GB2556235B

GB2556235B - Coupling seal

Info

Publication number: GB2556235B
Application number: GB1721532.8A
Authority: GB
Inventors: Parker Simon
Original assignee: Punk Couplings Ltd
Current assignee: Punk Couplings Ltd
Priority date: 2015-06-11
Filing date: 2016-06-10
Publication date: 2019-08-21
Anticipated expiration: 2036-06-10
Also published as: GB2556235A; WO2016198824A1; GB201721532D0

Description

COUPLING SEAL

[0001] This invention relates to seals for couplings.

[0002] International Patent Publications W02015/087080A (PUNK COUPLINGS LIMITED) 18.06.2015 and WO2015/087081A (PUNK COUPLINGS LIMITED) 18.06.2015 (published after the earliest priority date of the present application) describe and claim couplings including couplings comprising a central axis, an inner annular member having an axis coincident with the central axis , and an outer annular member with optionally one or more intermediate members in which the members comprise pairs of members one of the pair being contained within the second of the pair, with the inner member of a pair having an outer convex spherical periphery and the outer of the pair having an inner spherical concave periphery into which the outer convex periphery of the first inner member of the pair is received. The rotation of the outer one of a pair of second members is constrained to be about an axis perpendicular to central axis. In this particular invention, too, the members comprise spherical segments including a common centre.

[0003] In WO 2015/087080A the coupling comprises at least one elongate projection from one member of a pair of members into an elongate slot in the other of the pair of members, each projection and each slot being elongate in a plane containing or parallel to the central axis of the pair of members concerned, the slot and projection projecting in the direction of the said plane, and arranged to co-act with the pair of members to transmit torque from the innermost of the pair of members to the other member of the pair.

[0004] In WO2015/087081A the coupling comprises one or a diametrically opposed pair of axles disposed radially of the common centre of the pair of members coupling the first and second members for transmitting torsional load from one of the members to the other; the first and second annular members being constrained by the axle(s) to be rotatable one relative to the other about the axle(s).

[0005] The open design of these couplings as shown in WO2015/087080A and WO2015/087081A can lead to loss of lubricant in wet lubricated versions of the couplings and in any version, whether wet lubricated of not, to the ingress of dust and grit, which leads to wear, especially of the projections, slots, axles and bores in which they operate.

[0006] According to the present invention a coupling comprises a central axis, an inner annular member having an axis coincident with the central axis, and an outer annular member with optionally one or more intermediate members in which the members comprise pairs of members one of the pair being contained within the second of the pair, with the inner member of a pair having an outer convex spherical periphery and the outer of the pair having an inner spherical concave periphery into which the outer convex periphery of the first inner member of the pair is received in which the rotation of the outer one of a pair of second members is constrained to be about an axis perpendicular to central axis and in which the members comprise spherical segments including a common centre is characterised in that it additionally comprises one or a pair of seal support member having mounted thereon one or more annular seals, the one or more seals engaging the spherical periphery of one of the said annular member inside the seal support member.

[0007] In a first embodiment the coupling includes one or a pair of seal support members and characterised in that the one or pair of seal support members comprise inwardly directed seal support rings, the seal support rings being mounted within a first of the annular members and the annular seals engaging the spherical periphery of a second of said annular member, said second annular member being inside the first annular member.

[0008] In such an embodiment and comprising an inner member, three intermediate members and an outer member, two pairs of seals and seal rings are provided, one pair of seal rings mounted inside the outer member and with their associated seals engaging the outer spherical periphery of the second of the intermediate members, and the second pair of seal rings mounted inside the inner periphery of the second intermediate member with the associated seals engaging the outer periphery of the inner member.

[0009] In a second embodiment, the outer annular member has a spherical outer periphery and the seal support member comprises a housing having an inner hemispherical surface extending partially around the spherical outer periphery of the said outer annular member, The seal is mounted on the inner hemispherical surface of the housing and engaging the spherical outer periphery of the outer annular member.

[0010] When such coupling comprises one intermediate annular member, preferably the spherical outer periphery of the inner annular member, the spherical inner and outer peripheries of the both the intermediate annular member and the outer annular member and the inner hemispherical surface of the housing have a common centre and, ideally, the plane passing through the edge of the seal passes through the centre. However, the plane can pass through a point within the hemisphere which is off-set from the common centre but on the axis of the inner annular member.

[0011] In the second embodiment, ideally, the seal is mounted in a groove around the periphery of the inner hemispherical surface of the housing, [0012] In the second embodiment, ideally, the housing extends beyond the seal parallel to the axis of the inner annular member.

[0013] Preferably in the second embodiment the housing is formed contiguously with an input/output hub of the coupling, said hub being connected the input or output of the coupling and projecting from the hub is a shaft and engaging with the first inner annular member of the coupling.

[0014] Preferably In such an embodiment the outer annular member is formed with a lateral cylindrical extension, said extension connecting with the other of the output or input of the coupling.

[0015] In a coupling comprising at least one elongate projection from one member of a pair of members into an elongate slot in the other of the pair of members, each projection and each slot being elongate in a plane containing or parallel to the central axis of the pair of members concerned, the slot and projection projecting in the direction of the said plane, and arranged to co-act with the pair of members to transmit torque from the innermost of the pair of members to the other member of the pair, the intermediate ring(s) have one or more duct from the outer surface of each projection from the intermediate rings(s) to the sides of the intermediate rings. The purpose of the ducts in a wet lubricated coupling is to duct lubricant from the sides of the intermediate ring(s) to the slot in which the projection operates.

[0016] In a coupling having axles in bores to restrict rotation of members with respect to one another one or more ducts are provided in the axles within the bores leading again to the sides of the intermediate member(s).

[0017] In one arrangement the sides of intermediate member(s) incline inwards from the inner periphery of the member to the outer periphery of the member, the arrangement being such that at the rotation of the intermediate member one side is parallel to an adjacent seal support disc.

[0018] Further possible features of the invention are set out in the following description and in the claims.

[0019] The following description, by way of example only, refers to the accompanying drawings in which: [0020] Figures 1A to 1C show an example of a coupling in which Figure 1A is a cross-sectional view of Figure 1B along axis A2, Figure 1B is an axial view of the coupling, and Figure 1C is a perspective view of the coupling; [0021] Figures 2A to 2F show an example of a second coupling in which Figure 2A is an axial view along of the coupling, Figure 2B is a cross-sectional view along plane A-A in Figure 2A, Figure 2C is a cross-sectional view along plane B-B in Figure 2A, Figure 2D is an axial view showing the elements of the coupling un-aligned, Figure 2E is an axial cross-sectional view of the coupling in Figure 2A and Figure 2F is a cross sectional view along plane A-A of Figure 2D; [0022] Figures 3A to 3C show an axial view (figure 3A) and vertical and horizontal sections (figures 3B and 3C) of a coupling according to the invention; [0023] Figure 4 is an exploded view of the coupling of Figures 3A to 3C showing the individual components;

