Abstract:
A swivel comprises a first body component and a second body component with an interconnection assembly for interconnecting the first and second body components and to allow mutual rotation of the first and second components about a swivel axis. The swivel further includes a rotation limiting arrangement which, in a release condition, allows free mutual rotation of the first and second body components and in a first or a second locking condition restricts mutual rotation of the first and second body components. A user control is operable to selectively cause the rotation limiting arrangement to adopt one of a locking condition and the release condition. In the first locking condition, the rotation limiting arrangement prevents mutual rotation of the first and the second body components and in the second locking condition, the rotation limiting arrangement, allows limited mutual rotation of the first and second body components by less than 360°.

Description:
BACKGROUND TO THE INVENTION 
     Field of the Invention 
       [0001]    This invention relates to swivels. 
         [0002]    A swivel is an anti-torsion device for reducing the twisting loads within climbing and lifting systems. Traditionally, these have constituted of an assembly that includes pair of swivel bodies with a thrust or roller bearing joining the two bosses to enable them to spin independently. Without a swivel, torsional forces could cause damage or failure to other parts of a climbing or rigging system by applying a too high torsional loading, or alternatively could allow a mass to spin uncontrollably. Existing swivels are intended to provide a 360° rotation action and are able to rotate clockwise or anti-clockwise for an indefinite number of rotations. 
       SUMMARY OF THE INVENTION 
       [0003]    The present inventors have realised that in some applications in which a user might require a connection between components in which in one instance allows 360° rotation (as with a conventional swivel), in another instance allows a limited rotation range such as 220°, and in another prevents rotation. At present, this would require the user to uncouple themselves from their system to remove the swivel to stop rotation or attach to a fixed object, and there is no current solution available to limit rotation to a predefined angle. 
         [0004]    An aim of this invention is to provide a connecting component that can operate as a conventional swivel, can allow limited rotation, and/or prevent rotation altogether, and which allows a user to easily select the required mode of operation. 
         [0005]    To this end, the present invention provides a swivel comprising:
       a. a first body component and a second body component;   b. an interconnection assembly for interconnecting the first body component and the second body component and to allow mutual rotation of the first and the second components about a swivel axis;   c. a rotation limiting arrangement which, in a release condition, allows free mutual rotation of the first and the second body components and in a locking condition restricts mutual rotation of the first and the second body components; and   d. a user control operable to selectively cause the rotation limiting arrangement to adopt one or other of a locking condition and the release condition.       
 
         [0010]    The invention is preferably characterised in that in the first locking condition, the rotation limiting arrangement substantially prevents mutual rotation of the first and the second body components and in the second locking condition, the rotation limiting arrangement, allows limited mutual rotation of the first and the second body components by less than 360°. 
         [0011]    When using a swivel embodying the invention, it is possible for the user to select whether the swivel should allow free rotational movement between components to which it is connected or should restrict such rotational movement simply by operating the user control. This avoids the necessity of dismantling and re-assembling a climbing or rigging system in order to achieve that change of function. 
         [0012]    Alternatively or additionally, in the rotation limiting arrangement, in the second locking condition, typically, the limited mutual rotation is in excess of 90°. More typically, the limited mutual rotation may be in excess of 200° or 220°. There are further possible alternative arrangements. For example, the second rotation limiting arrangement may allow mutual rotation of the first and the second body components in a plurality of separate rotational ranges. Alternatively or additionally, the limiting arrangement, in the first locking condition, may substantially prevent mutual rotation of the first and the second body components at one of several mutual rotational positions. In some embodiments, the rotation limiting arrangement can be assembled in a plurality of configurations to enable the position of mutual rotation at which rotation is limited to be adjusted. 
         [0013]    Typically, a locking component of the rotation limiting arrangement, in a locking condition (i.e., the first or second locking condition), obstructs free movement of a cooperating component of the interconnection assembly. The rotation limiting arrangement is typically fixed against rotation with respect to the first body component and the cooperating component of the interconnection assembly is fixed against rotation with the second body component. The cooperating component of the interconnection assembly may include one or more recessed regions, and when the rotation limiting arrangement is in a locking condition, permits the cooperating component to occupy only a rotary position in which a recessed region is proximal to the locking component. 
