Abstract:
An improved portable squeeze chute apparatus includes a chute having an entrance end, an exit end, opposing sidewalls, a base and a frame. Each of the sidewalls has a plurality of openable and removable upper panels and openable lower panels for accessing upper portions and lower portions of an animal positioned in the chute. Each of the sidewalls is selectively positionable along a generally horizontal axis in order to immobilize lateral movement of an animal positioned in the chute. An exit gate is positioned at the exit end of the chute to prevent the animal from exiting forwardly from the chute. An entrance gate has interconnected entrance gate side portions for selectively preventing the animal from exiting rearwardly from the chute. Various portions of the apparatus are each controllable by a respective hydraulic chain drive assembly. One such portion includes a pair of arcably pivoting neck stretchers for selectively immobilizing the animal&#39;s head and neck while the animal is being worked. The controls for the hydraulically powered portions of the chute are disposed at the end of a pivotally mounted boom for easy control of the chute from any side of the chute. A removable and adjustable sternum support is also provided to safely support the animal while it is worked.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to livestock handling equipment and more particularly to a squeeze chute for selectively immobilizing an animal in a standing position to safely allow any number of operations to be safely performed on the animal.  
           [0003]    2. Description of the Prior Art  
           [0004]    In livestock operations it is often necessary to restrain the animals for palpating, immunizing, branding, treating, weighing, loading, etc. Corrals, loading chutes, alleyways, pens, and the like, have heretofore been constructed and employed by livestock operators and veterinarians for these purposes. These structures are often constructed permanently from materials such as stone, barbed wire, wooden rails, steel pipe, and the like. However the capital investment required for such permanent structures is often prohibitive to ranchers having small operations, particularly those that operate their livestock on small isolated tracts of grazing land. Furthermore, many such ranchers lease, rather than own, their grazing land and naturally wish to avoid making permanent, fixed improvements.  
           [0005]    A common solution to this problem is to physically transport the livestock to a remote location having the necessary equipment. However, transporting a herd of large animals tends to be relatively time-consuming and expensive. A round trip from the grazing pasture to a treatment facility requires loading, transporting, and unloading the animals twice. Naturally, the time and expense associated with transporting livestock increases with the distances and number of animals involved.  
           [0006]    A disadvantage with many prior art portable animal handling devices is that large animals can be hazardous to workers trying to direct and control them with such equipment. Animals that are unaccustomed to confinement frequently balk at entering confining structures and may even panic. After being restrained, an animal may then suddenly begin kicking or attempt to climb up or back out of the chute. Many of the prior art animal-working structures provide little or no protection from such hazards.  
           [0007]    Squeeze chutes can be provided with hydraulic power systems for opening and closing their gates and constricting and expanding their sidewalls to reduce or expand the size of the enclosure in which animals are received. Hydraulic power systems have the advantage of permitting control of the operable components from a single control station. However, these control systems are typically located in a fixed position at one end of the squeeze chute. This can limit the operator&#39;s view of the work being performed on the animal and typically limits the placement of the squeeze chute with respect to permanent structures located nearby.  
           [0008]    Prior art squeeze chutes are usually provided with sides that pivot inwardly about their bottom ends in order to squeeze livestock. Since the distance between the sides at the bottom must conform substantially to the width of the animal, this type of chute requires adjustment in the spacing of the sides if both large and small animals are to be handled. It is also difficult for large animals to enter or be driven into the chute because its width at the bottom is barely sufficient to accommodate the animal. In addition, the manner in which the sides pivot tends to shock or excite the animal and often causes the animal to lose its balance. The construction of the sides of existing squeeze chutes presents an additional problem in that the sides obstruct access to much of the animal&#39;s body, making examination and other operations on the animal difficult.  
           [0009]    Another problem with many prior art squeeze chutes relates to the operation of their gates. Squeeze chute gates often include a pair of panels, which are pivotally mounted on the squeeze chute frame so that they traverse arcs when they are moved between their open and closed positions. This motion tends to swing the panels into the faces of the animals, contributing to the animal&#39;s stress and sense of distress.  
