This invention relates to a locking mechanism, particularly a locking mechanism to selectively permit relative movement between two members, and more especially an automatically engageable locking mechanism to automatically prevent relative movement between two members except when the mechanism is disengaged.

Automatic locking mechanisms are required in a number of applications to automatically prevent relative movement between two members except when the mechanism is positively disengaged. One such application includes animal handling apparatus where it may be required for the apparatus to be closed to a required position relative to the size and/or location of an animal, and then to automatically lock such that the apparatus cannot be opened by movement of the animal.

In animal containment apparatus such as a cattle or sheep crush, a yoke is often closed either side of an animal’s neck. This requires to be closed to a required position by an operator and then to automatically lock in that position until it is required to release the animal.

According to a first aspect of the invention there is provided a locking mechanism to permit relative linear movement between first and second members when the locking mechanism is disengaged, and to prevent relative linear movement between the first and second members when the locking member is engaged, the locking mechanism including a locking arrangement including a linear passage with respective end sections and a mid-section, the mid-section being of reduced width relative to the end sections, the mid-section and at least part of the end sections of the passage being defined on opposite sides by the first and second members, a respective locking member being movably located in each end section, the locking member being of a size such that it cannot pass through the mid-section but can freely pass along the end sections, so that if the locking member is urged into the mid-section, it will jam between the first and second members to engage the locking mechanism, thereby preventing relative linear movement therebetween, an engagement member being provided beatable in the mid-section and selectively movable along the mid-section to urge a respective one of the locking members out of the mid-section towards the respective end section, to disengage the locking mechanism and permit relative movement between the first and second members.

The locking mechanism may be configured to be automatically urged to an engaged condition.

The locking members may be resiliently urged towards the mid-section so as to cause automatic engagement of the locking mechanism. A respective spring may be located at the closed end of each end section to urge the respective locking member to the mid-section.

The engagement member may be connected to a control member which is slidably movable to a limited degree relative to the first member. A handle arrangement may be connected to the control member to permit movement thereof by an operator.

The control member may be in the form of a sleeve slidably mounted on the first member.

The locking members and/or engagement member may be in the form of cylindrical members slidably movable along the linear passage, with their axes perpendicular to the longitudinal direction of the passage.

The second member may be slidably extendible through an opening extending through the first member. The first member may be in the form of a carriage slidably movable along the second member. The second member may be in the form of an elongate bar.

The locking mechanism may comprise a plurality of locking arrangements, and two locking arrangements may be provided on opposite sides to each other of the second member.

In one arrangement four locking arrangements are provided, with two on each side of the second member opposite a respective locking arrangement on the other side of the second member.

According to a first aspect of the invention there is provided animal containment apparatus comprising a yoke with a pair of yoke members selectively movable towards or away from each other, with a locking mechanism according to any of the preceding ten paragraphs, to permit the yoke members to be moved to required positions by an operator, and to automatically lock in the required positions.

The apparatus may be configured such that the yoke members are interconnected so as to simultaneously each move towards or away from the other.

A handle may be provided connected to the locking mechanism and extending to the side of the apparatus to be usable by an operator.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:-

Fig. 1 is a diagrammatic perspective view of a locking mechanism according to the invention; Fig. 2 is a diagrammatic side view of the apparatus of Fig. 1 in an engaged condition illustrating components of the mechanism;

Fig. 3 is a similar view to Fig. 2 but in a disengaged condition;

Fig. 4 is a similar view to Figs. 2 and 3 illustrating both the engaged and disengaged condition;

Fig. 5 is a diagrammatic end view of the mechanism of Fig. 1 ;

Fig. 6 is a cross sectional view along the line A-A of Fig. 5;

Fig. 7 is a detailed view of part of the engagement shown in Fig. 6.

Figs. 8 and 9 are respectively similar view to Figs. 6 and 7 but with the mechanism in a disengaged condition;

Fig. 10 is a diagrammatic view of a cattle crush in use with a yoke incorporating a locking mechanism according to the invention;

Figs. 11 and 12 are respectively diagrammatic perspective and end views of part of the cattle crush of Fig. 10 in a closed condition;

Figs. 13 and 14 are diagrammatic views of an upper part of the cattle crush yoke of Fig. 10 in respectively closed and open positions;

Fig. 15 is a diagrammatic perspective view of an upper part of the cattle crush yoke of Fig. 10 in a closed condition;

Fig. 16 is a further end view of an upper part of the cattle crush yoke of Fig. 10 in a closed condition; Figs. 17 and 18 are respectively plan views of part of the cattle crush yoke of Fig. 10 in closed and open positions; and

Fig. 19 is a perspective view of an upper part of the cattle crush yoke in a closed condition.

The drawings show a locking mechanism 10 including four locking arrangements 12, and Figs. 10 - 19 show such a locking mechanism 10 mounted on a cattle crush containment apparatus 14 controlling opening and closed of two yoke members 16.

The mechanism 10 includes a first member in the form of a carriage 18 slidably mounted on a second member in the form of an elongate bar 20. A control arrangement in the form of a sleeve 22 is slidably mounted over the carriage 18 and permitted a limited amount of longitudinal movement relative to the carriage 18.