[0024] Figures 5A to 5C show detail of the inner annular member of the coupling of Figures 3A to 3C and 4, figure 5A being an end on axial view, figure 5B being a vertical section, and figure 5C a top (side?) view of the inner annular member; [0025] Figures 6A and 6B show detail of the intermediate annular member of the coupling of Figures 3A to 3C and 4, figure 6A being an end on axial view, figure 6B being a vertical section; [0026] Figure 7 shows a an end view of a further development of the coupling of figures 3 to 6 with the seal support rings and seal removed but with further lubrication provision; [0027] Figure 8 is a vertical section on the line A-A of figure 7; [0028] Figure 9 is a section on the line C-C of figure 7; [0029] Figure 10 is a section on the line B-B of figure 7; [0030] Figure 11 is a side view of a coupling having the features of figures 7 to 10 with grease nipples for the introduction of lubrication; [0031] Figure 12 is a section on the line P-P of figure 11 showing grease galleries; [0032] Figure 13 shows an end view of a coupling of figures 7 to 12 with the cap and seal in place the invention and illustrating arrangements to relieve lubricant over-pressure; [0033] Figure 14 is a section on the line Q-Q of figure 13; [0034] Figure 15 is a section on the line R-R of figure 13; [0035] Figure 16 is an exploded view showing the components of the a coupling as illustrated in figures 7 to 14; [0036] Figures 17A, 17B, 17C and 17D illustrate in detail the centrifugal pump valve 154 shown in the coupling of figures 7 to 16; and [0037] Figures 18 to 24 illustrate an alternative embodiment of the invention to that shown in figures 3 to 6 and in which: [0038] Figure 18 is an end on view of the alternative embodiment looking in the direction of arrow E of figure 19; [0039] Figure 19 is a side view of the alternative embodiment; [0040] Figure 20 is a vertical section of the embodiment in the line A-A of figure 18; [0041] Figure 21 is a perspective view of the embodiment; [0042] Figure 22 is a section in the line C-C of figure 19; [0043] Figure 23 is a section in figure B-B of figure 19; [0044] Figure 24 is an end on view of the alternative embodiment with the drive shaft and output shaft misaligned by 17.5°; [0045] Figure 25 is a side view of the alternative embodiment with the drive shaft and output shaft misaligned by 17.5°; [0046] Figure 26 is a vertical section of the embodiment in the line A-A of figure 24; [0047] Figure 27 is a perspective view of the embodiment with the drive shaft and output shaft misaligned by 17.5°; [0048] Figure 28 is a section in the line C-C of figure 25; [0049] Figure 29 is a section in figure B-B of figure 24; [0050] Figure 30 is an exploded view of the coupling of Figures 19 to 30 showing the individual components; [0051] Figure 31 is a section though a coupling similar to that illustrated in figure 4 but having a flange to join the outer member to another item; [0052] Figure 32 is an isometric drawing of the intermediate member 402 of figure 31; [0053] Figure 33 shows an exploded view of the coupling of figure 31; [0054] Figure 34 is an end on view of an alternative embodiment to that shown in figures 31 to 33; [0055] Figure 35 is a side view of the alternative embodiment; [0056] Figure 36 is a vertical section of the embodiment in the line A-A of figure 30; [0057] Figure 37 is a perspective view of the embodiment; [0058] Figure 38 is a section in figure B-B of figure 31; [0059] Figure 39 shows an axial view of the coupling having waists formed in the members; [0060] Figure 40 shows a vertical section through of the coupling of figure 40; and [0061] Figure 41 shows an exploded view of the coupling of figures 39 and 40.

[0062] In Figures 1A to 1C, a coupling comprises a first, inner annular member 601, annular intermediate member 602 and an annular outermost member 603. Each of the members 601,602, 603 comprises spherical segments about the centre C. The inner annular member 601 is centred on a first axis A1, the inner annular member 601 having an outer peripheral surface S1 which is convexly spherical centred on the point C on the axis A1. The first inner annular member 601 has a central bore 40 which in this example has splines 42 for engaging a correspondingly splined shaft.

[0063] The intermediate annular member 602 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the first inner member 601. In this example the inner spherical surface S21 of the intermediate member 602 and the outer spherical surface S1 of the first inner member 601 are contiguous plain bearing surfaces.

[0064] Diametrically opposite elongate projections M1 and M11 extends radially of, and parallel to, the first axis A1 from the convex spherical surface S1 of the inner member 601. The radially outer surface of the projection also extends parallel to the spherical surface S1. The projections extend into complementary slots K1 and K11 in the inner concave surface S21 of the intermediate member 602. The projections M1, M11 and slots K1 K11 constrain the first inner member 601 and intermediate member 602 to rotate one relative to the other about a second axis A2 of rotation through and perpendicular to the first axis A1.

[0065] The intermediate member 602 has an outer periphery S22 which is convexly spherical. The outermost annular member 603 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 602. In this example the inner spherical surface S31 of the outermost member and the outer spherical surface S22 of the intermediate member 602 are contiguous plain bearing surfaces.

[0066] Second elongate projections M2 and M21 extend radially of, and parallel to, the first axis from the convex spherical surface S22 of the intermediate member 602. The radially outer surface of the second projections M2and M22 also extends parallel to the spherical surface.

[0067] The projections M2 and M21 extend into complementary, second, slots K2 and K21 in the inner concave surface of the outermost member 603. The second projection M2 and M21 and second slots K2 and K21 are perpendicular to the first projections M1, M11, and first slots K1, K11. They constrain the intermediate 602 and outermost 603 members to be rotatable one relative to the other about a third axis A3 of rotation through the centre point C, and perpendicular to both the first axis Aland second axis A2.

[0068] The inner member 601 is retained in the intermediate member 602, and the intermediate member 602 is retained in the outermost member 603.

[0069] One use of the couplings of Figure 1A to 1C is as a universal joint as it allows angular misalignment of the shafts by virtue of the relative rotation of the inner and outermost members about the second axis.

[0070] The coupling of Figures 1A to 1C has a flange 44, fixed to or integral with the third annular member for connecting the third annular member to a structural element, for example a shaft. The flange 44 may be replaced by splines or some other connecting means.

[0071] The projections M1, M11 and M2 M21 may be in intermediate member 602 and outermost member 603 respectively projecting into slots K1, K11, K2, K21 in inner member 601 and intermediate member 602.

[0072] The pairs of members 601 and 602, and 602 and 603 each comprise a pair of members as discussed above and in the claims.

[0073] In figures 2A to 2F, the coupling comprises an inner annular member 401 centred on a first axis, the inner annular member 401 having an outer peripheral surface S1 which is convexly spherical centred on the point C on the axis A1. The inner annular member 401 has a central cylindrical bore 40 has splines for engaging a correspondingly splined shaft.

[0074] An intermediate annular member 402 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the inner member 402. In this example the inner spherical surface S21 of the second member and the outer spherical surface S1 of the inner member 401 are contiguous plain bearing surfaces.

