendicular to the first axis (P.sub.1). The joint further comprises a compliant ring extending around the input and output shafts and having first and second pairs of opposed openings for receiving the first and second pivot pins.

A proprotor system for a tiltrotor aircraft having a helicopter flight mode and an airplane flight mode includes a yoke having a plurality of blade arms each having an inboard pocket with a load transfer surface. Each of a plurality of bearing assemblies is disposed at least partially within one of the inboard pockets. Each of a plurality of inboard beams is disposed at least partially between a centrifugal force bearing and a shear bearing of each bearing assembly and has a proprotor blade coupled thereto. Each of a plurality of independent shoes is coupled between one of the centrifugal force bearings and the yoke. Each shoe has a load transfer surface that has a contact relationship with the load transfer surface of the respective inboard pocket forming a centrifugal force load path therebetween.

A coupling comprises a pair of members: a first member comprising an outer convex spherical periphery centred about a central point and a torsional axis extending through the central point, and a second annular member has an inner concave spherical periphery centred on the central point and complementary to the outer periphery of the inner first member. The spherical surfaces of the inner and outer members co-act to transmit radial loads and loads acting along the common. Axles extend radially of the central point and couples the first and second annular for transmitting torsional load from one to the other. The each of the pair of members is rotatable one relative to the other about the said central point in a direction constrained by the axle arrangement.

A coupling comprises a pair of members: a first member comprising an outer convex spherical periphery centred about a central point and a torsional axis extending through the central point, and a second annular member has an inner concave spherical periphery centred on the central point and complementary to the outer periphery of the inner first member. The spherical surfaces of the inner and outer members co-act to transmit radial loads and loads acting along the common. Axles extend radially of the central point and couples the first and second annular for transmitting torsional load from one to the other. The each of the pair of members is rotatable one relative to the other about the said central point in a direction constrained by the axle arrangement.

A universal joint comprising a first band, a second band, and a third band. The three bands are cylindrical bands coaxial with one another with respect to a common axis. The first band and the second band are separated by a first slot, and the second band and the third band are separated by a second slot. Two connection points, which are diametrically opposed, assure the connection of the first band and of the second band. Two other connection points, which are diametrically opposed, assure the connection of the second band and of the third band. The two connection points between the first band and the second band are offset by substantially 90 in rotation about the common axis with respect to the two connection points between the second band and the third band.