IMPROVED HEADSAIL ASSEMBLY BACKGROUND [0001 ] This invention relates generally to heavy duty livestock gates used for controlling the passage of animals when moved from one location to another or for capturing animals to enable procedures or treatment operations to be performed on an animal. The invention is applicable to head bail gates installed in a variety of applications but is particularly well adapted for closing animal races. The invention provides an alternative to the known head bail assemblies used in such applications and includes a closing mechanism which improves initial travel speed, increases mechanical advantage for a user and allows more efficient operation.. It will be convenient to hereinafter describe the invention in relation to that particular application but it will be appreciated that the invention is not to be taken as limited to that application. PRIOR ART [00021 In order to properly run cattle and be able to carry out the various veterinary and management practices that are needed it is necessary to have various assets to assist the grazier. Apart from a working set of stockyards, the most needed piece of equipment is a cattle crush. A cattle crush consists of a rectangular frame which is placed at the head of a narrow lead up race and is big enough for a full grown animal to stand inside with a minimal amount of free area. [00031 Animal races and cattle crush capture gates are generally of a sturdy and strong construction, particularly where they are required to retain or control animal stock. For example, in animal races very strong and robust gates are required to resist high impact loads from animal movements. Gates installed in such races are generally hung between adjacent support posts or are mounted separately on articulating assemblies which allow gates to advance and retract. The gates are usually constructed from heavy duty metal material.
[00041 A typical known gate fittings mounted by swing hinges are disclosed in Australian patents 585997 (59259/86) and 506787 (29999/77). Other known gate assemblies including gates mounted by springs, hinges or equivalent to support posts are disclosed in United States Patents 4,813,182, 5,035,084 which are incorporated herein by reference. 10005] The above are examples of known gate supports and latching assemblies . In animal races, gates are generally of the conventional swing type or constructed on a runner or slide where there is insufficient room to allow sliding. Sliding gates are more practical in a confined space of a race and have the advantage of instant restriction to animal passage irrespective of the direction the animal is heading. In a case where a sliding gate closes from one side of an opening to another there is a delay in the gate reaching closure at an opposite style. This delay can allow an animal to pass through a race or avoid capture by head bails due to the time it takes for the gate to at least partially block off the opening. To prevent an animal from passing through a gate point, the gate must have advanced a distance which leaves an opening less than the width of a neck of a beast. Any greater than that distance and a beast may be able to break through. Where a gate slides across an opening from one side to another side this takes more time that the alternative of using opposing gates to close the same opening. [00061 Cattle crushes generally have a sliding gate at the entrance end so that once an animal has entered the gate can be closed across behind them so that they cannot back out. On either side of the crush are access gates so that an operator can get easy access to parts of the animal as well as some models of crush having an arrangement of gates which can be closed behind the beast so that a vet can perform duties like pregnancy testing without the risk of being kicked or crushed, At the front of a crush there is an assembly known as a head bail which allows the operator to capture and restrain an animal by the neck just behind the head. Head bails are employed to enable an operator to perform such functions as administration of oral medications, checking an animal's teeth for age and for fitting ear tags. The use of ear tags is widely used to provide animal identity. The ear tags allow scanning 2 for identification purposes several times during an animal's life, When an animal is caught by the neck it will often struggle violently thrusting its bead up and down posing danger for an operator. Reducing the aniount of movement of the head has been in the past assisted by the use of a chin bar (head lifter) specially shaped bail anns which assist in reducing the amount of head movement available as well as special add on structures that can be operated after the animal has been caught and can reduce the amount of movement from side to side. [0007 1 The best way to reduce animal head movement is to close the bail arms more tightly against the animal's head in the first place. If an animal is held loosely, it thinks it can escape restraint but if it is held more firmly, it will be more likely to submit. Efficient capture speeds up the process for the operator and animal. There are in existence, many different makes and models of headbail. The known headbails can be