Patent Publication Number: US-11376180-B2

Title: Gates for overhead lifting rails

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure claims priority to European Patent Application No. 16201815.4 filed 1 Dec. 2016 and entitled “Gates For Overhead Lifting Rails,” the entirety of which is incorporated by reference herein. 
     BACKGROUND 
     Field 
     The present disclosure relates to gates and gate systems for overhead lifting rails, and in particular to gates and gate systems for traverse rails for use in healthcare facilities for lifting and moving patients. 
     Technical Background 
     Caregivers may need to move patients from one location to another in a care facility. Sometimes, caregivers use lift systems to assist with lifting and/or moving a patient. The lift systems generally comprise overhead rails, both stationary and movable, and lifting carriages. While various lift systems and ancillary components have been developed, there is still room for improvement. In particular, there is a need to provide improved gates to prevent lifting carriages from leaving the rail, for example when so-called traverse rails, which are movable relative to the fixed, primary, rails are moved from a first primary rail to a second primary rail. Traverse rails may also combine with other traverse rails, and the requirement for providing improved gates to prevent lifting carriages from leaving the rail remains. There is also a need to improve the user experience, reduce wear and tear, and reduce the installation complexity. 
     SUMMARY 
     According to one aspect of the present disclosure, there is provided a gate for an overhead lifting rail. The gate comprises: a rail portion for suspending a lifting carriage; a locking pin movable between a first position and a second position, wherein in the first position the lifting carriage is blocked from traversing the rail portion, and in the second position the lifting carriage is able to traverse the rail portion; a locking pin magnetic portion coupled to the locking pin; and a gate magnetic portion fixed relative to the rail portion. At least one of the locking pin magnetic portion and the gate magnetic portion is a permanent magnet. Upon the gate engaging with a corresponding second gate also comprising a rail portion, a locking pin, a locking pin magnetic portion and a gate magnetic portion, the locking pin magnetic portion of the gate engages with the gate magnetic portion of the second gate such that, upon the rail portion of the gate being substantially aligned with the rail portion of the second gate, the locking pin is moved from the first position to the second position. 
     The use of magnets to move the locking pin removes the requirement for physical interaction between the gates. Such an arrangement not only reduces the wear on the gate components, but also increases the installation tolerances between the gates. This is because the components engage via magnetic fields, and so with no particular requirement for physical engagement, wear is reduced and the distance between the gates becomes of lesser importance. In addition, the noise associated with gates engaging with each other is reduced, which can be an important consideration in the healthcare facility environment. 
     According to a second aspect of the present disclosure, there is provided a gate system for an overhead lifting rail system. The gate system comprises: a first gate, and a second gate, each gate comprising: a rail portion for suspending a lifting carriage; a locking pin movable between a first position and a second position, wherein in the first position the lifting carriage is blocked from traversing the rail portion, and in the second position the lifting carriage is able to traverse the rail portion; a locking pin magnetic portion coupled to the locking pin; and a gate magnetic portion fixed relative to the rail portion. At least one of the locking pin magnetic portion and the gate magnetic portion is a permanent magnet. Upon the first gate engaging with the second gate, the locking pin magnetic portion of the first gate engages with the gate magnetic portion of the second gate, and the locking pin of the second gate engages with the gate magnetic portion of the first gate such that, upon the rail portions being substantially aligned, each locking pin is moved from the first position to the second position. 
     As discussed above, the use of magnets to move the locking pin removes the requirement for physical interaction between the gates. Such an arrangement not only reduces the wear on the gate components, but also increases the installation tolerances between the gates. This is because the components engage via magnetic fields, and so with no particular requirement for physical engagement, wear is reduced and the distance between the gates becomes of lesser importance. In addition, the noise associated with gates engaging with each other is reduced, which can be an important consideration in the healthcare facility environment. 
     As used herein the term “overhead lifting rail system” refers to a system of fixed and movable rails, mounted overhead either to the ceiling or between walls. The movable, or traverse rails, enables patient transfers perpendicular to the longitudinal length of the rail, that is to say in the x-y directions. Fixed rails are used where only movement in a single direction is required, for example over a patient bed, in bathrooms, or in corridors of the healthcare facility. The present gate system enables the two types of rail to be engaged to form a continuous rail, thus enabling the lifting carriage to move from the fixed rail to a traverse rail, or vice versa. Other types of rail components are also envisaged, including turntable switches, where fixed rails are coupled together with a rotatable turntable for selecting the desired pathway for the lifting carriage, and side rail switches for selecting between two fixed rails. 
     As used herein, the terms “vertical”, “horizontal”, “above”, “below”, “top”, and “bottom”, refer to the directions and relative positions of components associated with the gate system when mounted to, and supported by, a ceiling or between two walls. 