           [0010]    During particular treatment operations, the head of the animal must be firmly held in place to avoid injury to both the animal and the operator. For example, the application of ear tags, implants or other medicaments in the animal&#39;s ear is accomplished more safely if the animal&#39;s head is substantially immobilized. The same is true during the examination of the animal&#39;s eyes, ears and teeth. It is further preferred that the animal&#39;s neck be fully exposed and nearly motionless when taking blood samples from or making injections of any kind of serum into the animal&#39;s neck.  
           [0011]    The present methods of substantially immobilizing the animal&#39;s head all require substantial physical effort by the operator. Nearly all of the methods include use of a stanchion either fixed or formed as a part of a portable chute such as those used for de-horning. The animal is held in the stanchion to keep its body confined. Then, a tray or platform may be placed under the animal&#39;s head, which is pressed against the tray to hold it in place. An alternative prior art method uses fixed length arms, which extend outwardly from the stanchion gate. These arms are typically not adjustable and generally need to be used in combination with a nose ring and rope. If the animal becomes excited when this method is used, it is necessary for the operator to hold the head until the nose ring can be inserted and the rope tied before the desired operation can be carried out.  
           [0012]    Prior art squeeze chute designs typically limit the operator&#39;s ability to safely enter the rearward end of the chute, behind the animal, without compromising the physical restraint of the animal. Furthermore, such prior art designs are incapable of selectively immobilizing the animal&#39;s hip area without increasing the transverse squeeze pressure exerted by the opposing sidewalls. Accordingly, even if the operator is able to enter the chute behind the animal, simple animal husbandry operations are made difficult if not dangerous.  
           [0013]    As the animals are worked, some may have a tendency to lie down or even collapse under the surrounding conditions. Prior art squeeze chutes typically do not provide for a method of selectively and adjustably supporting the animal&#39;s abdomen. This not only increases the difficulty of working the animal but compromises the safety of the animal.  
           [0014]    What is needed is an animal working apparatus that provides working accessibility to an animal confined therein while assuring relative safety and comfort for both the confined animal being worked and the operators who are working the animal.  
         SUMMARY OF THE INVENTION  
         [0015]    The portable squeeze chute of the present invention is provided for restraining livestock during any number of operations, including branding, vaccinating, artificially inseminating, de-horning, or the like. The chute is generally comprised of a frame, an entrance gate, an exit gate, opposing sidewalls, and a base having adjustably removable sections. The sidewalls are connected to the superstructure such that they are selectively positionable along generally horizontally oriented axis, which extend transversely to the chute. The sidewalls remain parallel as they move equidistantly toward one another to provide equal squeezing pressure to both sides of the animal.  
           [0016]    Each of the opposing sidewalls is comprised of a plurality of lower panels, which are pivotable about generally vertical axis at the lower extremity of each sidewall to provide access to the lower portions of the animal. A lower panel latching mechanism selectively retains the lower panels in a closed configuration. The lower panels have planar inner surfaces to avoid providing footholds for an animal positioned in the chute.  
           [0017]    The opposing sidewalls are each further comprised of a plurality of removable upper panels, which are pivotable about generally vertical axis between open and closed positions. The upper panels provide access to the upper portions of an animal positioned in the chute. Upper panel latching mechanisms selectively retain the upper panels in their closed configurations.  
           [0018]    The entrance gate has a pair of cooperating entrance doors, which are interconnected so that they synchronously slide along a generally horizontal axis between open and closed positions. As the animal enters the chute, the entrance doors are closed to prevent the rearward movement of the animal. The exit gate is positioned opposite the entrance gate and is provided with opposing doors, which are adapted to selectively abut the sides of an animal&#39;s neck. The exit gate doors are interconnected such that they synchronously slide along a generally horizontal axis. When the exit gate is closed, the animal&#39;s forward and rearward movement is prevented and the animal can be safely worked. When the exit gate is opened, the animal&#39;s forward motion is no longer restrained and it is free to exit the chute.  
