Abstract:
A portable enclosure for capturing and retaining an animal features a pen carried alongside an ATV, a front opening in the pen, and at least one door movable between open and closed positions at the front opening. A lock member is carried above the front opening, and is displaceable into and out of a locking position engaging the door. A rotatable actuation member resides overhead of the lock member and is operable by a foot pedal to draw the at least one lock member upwardly out of the locking position to unlock the door. The same lock member acts in both the open and closed positions of the door by way of cooperation with strike plates on the door panel and an extension member projecting therefrom. The strike plates are shaped to return the lock member to a ready state for automatic locking during opening and closing of the door.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of animal husbandry, and more particularly to vehicle-mounted enclosures for catching calves in the field in a manner isolating the calves from protective mother cows for the safety of the farmer or rancher. 
       BACKGROUND 
       [0002]    In the field of animal husbandry, it has been previously proposed to mount a portable enclosure to an all-terrain vehicle (ATV) or other vehicle and use the same for the purpose of catching calves in the field shortly after birth to enable the farmer or rancher to apply identification tags, perform medical procedures or carry out other processing of the calves. The vehicle and enclosure combination allows the farmer or rancher to capture and process each calf in a manner safely isolated from the mother cow, whose protective instincts may otherwise pose a threat to the farmer or rancher attending to the calf. 
         [0003]    Examples of prior art enclosures of this type are found in U.S. Pat. No. 6,964,245, U.S. Pat. No. 7,389,746 and U.S. Pat. No. 8,061,303, and U.K. Patent Application GB2449900. Other examples of vehicle-carried livestock enclosures or carriers are found in U.S. Pat. No. 5,785,006, U.S. Pat. No. 6,035,808 and U.S. Pat. No. 7,685,970. 
         [0004]    Of the forgoing references, GB2449900 and U.S. Pat. No. 7,389,746 are the most relevant to the present invention, in that they attach to an ATV in a position residing alongside same and feature an openable/closeable door at a leading front end of the enclosure so that a calf can be captured by driving the vehicle up alongside the animal with the door in the open position in order to receive the calf through the open door into the interior of pen, at which point the door is promptly closed by the ATV operator. An operator opening in the vehicle-facing side of the enclosure allows the farmer or rancher to enter the enclosure for access to the captured calf in a manner safely isolated from the surrounding field, where the protective mother cow is likely to be nearby. 
         [0005]    Applicant has designed a new calf catching enclosure of this general type in which unique mechanisms for controlling operation of the openable and closeable doors are employed. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the invention there is provided a portable enclosure for attachment to a ground vehicle for capturing and retaining an animal, the portable enclosure comprising: 
         [0007]    a pen arranged for attachment to the ground vehicle in a working position residing thereaside; 
         [0008]    an front opening in the pen at a front end thereof that faces forwardly of the ground vehicle when the pen is attached thereto in the working position; 
         [0009]    at least one door movably mounted to the pen and movable between a closed position obstructing the front opening of the pen and an open position revealing the front opening of the pen; 
         [0010]    at least one lock member movably carried on the pen at a position overlying the front opening therein, the lock member being displaceable upwardly and downwardly between a locking position engaging the at least one door and a releasing position withdrawn from engagement with the at least one door; and 
         [0011]    at least one rotatable actuation member rotatably carried on the pen in a position overhead of the lock member and linked to the lock member such that rotation of the at least one actuation member in an unlocking direction draws the at least one lock member upwardly out of the locking position into the releasing position to allow movement of the at least one door between the open and closed positions. 
         [0012]    Preferably the at least one lock member is arranged to be engagable with the at least one door in both the open and closed positions thereof. 
         [0013]    Preferably the at least one door comprises: 
         [0014]    at least one door panel that resides in the front opening of the pen the closed position and, in said closed position, is engaged by the locking position of the at least one locking member to lock the at least one door in the closed position; and 
         [0015]    at least one extension member that extends out from the at least one door panel for engagement by the at least one locking member in the open position of the at least one door to lock the at least one door in the open position. 
         [0016]    Preferably the at least one door comprises a latching point at which the at least one door is engagable by downward movement of a respective locking member into the locking position, and an inclined ramp surface approaching the latching point in a manner increasing in elevation theretoward to lift the respective locking member out of the locking position during movement of the at least one door into a position aligning said respective locking member with the latching point, whereupon the locking member falls into the locking position and into engagement with the latching point. 