broadly divided into two , basic mechanical types which are adequate for the purpose but they all suffer from operating disadvantages as indicated below. The first known type of headbail can be described as Over Centre and the second type, the Push Pull. [0008] There are disadvantages with the over centre style of beadbail. Firstly, bail arms and lift, creating gaps below each one near the bottom of the support frame. This gap has the potential to be dangerous to the animal because if it is struggling and pulling back its front legs can slip through the gap under the bail arms. Secondly, the operator must predetermine the closed width they believe they will require for an animal before catching. [0009] There are also disadvantages with the push pull type headbail. Specifically, the linkage used in this style of head bail does not provide a mechanical advantage and even the strongest man has great difficulty in closing the bail arms tightly enough to stop an animal from moving its head about and making it difficult or even dangerous for the operator. What is ideally required is a head bail that uses the advantages of the known head bails. INVENTION 3 [0010] The present invention seeks to ameliorate the disadvantages of the prior art by providing an improved head bail which provides a significant mechanical advantage compared to the prior art bead bails. [0011] According to one embodiment the present invention provides a head bail assembly that includes bail arms that do not rise, an infinitely variable locking device and in addition, a new linkage which provides extra pressure from an over centre linkage is incorporated into the assembly. [0012 ] This invention provides an alternative to the known bead bail assemblies and more particularly provides an alternative closure assembly Eor an animal race. More particularly, the invention provides an opposing sliding gate assembly which closes an opening at a middle of a passage to prevent unwanted sliding gate. The invention further provides a head bail closure assembly in whicb two gate members slide in opposing directions under the action of an auxiliary mechanism which imparts increased mechanical advantage. The sliding gate assembly allows more efficient and speedy closure of an opening such that the speed of initial travel of the closure is increased but the physical effort to apply a clamping force is reduced by an auxiliary mechanism. [0013] In its broadest form the present invention comprises: a head bail assembly comprising; a. primary support frame including a base side support members and an overhead member a pair of bail arms mounted in opposing relationship and capable of movement responsive movement of an operating member between an open state in which a through passage is created between the bail arms and a closed state in which the passage is at least partially blocked by the bail arms, an actuating assembly for operating the opening and closing of the bail arms, 4 the actuating assembly connected at first and second locations on the primary support frame and including an auxiliary assembly connected to a lifting arm and a bail arm operating assembly respectively associated with each bail arm; the bail arm. operating assemblies arranged so that when the actuating assembly is actuated the auxiliary assembly activates the bail arm operating assemblies to urge the bail arms between the open state and closed state. Preferably the head bail assembly includes an extension member extending from the primary support frame which pivotally retains the lifting arm. [00141 The actuating assembly is preferably connected at the first location via the pivot which engages the lifting arn and the extension member. The actuating assembly is connected at the second location via a second pivot associated witb the primary frame. According to one embodiment, the handle is connected to the second pivot and is capable of moving the lifting atrn and the auxiliary assembly. The auxiliary assembly comprises first and second linkage members. A first end of each of each said first and second linkage members pivotally engages the lifting arm at the same pivot point. [0015] A second end of one the first and second linkage members pivotally engages one of the bail arm operating assemblies. Each bail arm operating assembly preferably comprises a first set of scissor arms and a second set of scissor arms. Each said the first and second set of scissor arms of each bail arm is linked via a linkage arm. Each of the first and second sets of scissor arms include a pivotal connection to the primary frame and a second connection to one bail arm. The first set of scissor arns pivotalIy engage via a pivot at an upper region of the bail arm. [0016] The second set of scissor atms pivotally engages via a pivot at a lower region of the bail arm so that the first and second sets of scissor arms connected to each bail arm transfer load applied to the linkage members of the auxiliary assembly. Forces opening and closing the bail arms are applied 5 from behind the bail arms. The operating handle is pivotally connected to the lifting arm and the lifting arm is connected intermediate its ends to the extension member of the primary frame. [0017] In an alternative