         [0014]    In typical embodiments, the locking component is moved by the user control to cause the rotation limiting arrangement to adopt one of a locking condition or the release condition. For instance, the locking component is rotated by the user control to cause the rotation limiting arrangement to adopt one of a locking condition and the release condition. In alternative arrangements, the locking component may be moved linearly. 
         [0015]    Movement of the locking component to the release position may cause a recess of the locking component to move to a position in which it is proximal to the cooperating component. Or, alternatively, movement of the locking component to a locking position may cause a projection of the locking component to move to a position in which it is proximal to the cooperating component. 
         [0016]    The interconnection assembly may include fasteners such as a nut and/or a bolt fixed for rotation with the first or the second body component. At least two of the nut, the bolt and the second body component are interconnected by interconnection formations, such as splines or mutually-engaging shaped formations, which could polygonal, e. g., square, triangular, hexagonal or star-shaped, amongst other possibilities. The interconnection assembly may also include a thrust bearing that permits rotational movement between the first body component and nut and bolt. Advantageously, a visible part of the nut or the bolt carries indicia that indicate to a user rotational positions of the first and second body components at which the rotation limiting component may adopt a locking condition. 
         [0017]    Each or either of the first and the second body components most typically includes a connection formation that allows it to be connected to another component. Such formations may include one or more of an eye, a hole, a boss, a shackle, a pulley or a carabiner, amongst many other alternative possibilities. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIGS. 1 and 2  are views in opposite directions of a swivel being a first embodiment of the invention in a first condition which permits free rotation; 
           [0019]      FIGS. 3 and 4  are exploded views corresponding to  FIGS. 1 and 2 ; 
           [0020]      FIGS. 5 and 6  show the swivel of  FIGS. 1 and 2  with a first body component shown semi-transparent and with the first body component omitted; 
           [0021]      FIG. 7  shows an application of the swivel of  FIGS. 1 to 4 ; 
           [0022]      FIGS. 8 and 9  show internal components of the swivel of  FIGS. 1 to 4  in the first condition of free 360° rotation; 
           [0023]      FIGS. 10 and 11  show internal components of the swivel of  FIGS. 1 to 4  in a second condition which permits limited rotation; 
           [0024]      FIGS. 12 and 13  show internal components of the swivel of  FIGS. 1 to 4  in a third condition which prevents rotation; 
           [0025]      FIG. 14  is a view equivalent to  FIG. 1  with the swivel in the third condition; 
           [0026]      FIG. 15  shows a second embodiment of the invention; 
           [0027]      FIG. 16  is an exploded view of a third embodiment of the invention; 
           [0028]      FIG. 17  is a cross-section of the embodiment of  FIG. 16 ; and 
           [0029]      FIG. 18  is a cross-section of splined components of the embodiment of  FIG. 16 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Embodiments of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings. 
         [0031]    With reference to  FIGS. 1 and 2 , a swivel embodying the invention comprises an eye  10  being a first body component and a boss  12  being a second body component. This configuration of swivel can be used to interconnect a rigid component  14  (shown in  FIG. 7 ) to which the boss  12  is attached, and a flexible component, such as a rope or webbing or a carabiner to which the eye  10  is attached. 
         [0032]    The eye  10 , a unitary metal component, comprises a loop that extends from a connection region. In the connection region, the eye  10  includes a bearing chamber  20  that is a cylindrical void centred on a swivel axis A of the swivel and opening in a direction facing away from the boss  12 . The eye  10  has a flat, annular bearing surface that faces towards the boss  12  and extends in a plane normal to the axis A. A circular aperture extends through the bearing surface centred on the axis A, passing through a base surface of the bearing chamber  20 . The aperture is of diameter less than that of the bearing chamber. A transverse cylindrical bore  22  extends through the eye  10  normal to the axis A, to partly intersect with the bearing chamber  20 . 
         [0033]    The boss  12 , a unitary metal component, is a body with an axial through-bore. The boss  12  has a short key  32  that projects from the body, into which the bore extends, and which is surrounded by an annular bearing surface on which is carried a washer  34 . The key  32  has a cylindrical outer surface and an axial bore of square section. The bore has a step such that a portion remote from the key  32  is of greater diameter than a portion at the key  32 . The body also has a transverse bore  36  that is used to connect it with another component. 