         [0017]    Preferably the latching point is carried on the at least one door panel and is engagable by downward movement a respective locking member into the locking position with the at least one door in the closed position, and a second latching point is carried on the at least one extension member and is engagable by downward movement of the respective locking member into the locking position with the at least one door in the open position. 
         [0018]    Preferably the at least one door comprises a strike plate mounted atop at least one door panel of said at least one door and defining the inclined ramp surface, and the first latching point comprises a hole in the strike plate for engagement by a respective locking member in the closed and locking positions of the at least one door and the respective locking member 
         [0019]    Preferably there is a second inclined ramp surface carried on the at least one extension member and approaching the second latching point in a manner increasing in elevation theretoward to lift the respective locking member out of the locking position during movement of the at least one door into the open position, whereupon the locking member falls into the locking position and into engagement with the second latching point. 
         [0020]    Preferably the at least one locking member is biased into the locking position. 
         [0021]    Preferably at least one spring biases the at least one locking member into the locking position. 
         [0022]    Preferably the at least one door is biased into the closed position. 
         [0023]    Preferably at least one gas spring is coupled between the pen and the at least one door and biases the at least one door into the closed position. 
         [0024]    Preferably a foot pedal is movably mounted on the pen at a position adjacent a bottom end thereof at a side thereof that resides adjacent to the ground vehicle in the working position, and a linking device is coupled between the foot pedal and the rotatable actuation member so as to drive rotation thereof under actuation of the foot pedal. 
         [0025]    Preferably the linking device comprises a link having a first end coupled to the foot pedal at a position eccentrically offset from a pivot axis of the foot pedal and a second end coupled to the rotatable actuation member at a position eccentrically offset from a rotational axis thereof such that pivoting of the foot pedal about its pivot axis drives rotation of the rotatable actuation member. 
         [0026]    Preferably the foot pedal is arranged to drive rotation of the rotatable actuation member in the unlocking direction under depression of the foot pedal. 
         [0027]    Preferably the rotatable actuation member is linked to the at least one lock member by at least one flexible member. 
         [0028]    Preferably the at least one flexible member is a flexible chain. 
         [0029]    Preferably the at least one door comprises two doors, and the at least one locking member comprises two locking members, one for each of the two doors. 
         [0030]    According to a second aspect of the invention there is provided a portable enclosure for attachment to a ground vehicle for capturing and retaining an animal, the portable enclosure comprising: 
         [0031]    a pen arranged for attachment to the ground vehicle in a working position residing thereaside; 
         [0032]    an front opening in the pen at a front end thereof that faces forwardly of the ground vehicle when the pen is attached thereto in the working position; 
         [0033]    at least one door movably mounted to the pen and movable between a closed position obstructing the front opening of the pen and an open position revealing the front opening of the pen; and 
         [0034]    a locking mechanism having at least one locking member arranged to engage with the at least one door in both the open and closed positions thereof, whereby the same at least one locking member locks the at least one door in both the open and closed positions. 
         [0035]    Preferably the locking mechanism is arranged to automatically engage the at least one locking member with the at least one door in both the open and closed positions thereof. 
         [0036]    Preferably the at least one door comprises: 
         [0037]    at least one door panel that resides in the front opening of the pen the closed position and, in said closed position, is engaged by the at least one locking member to lock the at least one door in the closed position; and 
         [0038]    at least one extension member that extends out from the at least one door panel for engagement by the at least one locking member in the open position of the at least one door to lock the at least one door in the open position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    One embodiment of the invention will now be described in conjunction with the accompanying drawings in which: 
           [0040]      FIG. 1  is a front side perspective view of a vehicle-carried calf-catching enclosure according to the present invention. 
           [0041]      FIG. 2  is an overhead plan view of the vehicle-carried calf-catching enclosure. 
           [0042]      FIG. 3  is a partial closeup view of the vehicle-carried calf catching enclosure, showing a spring loaded locking member at the front end thereof for automatically locking doors of the enclosure in both open and closed positions. 