[0075] A first pair of diametrically opposed axles X1 and X11 extend radially of, the first axis A1 on the third axis A3 to couple the inner member 401 to the intermediate member 402. The first gnd second axles constrain the inner and intermediate members to rotate one relative to the other about the third axis A3. The intermediate member 402 has an outer periphery S22 which is convexly spherical. An outer annular member 403 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 402. In this example the inner spherical surface S31 of the outer member 403 and the outer spherical surface S22 of the intermediate member 402 are contiguous plain bearing surfaces.

[0076] A second pair of diametrically opposed axles X2 and X21 extend radially of, the first axis A1 along the second axis A2 perpendicular to the third axis A3 to couple the intermediate member 402 to the outer member 403. The axles X2 and X21 constrain the intermediate 402 and outer 403 members to be rotatable one relative to the other about the second axis A2 of rotation through the centre point C, and perpendicular to the first axis A1 and perpendicular to the third axis A3. The second pair of axles allows relative rotation of the pair of members comprising intermediate and outer members 402 and 403 independently of the pair of members comprising inner and intermediate members 401 and 402.

[0077] The spherical surfaces S1, S21, S22 and S31 bear loads acting radially of the axis A1 and in the direction of the axis A1. The axles transmit torque between the inner 401, intermediate 402, and outer 403 members.

[0078] The inner member 401 is retained in the intermediate member 402, and the intermediate member 402 is retained in the outer member 403.

[0079] A first shaft or other structural element may be engaged in the central bore in the first annular member 401 and a second shaft or other structural element may be engaged with the outer member 403. For that purpose the outer member 403 may be fixed to or integral with a flange (not shown) or it may comprise other means, for example external splines, for coupling to a structural element.

[0080] One use of couplings of Figures 2A to 2F is as a universal joint. The coupling allows angular misalignment of the shafts by virtue of the relative rotation of the intermediate member 402 and outer member 403 about the third axis A3 and second axis A3 respectively.

[0081] Both the inner member 401 and the intermediate member 402 comprise spherical segments about the central point C.

[0082] Figures 3 to 6 show a coupling which is similar to the coupling shown in figure 1 but with the flange 44 (as shown in figure 1) omitted and according to the invention.

[0083] In figures 3 to 6 a coupling to the invention comprises a first, inner annular member 601, intermediate annular intermediate member 602 and an annular outermost member 603. Each of the members 601,602, 603 comprises spherical segments about a common centre (the point C in figurel). The inner annular member 601 has an outer peripheral surface S1 which is convexly spherical centred on the point C. The first inner annular member 601 has a central bore 40 which in this example has a keyway 42 engaging a correspondingly splined shaft.

[0084] The intermediate annular member 602 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the first inner member 601.

[0085] Diametrically opposed elongate projections M1, M11 extend radially of, and parallel to the axis of annular member 601 from the convex spherical surface S1 of the inner member 601. The radially outer surfaces of the projections M1, M11 also extend parallel to the spherical surface S1, alternatively the outer surfaces of the projections M1, M11 can be cylindrical The projections extend into complementary slots K1, K11 in the inner concave surface S21 of the intermediate member 602. The projections M1, M11 and slots K1, K11 constrain the first inner member 601 and intermediate member 602 to be rotatable one relative to the other about a second axis of rotation through but perpendicular to the axis of the inner annular member 601, hereinafter called the first axis.

[0086] The intermediate member 602 has an outer periphery S22 which is convexly spherical. The outermost annular member 603 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 602.

[0087] Second elongate projections M2, M21 extend radially of, and parallel to, the first axis from the convex spherical surface S22 of the intermediate member 602. The radially outer surfaces of the second projections M2, M21 also extend parallel to the spherical surface S22; alternatively the outer surfaces of the projections M2, M21 can be cylindrical.

[0088] The projections M2, M21 extend into complementary, second, slots K2, K21 in the inner concave surface S31 of the outermost member 603. The second projections M2, M21 and second slots K2, K21 are orthogonal to the first projections M1, M11, and first slots K1, K11. They constrain the intermediate 602 and outermost 603 members to be rotatable one relative to the other about a third axis of rotation and perpendicular to both the first axis and second axis.

[0089] The inner member 601 is retained in the intermediate member 602, and the intermediate member 602 is retained in the outermost member 603. For this purpose the intermediate member 602 has parallel loading slots 620, and the outer member 603 has parallel loading slots 630. The inner member 601 is inserted into the central aperture of member 602 using loading lots 620 and then turned to be retained by the concave inner surface S21 of member 602. The intermediate member 602 thus retaining the inner member 601 is itself retained in the outer member 603 by inserting intermediate member 602 into the central aperture of member 603 using loading slots 630 and then turning intermediate member 602 to be retained by the concave inner surface S31 of member 603.

[0090] The outer ring has an inner step 634 at each edge. The inner steps 634 retain seal support members which in this case are seal support rings 18 comprising the having central apertures 20 around the convex periphery S1 of inner member 601. Ring seals 22 are fitted to the rim 24 of the seal support apertures 20, closing any space between the rims 24 and the convex outer surface S1 of inner member 601. The sides 621 joining the convex outer periphery S22 and the inner concave periphery S21 of intermediate member 602 are inclined inwards from the inner periphery of the member to the outer periphery of the member as seen in figures 3A and 3B.

[0091] The purpose of the inclined sides 621 is to allow the intermediate member 602 greater range of movement before one of the sides 621 or the other contacts the seal support rings 18. If the sides were parallel the range of rotation of intermediate member 602 about inner member 601 would be restricted. The benefit of the bevelled sides can be seen in figures 3B and 3C.

[0092] In a wet lubricated joint, the intermediate member 602 has a duct 150 to allow the passage of lubricant between their outside peripheries (S1 and S22) and their inner peripheries.

[0093] The inner member 601 and intermediate member 602 have ducts 132 and 152 leading from the sides 614 and 624 the projections M1, M11, and M2, M21 to outer surfaces of projections M1, M11 and M2, M21 respectively.

[0094] The arrangements for the inner annular member 601 can be seen more clearly in figure 5 and for the intermediate annular member 602 in figure 6. Visible in figures 5 and 6 is the fact that the sides 614 and 624 of the projections M1, M11 and M2, M21 slope towards one another travelling from the periphery of the member concerned to their extremity of the projection(s) in the slot(s) to allow the projections M1, M11 and M2, M21 maximum movement in their slots K1, K11 and K2, K21 respectively. In figure 6B too it can be seen that duct 150 enters the slots K1, K11 on the inner periphery S21 of intermediate member 602.

[0095] One use of the coupling of Figures 3 to 5 is a universal joint as it allows angular misalignment of shafts by virtue of the relative rotation of the inner and outermost members about the second axis. To allow a shaft to be connected into the central aperture 40 of the inner member 601, a keyway or splines 44 is/are provided into which a spline(s) of a shaft engages. The outer ring 603 is also provided with a slot 633 into which and internal key or splines of a second shaft can be engaged.