           [0019]    A pair of elongated neck-stretchers are pivotally mounted adjacent the top portion of the exit gate. When the exit gate is in its closed position, the neck-stretchers can be selectively extended in an arcing direction to engage the lower rearward portion of the animal&#39;s head to immobilize the same.  
           [0020]    A hip-immobilizing arm is provided for selectively restraining the hip area of the animal. Once the hip area of the animal is restrained, the operator can enter the squeeze chute through one of two rear doors that are mounted to the frame of the chute between the entrance gate and each of the opposing sidewalls. In this position, the operator can safely perform several procedures at the rear of the animal.  
           [0021]    A hydraulically powered, roller chain assembly is provided for mechanically operating the opposing sidewalls, the entrance and exit gates, the neck-stretchers and the hip-immobilizing arm. A central control station is provided, which allows a single person to easily operate the squeeze chute. The control station is disposed at the end of a pivotally mounted boom to allow the operator to control the chute from nearly any position around the chute.  
           [0022]    An elongated abdomen support is removably secured to the floor of the squeeze chute, between its entrance and exit ends. The abdomen support prevents the animal from laying down while it is being worked. The height of the abdomen support is adjustable to accommodate different sized animals.  
           [0023]    It is one of the important objects of the present invention to provide an improved livestock squeeze chute which includes upright sides that remain parallel at all times and are moved equidistantly toward one another to squeeze the animal equally from each side.  
           [0024]    Another important object of the invention is to provide a squeeze chute which is able to accommodate both large and small animals without the necessity of structural changes or adjustments.  
           [0025]    An additional object of the invention is to provide a squeeze chute in which both the squeeze and release functions of the chute can be fully operated easily and rapidly by a single man from either side of the chute.  
           [0026]    A further object of the invention is to provide a squeeze chute having side doors to provide the operator with easy access to the interior of the chute behind the restrained animal.  
           [0027]    An additional object of the invention is to provide a squeeze chute having easily openable and removable panels and doors on the sides to facilitate access to the entire body of the animal.  
           [0028]    A further object of the invention is to provide a squeeze chute having structure that prevents the restrained animal from climbing out the top end of the squeeze chute.  
           [0029]    An additional object of the invention is to provide a squeeze chute having a removable abdomen support that is adjustable in height to accommodate animals of different height.  
           [0030]    A further object of the invention is to provide a squeeze chute having removable floor panels.  
           [0031]    An additional object of the invention is to provide a squeeze chute having floor panels that are comprised of a plurality of horizontally and vertically spaced traction steps.  
           [0032]    A further object of the invention is to provide a squeeze chute having a device for selectively restraining the hip area of the animal.  
           [0033]    An additional object of the invention is to provide a squeeze chute wherein the retraining functions are hydraulically powered to allow a single operator to restrain the selected animal.  
           [0034]    A further object of the invention is to provide a squeeze chute having a hydraulically powered, roller chain assembly for easily and efficiently operating the restraining structures of the squeeze chute.  
           [0035]    An additional object of the invention is to provide a squeeze chute that selectively restrains an animal while reducing the incidence of injury to the animal and operator alike.  