           [0043]      FIG. 4  schematically illustrates use of a foot-pedal lock release mechanism, as would be seen from the left side of  FIG. 1 , to release the spring loaded locking member of  FIG. 3  and enable automatic closing of the doors from their open positions. 
           [0044]      FIGS. 5A, 5B and 5C  are overhead views of one of the doors of the vehicle-carried calf catching enclosure in closed, open and intermediate positions, respectively, as would be viewed along cross-sectional line A-A of  FIG. 1 . 
           [0045]      FIGS. 6A through 6D  illustrate use of an inclined ramp surface of a strike plate on a door panel of one of the doors of the vehicle-carried calf catching enclosure during closing of the door in order to raise the spring loaded locking member to a ready state for subsequent automatic re-deployment thereof once the door is fully closed. 
           [0046]      FIGS. 7A and 7B  another a strike plate on an extension member of one of the doors, which features another ramp surface that is inclined in two directions relative to an axis of the extension member in order to similarly ready the spring-loaded locking member for automatic re-deployment thereof once the door is fully opened. 
       
    
    
       [0047]    In the drawings, like characters of reference indicate corresponding parts in the different figures. 
       DETAILED DESCRIPTION 
       [0048]      FIG. 1  illustrates a calf-catching enclosure  10  of the present invention for mounting on an ATV or other vehicle  200  in a position residing alongside same, as shown in the overhead plan view of  FIG. 2 . The enclosure features a pen  12  having parallel front and rear walls  14 ,  16  and parallel inner and outer side walls  18 ,  20  extending between the front and rear walls to delimit an interior space of the pen between the four walls. Each wall includes a frame of rectangular metal tubing, and a mesh or grid formed of smaller metal rods perpendicularly crossing one another between members of the frame. The two side walls  18 ,  20  consist of an inner wall  18  that faces laterally toward the ATV and an opposing outer wall  20  that faces laterally away therefrom. The outer wall  20  consists of a singular panel whose area is bound on all four sides thereof by respective frame members, and which is overlaid with the respective mesh or grid. The inner wall  18  instead consists of two smaller panels  22 ,  24  upstanding from a bottom frame member  26  of the wall on opposite sides of an operator access opening  28  in the wall  18  through which the user of the enclosure  10  can enter and exit the interior space of the pen  12 . Except for a reinforcement member  30  of the frame that lies parallel to a bottom frame member  26  at a short height thereabove to span between upright frame members  32 ,  34  of the two panels  22 ,  24 , the operator access opening  28  is entirely unobstructed to give the operator convenient access to the interior of the pen. The rear wall  16  features a singular mesh or grid spanning between respective upright frame members  36 ,  38  at the rear ends of the two side panels overtop of a bottom frame member  40  of the rear wall  16 . 
         [0049]    A ground wheel  42  is rotatably mounted to a bottom frame member  44  of the outer side wall  20  to rollingly carry the pen on the ground during use. At the inner side of the pen  12 , a pair of lateral arms  46  project perpendicularly from the bottom frame member  26  of the inner side wall  18  at opposing ends thereof that reside at the corners between this side wall  18  and the front and rear walls  14 ,  16 . These arms  44  lie in the same plane as the bottom frame member  26  of the inner wall, and each carry a respective hitch coupler  46  at the distal end of the arm furthest from the bottom frame member  26 . The hitch couplers  48  mate with a respective hitch balls at the front and rear ends of the ATV, as shown in  FIG. 2 . Each arm is held rigidly by angled reinforcement members  50 ,  52  extending from the arm to the bottom and upright frame members  26 ,  36 ,  56  of the inner side wall. As shown in  FIG. 2 , with each hitch coupler  48  mated and locked to the respective hitch ball of the ATV  200 , the ground wheel  42  rollingly supports the pen  12  alongside the ATV for conveyance therewith in a forward working direction F during operation of the ATV. Use of two hitch couplers at the same low elevation in the plane of the of the bottom frame members of the pen to connect to two lower frame-level ball hitches on the ATV provides the enclosure with confident stability during use. 