embodiment, the operating handle is pivotally connected to a linkage assembly connected to the lifting arm. In this embodiment, the linkage assembly includes a link arm operably connected at one end to the operating handle and at an opposite end to scissor arms. [0018] One said scissor arms of the linkage assembly is pivotally connected to the lifting arm and another arm of said scissor arms is pivotally connected to the primary frame. When the handle is operated, the linkage assembly causes a lifting an to be selectively raised or lowered to either close or open the bail arms. It will be appreciated that the assembly can be arranged to alter the travel of the handle to determine whether it opens or closes. [0019] The bail arms are according to one embodiment, mounted on an overhead member of the primary frame via wheels which allow the bail arms to run freely during opening and closing [0020] The operating handle has up to 90 degrees of rotation when operating to open or close the bail arms such during the process of closing the bead bail, approximately three quarters of movement of the bail arms occurs with approximately one third of handle movement. A final one quarter of a total bail arm movement is enabled by approximately two thirds of the handle movement. The geometry of the handle and actuating assembly can be altered to change the relationship of the extent of travel of the handle relative to the travel of the bail arms. [0021] In another broad form the present invention comprises: a head bail assembly comprising a main support frame including a base and an overhead support, 6 a pair of bail arms capable of advancing and retracting responsive to an operating member, an extension member extending from the main support frame which retains a lifting arm. pivotally attached to the extension member and which engages an auxiliary assembly; the auxiliary assembly receiving and retaining a bail arm operating assembly for a First bail arm and which includes two scissor assemblies joined by a linkage arm, the auxiliary assembly receiving and retaining a bail arm operating assembly for a second bail arm and which includes two scissor assemblies joined by a linkage arm, the scissor assemblies operatively engaging the bail arms; an operating arm which co operates with the auxiliary assembly to move the bail arms between an open state and at least a partially closed state in which the bail arms engage an animal; wherein the opening and closing of the bail arms is responsive to actuation of the bail arn operating assemblies wben the operating member is moved. [0022 ] In its broadest form the present invention comprises: a headbail assembly comprising a main support frame including an overhead support, a pair of bail arms capable of advancing and retracting responsive to an operating member retained by the overhead support, an extension arm extending from the main support frame which retains a first strut which engages an auxiliary assembly and is pivotally attached to the extension arm and at one end receives and retains a first scissor assembly which includes scissor members which engage respectively second and third 7 scissor members; the second and third scissor assemblies operatively engage the bail anns; an operating ann which co operates with the first scissor assembly to move the bail arms between a retracted state and an extended state in which the bail arms engage an animaL [0023] According to one embodiment, the operating arm is directly attached to the first strut. According to an alternative embodiment the operating arm is indirectly attached to the strut via a linkage arm which engages a ourth scissor assembly. [0024 ] In another broad form the present invention comprises: a gate assembly comprising a main frame including an overhead support, a pair of bail arms which are slidably retained by the overhead support, an extension member extending form the main frame an auxiliary assembly operable by an operating arm and which includes a first scissor assembly which enables the bail arms to move between a retracted and extended state responsive to the operating arm. [0025 ] Preferably the bail arms are mounted to the overhead support member via rollers which allow the bail arms to move between the open and closed configurations. Preferably the bail arms are mounted to the overhead support member via rollers which allow the bail arms to move between the open and closed or extended and retracted state. The head bail assembly includes first and second side stiles and at least an upper rails, The upper rail is either separate from or integral with the overhead support member. Preferably the head bail assembly is biased to a closed condition. 8 [0026 ] The present invention provides an alternative to the known prior art and the shortcomings identified. The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying representations, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention- In the accompanying illustrations, like reference characters designate the same or similar parts throughout the several views. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. BRIEF DESCRIPTION OF DRAWINGS [0027] The invention will now be described in more detail according to a preferred but non limiting embodiment and with reference to the accompanying illustrations. Figure 1 shows an elevation view of a head bail gate assembly in an open position according to the over centre arrangement of the prior art, Figure 2 shows an elevation view of a head bail gate assembly of figure 12 is a closed position. Figure 3 shows an elevation view of a push pull version of headbail in a closed state according to the prior art, Figure 4 shows an elevation view of a push pull version of headbail in an open state. Figure 5 shows a front elevation of a headbail according to a preferred embodiment of the invention assembly in which the gates are in an open state 9 Figure 6 shows an elevation view of the head bail of figure 5 in a closed state. Figure 7 shows an elevation view of a headbail according to an alternative embodiment. DETAILED DESCRIPTION [0028] The invention to be described below according to a preferred embodiment provides a gate assembly alternative to the known gate assemblies used in such applications and includes a self closing mechanism which allows opposing gate sections to close across an opening. The invention also relates to a mechanism for effecting such gate closure. A detailed description of two categories of prior art bead bails will assist in identifying the present invention and its operational advantages by a comparison with the prior art assemblies. (0029] Figure 1 is a simple drawing of an over centre head. bail in an open position. The head bail consists of a main frame 1. which have mounted thereon bail arms 1.5 and 16. Linkage arms 6, 7, 8, and 9 respectively pivot about pivot points 2, 3, 4, and 5. Bail arms 15 and 16 are connected to links 6, 7, 8, and 9 by pivot points 10, 11, 12 and 13. Link 17 is fitted to the top of bail arm 1.5 at pivot point 20, and link 18 is fitted to the top of bail arm 16 at pivot point 21. Operating loads to the bail arms are transmitted through these pivot points. Mount 25 is welded to the top of the main frame 1. Rocker arm 24 is mounted at point 26. One end of the rocker arm 24 is joined to links 17 and 18 by link arm 19. Mount 29 is welded to the main frame 1 and retains handle 31 via pivot point 30. Part way along the handle 31 is an adjustment block 33 which can be shifted longitudinally along the handle 31 in small increments which can be selected by an operator. Link 28 connects rocker 24 to adjustment block 33, via pivots 27 and 32. [0030] Figure 2 shows the prior art head bail of figure I with corresponding numbering with bail arms 15 and 16 in a closed state. In a closed state the pivot points 27, 30 and 32 are almost in a straight aligmnent. Pivot point 32 10 is now located slightly inside the line between 27 and 30. To put it another way, point 32 has gone over centre. This over centre geometry provides the locking which holds the head bail closed to restrain an animal. [00311 There are three major disadvantages with this style of head bail. Firstly, as the bail arms 15 and 16 are moved towards each other the links 6, 7, 8 and 9 rotate on their mounts and cause the bail arms to lift, creating gaps 36 and 37 below each one near the bottom of frame 1. This gap has the potential to be dangerous to the animal because if it is struggling and pulling back its front legs can slip through the gap under the bail arms. Often the only way to get the legs back is to open the head bail and that means that the bail arms will lower onto the animals legs potentially causing injury. Secondly, the operators must predetermine the closed width they believe they will require for an animal before catching. The width is determined by shifting the locking block 33 along the handle 31. Various known makes and models have different ways of locking adjustment block 33 in position prior to catching. If adjustment block 33 is set too wide then the catching operation will be less effective and the animal will be able to move its head and may even be able to pull it out backwards. If the animal succeeds in pulling out it will then have to be captured again. If adjustment block 33 is set too narrow it will not be possible to close the head bail fully, so the animal will have to be released, so the adjustment block 33 can be reset prior to re capture of the animal. Linkage arms 17 and 18 engage respective bail arms 15 and 16 respectively via pivot points 20 and 21. Thus load is transmitted from handle 31 -to arms 15 and 16 via respective arms 17 and 1 8. Handle 31 acting on link 24 transfers load directly to pivots 20 and 21. Plates 34 and 35 are connected to bail arms 15 and 16. [0032) It was mentioned earlier that the head bail is mounted on a crush. Occasionally there is no proper crush and the head bail is mounted onto a couple of simple panels to form. a race. In each case however it is highly desirable to be able to open or close the head bail from behind the animal, and almost all modem crushes or head bails have a rear closing handle set up about 2 meters behind the head bail. This handle is connected to the head 11 bail via a solid link which allows the operator to open or close the head bail using the handle 31 which is mounted on the bead bail proper or a second handle mounted further back on the crush behind the