     As will now be appreciated, the gate system of the present disclosure enables the safe coupling of two rail portions of an overhead rail system, where at least one rail portion is movable substantially perpendicular to the longitudinal length of the other. 
     To enable the first gate and the second gate to engage, the locking pin magnetic portion of the first gate may be provided at a first vertical distance from the rail portion, and the locking pin magnetic portion of the second gate may be provided at a second vertical distance from the rail portion. In this way, as the first gate engages with the second gate, there is no interference, physical or magnetic, between the locking pin magnetic portions. The gate magnetic portion of the first gate is correspondingly provided at the second vertical distance from the rail portion, and the gate magnetic portion of the second gate is correspondingly provided at the first vertical distance from the rail portion. 
     Each gate magnetic portion may be configured to magnetically attract the respective locking pin magnetic portion, or vice versa in dependence on which magnetic portion is a permanent magnet. Each gate magnetic portion may be provided substantially at a centre line of the respective gate. Various configurations of magnetic portions are envisaged. The gate magnetic portion may be a permanent magnet, the locking pin magnetic portion being formed of a ferromagnetic material. Alternatively, the gate magnetic portion is a permanent magnet, the locking pin magnetic portion being a permanent magnet. In a further alternative, the gate magnetic portion is formed of a ferromagnetic material, the locking pin magnet being a permanent magnet. 
     Optionally, each locking pin magnetic portion protrudes from the respective gate, and each gate magnetic portion is provided in a recessed channel in the respective gate, the recessed channel extending from a first side to a second side of the gate. The recessed channels may be provided in the vertical opposing faces of the gates. An edge of each recessed channel may comprise a cam profile configured to engage the respective locking pin magnetic portion and move the locking pin from the second position to the first position upon the first gate and the second gate being disengaged. The edge of each recessed channel comprising the cam profile may be the top edge of the channel. The cam profile may be substantially symmetrical about a centre line of the gate. In this way, the gates may be engaged from either transverse direction. The bottom edge of each recessed channel may be planar. 
     Where the recessed channels comprise a cam profile, each gate magnetic portion may have a shape which conforms to the cam profile. That is to say, the gate magnetic portion is shaped to fit within the recess, and follow the upper, cammed, profile of the recessed. As will be appreciated, the gate magnetic portion therefore forms the cam profile which is followed by the locking pin magnetic portion to move the locking pin from the first position to the second position. 
     In embodiments of the present disclosure, there is no physical interaction between the locking pin magnetic portion and either the edges of the recess or the gate magnetic portion. In this way, the gate system is less susceptible to misalignment, and has reduced wear on the components. 
     Each locking pin may be slidably movable from the first position to the second position. In the first position, a distal end of the locking pin may protrude through a hole in the rail portion to block the lifting carriage from traversing the rail portion. In the second position, the distal end of the locking pin may not protrude through the hole in the rail portion. 
     The locking pin magnetic portion may be displaced from the longitudinal axis of the locking pin in a direction towards an engagement face of the gate. That is to say, in a direction towards the other gate when the gates are engaged. The locking pin magnetic portion may be coupled to, and displaced from, the locking pin by a shaft portion which extends substantially perpendicularly from longitudinal axis of the locking pin. The shaft portion may be coupled to the locking pin by a threaded connection, or by welding, or by any other suitable coupling such as brazing or adhesion. 
     Each gate may comprise a bearing insert for supporting the locking pin, and enabling the locking pin to slide along its longitudinal axis. Where the locking pin magnetic portion is coupled to the locking pin by a shaft portion, the bearing insert may have a slot for receiving the shaft portion. The bearing insert may be formed of a polymer, such as a phenolic resin, nylon, PTFE, or polyethylene, in particular Ultrahigh-molecular weight polyethylene (UHMWPE). In embodiments, the bearing insert is formed of polyoxymethylene (POM), also known as acetal. 
     The locking pin may be formed of metal, in particular steel, such as stainless steel. 
     In embodiments, each gate magnetic portion comprises a first gate magnet, and a second gate magnet, the first gate magnet being configured to magnetically attract the respective locking pin magnetic portion, and the second gate magnet being configured to magnetically repel the locking pin magnetic portion towards the first gate magnet. The first gate magnet and the second gate magnet may be provided substantially on the centre line of the gate. In embodiments, the first gate magnet and the second gate magnet may be permanent magnets. The locking pin magnetic portion may comprise a first locking pin magnet, and a second locking pin magnet. The first locking pin magnet may be configured to be magnetically attracted to the first gate magnet, the second locking pin magnet being configured to be magnetically repelled from the second gate magnet. 
     In a further alternative, the gate comprises only a second gate magnet, the second gate magnet being configured to magnetically repel the locking pin magnetic portion. In this alternative, the locking pin magnetic portion comprises a permanent magnet configured to magnetically repel the second gate magnet. In this way, the locking pin is moved from the first position to the second position. 