         [0050]    The front wall  14  features an upper panel  54  bound at its ends by a pair of upright frame members  56 ,  58  shared by the front wall with the inner and outer side walls  18 ,  20 . Upper and lower cross-bars  60 ,  62  spanning perpendicularly between the upright frame members  56 ,  58  complete the perimeter of the upper panel  54 . A respective mesh or grid of the panel is fixed in place over the front side or rear of the panel&#39;s perimeter. The upper panel  54  spans only a partial elevation of the front wall  14 , for example approximately half of this elevation in the illustrated embodiment. A front opening  64  of the pen  12  resides beneath this fixed upper panel  54 , and has a pair of doors  66 ,  68  pivotally mounted therein for movement of the doors  66 ,  68  between closed positions obstructing this opening  64  ( FIGS. 1, 2, 5A ) and open positions ( FIG. 5B ) revealing the front opening  64  to enable entrance of a calf to the interior space of the pen through this opening  64 . Each door  66 ,  68  features a main door panel  70  having a frame that delimits a generally rectangular area occupied by, or overlaid with, a respective mesh or grid, just like the panels of the pen walls. Each door panel  70  is hinged to a respective one of the upright frame members  56 ,  58  at the corners between the front and side walls of the pen  12  for swinging movement of the door between the open and closed positions about the generally vertical pivot axes of the hinges  72 . 
         [0051]    A top frame member  74  of each door panel  70  has a respective strike plate  76  welded or otherwise affixed thereatop. As best shown in the closeup view of  FIG. 3 , each strike plate  76  has a bent shape with a horizontal front portion  78  cantilevered forwardly from the horizontally oriented top frame member  74  of the door panel  70 , and an angled rear portion  80  sloping downwardly and rearwardly from the top frame member  74  of the door panel  70 . The terms horizontal and vertical, as used herein, are with particular reference to the illustrated level orientation of the pen  12  in  FIGS. 1 and 2 , in which the coplanar bottom frame members of the pen reside in a horizontal plane, and the walls and doors of the pen all reside in vertical planes with the top frame. It will be appreciated that in use, the specific orientation of the pen may vary somewhat and reside in a slightly tilted orientation, for example due to variation in the ground surface on which the ATV and pen are disposed, variation between the hitch to ground measurement of the ATV versus the wheel axis to ground measurement of the pen&#39;s ground wheel, and or due to variation between hitch to ground measurement at the front and rear ends of the ATV. The front portion  78  of each strike plate  76  features a respective hole  82  passing vertically therethrough to define a latching point at which the door is engagable by a respective locking member  84  mounted to the upper panel of the front wall for locking the door in the closed position. 
         [0052]    With continued reference to  FIG. 3 , each locking member  84  in the illustrated embodiment is an L-shaped latch pin having a vertical leg  84   a  for engaging the strike plate  76  of the respective door at the latching point hole  82  therein, and a horizontal leg  84   b  projecting laterally from the top end of the vertical leg  84   a.  Each locking member  84  is carried by a respective mounting bracket  86 , which features two forward-projecting horizontal flanges  88 ,  90  fixed to a backing plate  92 , which in turn is affixed to the front face of the lower cross-bar  62  of the front wall&#39;s upper panel  54  above the front opening  64  of the pen  12 . The vertical leg  84   a  of the locking member  84  passes through a pair of aligned holes in the two flanges  88 ,  90 . A stop collar  94  is affixed to the vertical leg  84   a  of the locking member  84  at a position residing between the two flanges  88 ,  90  of the mounting bracket  86 , and has a diameter exceeding that of the hole in the lower flange  90  of the mounting bracket  86 . The stop collar  94  limits downward movement of the locking member  84  and defines a default lock-engaging position thereof in which the vertical leg  84   a  of the locking member reaches downwardly far enough to penetrate the latch point hole  82  in the strike plate  76  of the door panel  70 , when in the closed position. A compression spring  96  coils around the vertical leg  84   a  of the locking member  84  between the stop collar  94  and the upper flange  88  of the mounting bracket  86  in order to bias the locking member downwardly into the default lock-engaging position. In the closed position of each door, the door panel  70  resides within the front opening  64  of the pen beneath the lower cross-member  62  of the front wall&#39;s upper panel  54 , and the front portion  78  of the door panel strike plate  76  reaches forwardly out from the front opening  64  of the pen to align the hole  82  of the strike plate  76  with the holes of the two mounting bracket flanges  88 ,  90 , thereby enabling engagement of the locking member  84  with the strike plate in order to latch the door in place. 