           [0036]    These and other objects will be apparent to those skilled in the art.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    [0037]FIG. 1 is a rear perspective view of the squeeze chute of the present invention;  
         [0038]    [0038]FIG. 2 is a front perspective view of the exit gate of the squeeze chute in an open position;  
         [0039]    [0039]FIG. 3 is a plan view of the squeeze chute of the present invention;  
         [0040]    [0040]FIG. 4 illustrates the chain-drive system of the squeeze chute of the present invention;  
         [0041]    [0041]FIG. 5 is a schematic of the hydraulic assembly of the squeeze chute of the present invention;  
         [0042]    [0042]FIG. 6 is a partial perspective view of the entrance gate of the squeeze chute of the present invention and the associated upper horizontal chain-drive assembly;  
         [0043]    [0043]FIG. 7 is a partial perspective view of a lower horizontal chain-drive assembly of the squeeze chute of the present invention;  
         [0044]    [0044]FIG. 8 is a side view of the neck extender of the squeeze chute of the present invention in an extended position;  
         [0045]    [0045]FIG. 9 is a side view of the hip immobilizer of the squeeze chute of the present invention in an extended position;  
         [0046]    [0046]FIG. 10 is a front perspective view of the interior of the squeeze chute of the present invention;  
         [0047]    [0047]FIG. 11 is an exploded view of the hip immobilizer of the squeeze chute of the present invention;  
         [0048]    [0048]FIG. 12 is side elevation view of the abdomen support of the squeeze chute of the present invention;  
         [0049]    [0049]FIG. 13 is a perspective view of the lower side doors of the squeeze chute of the present invention;  
         [0050]    [0050]FIG. 14 is a perspective view of an upper sidewall door of the squeeze chute of the present invention and an associated mounting pin;  
         [0051]    [0051]FIG. 15 is a side elevation view of a rear access door of the squeeze chute of the present invention;  
         [0052]    [0052]FIG. 16 is a front elevation view of the squeeze chute of the present invention illustrating the operation of the hip immobilizing arm;  
         [0053]    [0053]FIG. 17 is front elevation view of the exit gate of the squeeze chute of the present invention in a closed immobilizing position; and  
         [0054]    [0054]FIG. 18 is a perspective view of an alternate embodiment of an upper sidewall door of the squeeze chute of the present invention and an associated mounting pin. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0055]    A squeeze chute  10  for working livestock, shown in FIGS.  1 - 3 ,  8 ,  16  and  17 , is generally provided with a frame  12  having upper and lower ends and entrance and exit ends. An elongated, generally horizontal base  14  is connected to the frame  12 , closely adjacent the lower end thereof, and extends between the entrance and exit ends of the chute  10 . An entrance gate  16  is operatively secured to one end of the base  14  and is adapted to selectively slide in a transverse manner, between open and closed positions. An exit gate  18  is operatively secured to the opposite end of the base  14  and is also adapted to slide in a transverse manner, between open and closed positions. Opposing sidewalls  20  and  20 ′ are provided between the entrance gate  16  and exit gate  18 .  
         [0056]    Opposing sidewalls  20  and  20 ′ are operatively secured to the frame  12 , intermediate its entrance and exit ends. Sidewalls  20  and  20 ′ are selectively positionable along a generally horizontal axis, which extends transversely to the chute  10 , for immobilizing the lateral movement of the animal within the chute  10 . The sidewalls  20  and  20 ′ remain parallel and substantially vertical as they move equidistantly toward one another to provide equal squeezing pressure to both sides of the animal.  
         [0057]    Opposing sidewalls  20  and  20 ′ are substantially similar in structure. Accordingly, only sidewall  20  will be structurally described herein. Sidewall  20  is generally rectangular in shape, having upper and lower ends and opposite sides. A plurality of horizontally spaced lower panels  22  are provided adjacent the lower end of sidewall  20 , as illustrated by FIG. 13. Each lower panel  22  is manually pivotable about a generally vertical axis between open and closed positions to provide access to lower portions of the animal. A latch  24  is provided for selectively securing each lower panel  22  in their respective closed positions. The lower panels have planar inner surfaces  24  to avoid providing footholds for an animal positioned in the chute in the event that the animal attempts to exit the chute.  
         [0058]    A plurality of horizontally spaced upper panels  26  are provided adjacent the upper end of sidewall  20 , as illustrated by FIGS. 1, 10 and  14 . The upper panels  26  are each generally comprised of an inverted, vertically oriented, U-shaped bar  27 , which allows individuals working an animal positioned in the chute to remain outside the chute and reach the upper portions of an animal positioned in the chute. Flexible panels  25  are secured to each of the U-shaped bars  27  to cover the openings therein.  