[0096] In operation, as the members rotate with respect to one another, the gaps between the sides 621 of the intermediate member and the seal support rings 18 will increase and decrease on each side of the intermediate member 602 alternately. The decrease in the gap has the effect of pumping lubricant in the gaps whose size is decreasing though the ducts 152, and then one through duct 150. Likewise movement of projections M1, M11 in slots K1, K11, and projections M2, M21 in slots K2, K21 forces lubricant into and out the gap between the sides 614 and 624 of the projections M1, M11 and M2, M21 establishing a pumping action which circulates lubricant though ducts 132, 150 and 152.

[0097] Although an equivalent system to that shown in figures 3 to 5 has not been fully described with reference to the coupling illustrated in figure 2, the skilled reader will immediately appreciate how the construction principles of figures 3 to 5 can also be applied to that structure.

[0098] Large couplings transmitting high torques at high speed may experience wear of the spherical surfaces of the annular members. The coupling of figures 7 to 17 shows a number of additional measures which may be used to enhance lubrication of couplings of the invention.

[0099] The coupling of figures 7 to 17 have the same main components as the coupling described with reference to figures 3 to 6, although these components are shown in figures 7 to 17, they are not described again in detail, and the reader should refer to figures 3 to 6 for detail of these.

[0100] In figures 7 to 17 ducts 161 pass between the slots K2, K21 and the outer spherical surface of the intermediate member 602, these into galleries 160 for grease.

[0101] Annular grooves 162 and 164 are provided circumferentially around the inner periphery of intermediate member 602 and outer member 603 respectively, these are again to assist movement of lubricant around the coupling.

[0102] Further additional radial ducts 160 are through the intermediate member 602 linking the grooves 162 and 164. These radial ducts 160 join, on reaching the peripheral outer surface of intermediate member 602, with ducts 156, which pass through the sides 624 of intermediate members 602 and are routed to the outer peripheral surface as shown. Slit valves are 158 provided in the ducts 156 (see figure 15). The slit valves allow flow of lubricant from the sides 624 of intermediate member to the groove 164 under the action of the closing of the gap between the sides 624 of intermediate member 602 and seal support rings18.

[0103] The ducts 152 are provided with centrifugal pump valves 154 which open and close to provide a pumping action caused by opening and closing of the space between the seal support ring 18 and the sides 624 of intermediate member and 621 of projections M2 and M21. Detail of centrifugal valves 154 is seen in figures 17A to 17C (+17D). A spring 184 seated in the duct 152, urges a valve 183 against valve seat 182, in a plunger body 180, with a mouth 181 leading to the valve 183. The movement of the sides 624 of the intermediate member and of the sides 621 of projections M2, M21, increases and decreases the volume of the space 133 between the sides 621 and 624 and the seal support ring 18. As the space 133 decreases, pressure on lubricant in that area increases forcing the valve 183 open against the spring 184 so that any lubricant in the mouth 181 is forced past the valve 183. Once the peak pressure has passed after the spring closes the valve will close against seat 182 thus trapping lubricant behind the valve. As the speed of rotation of the coupling increases the centrifugal effect on the plunger 180 causes it to travel outwards along the duct 152 and thus the plunger 180 is forced further against the spring 184, this has the effect of increasing the pressure on the closed valve, increasing its sealing effect preventing back flow of lubricant from the outer periphery of the intermediate, it also forces lubricant from the duct 152 into the groove 164 and through the ducts 161 into the area around the projections and also into the rest of the coupling through the lubrication grooves 162 and 164 and galleries 160.

[0104] In some applications the spring 184 may be replaced by springs of different strengths, one urging against the valve 183, the other urging plunger 180. The centrifugal valves 154 are best placed on a central plane of the coupling to maximise the centrifugal effect on the valves. The valve will provide for a continuous lubricant flow when used in rapid start/stop operations.

[0105] The outer annular member 603 has an inset portion 170 set in to its outer surface (see figure 11). A grease nipple 172 is mounted in the inset 170 with a duct leading to an injector 174 opposite a further duct 176 passing between the outer periphery and inner periphery of the intermediate members, allowing grease to be injected into the groove 162 and 164 though the ducts 132 projections M1, M11 projections and ducts 160 (see figure 12 especially).

[0106] The coupling has the seal and seal support rings in place as described with reference to figures 3 to 6, but in this case the seal support rings 18 end cap18 has a seat 19 around its outside diameter. Seated in seat 19 is an over-pressure flap valve 26 which can be a sprung steel ring (as shown -with a slit 27 to allow opening and closing) or an elastomeric material or fibreglass. The seal support rings have a plurality of holes 28 through it to allow excess lubricant through to be released from the coupling through the over-pressure flap valve 26.

[0107] The valve 183 of the centrifugal valve 154 can be changed for one a different design to that shown, for example a bucket seal of the kind used in bicycle pumps could be used. They use the pressure on one side to cause the valve to open out against the bore providing a better seal. In the reverse direction the seal collapses away from the bore allowing lubricant to pass.

[0108] The grooves 162 and 164 are described as being around the inner peripheries of the outer and intermediate annular members; they could also be formed in the outer peripheries of the intermediate and inner members respectively.

[0109] In the embodiment of figures 3 to 6 but with a coupling comprising an inner member, three intermediate members and an outer member, two pairs of seals and seal mounting rings are provided, one pair of seals rings mounted in steps at the ends of the concave inner surface of outer member and with their associated seals engaging the outer convex spherical periphery of the second intermediate members, and the second pair of seal rings mounted in steps at the ends of the inner concave periphery of the second intermediate member with the associated seals engaging the outer convex periphery of the inner member.

[0110] An alternative embodiment to those illustrated with reference to figure 3 to 6 is shown in figures 18 to 30. Conventional coupling are generally shrouded by a “boot” to improve impact or blast damage resistance. This alternative embodiment provides improved blast or impact damage particularly for safety critical applications.

[0111] The coupling links an input shaft 211 and an output shaft 213, and comprises an input hub 215 and an output hub 217. For clarity the input and output shafts 211 and 213 are only shown in figure 19.

[0112] The input hub 215 has, at one end; a cylindrical profile 221, with a central bore 223 into which the input shaft 211 can be inserted. A longitudinal keyway 225 is provided in the central bore 223 to receive a key on the input shaft 211. The other end of the input hub 215 has a shaft 227 extending into the central bore 229 of inner annular member 601 of the coupling. The shaft 227 has a keyway 231, with the inner bore of the inner annular member 601 having a corresponding keyway 233. A key 235 is inserted in the keyways 231 and 233 to pass rotational movement of shaft 227 to inner annular member 601.

[0113] The coupling comprises a first, inner annular member 601, intermediate annular intermediate member 602 and an annular outermost member 603. Each of the members 601, 602, 603 comprises spherical segments about a common centre C (the same as the point C in figurel). The inner annular member 601 has an outer peripheral surface S1 which is convexly spherical centred on the point C.

[0114] The intermediate annular member 602 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the first inner member 601.