     Where each of the first gate and the second gate comprises a recessed channel, the first gate magnet may be provided in the top edge of the recessed channel, and the second gate magnet may be provided in the bottom edge of the recessed channel. As described above, the locking pin magnetic portion may be coupled to, and displaced from, the locking pin by a shaft portion which extends substantially perpendicularly from longitudinal axis of the locking pin. The shaft portion may be coupled to the locking pin by a threaded connection, or by welding, or by any other suitable coupling such as brazing or adhesion. In this embodiment, the locking pin magnetic portion, and the first and second gate magnets are configured to attract and repel in a substantially vertical direction. As will now be appreciated, as the first gate is engaged with the second gate the locking pin magnetic portion approaches the second gate magnet, and is repelled from the second gate magnet towards the first gate magnet which attracts the locking pin magnetic portion, thus moving the locking pin from the first position to the second position. In this way, the locking pin magnetic portion moves in free space, for example within the recessed channel where provided, and does not physically engage with the other of the gates until it is repelled by the second gate magnet and is held against the first gate magnet by magnetic attraction. 
     The first gate may further comprise at least one alignment magnet, and the second gate may comprises at least one corresponding alignment magnet, the alignment magnets being configured to magnetically attract each other. In this way, the gates, and hence rail portions, are held in alignment by the alignment magnets, and therefore the gates will not move apart unless forced to by an operator. When the alignment magnets are engaged with each other, the locking pin magnet and the gate magnet are also aligned. 
     The magnets may be permanent magnets, and may be rare-earth magnets such as neodymium magnets. Neodymium magnets are an alloy of Neodymium, Iron, and Boron. 
     The rail portion may be formed of a C-shaped channel arranged such that, when the gate is supported from a ceiling, its open side is at the bottom. In this configuration, the rail portion comprises a through hole, aligned with the locking pin, for enabling the locking pin to move to the first position and block the lifting carriage from traversing the rail portion. 
     The rail portion may be formed integrally with a main body portion of the gate. A face of the main body portion, opposite the face comprising the gate magnetic portion and locking pin magnetic portion, may comprise one or more recesses configured to receive an overhead lifting rail. The main body portion may comprise one or more recesses for receiving different sized overhead lifting rails. For example the main body portion may comprise one or more recesses for receiving standard overhead rails having a height of 70 mm, or 100 mm, or 140 mm. 
     The main body of the gate may be formed of metal, in particular aluminium. The main body may be formed by casting. 
     The gate system may be configured such that the distance between the gate magnetic portion and the locking pin magnetic portion is between about 1 mm, and about 10 mm, or even between about 2 mm and about 5 mm. The system may further include an installation tool for setting the distance between the first gate and the second gate during installation. 
     Each gate may be configured to be mountable to a ceiling, either directly or via a mounting arm or the like. Mounting arms may be conventionally referred to as “pendants” and form a part of conventional ceiling mounted lifting systems. Alternatively, or in addition, each gate may be suspended directly from a rail, which in turn is mounted to a ceiling, or to a wall. 
     According to a further aspect of the present disclosure, there is provided a gate system for an overhead lifting rail system. The gate system comprises: a first gate comprising: a rail portion for supporting a lifting carriage; and a bridging element pivotally coupled adjacent a proximal end to the rail portion; and a second gate comprising: a rail portion for suspending a lifting carriage; and a bridging element support portion. Upon the first gate engaging with the second gate, a distal end of the bridging element of the first gate engages with the bridging element support portion of the second gate to form a bridge between the first gate and the second gate. The distal end of the bridging element and the bridging element support portion are configured such that the ends of the bridging element are substantially aligned with the respective ends of the rail portions of the first and second gates. 
     When operating an overhead rail system problems may arise when transitioning from a traverse rail to a fixed rail because of deflections of the traverse rail under load which cause a vertical misalignment between the traverse rail and the fixed rail. Although conventional systems allow the misalignment to be overcome using additional force, the result is an uncomfortable ride for the patient being lifted, and additional wear on the system components. 
     The present disclosure mitigates these disadvantages by providing a bridging element having a distal end which engages with the gate of the fixed rail, and pivots at a proximal end to form a bridge between the traverse rail and the fixed rail. 
     In embodiments, the bridging element is pivotally coupled at a position substantially aligned with a lifting carriage support surface of the rail portion. In this way, the bridging element is pivotal in such a way that ensures the lifting carriage support surface of the bridging element is always substantially aligned with the lifting carriage support surface of the rail portion. 
     The pivot may be formed of a first shaft and a second shaft, each shaft disposed on opposite sides of the rail portion. Corresponding plain bearings are provided in the first gate configured to receive the first shaft and the second shaft. The first and second shaft portions and plain bearings may be coated. The coating may be formed by galvanization, or by electropolishing. 