         [0053]    A respective upright  98  stands vertically upward from the lower cross-bar  62  of the upper panel  54  of the front wall  14  at a position adjacent each one of the mounting brackets  86 , and a rotatable actuation member  100  is provided in the form of a horizontal rod or shaft journaled to the two uprights  98  for rotation about the shaft&#39;s longitudinal axis. Beside each upright  98 , a respective flexible member  102  in the form of a flexible chain has an upper end welded or otherwise affixed to the rotatable actuation member  100 , and a lower end welded or otherwise affixed to the horizontal leg  84   b  of the respective locking member  84 . The flexible members  102  thereby link the rotatable actuation member  100  to the two locking members  84  such that rotation of the rotatable actuation member  100  in an unlocking direction D acts to wind more of the flexible member  102  around the rotatable actuation member  100 , thereby pulling the two locking members  84  upward. 
         [0054]    A foot pedal  104  is pivotally mounted to the upright member  32  of the front panel  22  of the inner side wall  18  at a short height above the lower frame member  26  thereof. The foot pedal  104  is in the form of a flat plate  104   a  affixed to a circular rod  104   b  at its forward end. The circular rod  104  reaches horizontally into the interior space of the pen  12  through a hollow sleeve  106  that is affixed to the front side of the upright frame member  32 . A connection lug  108  is affixed to the end of the rod  104   b  that resides inside the pen, and projects radially upward from the rod  104   b.  A linking device  110  in the form of an elongated tie-rod has one end thereof coupled to the connection lug  108  at a point located eccentrically outward from the rod  104   b.  The rotatable actuation member  100  likewise features a respective connection lug  112  projecting radially upward therefrom for connection to the second end of the linking device  110  at a position located eccentrically outward from the rotatable actuation member  100 . A pair of stop tabs  114 ,  116  are affixed to the upright frame member  32  on which the foot pedal is carried at the side of the upright frame member  32  facing toward the ATV, and are positioned respectively above and below the foot pedal plate  104   a  to limit pivoting of the foot pedal  104  in both upward and downward directions about its horizontal pivot axis, as defined by the rod  104   b.  With the linking device  110  connected between the foot pedal  104  and the rotatable actuation member  100 , depression of the foot pedal plate  104   a  downward toward the lower stop  116  pulls the actuation member&#39;s connection lug  112  rearward to rotate the actuation member  100  in the unlocking direction D that wraps more of the flexible chains  102  rearwardly over the top of the actuation member  100 . 
         [0055]    In addition to the door panel and the respective strike plate  76  mounted thereon, each door features an extension member  118  affixed to the rear facing side of the top frame member  74  of the door panel  70 , as perhaps best shown in  FIG. 5A . The extension member of the illustrated embodiment is formed of a bent piece of rectangular metal tubing, which has a first portion  118   a  extending generally along the top frame member  74  past the outer end thereof nearest to the side wall of the pen to which the door is hinged. Here, the extension member  118  bends through a curvature of more than 90° but less than 180°, so that a second portion  118   b  of the extension member  118  extends rearwardly away from the door panel  70  while angling back toward, without reaching, a vertical plane P that cuts perpendicularly through the door panel  70  at the location of the strike panel  76  thereon. In the door&#39;s closed position, the extension member reaches outwardly through an opening in the mesh or grid of the respective side wall  18 , 20  of the pen, as can be seen in  FIG. 2 . 
         [0056]    The distal end of each extension member carries a respective strike plate  120 , which like the strike plate  76  of each door panel  70  features a hole  122  passing perpendicularly therethrough. A cross-member  124  spans between the two portions  118   a,    118   b  of the extension member at a distance from the curved bend  118   c  that joins these two portions together. A biasing member  126  in the form of a tension gas spring has one end pivotally coupled to the cross-member  124 , and the other end pivotally coupled to the lower cross-bar  62  of the front wall&#39;s upper panel  54  near a mid-point thereof, for example at a mounting lug  128  projecting rearwardly from the cross-bar  62 , as shown in  FIGS. 2 and 5 . 