[0115] Diametrically opposite elongate projections M1, M11 extends radially of, and parallel to the axis of annular member 601 from the convex spherical surface S1 of the inner member 601. The outer surfaces of the projections M1, M11 also extend parallel to the spherical surface S1, alternatively the outer surfaces of the projections M1, M11 can be cylindrical The projections extend into complementary slots K1, K11 in the inner concave surface S21 of the intermediate member 602. The projections M1, M11 and slots K1, K11 constrain the first inner member 601 and intermediate member 602 to be rotatable one relative to the other about a second axis of rotation through but perpendicular to the axis of the inner annular member 601 - the first axis.

[0116] The intermediate member 602 has an outer periphery S22 which is convexly spherical. The outermost annular member 603 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 602.

[0117] Second elongate projections M2, M21 extend radially of, and parallel to, the first axis from the convex spherical surface S22 of the intermediate member 602. The radially outer surfaces of the second projections M2, M21 also extend parallel to the spherical surface S22; alternatively the outer surfaces of the projections M2, M21 can be cylindrical.

[0118] The projections M2, M21 extend into complementary, second, slots K2, K21 in the inner concave surface S31 of the outermost member 603. The second projections M2, M21 and second slots K2, K21 are orthogonal to the first projections M1, M11, and first slots K1, K11. They constrain the intermediate 602 and outermost 603 members to be rotatable one relative to the other about a third axis of rotation and perpendicular to both the first axis and second axis.

[0119] The inner member 601 is retained in the intermediate member 602, and the intermediate member 602 is retained in the outermost member 603. For this purpose the intermediate member 602 has parallel loading slots 620, and the outer member 603 has parallel loading slots 630. The inner member 601 is inserted into the central aperture of member 602 using loading slots 620 (seen in figures 22 and 24) and then turned to be retained by the concave inner surface S21 of member 602. The intermediate member 602 thus retaining the inner member 601 is itself retained in the outer member 603 by inserting intermediate member 602 into the central aperture of member 603 using loading slots 630 (seen in figures 20, 22 and 24) and then turning intermediate member 602 to be retained by the concave inner surface S31 of member 603.

[0120] The input hub 215 also has a housing 241 which in this embodiment is the seal support member extending partially around the outside of the coupling. The inner surface of the housing has a hemispherical spherical inner surface 243. The hemispherical surface 243 extends around one half of the outer annular ring to a plane on the line HH (in figure 20), which is also the axis of rotation A2 as in figure 1. Beyond the plane intersecting the line HH, the housing is cut away to provide a surface 259 that is parallel to the axis A1 of the coupling. This cut away portion 259 enables the outer annular ring to be fitted into housing. The function of this housing 241 and its hemispherical inner surface 243 is described further below. Shaft 227 projects from the hemispherical surface 243 into bore 229 of the inner annular member 601.

[0121] The outer member 603 has a contiguous cylindrical extension 245, extending from the coupling in an opposite direction to the cylindrical profile 221 of input hub 215. Together the outer member 603 and the extension 245 form the output hub 217. Cylindrical extension 245 has an inner bore 247 into which output shaft 213 may be received. The bore has a keyway 249 to receive a key on the output shaft 213, thus to pass torque and rotational motion of the outer annular member 603 to the output shaft 213.

[0122] The outer surface of outer annular member 603 is has an outer spherical surface 251 corresponding to the hemispherical inner surface 243 of housing 241. The hemispherical housing and the outer annular member 603 can, in the design illustrated, rotate about each other by up to 17.5°. By altering the relative dimensions of the components the degree of rotation can be increased of decrease, but any increase may come with a lessening of the overall strength of the coupling.

[0123] The periphery of the hemispherical inner surface 243 of the housing 241 has a groove 253 in which an annular seal 255 is housed, the seal 255 sealing between the housing 241 and the outer spherical surface of the outer annular member 603. The spherical inner surface 243 of the housing and the outer spherical surface 251 of the outer member 603 are also centred on point C (i.e. they are concentric with the spherical surface S1, S21, S22 and S31 of the annular members 601 (S1), 602 (S21, S22), 603 (S31), and a seal plane H-H (marked in figure 20) is formed at the edge 257 of seal 255 and passing through the centre point C. It is possible to construct the groove 253 slightly further to the left as seen in figure 20, so that the plane HH passes through a point on the axis A1 further to the left (when viewed as in figure 20).

[0124] A snap ring 237 engaging in a circumferential groove 239 in shaft 227 bears on the one side 230 of the inner annular member 601 holding the input hub (and thus housing 241) in place with respect to the rest of the assembly, and the outer spherical surface of the 251 of the outer member in particular. The snap ring 237 also holds key 235 in place in keyways 231 and 233.

[0125] To assemble the coupling inner annular member 601 is located within intermediate ember 602, and intermediate member within outer member 603 as described previously. Key 235 is located in keyway 231 and snap ring 237 is over-compressed within grove 239. The shaft 227 is then forced through the bore 229 of the inner annular member 601. When the snap ring 237 reaches the opposite end of bore 229 it expands locating against side 230 of the inner annual member, locking the whole assembly in place. As shown in the figures the snap ring has a rectangular cross section, and once the snap ring is located in pace, the assembly is not easily dismantled. A circular cross section snap ring would be used should it be required to dismantle the assembly more easily. In an embodiment in which the shaft 227 and the bore 229 of inner annular member 601 have co-operating splines (for example the splines 42 of figure 1A to 1C), the groove 239 may be formed in the splines, and the snap ring expanded into place in the groove in the splines in bore 229 [0126] By looking at figure 20 it can be seen that the coupling is completely sealed and dust and grit excluded by a combination of the shape of the input hub 215 and the seal 255 engaging the outer surface 251 of the outer annular member 603 thus in a wet lubricated coupling oil is completely sealed within the coupling.

[0127] As described previously with respect to figures 3 to 17, in the embodiment of figures 18 to 30, the sides 621 joining the convex outer periphery S22 and the inner concave periphery S21 of intermediate member 602 are inclined inwards from the inner periphery of the member to the outer periphery of the member.

[0128] In a wet lubricated joint, the intermediate member 602 has a duct 150 to allow the passage of lubricant between their outside peripheries (S1 and S22) and their inner peripheries.

[0129] The inner member 601 and intermediate member 602 may also have ducts 132 and 152 leading from the sides 614 and 624 the projections M1, M11, and M2, M21 to outer surfaces of projections M1, M11 and M2, M21 respectively as discussed in figures 3 to 17.

[0130] In operation, as the members rotate with respect to one another, the gaps between the sides 621 of the intermediate member and input hub 215 on the one hand and the output hub 217 on the other will increase and decrease on each side of the intermediate member 602 alternately. The decrease in the gap has the effect of pumping lubricant though the ducts 152 and through duct 150. Likewise movement of projections M2, M21 in slots K2, K21 forces lubricant into and out the gap between the sides 624 of the projections M2, M21 establishing a pumping action which also circulates lubricant though ducts 150 and 152.