         [0059]    It is preferred that only one side of the flexible panels  25  be secured to the U-shaped bars  27  to permit the operator to selectively move the panels aside and reach through the U-shaped bars  27 . It is contemplated that one or more flexible panels  25  can be  15  used with each U-shaped bar  27 .  
         [0060]    The lower ends of the U-shaped bars  27  have openings  28  formed therein, which are adapted to removably receive elongated mounting pins  30 . The mounting pins  30  are secured to the sidewall  20  and extend generally vertically therefrom, so that each upper panel  26  can be removably secured to the sidewall  20 . The upper  20  panels are pivotable about the generally vertical axis of mounting pins  30  between open and closed positions. Each upper panel  26  is provided with a latch  32  to selectively retain the upper panels  26  in their respective closed configurations. The upper panels  26  thus selectively provide manual access to the upper portions of an animal positioned in the chute.  
         [0061]    In an alternate embodiment, shown in FIG. 18, the opposing sidewalls  20  and  20 ′ could be provided with one or more upper panels  29 . Preferably, the upper panels  29  are secured to the mounting pins of opposing sidewalls  20  and  20 ′ in a manner similar to that of panels  26 . Panels  29  primarily differ from panels  26  in that panels  29  are wider than panels  26  so that, when the panels  29  are secured adjacent to the exit end of chute  10 , greater access is given to the animal&#39;s shoulder area for such procedures as vaccinations and the like. Due to the increased width of the U-shaped frame of panel  29 , it is preferred that the opening formed therein be filled or covered with a plurality of rigid bars  31 , rather than a single flexible panel  25 . However, it is contemplated that a combination of rigid bars  31  and flexible panels  25  could be used to fill the opening. The panels  29  open and close in a manner similar to the panels  26  and are selectively latched to the opposing sidewalls  20  and  20 ′ to prevent the panel  29  from freely opening due to movement by the animal.  
         [0062]    An entrance gate  16  is provided at the entrance end of the chute  10 , as illustrated by FIGS. 1, 3 and  6 . Entrance gate  16  is selectively movable between open and closed positions to allow the animal to enter the chute  10  and prevent it from exiting rearwardly therefrom. The entrance gate  16  is generally comprised of a pair of cooperating entrance doors  34  and  34 ′, which are interconnected so that they synchronously slide equally along a generally horizontal axis between the open and closed positions.  
         [0063]    The entrance doors  34  and  34 ′ are provided with upper and lower L-shaped tabs  36  for operatively, slidably connecting the upper ends of entrance doors  34  and  34 ′ to the upper end of frame  12 . Elongated, horizontally disposed brackets  38  retain the vertical portion of each tab  36 , while an elongated slot  40  operatively receives the horizontal portion of each tab  36 . The lower tabs  36  operatively and slidably connect the lower ends of entrance doors  34  and  34 ′ to the lower end of frame  12 . The bottom end of entrance doors  34  and  34 ′ are provided with a roller  42 , which is rotatably secured thereto. Rollers  42  operatively engage the lower portion of frame  12  to allow entrance doors  34  and  34 ′ to smoothly slide between their respective open and closed positions.  
         [0064]    Entrance doors  34  and  34 ′ are further comprised of panels  44 , which form the majority of the front and back surface area of entrance doors  34  and  34 ′. The opposite ends of panels  44  are operatively received by elongated, vertically disposed brackets  46 , which are secured to the sides of frame  12 . Brackets  46  help to guide entrance doors  34  and  34 ′ between their respective open and closed positions and prevent the longitudinal movement of entrance doors  34  and  34 ′ with respect to chute  10 .  