     Each end of the bridging element support portion may comprise a tapered portion. The tapered portions may be configured to enable the bridging element to engage with the support portion when there is a vertical misalignment between the first gate and the second gate. 
     In embodiments, the bridging element support portion is formed of an edge of a recessed channel extending from a first side to a second side of the gate. Where the bridging element support portion comprises tapered end portions, the tapered portions may be provided on the bottom edge of the recess. The top edge of the recess may also comprise upper tapered end portions. 
     The tapered portions may be configured such that the distance from the bottom of the gate to the end of the tapered portion proximal to the support portion is between about 3 mm and about 15 mm greater than the distance from the bottom of the gate to the distal end of the tapered portion. 
     The second end of the bridging element configured to engage with the support portion may comprise a cantilever vertically offset from the bridging element. The cantilever may be L-shaped. The end of the cantilever configured to engage with the support portion may comprise a coating, such as a low friction coating. For example, the low friction coating may be formed of a polymer, such as a phenolic resin, nylon, PTFE, or polyethylene, in particular Ultrahigh-molecular weight polyethylene (UHMWPE). A particularly effective coating may be PTFE. Providing a coating reduces the friction between the bridging element and the bridging element support portion and therefore may reduce noise and wear. 
     The bridging element, and gate, may be configured such that the distal end of the bridging element is movable between about −3 mm and about 10 mm on pivoting from a position substantially planar with the rail portion. Movement upwards is defined as positive, and movement downwards is considered negative. Therefore, −3 mm is equivalent to the distal end moving 3 mm down, and 10 mm is equivalent to the distal end moving 10 mm up. In embodiments, the bridging element, and gate, are configured such that the distal end of the bridging element is movable between about −3 mm and about 5 mm, or even between about −3 mm and about 5 mm, on pivoting from a position substantially planar with the rail portion. A stop may be provided on the bridging element to prevent further pivotal movement, or alternatively the bridging element may be prevented from further pivotal movement by abutting a portion of the gate. 
     The features of the gate and gate system of the first and second aspects of the present disclosure may be combined with the further aspect of the present disclosure. As such, the first gate and the second gate of the gate system according to the further aspect of the present disclosure may each further comprise: a locking pin movable between a first position and a second position, wherein in the first position the lifting carriage is blocked from traversing the rail portion, and in the second position the lifting carriage is able to traverse the rail portion; a locking pin magnetic portion coupled to the locking pin; and a gate magnetic portion fixed relative to the rail portion. At least one of the locking pin magnetic portion and the gate magnetic portion is a permanent magnet. Upon the first gate engaging with the second gate the locking pin magnetic portion of the first gate engages with the gate magnetic portion of the second gate, and vice versa, such that, upon the rail portion of the first gate being substantially aligned with the rail portion of the second gate, each locking pin is moved from the first position to the second position. 
     As will be appreciated, all of the features of one aspect of the embodiments described above may be combined in any suitable combination with the features of the further aspect of the present disclosure. 
     As used herein, the terms “may” and “optionally” refer to features of the present disclosure which are not essential, but which may be combined with the claimed subject matter to form various embodiments of the disclosure. 
     Furthermore, any feature in one aspect of the disclosure may be applied to other aspects of the disclosure, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination. 
     It should also be appreciated that particular combinations of the various features described and defined in any aspects of the disclosure can be implemented and/or supplied and/or used independently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The gates and gate systems will be further described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1( a )  shows a locking gate system for an overhead lifting rail system; 
         FIG. 1( b )  shows another portion of the locking gate system for an overhead lifting rail system of  FIG. 1( a ) ; 
         FIG. 2  shows a cut-away view of the gate system shown in  FIGS. 1( a ) and 1( b ) ; 
         FIG. 3( a )  shows a further cut-away view of the gate system shown in  FIGS. 1( a ) and 1( b ) ; 
         FIG. 3( b )  is one example of a locking pin for use in the gate system shown in  FIGS. 1( a ) and 1( b ) ; 
         FIG. 3( c )  is one example of a locking pin for use in the gate system shown in  FIGS. 1( a ) and 1( b ) ; 
         FIG. 3( d )  is one example of a locking pin for use in the gate system shown in  FIGS. 1( a ) and 1( b ) ; 
         FIG. 4( a )  shows an alternative embodiment of a locking gate system for an overhead lifting rail system; 
         FIG. 4( b )  shows another portion of the locking gate system for an overhead lifting rail system of  FIG. 4( a )   
         FIG. 5  shows an exploded view of a gate as shown in  FIG. 4( a ) ; 
         FIG. 6  shows an alternative view of the gate system shown in  FIGS. 4( a ) and 4( b ) ; 
         FIG. 7( a )  shows a bridging gate system for an overhead lifting rail system; 
         FIG. 7( b )  shows another portion of the bridging gate system for the overhead lifting rail system of  FIG. 7( a ) ; 
         FIG. 8  shows a cut-away view of an alternative embodiment of a bridging gate; 
         FIG. 9( a )  shows an alternative embodiment of a bridging gate for a bridging gate system comprising the bridging gate shown in  FIG. 8 ; 
         FIG. 9( b )  shows an alternative view of the gate system shown in  FIG. 8 ; 
         FIG. 10  shows a cut-away view of the gate system of the gate system shown in  FIG. 9 ; and 
         FIG. 11  shows an end view of a gate. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates generally to overhead lifting systems for lifting and moving patients in healthcare facilities. Although it will be appreciated that the system has other uses. Such overhead lifting systems comprise fixed overhead rails, and moving, traverse, rails, and lifting carriages which run along the rails and have lifting and lowering mechanisms. The rails are generally supported by a ceiling or between two walls. The traverse rails are themselves mounted to rails, which generally run perpendicularly to enable the traverse rails to be moved between different fixed rail portions. The present disclosure is concerned with the gates which enable the lifting carriage to pass safely from a fixed rail to a traverse rail. 