[0131] As shown the coupling of figures 18 to 30 can cope with shaft misalignments of up to 17.5° between an input shaft 211 and an output shaft 213 connected to an input hub 215, However by reducing the diameter of body 245 of the output hub 217, the degree of misalignment can be increased, although with the risk that the overall strength of the coupling will weaken.

[0132] The sealing system, shown in figures 18 to 30 is strong and robust, although an additional convoluted rubber sheath could be fitted around the outside of the coupling as an additional safeguard against ingress of contaminants.

[0133] The construction of figures 18 to 30 can equally be applied to a coupling having more than one intermediate annular member, say a coupling having three intermediate members.

[0134] In one embodiment the one or more of seal support members comprise inwardly directed seal support rings, the seal support rings being mounted within a first of the annular members and the annular seals engaging the spherical periphery of a second of said annular member, said second annular member being inside the first annular member. Preferably two pairs of seals and seal rings are provided, one pair of seal rings mounted inside the outer member and with their associated seals engaging the outer spherical periphery of the second of the intermediate members, and the second pair of seal rings mounted inside the inner periphery of the second intermediate member with the associated seals engaging the outer periphery of the inner member.

[0135] Figures 31 to 38 show how the embodiments illustrated in figures 7 to 30 are applied to a coupling whose members are linked by axles as in figure 2 rather than by projections engaging in slots as in figure 1. It should be stated that the arrangements shown in figures 3 to 6 apply directly to the coupling of figure 2.

[0136] The coupling shown in figures 31 1o 33 is analogous to that of figures 7 to 17 and is a lubricated version of the coupling of figure 2 but in which the outer member 403 is formed with a flange 405. The coupling comprises an inner annular member 401 and intermediate member 402 and an outer member 403. Rotation of the intermediate member 402 about the inner member 401 is constrained to rotate with respect to one another on an axis A2 perpendicular to central axis A1 by coupling these members with diametrically opposed axles X1 and X1. The outer annular member 403 is constrained to rotate in respect of the intermediate 402 by diametrically opposed axles X2 and X21, whose axes A3 is mutually perpendicular to the central axis A1 and axis of axles X1 and X11. The inner member 401 has a central bore 411 to receive a driving shaft (not shown) with a keyway 412 to receive a keyway on the driving shaft and to force the inner annular member 401 to rotate with the driving shaft, [0137] The outer member 403 has a flange 405 to couple to an external member.

[0138] The outer member 403 has inner steps 432. The inner step 432 retains seal support discs 18 with a central aperture 20. Ring seals 22 are fitted to the rim 24 of the seal support discs 18 around apertures 20, closing any space between the rims 24 and the convex outer surface S1 of inner member 401.

[0139] The sides 421 joining the convex outer periphery S22 and the inner concave periphery of intermediate member S21 can be inclined inwards from the outer periphery of the member to the inner periphery of the member. The purpose of the inclined sides is to allow the intermediate member 402 greater range of movement before one of the sides 421 or the other contacts the seal support discs 18. If the sides were parallel the range of rotation of intermediate member 402 about inner member 401 would be restricted. A further O-ring seal 19 engages between seal 18 and the side faces 431 of outer member 403.

[0140] The axles X, X11, X2, X21are mounted in axle holes H1, H11.H2, H21 respectively [0141] Lubrication ducts 415 run between the side faces 421 of intermediate member 402 and each of the axle holes H1, H11, H2, and H21. Further lubrication 417 pass through the intermediate member 402 from one side 421 to the other. There ducts 417 are disposed in the intermediate member about midway between each of the lubricating ducts 415. An annular channel 416 is formed at the apex of inner spherical surface S21 of the intermediate member 402, and further lubricating ducts 418 pass radially through the intermediate member 402, intersecting perpendicularly ducts 417, to the outer spherical surface S22 of intermediate member 402. A further annular channel 426 is formed at the apex of inner spherical surface S31 of the outer member 403.

[0142] In operation, as the members rotate with respect to one another, the gaps between the sides 421 of the intermediate member 402 and the seal support disc 18 will increase and decrease as the annular member 402 is rotated. This has the effect of pumping lubricant around the device. Additional lubrication can be supplied, if needed through axle holes H2 and H21.

[0143] Pairs of loading slots L1 and L3 enable assembly of the coupling.

[0144] An alternative embodiment of the invention to that of figures 31 to 33 is shown in figures 34 to 38 which illustrate the application of a seal to a coupling shrouded by a “boot” to improve impact or blast damage resistance.

[0145] In figures 34 to 38 a coupling between an input shaft 211 and an output shaft 213, comprises an input hub 215 and an output hub 217. For clarity the input and output shafts 211 and 213 are only shown in figure 18.

[0146] The input hub 215 has, at one end; a cylindrical profile 221, with a central bore 223 into which the input shaft 211 can be inserted. A longitudinal keyway 225 is provided in the central bore 223 to receive a key on the input shaft 211. The other end of the input hub 215 has a shaft 227 extending into the central bore 229 of inner annular member 601 of the coupling. The shaft 227 has a keyway 231, with the inner bore of the inner annular member 401 having a corresponding keyway 233. A key 235 is inserted in the keyways 231 and 233 to pass rotational movement of shaft 227 to inner annular member 401.

[0147] The coupling comprises a first, inner annular member 401, intermediate annular intermediate member 402 and an annular outermost member 403. Each of the members 401,402,403 comprises spherical segments about a common centre C (the same as the point C in figure 4). The inner annular member 401 has an outer peripheral surface S1 which is convexly spherical centred on the point C.

[0148] The intermediate annular member 402 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the first inner member 401.

[0149] Diametrically opposite axles X1, X11 extends radially along an axis A2 perpendicular to the axis A1 of annular member 401 from axle apertures in the inner member 402 into apertures in inner member 401. The axles X1 and X11 constrain the first inner member 401 and intermediate member 402 to be rotatable one relative to the other about the axis A2 perpendicular to the central axis A1 of the inner annular member 401 - the first axis.

[0150] The intermediate member 402 has an outer periphery S22 which is convexly spherical. The outermost annular member 403 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 402.

[0151] Second pairs of axles X2 and X21, mounted in the outer member 403 and diametrically opposed to one another on an axis A3 which is perpendicular to both axes A1 and A2 extend into axles holes in intermediate member 402. Axles X2 and X21 constrain the intermediate member 402 and outer member 403 members to be rotatable one relative to the other about axis A3 and perpendicular to both the first axis A1 and second axis A2.

[0152] The inner member 401 is retained in the intermediate member 402, and the intermediate member 402 is retained in the outermost member 403.

[0153] The input hub 215 also has a housing 241 which in this embodiment is the seal support member extending partially around the outside of the coupling. The inner surface of the housing has a hemispherical spherical inner surface 243. The hemispherical surface 243 extends around one half of the outer annular ring to a plane on the line HH (in figure 17); line HH is also the axis of rotation A2 as in figure 1. Beyond the plane intersecting the line HH, the housing is cut away to provide a surface 259 that is parallel to the axis A1 of the coupling. This cut away portion 259 enables the outer annular ring to be fitted into housing. The function of this housing 241 and its hemispherical inner surface 243 is described further below. Shaft 227 projects from the hemispherical surface 243 into bore 229 of the inner annular member 401.