animal. [0033] The over centre system does not lend itself to this practice. Over centre assembly has one major advantage. If adjustment block 33 is set correctly the mechanical advantage that the over centre linkage employs means that the bail arms can be closed sufficiently firmly against an animal's neck to prevent head movement but not so tight that the animal is injured. [0034] The handle 31 accommodates locking mechanism 33 and articulates about pivot point 30. During the process of closing the head bail and opening the head bail handle 31 moves out into the operating area having the distinct possibility of causing injury to either the operator if he happens to be using the front handle or to a bystander if the operator is using the rear handle. If there is any system failure and the head bail happens to open accidentally when under pressure the two links 28 and 31 could cause a fatal injury. Since these links are at approximately at head height, the consequences of an accident could be extreme considering the forces that can be applied by an animal pulling back. The known over centre mechanism when applied to drop away handles and latching methods has the potential to cause serious injury. An over centre mechanism was the best method for exerting pressure on the bail arms. [0035 ] Figure 3 shows a head bail of the push/ pull type has a main frame 41 and two bail arms 42 and 43. Link 46 engages link arms 47, 48, 49 and 50. Link arm 45 joins link arms 51, 52, 53 and 54. This linkage structure has the effect of allowing the bail arms to move inwards and yet remain vertical. Bail arms 42 and 43 include mounted thereon wheels 67 and 68 which run along the overhead frame member 55 so that the bail atms remain at a consistent height and no gap is created below it. Rocker ann 56 which is operated by arm. 64 can rotate through approx 90 degrees and is mounted at pivot point 57 on a sub assembly not shown. Rocker 56 is joined at one end to bail arm. 42 by link 58 at pivot points 59 and 60 and is joined at its other 1.2 end to bail arm 42 by link 61 through pivot points 62 and 63. Also, not pictured is an infinitely variable locking device which can hold the bail arms securely at precisely the width the operator wishes. Figure 4 shows the head bail of figure 3 with corresponding numbering in an open state. [0036] The push pull style of head bail described above has two distinct advantages. Firstly, because the bail arms do not rise when being closed, no gap is created below them and this results in a safer environment for the animal. Secondly, because this style of head bail lends itself to an infinitely variable locking or latching system the bail arms can be closed to any width the operator wants without any pre set conditions. There is one major disadvantage namely, the linkage used in this style of head bail does not provide a mechanical advantage and even the strongest man has great difficulty in closing the bail arms tightly enough to stop an animal from moving its head about and making it difficult or even dangerous for the operator. Smaller men and women just aren't strong enough to exert enough pressure to be able to properly restrain an animal. making operations on the animal difficult. Because of this inability to apply pressure, the industry has developed over the years various types of head immobilising devices such as chin bars, head clams, scoops etc. [00371 Figure 5 shows a front elevation of a bead bail assembly 70 in an open state according to a preferred embodiment of t-he invention. Assembly 70 includes main frame 71 and bale arms 72 and 73. The main frame 71 has been extended by the addition of extension 74 to provide a solid mount for lifting ann 75 which is supported at a pivot point 76. Lifting ann 75 pivots on 76 and extends towards the middle of the main frame 71. At the opposite end to pivot 76 is another pivot point 77 and part way along its length is a pivot point 78. The bail ann links 79 and 80 are joined at connection 81, and at this point, linkage ann 82 is also connected to pivot point 81 at one end and to pivot point 77 at the other end. Link 80 is also connected at Pivot 38. Similarly links 86 and 85 are joined at point 87. Link 85 is also connected at pivot point 40 and link 86 is connected at pivot point 41. Link arm 88 is also connected at one end to pivot point 87 and to pivot point 77 at the other 13 end. Lifting arm 75 is now connected to the bail arms 72 and 73 by the link arms 82 and 88. In comparison to the head bail described with reference to Figs I and 2 this assembly 70 wbilst not the same, has some similarities to the method used to close the bail ans on the Over Centre head bails. Tn order to raise the lifting arm, another sub assembly is provided which comprises links 92 and 93. Members 92 and 93 are joined at pivot point 94 which is located adjacent ( but not connected to) wheel 95 at the top of bail arm 73 and wheel 96 . Pivot point 76 is fixed solid to the main frame 71 and link 92 is also fitted to pivot 76 and is joined to link 93 at pivot point 94 and the other end of link 93 is fitted to pivot point 78 which is solidly mounted to lifting arm 75. Also connected at point 94 is link 99 which extends across the top overhead member 