       FIGS. 1( a ) and 1( b )  show an example of one such gate system, which is a locking gate system, comprising a first gate  100  and a second gate  102 . In this example, the gate  100  is coupled to a traverse rail (not shown), and the gate  102  is coupled to a fixed rail  104 . For ease of reference, the faces  106  and  108  of the gates which engage with each other are shown facing away from each other, but as will be appreciated, in use, the faces  106  and  108  face each other. The first gate  100  and the second gate  102  each comprise, inter alia, a rail portion  110 ,  112 , a locking pin  114 ,  116 , a locking pin magnet  118 ,  120 , a first gate magnet  122 ,  124 , a second gate magnet  126 ,  128 , and a recessed channel  130 ,  132 . The first gate  100  and second gate  102  each further comprise alignment magnets  134   a ,  134   b ,  134   c ,  134   d ,  136   a ,  136   b ,  136   c ,  136   d  respectively provided at the corners of the engaging faces  106  and  108 . The alignment magnets  134  are configured to be magnetically attracted to the alignment magnets  136 . That is to say, the north pole of the magnets  134  faces outwards, and the south pole of the magnets  136  faces outwards (or vice versa). 
     The locking pin magnet  118 ,  120  is coupled perpendicularly to the respective locking pin  114 ,  116  by a shaft (not shown). The locking pin  114 ,  116  is vertically slidable within a bearing  138 ,  140  to enable the pin to slide from a first position, as shown in  FIG. 1 , to a second position. As the locking pin  114 ,  116  slides from the first position to the second position, the locking pin magnet shaft slides within the slot  142 ,  144 . 
     In the first position, the locking pin  114 ,  116  blocks the rail portion  110 ,  112  so that a lifting carriage is blocked from traversing the respective rail portion. In this way, when the rail portion  110  is not aligned with the rail portion  112  the locking pins  114 ,  116  prevent the lifting carriage from rolling off the end of the rail. 
     As can be seen, each recessed channel  130  and  132  has an upper edge with a cammed profile. The lower edge of each recessed channel is substantially planar, but is shown having tapered end portions. 
     The second gate  102  is mounted to a ceiling (not shown) by the mounting support  146 . The first gate  100  is mounted to a traverse rail (not shown), which in turn is mounted to the ceiling by further guide rails which enable movement of the traverse rail perpendicularly to the longitudinal length of the rail. 
     In this example, the main body of each gate  100 ,  102  is formed of aluminium to reduce the total weight as compared to, for example, steel, and to reduce or eliminate the magnetic interference between the main body and the gate magnet and locking pin magnet. The locking pins  114 ,  116 , and shaft portions for coupling the locking pin magnets to the locking pins are formed of steel. The magnets are formed of an alloy of Neodymium, Iron, and Boron, which are commonly known simply as Neodymium magnets. The bearings  138 ,  140  are formed of polyoxymethylene (POM). 
       FIGS. 2 and 3  show the gates  100  and  102  in the process of engaging with each other, and the respective locking pins being moved from the first position to the second position. It is noted that throughout the figures, like reference numerals refer to like features. 
     In  FIG. 2 , the gate  100 , attached to the traverse rail  200  movable in the direction X, is shown at the initial stage of engagement with the gate  102  attached to the fixed rail  104 . As can be seen, the locking pin  114  is in the first position, and would prevent a lifting carriage from traversing the rail portion  110  in direction Y. The locking pin magnet  118  is shown at a first end of the recessed channel  132  of gate  102 . The first gate magnet  122  and the second gate magnet  126  of the first gate  100  are also shown. As can be seen, the first gate magnet  122  is recessed into the upper edge of the recessed channel to provide a smooth surface. Likewise, the second gate magnet  126  is recessed into the lower edge of the recessed channel. It is noted that the shaft portion  202  is shown which couples the locking pin magnet  118  to the locking pin  114 . 