[0154] The outer member 403 has a contiguous cylindrical extension 245, extending from the coupling in an opposite direction to the cylindrical profile 221 of input hub 215. Together the outer member 403 and the extension 245 form the output hub 217. Cylindrical extension 245 has an inner bore 247 into which output shaft 213 may be received. The bore has a keyway 249 to receive a key on the output shaft 213, thus to pass torque and rotational motion of the outer annular member 403 to the output shaft 213.

[0155] The outer surface of outer annular member 403 is has an outer spherical surface 251 corresponding to the hemispherical inner surface 243 of housing 241. The hemispherical housing and the outer annular member 403 can, in the design illustrated, rotate about each other by up to 17.5°. .By altering the relative dimensions of the components the degree of rotation can be increased of decrease, but any increase may come with a lessening of the overall strength of the coupling.

[0156] The periphery of the hemispherical inner surface 243 of the housing 241 has a groove 253 in which an annular seal 255 is housed, the seal 255 sealing between the housing 241 and the outer spherical surface of the outer annular member 403. The spherical inner surface 243 of the housing and the outer spherical surface 251 of the outer member 403 are also centred on point C (i.e. they are concentric with the spherical surface S1, S21, S22 and S31 of the annular members 401 (S1), 402 (S21, S22), 403 (S31), and a seal plane H-H (marked in figure 17) is formed at the edge 257 of seal 255 and passing through the centre point C. It is possible to construct the groove 253 slightly further to the left as seen in figure 18, so that the plane HH passes through a point on the axis A1 further to the left (when viewed as in figure 17).

[0157] A snap ring 237 engaging in a circumferential groove 239 in shaft 227 bears on the one side 230 of the inner annular member 401 holding the input hub (and thus housing 241) in place with respect to the rest of the assembly, and the outer spherical surface of the 251 of the outer member in particular. The snap ring 237 also holds key 235 in place in keyways 231 and 233.

[0158] To assemble the coupling inner annular member 401 is located within intermediate ember 402 and axles X1 and X11 fitted in place. The assembly of the inner and intermediate members is then placed in the outer member 403 and axles X2 and X21 fitted. Key 235 is located in keyway 231 and snap ring 237 is over-compressed within grove 239. The shaft 227 is then forced through the bore 229 of the inner annular member 601. When the snap ring 237 reaches the opposite end of bore 229 it expands locating against side 230 of the inner annual member, locking the whole assembly in place. As shown in the figures the snap ring has a rectangular cross section, and once the snap ring is located in place, the assembly is not easily dismantled. A circular cross section snap ring would be used should it be required to dismantle the assembly more easily. In an embodiment in which the shaft 227 and the bore 229 of inner annular member 401 have co-operating splines (for example the splines of figure 4), the groove 239 may be formed in the splines, and the snap ring expanded into place in the groove in the splines in bore 229 [0159] It can be seen that the coupling of figures 34 to 38 is completely sealed and dust and grit excluded by a combination of the shape of the input hub 215 and the seal 255 engaging the outer surface 251 of the outer annular member 403 thus in a wet lubricated coupling oil is completely sealed within the coupling.

[0160] As described previously with respect to figures 31 to 33, in the embodiment of figures 34 to 38, the sides 421 joining the convex outer periphery S22 and the inner concave periphery S21 of intermediate member 402 are inclined inwards from the inner periphery of the member to the outer periphery of the member.

[0161] In a wet lubricated joint, the lubrication arrangements of figures 31 to 33 to 14 could be adopted.

[0162] The coupling shown in figures 34 to 38 can cope with shaft misalignments of up to 17.5° between an input shaft 211 and an output shaft 213 connected to an input hub 215, However by reducing the diameter of body 245 of the output hub 217, the degree of misalignment can be increased, although with the risk that the overall strength of the coupling will weaken.

[0163] As with the system of figures 18 to 30, the sealing system, shown in figures 34 to 38 is strong and robust, although an additional convoluted rubber sheath could be fitted around the outside of the coupling as an additional safeguard against ingress of contaminants.

[0164] In figures 39 to 41 a coupling comprises an inner annular member 401, an intermediate member 402 and an outer member 403. The inner member 401 is centred on a first axis A1 and has an outer peripheral surface S1 which is convexly spherical centred on the point C on the axis A1. The inner annular member 401 has a central keyway 476 for engaging a key on a shaft.

[0165] The intermediate annular member 402 has an inner peripheral surface S21 which is concavely spherical complementary to the outer surface S1 of the first inner member 401. In this example the inner spherical surface S21 of the intermediate member 402 forms a female race and the outer spherical surface S1 of the first inner member the male bearing surface.

[0166] A first pair of diametrically opposed axles X1 and X11 extend radially of, the first axis A1 on the third axis A2 to couple the inner member 401 to the intermediate member 402. The first and second axles constrain the inner and intermediate members to rotate one relative to the other about the third axis A2. The intermediate member 402 has an outer periphery S22 which is convexly spherical. The intermediate member 402 has an outer periphery S22 which is convexly spherical and forms a second male surface of the invention. The outermost annular member 403 has an inner peripheral surface S31 which is concavely spherical complementary to the outer surface S22 of the intermediate member 402. The inner spherical surface S31 of the outermost member forms a second female race of the invention.

[0167] A second pair of diametrically opposed axles X2 and X21 extend radially of, the first axis A1 along the second axis A3 perpendicular to the third axis A2 to couple the intermediate member 402 to the outer member 403. The axles X2 and X21 constrain the intermediate 402 and outer 403 members to be rotatable one relative to the other about the second axis A3 of rotation (see Figure 25) through the centre point C, and perpendicular to the first axis A1 and perpendicular to the third axis A2. The second pair of axles allows relative rotation of the pair of members comprising intermediate and outer members 402 and 403 independently of the pair of members comprising inner and intermediate members 401 and 402.

[0168] The male bearing surface S1 of inner member 401 has a cylindrical waist which forms a pair of loading slots. The waist is positioned between axles X1 and X11. The width of the member 401 across the waist is just less than the aperture 474 of intermediate member 402.

[0169] To assemble the inner member 401 within the intermediate member 402, inner member 401 is lined up within intermediate member 402 to be at right angles to intermediate member 402. Inner member 401 is now rotated to bring surface S1, the male spherical bearing surface, into contact with the inner periphery S21 of the intermediate member40 2.

Axles X1 and X11 are then inserted into their axle holes.

[0170] Similarly the male bearing surface S21 of intermediate member 402 has a cylindrical waist which forms a pair of loading slots. The waist is positioned between axles X2 and X21. The width of the member 402 across the waist is just less than the aperture 475 of the outer member 403 [0171] To assemble the intermediate member 402 within the outer member 403, intermediate member 402 is lined up within outer member 403 to be at right angles to intermediate member 403. Intermediate member 402 is now rotated to bring surface S22, the male spherical bearing surface, into contact with the inner periphery S31 of the outer member. Axles X2 and X21 are then inserted into their axle holes and held in place with an interference fit with the axle holes in outer member 403.