         [0057]    The strike plate  120  of each extension member  118  is tilted relative to a longitudinal axis A 1  of the second portion  118   b  of the extension member  118  in two different dimensions. Firstly, moving along the longitudinal axis A 1  toward the free end  120   a  of the strike plate  120  that is situated furthest from the distal end  118  of the extension member, the strike plate  120  slopes obliquely downward relative to the longitudinal axis A 1  by an acute angle, as shown in  FIG. 7B . Secondly, the strike plate  120  is tilted about its own longitudinal axis A 2  so that its side edge  120   b  facing toward the door panel  70  is lower than its other side edge  120   c  that faces away from the door panel  70 . Accordingly, the strike plate  120  on each extension arm  118  is tilted relative thereto in both the length and width directions of the strike plate  120 . 
         [0058]    In the open position of each door, the extension member  118  thereof positions its strike plate  120  beneath the respective locking member mounting bracket  86  with the strike plate hole  122  in alignment with the holes of the mounting bracket flanges  88 ,  90 , thereby enabling receipt of the locking member  84  in a latched state with the strike plate  120 . Accordingly, the strike plate  120  on the extension member acts similar to the strike plate  76  of the door panel  70 , but to lock the door in the open position rather than the closed position.  FIGS. 5A and 5B  show one of the doors  66  in its closed and open positions respectively, while  FIG. 5C  shows the door  66  in an intermediate position during movement between the open and closed positions. 
         [0059]    To prepare the calf catching enclosure  10  for use, the two hitch couplers  48  are coupled to the front and rear hitch balls of an ATV. The installation of front and rear frame-height ball hitches on an ATV is already known in the art, and therefore not described herein in further detail. At the front end of the enclosure, at a position inside or outside the pen, the user manually pulls up the locking member  84  of one door (against the downward biasing force of the respective compression spring  96 ) in order to withdraw the vertical leg  84   a  of the locking member from the latching point hole  82  in the respective door panel strike plate  76 , thereby unlocking the closed door. With the locking member held in this withdrawn position, the user swings the door outwardly from the closed position in the front opening  64  of the pen into the open position shown in  FIG. 5B . With the locking member released  84 , the respective compression spring  96  forces the respective locking member  84  downwardly into engagement with the latching point hole  122  in the extension member strike plate  120 , thereby locking the door in the door in the open position. This process of unlocking, opening and automatically relocking the door is then repeated for the other door, thus putting the enclosure in a ready condition for use. 
         [0060]    The user drives the ATV in the forward working direction F, thus conveying the pen  12  forwardly alongside the ATV with the front doors of the pen secured in the open positions. The user drives up alongside a calf, thereby transitioning the calf from the open environment into the interior of the pen via the front opening  64  due to the open state of the doors during this process. As soon as the calf is inside the pen, the user, from the operating seat of the ATV, depresses the foot pedal plate  104   a  of the foot pedal  104  downwardly, thus withdrawing both locking members  84  upwardly into their lock-releasing positions unlocking the currently open doors of the pen, at which point the two gas springs  126  automatically pull the two doors closed in order to secure the calf inside the pen. 
         [0061]      FIG. 6  schematically illustrates how each locking member  84  and the corresponding door panel strike plate  76  cooperate during the closing of the respective door to achieve automatic re-locking of the door upon arrival thereof in the fully closed position. As the door is being closed, i.e. moving from the fully open position of  FIG. 5B  through the intermediate position of  FIG. 5C  and onward toward the fully closed position of  FIG. 5A , the inclined ramp portion  80  of the door panel strike plate  76  approaches the locking member&#39;s mounted position on the front wall of the pen, as schematically shown in  FIG. 6A . The lower end  80   a  of the inclined ramp portion  80  is situated at an elevation below that at which the lower end of the locking member&#39;s vertical leg  84   a  resides when in its lowest spring-biased lock-engaging position. The elevation of the horizontally cantilevered portion  78  of the door panel strike plate  76 , i.e. the elevation at which the inclined ramp portion  80  joins to the horizontal portion  78 , equates to an attainable elevation of the locking member&#39;s lower end that occurs prior to full compression of the respective spring  86 . Turning to  FIG. 6B , as the inclined ramp portion  80  of the door panel strike plate  76  reaches the mounted position of the locking member  84 , the bottom end of the locking member comes into contact with the ramp portion  80  and rides upwardly therealong as the door panel continues toward the closed position, whereby the locking member  84  is pushed upwardly against the bias of the compression spring  86 . Turning to  FIG. 6C , the lower end of the locking member  84  rides up onto the horizontal portion  78  of the strike plate  76  and comes into alignment with the latch hole  82  as the door reaches the fully closed position. At this point, with reference to  FIG. 6D , the compression spring  86  forces the bottom end of the locking member  84  downwardly through the latch hole  82 , thereby automatically locking the door in the fully closed position. 