     Upon the first gate  100  being traversed into alignment with the second gate  102 , the second gate magnet  126  of the first gate  100  repels the locking pin magnet  120  of the second gate  102 , and the second gate magnet  128  of the second gate  102  repels the locking pin magnet  118  of the first gate  100 . The locking pins  114  and  116  are therefore repelled away from the first position towards the second position. In addition, the first gate magnet  122  of the first gate  100  attracts the locking pin magnet  120  of the second gate  102 , and the first gate magnet  124  of the second gate  102  attracts the locking pin magnet  118  of the first gate  100 . The locking pins  114  and  116  are therefore also attracted towards the second position, and, while the gates  100  and  102  are aligned, the locking pins  114  and  116  are maintained in the second position by the first gate magnets  122  and  124 . 
     In this aligned configuration, the alignment magnets  134  and  136  maintain the gates together until a user, such as a healthcare professional, moves the traverse rail. 
     With the gates aligned, and the locking pins in the second position, a lifting carriage is free to traverse the rails from the fixed rail to the traverse rail or vice versa in the Y direction. This is because a substantial portion of a lifting carriage of this type runs within the rails, being supported by the support surface of the rails  300 , as shown in  FIG. 3( a ) . 
       FIGS. 3( b ), 3( c ) and 3( d )  each show a variant of a locking pin configured for use in a gate system as described with reference to  FIGS. 1, 2 and 3 ( a ). 
       FIG. 3( b )  shows that locking pin  116 , as described above. The locking pin magnet  120  is coupled to the locking pin  116  by shaft portion  302 . The locking pin magnet  120 , is formed of a first locking pin magnet  304  and a second locking pin magnet  306 . The first locking pin magnet is configured to be magnetically attracted to the first gate magnet  122 , and the second locking pin magnet is configured to the magnetically repelled from the second gate magnet  126 . 
       FIG. 3( c )  shows a variant of a locking pin  308 , which comprises a locking pin magnet  310  coupled to the locking pin  308  by shaft portion  312 , and a locking pin magnet  314 . In this example, the locking pin magnet  310  is configured to be magnetically attracted to gate magnet  122 . A second locking pin magnet is not provided, and as such the second gate magnet  126  is also not provided. 
       FIG. 3( d )  shows a variant of a locking pin  316 , which comprises a locking pin magnetic portion  318  coupled to the locking pin  316  by a shaft portion  320 . The locking pin magnetic portion  318  is formed of a ferromagnetic material, such as steel. As such, the first gate magnet  122  is configured to magnetically attract the ferromagnetic locking pin magnetic portion  318 . 
     As will be appreciated, equivalent variants of locking pin  114  to the variants of locking pin  116  shown in  FIGS. 3( b ), 3( c ) and 3( d )  are envisaged. 
     As the first gate  100  is traversed away from the alignment configuration, the locking pin magnets  118  and  120  move away from the first gate magnets  122  and  124 , and so the locking pin, under gravity, moves back from the second position to the first position. In addition, the upper edge of the recessed channel having a cammed profile can apply a direct force to the locking pin magnets to assist the movement of the locking pins from the second position to the first position. As will be appreciated, this ensures that if the locking pins become stuck in the unlocked, second position, for any reason, the gate system fails safe because the locking pin magnets will engage with the upper edge of the recess and prevent the gates from being separated. By “fail safe”, it is meant that in no situation is it possible for the gates to be in a configuration where the locking pins are in the unlocked position, and the lifting carriage can fall from the end of the rail. 
       FIGS. 4( a ) and 5( b )  show an alternative example of a locking gate system. The example shown in  FIGS. 4( a ) and 4( b )  comprises a first gate  400  and a second gate  402 , and is of generally similar construction to the example described above with reference to  FIGS. 1 to 3 . In this example, the gate  400  is coupled to a traverse rail (not shown), and the gate  402  is coupled to a fixed rail (not shown). For ease of reference, the faces  404  and  406  of the gates which engage with each other are shown facing away from each other, but as will be appreciated, in use, the faces  404  and  406  face each other. The first gate  400  and the second gate  402  each comprise, inter alia, a rail portion  408 ,  410 , a locking pin  412 , a locking pin magnet  414 ,  416 , a gate magnet  418 ,  420 , and a recessed channel  422 ,  424 . The first gate  400  and second gate  402  each further comprise alignment magnets  426   a ,  426   b ,  426   c ,  426   d ,  428   a ,  428   b ,  428   c ,  428   d  respectively provided at the corners of the engaging faces  404  and  406 . The alignment magnets  426  are configured to be magnetically attracted to the alignment magnets  428 . That is to say, the north pole of the magnets  426  faces outwards, and the south pole of the magnets  428  faces outwards (or vice versa). 