[0172] In figures 39 to 41, the axles and holes may be replaced by projections and slots as described in figure 1.

[0173] The arrangements of figures 39 to 41 may be used in conjunction with the embodiments of figures 3 to 38 b replacing the intermediate member as shown in those figures with one of the kind shown in figures 39 to 41, which has a waist 679 in the outer surface S22, but loading slots in the inner surface S21. In the construction shown in figures 7 to 38, it would not be possible to provide waists in the outer surface S1 of the inner member as that prevent the seal 22 from sealing against the outer surface S1 of the inner member 401 or 601 as appropriate.

[0174] In addition to aiding loading the intermediate member 402 in the outer member 403, the space thus formed between the waited portion 479 and the inner periphery S31 of the outer member 403 acts as a reservoir for lubricant or grease, greatly enhancing the lubrication of the coupling and extending its life span. In a coupling following the construction principles of figure 1, the waited intermediate member would be member 602 with the reservoir equivalent to item 479 in figures 39 to 41 formed between the outer member 603 and intermediate member 602.

Claims

1. A coupling comprising a central axis, an inner annular member having an axis coincident with the central axis, and an outer annular member with one or more intermediate members in which the members comprise pairs of members one of the pair being contained within the second of the pair, with the inner member of a pair having an outer convex spherical periphery and the outer of the pair having an inner spherical concave periphery into which the outer convex periphery of the first inner member of the pair is received in which the rotation of the outer one of a pair of second members is constrained to be about an axis perpendicular to central axis and in which the members comprise spherical segments including a common centre is characterised in that it additionally comprises one or a pair of seal support member having mounted thereon one or more annular seals, the one or more seals engaging the spherical periphery of one of the said annular member inside the seal support member.

2. A coupling according to claim 1 characterised in that one or a pair of the seal support members comprise seal support rings, the seal support rings being mounted within one of said annular members annular member and the annular seals engaging the spherical periphery of a second of said annular member inside the annular member within which the seal support rings(s) are mounted.

3. A coupling according to claim 2 in which the seal support ring has holes through for to relieve lubricant over pressure.

4. A coupling according to claim 3 in which an over-pressure flap valve is seated around the outside of the seal ring.

5. A coupling according to any one of claims 1 to 3 and comprising an inner member, three intermediate members and an outer member characterised in having one or a pair of seal rings mounted inside the outer member and with the associated seal(s) engaging the outer spherical periphery of the second of the intermediate members, and a second or second pair of seal rings mounted inside the inner periphery of the second intermediate member with the associated seals engaging the outer periphery of the inner member. \

6. A coupling according to claim 2 or claim 2 and any one of claims 3 to 5 having one intermediate member characterised in that the sides of the intermediate member incline outwards from the outer periphery of the member to the inner periphery of the member, the arrangement being such that at the rotation of the intermediate member one side is parallel to an adjacent seal support ring.

7. A coupling according to claim 1 characterised in that the outer annular member has a spherical outer periphery and the seal support member comprises a housing having an inner hemispherical surface extending partially around the spherical outer periphery of the said outer annular member, the outer annular member having an outer spherical surface, and a the seal mounted on the inner hemispherical surface of the housing and engaging the spherical outer periphery of the outer annular member.

8. A coupling according to claim 7 in which the coupling comprises one intermediate annular member, and characterised in that the spherical outer periphery of the inner annular member, the spherical inner and outer peripheries of the both the intermediate annular member and the outer annular member and the inner hemispherical surface of the housing have a common centre.

9. A coupling according to claim 8 characterised in that a plane passing through the edge of the seal passes through the centre.

10. A coupling according to any one of claims 7 to 9 in which the seal in mounted in a groove around the periphery of the inner hemispherical surface of the housing,

11. A coupling according to any one of claims 7 to 10 characterised in that the housing extends beyond the seal parallel to the axis of the inner annular member.

12. A coupling according to any one of claims 7 to 11 characterised in that the housing is formed contiguously with an input/output hub of the coupling, said hub being connected the input or output of the coupling and projecting from the hub is a shaft and engaging with the first inner annular member of the coupling.

13. A coupling according to claim 12 characterised in that the outer annular member is formed with a lateral cylindrical extension, said extension connecting with the other of the output or input of the coupling.

14. A coupling according to any claim 12 or 13 in which the housing is held in place with the respect to the outer spherical surface of the outer annular member by a snap ring engaging the shaft and a side of the inner annular member.

15. A coupling according to any preceding claim and comprising at least one intermediate member and at least one elongate projection from one member of a pair of members into an elongate slot in the other of the pair of members, each projection and each slot being elongate in a plane containing or parallel to the central axis of the pair of members concerned, the slot and projection projecting in the direction of the said plane, and arranged to co-act with the pair of members to transmit torque from the innermost of the pair of members to the other member of the pair, characterised in that the intermediate ring(s) have one or more duct from sides of each projection from the intermediate member to the periphery of the projections.

16. A coupling according to claim 15 characterised in that the sides of the elongate projections slope towards one another travelling from the periphery of the member concerned to their extremity of the projection(s) in the slot(s).

17. A coupling according to claim 15 or 16 having a valve in each duct.

18. A coupling according to claim 17 in which the valve opens to permit the passage of lubricant from the sides of the elongate projections to the periphery of the projections under pressure of lubricant beside the side of the projection.

19. A coupling according to claim 17 or 18 in with the valve is mounted in a plunger and the plunger moves against a spring to pump lubricant from the duct under the centrifugal force generated by rotation of the coupling.

20. A coupling according to claim 19 in which the spring urges the valve towards a closed position.

21. A coupling according to any preceding claim having circumferential grooves around the inner peripheries of the outer and intermediate annular members and/or in the outer peripheries of the intermediate and inner annular members respectively.

22. A coupling according to claim 20 having one or a plurality of ducts through the intermediate annular member between one circumferential groove and the other.

23. A coupling according to claim 21 or 22 having one or more ducts between the sides of the intermediate annular member and the circumferential groove in the inner periphery of the outer member or the outer periphery of the intermediate member.

24. A coupling according to claim 23 in which the duct(s) have one way valves only permitting lubricant flow from the sides to the groove.

25. A coupling according to any one of claims 21 to 24 having a grease nipple in the outer member, said grease nipple being connected through a duct passing through the intermediate annular member to the groove in the inner periphery of the intermediate annular member or outer periphery of the inner member.

26. A coupling according to any one of claims 1 to 14 having axles in bores to restrict rotation of members with respect to one another characterised in that one or more ducts are provided in the an intermediate passing from the outer periphery to the inner periphery.

27. A coupling according to claim 26 having a circumferential groove one or more of the inner and outer peripheries of the members.

28. A coupling according to any preceding claim in which an intermediate member has a waist forming loading slots both in the outer periphery and the inner periphery.