         [0062]    This self-locking closure of the door means that the pedal-initiated closing of the two doors during use of the enclosure to capture a calf will automatically lock the doors in their closed positions to prevent escape of the calf from the interior of the pen. The user can enter the interior of the pen from the operator seat of the ATV through the operator access opening  28  in the inner side wall  18  of the pen, and tend to the calf in a position safely isolated from the mother cow by the walls of the pen and by the ATV, which bocks the mother cow&#39;s access to the operator access opening  28 . Once the calf has been tagged, treated or otherwise processed, the user remains safely inside the pen and manually lifts the horizontal leg  84   b  of the locking member  84  of one or both of the doors in order to release the locking member from its latched condition with the respective door panel strike plate  76 , and pushes the respective door panel outward from the closed position toward the open position to allow the calf to exit the pen and return to the surrounding field environment. 
         [0063]    When opening the doors during preparation of the enclosure for use, the tilted orientation of each extension member strike plate  120  works in the same manner as the bent shape of the door panel strike plate  76  to force the respective locking member  84  upwardly as the door approaches the position in which it is to be locked. That is, the extension member strike plate  120  slopes upwardly toward the latch point hole  122  therein from the distal end  120   a  and from lower side edge  120   b,  whereby the area between the latch point hole  122  and distal end  120   a  and lower side edge  120   b  defines an inclined ramping surface that increases in elevation toward the latch point hole  122  in order to drive the lower end of the locking member  84  upwardly against the bias of the respective compression spring  86  as the respective door approaches the fully open position of  FIG. 5B  from the closed and intermediate positions of  FIGS. 5A and 5C . As the door reaches the fully opened position aligning the latch point hole  122  with the raised lower end of the locking member  84 , the compression spring  86  forces the lower end of the locking member  84  downwardly through the latch point hole  122  in order to automatically lock the door in the fully opened position. 
         [0064]    The forgoing embodiment of the present solution includes a number of novel, inventive and potentially advantageous features, including the unique arrangement of a rotatable actuation member for raising the downwardly biased locking members up into released positions allowing movement of the doors, foot pedal operation of the actuation member for convenient unlocking of the doors from the operator seat of the ATV, the use of the same members  84  to secure each doors in both the open and closed positions, and the use of inclined strike plate ramp surfaces to automatically lift the locking members into ready positions for subsequent deployment during an automatic locking action. 
         [0065]    While the illustrated embodiment features two doors, each having a respective locking member and pair of strike plates, it will be appreciated that an alternate embodiment may feature a singular door spanning the width of the front opening from one hinged side while employing similar use of a the same lock member to lock the door in the open and closed positions. It will also be appreciated that the unique overhead actuation member for releasing the locked condition of the door(s) may rely on an input other than a foot operated pedal to initiate its rotational action. Additionally, the overhead actuation member and/or the use a sloped strike plate to control the locking member(s) may be used regardless of whether that locking member is used to lock the door in both open and closed positions, or to lock the door in only one of those positions. While the illustrated embodiment uses gas springs to bias the doors toward the closed position, and compression springs to bias the locking members toward the locking position, it will be appreciated that other biasing means may be employed. For example, in one embodiment, gravitational biasing of the locking member(s) downwardly toward their lock-engaging positions may be sufficient without an additional resilient such as the disclosed compression spring. It will also be appreciated that the particular shape of the pen and its interior space may be varied. 
         [0066]    For example, in one embodiment (not shown) the rear wall may be built out over a partial span of its width to accommodate a smaller floor-equipped cage inside the larger pen for transporting a calf from its captured position in the field, whereby the built-out area of the rear wall would change the shape of the overall interior space of the pen from the rectangular volume of the illustrated embodiment. 
         [0067]    Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the scope of the claims without departure from such scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.