     The locking pin magnet  414 ,  416  is coupled perpendicularly to the respective locking pin by a shaft (not shown). The locking pin is vertically slidable within a bearing to enable the pin to slide from a first position, as shown in  FIG. 4( a ) , to a second position, as shown in  FIG. 4( b ) . As the locking pin slides from the first position to the second position, the locking pin magnet shaft slides within the slot  430 ,  432 . 
     In the first position, the locking pin blocks the rail portion  408 ,  410  so that a lifting carriage is blocked from traversing the respective rail portion. In this way, when the rail portion  408  is not aligned with the rail portion  410  the locking pins prevent the lifting carriage from rolling off the end of the rail. 
     As can be seen, each recessed channel  422  and  424  has an upper edge with a cammed profile. The lower edge of each recessed channel is substantially planar, but is shown having tapered end portions. 
     The second gate  402  is mounted to a ceiling (not shown) by a mounting support in a similar manner to the example described above with reference to  FIGS. 1 to 3 . The first gate  400  is mounted to a traverse rail (not shown), which in turn is mounted to the ceiling by further guide rails which enable movement of the traverse rail perpendicularly to the longitudinal length of the rail. 
     In this example, the main body of each gate  400 ,  402  is formed of aluminium to reduce the total weight as compared to, for example, steel, and to reduce or eliminate the magnetic interference between the main body and the gate magnet and locking pin magnet. The locking pins and shaft portions for coupling the locking pin magnets to the locking pins are formed of steel. The magnets are formed of an alloy of Neodymium, Iron, and Boron, which are commonly known simply as Neodymium magnets. The bearings are formed of polyoxymethylene (POM). 
       FIG. 5  shows an exploded view of first gate  400 . The components of first gate  400  are shown in greater detail. As described above the locking pin  412  is housed in a bearing  500 , which is inserted into the main body of the first gate  400 . The locking pin magnet  414  is coupled to the locking pin  412  by the shaft portion  502 . The shaft portion  502  is screwed into the locking pin using threaded portion  504 . The slot  430  is formed using an insert  506 , formed of the same material as the bearing  500 . Also shown are cover plates  508  and  510 . 
     In particular,  FIG. 5  shows that the gate magnet is provided with a cammed profile which matches the cammed profile of the upper edge of the recessed channel. 
     Upon the first gate  400  being traversed into alignment with the second gate  402 , the gate magnet  418  of the first gate  400  attracts the locking pin magnet  416  of the second gate  402 , and the gate magnet  420  of the second gate  402  attracts locking pin magnet  414  of the first gate  400 . The locking pin magnets are drawn along the cammed profile of the gate magnets, and thereby move the locking pins from a first, locked, position to a second, unlocked position upon the first gate  400  and the second gate  402  being aligned. 
     In this aligned configuration, the alignment magnets  426  and  428  maintain the gates together until a user, such a healthcare professional, moves the traverse rail. 
     With the gates aligned, and the locking pins in the second position, a lifting carriage is free to traverse the rails from the fixed rail to the traverse rail or vice versa. This is because a substantial portion of a lifting carriage of this type runs within the rails, being supported by the support surface of the rails. 
     As the first gate  400  is traversed away from the alignment configuration, the locking pin magnets continue to follow the cammed profile of the gate magnets, and thereby move the locking pins back from the second position to the first position. In addition, the upper edge of the recessed channel, also having a cammed profile, if needed can apply a direct force to the locking pin magnets to assist the movement of the locking pins from the second position to the first position. As will be appreciated, this ensures that if the locking pins become stuck in the unlocked, second position, for any reason, the gate system fails safe because the locking pin magnets will engage with the upper edge of the recess and prevent the gates from being separated. By “fail safe”, it is meant that in no situation is it possible for the gates to be in a configuration where the locking pins are in the unlocked position, and the lifting carriage can fall from the end of the rail. 
     Referring now to  FIG. 6 , the method of installation of a gate system is shown. Although the example shown in  FIG. 6  relates to  FIGS. 4 and 5 , the installation process is also applicable to the example shown in  FIGS. 1 to 3 . As can be seen, the process of installation requires the second gate  402  to be mounted to a ceiling using support  600 . The first gate  400 , attached to the traverse rail  602  is then adjusted into position using tool  604 . Tool  604  has a plurality of pins which engage with corresponding holes in the gates  400  and  402  to ensure the proper separation between the gates. The separation may be between about 3 mm and 5 mm. 
     As will be appreciated, the components of the second gate  402  are identical to those used in the first gate  400 , except for the distance of the recessed channel from the rail portion to avoid interference between the locking pin magnets. 
     In addition, it will also be appreciated that the gate system described above with reference to  FIGS. 1 to 3  is similar to the gate system described with reference to  FIGS. 4 to 6 , and both systems are constructed in similar manners, and from similar materials. 