         [0065]    An exit gate  18  is provided at the exit end of the chute  10 , as illustrated by FIGS. 2, 3 and  17 . Exit gate  18  is selectively movable between open and closed positions to selectively permit and prevent at least the forward movement of the animal. The exit gate  18  is generally comprised of a pair of cooperating exit doors  48  and  48 ′, which are interconnected so that they synchronously slide equally along a generally horizontal axis between the open and closed positions. The inner ends of exit doors  48  and  48 ′ serve as a neck clamp, which is adapted to selectively abut opposing sides of an animal&#39;s neck, as illustrated by FIG. 17. In this closed position, the animal&#39;s forward and rearward movement is prevented and the animal can be safely worked.  
         [0066]    The exit doors  48  and  48 ′ are provided with upper and lower L-shaped tabs  36 ′, which are substantially similar in structure and function to those used on entrance gate  16 . The upper tabs  36 ′ operatively and slidably connect the upper ends of exit doors  48  and  48 ′ to the upper end of frame  12 . An elongated, horizontally disposed mounting shaft  50  (discussed in further detail below) retains the vertical portion of each tab  36 ′, while an elongated slot  40 ′ operatively receives the horizontal portion of each tab  36 ′. The lower tabs  36 ′ operatively and slidably connect the lower ends of exit doors  48  and  48 ′ to the lower end of frame  12 . The bottom end of exit doors  48  and  48 ′ are provided with a roller  42 ′, which is rotatably secured thereto. Rollers  42 ′ operatively engage a platform  43  secured to the lower portion of frame  12  to allow entrance doors  48  and  48 ′ to smoothly slide between their respective open and closed positions.  
         [0067]    Exit doors  48  and  48 ′ are further comprised of panels  44 ′, which are structurally and functionally similar to panels  44  of entrance gate  16 , that form the majority of the front and back surface area of entrance doors  48  and  48 ′. A plurality of vertically spaced, generally U-shaped members  52  are secured to the inner edges of exit gates  48  and  48 ′ and extend outwardly therefrom, adjacent the front surface of exit gate  48  and  48 ′. U-shaped members  52  provide additional structural support to panels  44 ′ to restrict the forward movement of the animal.  
         [0068]    Elongated neck-stretchers  54  and  54 ′ are pivotally, slidably secured to mounting shaft  50 , adjacent the top portion of the exit gate  18  and extend in a generally downward direction along the inner edges of exit doors  48  and  48 ′. When the exit gate  18  is in its closed position, the neck-stretchers  54  and  54 ′ can be arcably pivoted between extended and retracted positions. As the neck stretchers  54  and  54 ′ extend, they engage the lower rearward portion of the animal&#39;s head and extend the same in an upward and outward direction to immobilize the animal&#39;s head in an operable position. Neck-stretchers  54  and  54 ′ can be secured to mounting shaft  50  so that neck-stretchers  54  and  54 ′ extend generally perpendicularly from the longitudinal axis of mounting shaft  50 , as shown in FIGS. 2, 4 and  17 . In an alternate embodiment, however, mounting brackets  55  and  55 ′ are used to secure neck-stretchers  54  and  54 ′ to mounting shaft  50  so that, while neck-stretchers  54  and  54 ′ extend generally perpendicularly to mounting shaft  50 , they are offset a short distance “x” from the longitudinal axis of mounting shaft  50 . In this off-set position, the arc traversed by neck-stretchers  54  and  54 ′ is broadened somewhat. The distance “x” to which the neck-stretchers  54  and  54 ′ are off-set can be varied according to the breadth of arcing motion desired.  
         [0069]    An elongated abdomen support  56  is provided intermediate the entrance and exit gates, as illustrated in FIGS. 3, 10 and  12 . Abdomen support  56  is comprised of a generally angular elongated beam  58 , having first and second ends, and an elongated, generally vertically disposed support  60 . The support  60  is pivotally connected to beam  58  adjacent the first end thereof. The opposite end of support  60  and the second end of beam  58  are provided with generally U-shaped collars  62  and  62 ′, which are adapted to be removably secured to the base  14 . The height of abdomen support  56  is adjusted by operatively engaging support  60  at different angles with respect to base  14 . When support  60  is substantially vertically disposed, abdomen support  56  will be at its maximum height from base  14  to accommodate larger animals. As the angle of support  60  with respect to base  14  is decreased, the height of abdomen support  56  with respect to base  14  will proportionately decrease to support smaller animals.  