100 of the frame 71 to a handle and latching assembly (not shown). Shown is pivot point 101 which is mounted on the main frame 71. Link 102 rotates on point 101 and is connected to link 99 at point 103. When the handle 104 is rotated, link 34/99 is moved sideways pulling on pivot point 94, causing links 92 and 93 to stand up causing the lifting arm 75 to rise, which in turn lifts links 82 and 88 which causes the bail arms 72 and 73 to be forced towards each other into a catching position. Wheels 95 and 105 travel along overhead member 108. Likewise wheels 96 and 97 travel below overhead member 108 and help guide travel of bail arms 72 and 73 during opening and closing of bails arms 72 and 73. When the bail arms are closed tinder real pressure, they have a tendency to want to lift and tend to bind or jam against the underside of the main frame. The wheels have been added so that when the bail arms lift they run freely against the overhead member 100. Bail arm 73 is operated under the action of bail arm operating assembly which includes link 80 and 82. Lik arm 109 joins scissor arms 110 and 111. Bail arm 73 is operated under the action of bail arm operating assembly 112 which includes link 85 and 86 at one end. Link arm 113 joins scissor arms 114 and 115. [0038] Figure 6 shows an elevation view of the head bail assembly 70 of figure 5 in a closed state. It can be seen in Fig 6 that link 102 has rotated and in conjunction with link 99 has brought point 94, 101 and 103 into line, and whilst the assembly 70 has not moved to a position of over centre, it is 14 very close to being over centre and has reached a point where the sideways movement of 99 is small and has stopped causing any worthwhile closing action of the bail arms. There is an independent handle and locking mechanism (not shown) and so the over centre locking in its own right is not needed. The mechanism does get to a position which is almost at the point of being over centre providing a significant mechanical advantage. [0039 ] The interaction of links 92, 93, 99 and 31 have another advantage in that while the handle 104 will rotate approx 80 degrees in the process of closing the headbail, approximately three quarters of the movement of the bail arms will occur in only about one third of handle movement. The final one quarter of bail arm movement is leveraged by approx two thirds of the handle movement, so the first part of the closing action is faster than other versions of headbail and the final part of the closing is slightly slower but much more force can be applied against the neck of an animal. Both these attributes - i.e. fast initial travel and high load when positive animal capture is required. [0040] Figure 7 shows an elevation view of a headbail assembly 120 according to an alternative embodiment. The head bail assembly 120 of figure 7 comprises a main frame 121 including supports 122 and 123 to which are connected base 124 and overhead member 125. Bail arms 126 and 127 are shown in a closed state. It can be seen in Fig 7 that operating handle 128 is pivotally attached to pivot 129 of extension member 130 and terminates at pivot 131 which also engages lifting arm 132. Ann 132 is also attached to extension member 134 at pivot 135 and terminates at pivot 136 which retains auxiliary assembly arms 1.37 and 138. Arm 137 joins bail ann actuating assembly 140 at pivot 141. Pivot 141 also engages scissor arms 142 and 143. Linkage 144 terminates at pivot 145 which retains scissor arms 146 and 147. Ann 142 attaches to support 122 via pivot 148 Ar 143 engages bail arm 126 via pivot 150. Likewise arm 146 is pivotally attached to support 122 via picot 149. Arm 147 attaches to bail arm 126 via pivot 151. 15 Arm 138 joins bail arm actuating assembly 152 at pivot 153. Pivot 153 also engages scissor arms 154 and 155. Linkage 156 terminates at pivot 157 which retains scissor arms 158 and 159. Scissor arm 158 attaches to bail arm 127 via pivot 160 and scissor ann 159 engages support 123 via pivot 161. [0041] The interaction of links 132, 137, 138 have advantage in that while the handle 128 will rotate approx 80 degrees in the process of closing the head bail arms 1.26 and 127, approximately three quarters of the movement of the bail arms will occur in only about one third of handle movement. The final one quarter of bail arm movement is leveraged by approximately two thirds of the handle movement, so the first part of the closing action is faster than other versions of head bail and the final part of the closing is slightly slower but much more force can be applied against the neck of an animal. Both these attributes - i.e. fast initial travel and high load when positive animal capture is required. Another advantage of the assemblies according to the invention. is that the loads are applied in a. more optional location to gain mechanical advantage. Specifically the loads are applied at the back of the bail arms during opening and closing which provides more positive loading on opening and closing.. [0041] Tt will be recognised by persons skilled in the art that numerous variations and modification may be made to the invention broadly described herein with out departing from the overall spirit and scope of the invention. 16