       FIGS. 7( a ) and 7( b )  show a further gate system for an overhead lifting rail system. The gate system comprises a first gate  700 , and a second gate  702 . The first gate  700  is attached to a fixed rail  704 , and the second gate is attached to a traverse rail  706 . The gate system shown in  FIG. 7  is a bridging gate system which enable the smooth running of a lifting carriage between the gates even when there is a vertical misalignment between the gates. The present example is capable of operating with a vertical misalignment of up to about 3 mm. 
     For ease of reference, the faces  708  and  710  of the gates which engage with each other are shown facing away from each other, but as will be appreciated, in use, the faces  708  and  710  face each other. The first gate  700  comprises, inter alia, a bridging element  712  pivotally coupled at a proximal end to the main body of the first gate by pivots  713 . The distal end of the bridging element  712  comprises an L-shaped cantilevered portion  714 , which is displaced upwards from the top of the bridging element  712  to prevent interference with the lifting carriage. 
     The second gate  702  comprises, inter alia, a rail portion  716 , and a bridging element support  718  configured to support the cantilevered portion  714  of the bridging element  712  when the gates are engaged. 
     The bridging element support  718  is formed by a recessed channel  720  in the face  710  of the second gate. As can be seen, the recessed channel has tapered end portions  722  and  724 . 
     In use, as the second, traverse rail, gate  702  engages with the first, fixed rail, gate  700 , the cantilevered portion  714  of the bridging element  712  engages with the lower edge of the recessed channel, i.e. the bridging element support  718 . The relative dimensions of the bridging element support  718  and the cantilevered portion  714  are such that the lifting carriage support portion  726  of the bridging element  712  is substantially aligned with the lifting carriage support portion  728  of the rail portion  716 . As will now be appreciated, any vertical misalignment, i.e. in the Z direction, will cause the bridging element  712  to pivot about the pivots  713  and maintain the alignment of the various lifting carriage support portions of the rails. Therefore, the gate system has the advantage of reducing the force required to push the lifting carriage over any steps in the rail caused by misalignment, and also reduces noise, and wear on the system. Such misalignment generally occurs when the traverse rail is under load due to a patient being lifted by a lifting carriage being supported by the traverse rail. 
     The tapered end portions  722  and  724  enable the engagement of the first gate and second gate even when the traverse rail is already under load. This is because the ends of the recessed channel are about 5 mm lower than the middle of the recessed channel forming the bridging element support  718 . 
     The example shown in  FIG. 7  may further comprise alignment magnets as described above with reference to  FIGS. 1 to 6 . 
       FIG. 8  shows an alternative example of a gate for use in a gate system for an overhead lifting rail system. The example shown in  FIG. 8 , in effect, combines the locking gate features described above with reference to  FIGS. 1 to 3 , and the bridging gate features described above with reference to  FIG. 7 . As can be seen in this cut-away of gate  800 , the gate comprises a bridging element  802  similar to bridging element  712 , pivotally coupled to the main body of the gate by pivots  804 . Again, similarly to the example shown in  FIG. 7 , a cantilevered support  806  is provided. The bridging element  802  further comprises a through hole for enabling the locking pin  116  to pass therethrough. The locking pin comprises the locking pin magnet  120  coupled to the locking pin by a shaft portion, the shaft portion being slidable in a slot  144 . 
     Referring now to  FIGS. 9( a ) and 9( b ) , it can be further seen that the gate system comprises the features of the locking gate system described above with reference to  FIGS. 1 to 3  in combination with the bridging gate system of  FIG. 7 . However, it is envisaged that, in the alternative, the locking gate system of  FIGS. 4 to 6  could be combined with the gate system of  FIG. 7 . In use, the gate system, shown in  FIGS. 9( a ) and 9( b ) , and in the cut-away shown in  FIG. 10 , operates in a manner as described above with reference to  FIGS. 1 to 3 , and  FIG. 7 , and is referred to here. 
     In all of the above described examples, the rear face of the gates, that is to say the face opposite the engaging face, comprises recessed portion for receiving and mounting the rail portions.  FIG. 11  shows a rear face  1100  of a gate. As can be seen, each rear face is configured such that any one of three standard rail sizes, H70, H100 or H140 can be mounted to the gate. In each case, the rail is mounted using a self-tapping screw, screwed through the main body of the gate and into the side edge of the rail. The rail sizes relate to the rail heights, being 70 mm, 100 mm, or 140 mm. 
     Although the first gate and second gate are designed to work together, either gate may be supplied separately, for example where a healthcare facility may have multiple fixed rails for each traverse rail. 
     The specific embodiments and examples described above illustrate but do not limit the present disclosure. It is to be understood that other embodiments may be made and the specific embodiments and examples described herein are not exhaustive.