         [0070]    Base  14  is preferably comprised of a plurality of separate floor panels that are adapted to be removably connected to the lower end of frame  12  so that each such panel may be removed or interchanged. The individual panels are preferably comprised of a plurality of elongated bars  64 , extending transversely to frame  12 , in horizontally spaced relation to one another. It is further preferred that the elongated bars  64  be arranged in vertical spaced relation to one another to form alternating upper and lower traction steps  66  and  68 . The traction steps  66  and  68  provide the animal with the necessary traction to move through the chute in wet or muddy conditions. The removable feature of each base panel allows the operator vary the number of traction steps, if any, along the length of base  14 .  
         [0071]    At least one hip-immobilizing arm  70  can be removably secured to one of the sidewalls  20  or  20 ′, as illustrated in FIGS. 3, 10,  11  and  16 . The immobilizing arm  70  is comprised of an elongated arm  72 , having an engaging member  74  pivotally secured at one end thereof. The opposite end of arm  72  is pivotally secured to a first pin  76  within mounting box  78 . Cylinder  80  is rotatably secured at one end to arm  72  and rotatably secured at its opposite end to a second mounting pin  82  within mounting box  78 . Mounting box  78  is further comprised of a mounting sleeve, which is adapted to removably receive any of the mounting pins  30  along sidewalls  20  or  21 ′. Latch  84  is provided adjacent the top of mounting box  78  to releasably secure mounting box  78  to sidewall  20  or  20 ′, adjacent the top end thereof. Lever  86  is provided for engaging and releasing latch  84 .  
         [0072]    The immobilizing arm  70 , illustrated by FIGS. 9, 10 and  11 , can be selectively moved between extended and retracted positions. In its extended position, immobilizing arm  70  selectively engages the animal, adjacent the animal&#39;s hip for immobilizing the same, FIG. 16. In the immobilized position, the operator can enter the chute through either of rear access doors  86  or  86 ′, illustrated in FIGS. 1, 10 and  15 , to perform various operations at the rear of the animal. Rear access doors  86  and  86 ′ are provided with tabs  88  at their lower ends to prevent the doors  86  and  86 ′ from opening outwardly. Pistons  90  are provided at the upper end of doors  86  and  86 ′, which automatically move the doors  86  and  86 ′ to their closed positions. Once the operator has exited the chute  10  through rear access door  86  or  86 ′, immobilizing arm  70  can be retracted to allow the animal&#39;s hip area to freely move transversely with respect to the chute  10 .  
         [0073]    An anti-rear device  92  is provided along the top of the chute  10 , adjacent the exit end thereof. It is preferred that the anti-rear device  92  be provided with at least one elongated transverse bar  94  and at least one elongated longitudinal bar  96 . FIGS. 1 and 2 illustrate one embodiment of the anti-rear device  92 , which comprises a single transverse bar  94  extending between the sides of frame  12  and two longitudinal bars  96  extending from the middle of transverse bar  94  to the exit end of frame  12 . This configuration of anti-rear bars prevents the animal from attempting to climb out of the top of the chute  10 .  
         [0074]    The movement of entrance gate  14 , exit gate  16 , sidewalls  20  and  20 ′, neck stretchers  54  and  54 ′, and hip-immobilizing arm  70 , is preferably provided by a hydraulically powered roller chain assembly system  98 , illustrated by FIGS. 4 and 5. The hydraulic pump is powered by an electric motor or gas engine (not shown), sufficient to generate approximately 700 psi of hydraulic pressure to a valve bank  100 . Hydraulic pressure that is not used is returned to the hydraulic reservoir  102  through a filter head  104 .  