         [0034]    In the assembled swivel, the eye  10  and the boss  12  are disposed such that their bearing surfaces face one another and are in contact with the washer  34 , and the key  32  of the boss projects into the circular aperture of the eye  10 , wherein it is a close sliding fit. 
         [0035]    A thrust bearing  40  is located within the bearing chamber  20 , a first race of the thrust bearing being carried on the base surface of the bearing chamber  20 . An axle nut  42  is also located within the bearing chamber  20 . The axle nut  42  has an axial threaded bore and an annular bearing surface which is in contact with a second race of the thrust bearing  40 . A spigot  44  of square section projects centrally from the bearing surface of the axle nut  42  and extends into the bore of the key  32 , wherein it is a close fit. Thus, rotation of the axle nut  42  with respect to the boss  12  is prevented. An axle bolt  48  has a head and an externally threaded shank. The head is located against the step within the bore of the boss  12 , and the shank extends through the key  32  to make threaded connection with the bore of the axle nut  42 . A grub screw  46  is tightened in a tapped bore in the boss  12  to make contact with the head of the axle bolt  48  to prevent rotation of the axle bolt  48  with respect to the boss  12  and the axle nut  42 . 
         [0036]    It will be seen that the arrangement described above is essentially that of a conventional swivel. The thrust bearing  40  and the bearing surfaces allow the eye  10  to rotate about the axis A with respect to the boss  12 , and the axle nut  42  and the axle bolt  48  prevent separation of the eye  10  and the boss  12 . 
         [0037]    The axle nut  42  has a cylindrical outer surface within which a first and a second channel  50 ,  52 , each being of arcuate cross-section, are formed. The first channel  50  extends peripherally around the nut  42  for approximately 220° and has a base that, for most of its length, follows an arcuate path within the circular cross-section of the nut  42 . The second channel  52  extends peripherally around the nut  42  for approximately 60° and has a base that follows a straight chord that within the circular cross-section of the nut  42 . The channels  50 ,  52  are formed on the nut  42  at a position such that the nut can be rotated to position the channels adjacent to the place at which the transverse bore  22  of the eye  10  intersects the bearing chamber  20 . 
         [0038]    A locking shaft  58  is located within the transverse bore  22 . The locking shaft  58  has a cylindrical shank  60 , carrying a head  62  at one of its ends and having an axial tapped hole extending into an opposite end portion. An end portion  64  of the shank  60  surrounding the tapped hole is formed with a square cross-section. This allows the locking shaft  58  to be installed in the transverse bore  22  by inserting the tapped end of the shank  60  into the bore until the head  62  makes contact with the eye  10 , whereupon further movement is prevented. An operating lever  66  is secured to the locking shaft  58  by a cap screw  68 , the operating lever  66  having a recess into which the end portion of square cross-section is received. The presence of the operating lever  66  prevents removal of the locking shaft  58  from the bore  22  and also allows a user to rotate the locking shaft  58  within the bore  22 . 
         [0039]    A channel  70  is formed in the shank  60  of the locking shaft  58 . The channel  70  is arcuate in section and is centred on a locus that, when the shaft is suitably rotated, as shown in  FIG. 8 , is coincident with the swivel axis A. Close to the head  62  of the locking shaft  58 , two circumferentially-spaced recesses  72  are formed in the shank  60 . 
         [0040]    Within the eye  10 , a ball bearing  74  is pressed by a spring against the shank  60 , such that the ball bearing  74  can enter one or other recess  72  to provide a detent at one of two rotary positions of the locking shaft  58 , which will be referred to as the locking and the release positions. This is achieved by moving the operating lever  66  between the positions shown in  FIGS. 1 and 14 . At the release position, the channel  70  faces directly towards the axle nut  42 , as shown in  FIG. 8 . At the locking position, a full-radius portion of the shank  60  faces towards the axle nut  42 , as shown in  FIGS. 10 and 12 . 
         [0041]    In the release position, there is no interference between the locking shaft  58  and the axle nut  42  which allows free rotation between the eye  10  and the boss  12 . However, in the locking position, the axle nut may only adopt a rotational position that causes one or other channel  50 ,  52  to face the locking shaft  58 . Any attempt to rotate the axle nut to a position in which a part that has no recess faces towards the locking shaft  58  is prevented as the locking shaft  58  comes into contact with the end of the channel  50 ,  52 . It will also be seen that the locking shaft  58  cannot be rotated into the locking position unless there is one or other channel  50 ,  52  adjacent to it. 