Each locking arrangement 12 includes a linear passage 24 formed by a recess 26 in the carriage 18 facing the elongate bar 20, the recess 26 is profiled such that the passage 24 defined between the recess 26 and the bar 20 has closed ends 28 extending through end sections 20 leading to a mid-section 32, with the closed ends 28 of the recess 26 gently bowed towards the elongate bar 20 to thereby define end sections 30, leading to the mid-section 32 defined against the elongate bar 20, which mid-section 32 is narrower than the end sections 30 on either side.

A compression spring 34 is located in each end section 30. Each spring 34 engages against a respective locking member 36 in the form of a cylindrical member which is a sliding fit in the linear passage, but is too large to fully enter the mid-section 32, and as a one of the locking members 36 enters the mid- section 32 it will jam between the carriage 18 and elongate bar 20 to prevent relative movement therebetween. Located between each pair of locking members 36 an engagement member 38 is provided which extends across the control member sleeve 22 through a slot 40 in the carriage 18 wall so as to define the limited longitudinal movement possible between the sleeve 22 and the carriage 18. As can be seen the engagement member 38 is of smaller diameter than the locking members 36 and can therefore locate in the narrowest part, the mid-section 32, of the linear passage 24.

Figs. 2, 6 and 7 show the locking mechanism 10 and hence each locking arrangement 12 in a relaxed condition which will automatically be engaged. If it is attempted to move the carriage 18 in either direction, the forward locking member 36 relative to the direction the carriage 18 is being urged would engage further between the carriage 18 and the elongate bar 20 to jam therebetween and thereby prevent relative movement therebetween.

If it is for instance desired to move the carriage 18 to the right as shown in the drawings, then the sleeve 22 will first be moved to the right to the maximum possible amount as shown in Figs. 3, 8 and 9. This will cause the engagement members 38 to be moved to the right as shown in the drawings thereby urging the right hand, forwards relative to the desired movement, locking members 36 against the respective springs 34, such that the right hand and hence forwards locking members 36 will not jam between the carriage 18 and elongate bar 20. The left-hand rearwards locking members 34 will tend to roll between the moving carriage 18 and elongate bar 20 and not jam therebetween. Fig. 4 shows the two positions of the sleeve 22 and hence engagement members 34. Once the sleeve 22 is no longer urged to the right, by virtue of the respective pairs of springs 34, the mechanism will return to the relaxed engaged condition as shown for instance in Fig. 2.

As indicated, Figs. 10 to 19 show a cattle crush 14 with such a locking mechanism 10 controlling opening and closing of the yoke members 16. As can been seen the elongate bar 20 extends above the yoke members 16, and the carriage 18 is slidably mounted thereon. A cranked handle 42 is pivotally connected to the top of the sleeve 22 mounted on the carriage 18, and extends to one side of the cattle crush 14. Figs. 1 1 and 12 show possible different positions of the handle 42.

If the handle 42 is pulled outwardly this will cause the yoke members 16 to open, and if the handle 42 is pushed inwardly towards the cattle crush 14 the yoke members 16 will close. If the handle 42 is pulled or pushed, this will initially move the sleeve 22 moving the mechanism 10 to a disengaged condition. Further movement will then move the carriage 18. When pressure is not being applied to the handle 42 in either direction, pressure will not therefore be applied to the sleeve 22 and the locking mechanism 10 will revert to a relaxed engaged condition.

The yoke members 16 are interconnected so as to simultaneously each move together or apart. This arrangement is provided by a pair of gear racks 44 each connected to a respective one of the yoke members 16. As can be seen a gear 46 with a vertical axis engages between the two gear racks 44, such that when a one of the gear racks 44 moves in one direction, the other gear rack 44 will move in an opposite direction. In practice, the locking mechanism 10 would only be connected to a one of the yoke members 16, but with the above arrangement movement of this one yoke member will cause the other yoke member 16 to move.

Fig. 16, 17 and 19 show the yoke members 16 closed, whilst Fig. 18 shows the yoke members 16 open, in which instance the handle 42 would have been pulled outwardly. As can be seen the gear 46 is now engaging with opposite ends of the gear racks 44 relative to when the yoke members 16 are closed together. There is thus described a locking mechanism, and also a cattle crush incorporating such a mechanism to control movement of the yoke members. The locking mechanism provides for automatic engagement when no pressure is applied to a control handle in either direction, and automatic disengagement when the handle is moved in either direction. The apparatus is of a relatively straightforward mechanical construction and can therefore operate long term in potentially relatively harsh conditions without requiring any substantial maintenance. Providing a number of locking arrangements opposite each other provides a significant locking force.

Whilst the locking mechanism above is described in relation to use with a cattle crush, it is to be realised that such a locking mechanism could be used in a wide range of applications, in for instance animal handling apparatus and also many other situations.

Various other modifications may be made without departing from the scope of the invention. For instance, a different number and/or arrangement of locking arrangements could be provided. In some instance, it may be that only a single locking arrangement would be required. A different resilient urging arrangement could be used other than the springs described. The locking members and/or engagement members may take a different form.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.