         [0042]    This provides three conditions of operation:
       a first condition (the release condition), shown in  FIGS. 8 and 9 , in which the locking shaft  58  is in the release position, in which the eye  10  and the boss  12  can rotate freely about the swivel axis A;   a second condition (the first locking condition), shown in  FIGS. 10 and 11 , in which the locking shaft  58  is in the locking position and is adjacent to the first channel  50 , in which the eye  10  can rotate with respect to the boss  12  about an angle that is restricted by the circumferential length of the first channel (approximately 220° in this embodiment); and   a third condition (the second locking condition), shown in  FIGS. 12 and 13  in which the locking shaft  58  is in the locking position and is adjacent to the second channel  52 , in which the rotation of the eye  10  with respect to the boss  12  is substantially prevented.       
 
         [0046]    It will be noted that the position and depth of the second channel  52  is chosen such that the shank  60  of the locking shaft  58  closely approaches its base to minimise possible rotational movement of the axle nut  42 . 
         [0047]    For the assistance of a user, several indicia may be provided on the swivel. Locked and unlocked symbols  80 ,  82  indicate to a user the positions of the operating lever  66  corresponding to the locking and release positions of the locking shaft  58 . A visible outer surface of the axle nut  42  has visible indicia  84 ,  86  and an associated pointer  88  is carried on the eye  10 . Only when the eye  10  is rotated to a position in which the pointer  88  is adjacent to one of the indicia  84 ,  86 , may the operating lever  66  be moved to the locking position. The indicia  84 ,  86  are formed to indicate symbolically the amount of rotation provided by the second condition of operation or that in the third condition, no rotation will be possible. 
         [0048]    In the embodiment of  FIG. 15 , the second body component is an eye  112 , but the swivel is otherwise identical in construction and operation to that described above. This is just one example of many possible alternative embodiments of the invention. 
         [0049]    In modifications to this embodiment, the second channel  52  may be omitted, which allows the circumferential extent of the first channel to be increased. Such an embodiment can adopt only the first and second conditions. Alternatively, several channels similar to the second channel  52  may be provided. Such an embodiment can adopt only the first and third conditions, but the swivel can be locked in the third condition with the first and the second body components at several different positions of mutual rotation. Further combinations of grooves of both types may be provided to implement different patterns of rotation. 
         [0050]    Additional versatility in the positions at which rotation of the body components  10 ,  12  are limited can be provided by a modification to the key  32  and the spigot  44 . In the above-described embodiment, these are of square section, but the functional requirement is that they couple together for rotation when the spigot  44  is inserted into the key  32 . The square arrangement allows the components to be connected together in four distinct orientations, which means that the first and second body components  10  can adopt one of four distinct orientations when in the third condition. If, instead of being square, the spigot  44  and the key  32  are splined, then a greater range of orientations between the components can be adopted, and depending on the required use/orientation requirements of the swivel i.e. the positions of locked rotation and limited rotation are not limited to the orientations shown in the figures. Thus, the rotation limiting arrangement can be assembled in a plurality of configurations to enable the position of mutual rotation at which rotation is limited to be adjusted. 
         [0051]    It will be seen that, when the rotation of the body components  10 ,  12  is limited, then rotation is prevented by a torque that arises between the axle nut  42  and the boss  12 , rotational coupling being achieved by interaction of the spigot  44  and the key  32 . 
         [0052]    In the embodiment shown in  FIG. 16 , the boss  212  has an externally splined spigot  232  that engages with a splined bore  244  in the axle nut  242 . The axle nut  242  is received in a chamber  220  of the eye  210 . The axle bolt  248  has a head that abuts the axle nut  242 , and a threaded shaft that passes through the axle nut  242  to be received in a threaded bore in the boss  212 . A circumferential groove  246  is formed close to a free end of the threaded shaft. Grub screws  248  are inserted into bores in the boss  212  to engage with the groove  246  and thereby prevent removal of the axle bolt  248  from the boss  212 . 
         [0053]    The splines may be equally-spaced, in which case the boss  212  and the axle nut  242  may be interconnected, as described above, in multiple relative rotational positions. Alternatively, they may be configured to permit interconnection in a unique relative rotational position, for example, by omission of one spline in each component  212 ,  242 , as shown in  FIG. 18 .