         [0075]    The valve bank  100  is comprised of six valves. Six individual levers, displayed on a central control panel  106 , manipulate the valves. For ease of operation, the control panel  106  is disposed at the end of a segmented boom  108 . The boom  108  is pivotally secured to the top of frame  12  so that the operator can move the control panel  106  to any location around the chute  10 .  
         [0076]    Entrance gate  16  is moved between open and closed positions through the manipulation of a first lever  110 . By pulling the first lever  110 , a first valve  112  is activated and hydraulic pressure is directed to a cylinder  114 , causing the cylinder  114  to retract. Cylinder  114  is coupled to a vertically disposed roller chain  116 , which extends between two double sprockets  118  and  120 . Double sprockets  118  and  120  are coupled to horizontally disposed roller chains  122  and  124 . Horizontal roller chain  122  is disposed along the top of the chute  10 , adjacent the entrance gate  16 . Horizontal roller chain  124  is disposed along the bottom of the chute  10 , adjacent the entrance gate  16 . As the cylinder  114  retracts, the vertical roller chain  116  rotates double sprockets  118  and  120 , which rotate horizontal roller chains  122  and  124 . Horizontal roller chains  122  and  124  are each connected to L-shaped tabs  36  that guide entrance doors  34  and  34 ′ between their open and closed positions. Accordingly, as horizontal roller chains  122  and  124  rotate, the entrance gate  16  is moved to its open position. When the first lever  110  is pushed in the opposite direction, the aforementioned cycle is reversed, and the entrance gate  16  is moved to its closed position.  
         [0077]    Exit gate  18  is moved between open and closed positions through the manipulation of a second lever  126 . By pulling the second lever  126 , a second valve  128  is activated and hydraulic pressure is directed to cylinder  130 , causing the cylinder  130  to retract. Cylinder  130  is coupled to a vertically disposed roller chain  132 , which extends between double sprockets  134  and  136 . Double sprockets  134  and  136  are coupled to horizontally disposed roller chains  138  and  140 . Horizontal roller chain  138  is disposed along the top of the chute  10 , adjacent the exit gate  18 . Horizontal roller chain  140  is disposed along the bottom of the chute  10 , adjacent the exit gate  18 . As cylinder  130  retracts, vertical roller chain  132  rotates double sprockets  134  and  136 , which rotate horizontal roller chains  138  and  140 . Horizontal roller chains  138  and  140  are each connected to L-shaped tabs  36 ′ that guide exit doors  48  and  48 ′ between their open and closed positions. Accordingly, as horizontal roller chains  138  and  140  rotate, the exit gate  18  is moved to its open position. When the second lever  126  is pushed in the opposite direction, the aforementioned cycle is reversed, and the exit gate  18  is moved to its closed position.  
         [0078]    The synchronous positioning of opposing sidewalls  20  and  20 ′ is controlled through the manipulation of a third lever  142 . By pulling the third lever  142 , a third valve  144  is activated and hydraulic pressure is directed to a cylinder  146 , causing the cylinder  146  to retract. Cylinder  146  is coupled to a vertically disposed roller chain  148 , which extends between upper and lower double sprockets  150  and  152 . Double sprockets  150  and  152  are coupled to horizontally disposed roller chains  153  and  155 . The upper double sprocket  150  is pinned to a drive shaft  151  that extends to the right rear corner of chute  10  and is pinned to double sprocket  154 . Vertical roller chain  156  is coupled to double sprocket  154  at one end and double sprocket  158  at the opposite end. Double sprockets  154  and  158  are coupled to horizontally disposed roller chains  160  and  162 . Horizontal roller chains  153 ,  155 ,  160  and  162  are each connected to a pair of tabs  164  and  164 ′ that are coupled to opposing sidewalls  20  and  20 ′. Accordingly, as the horizontal roller chains rotate, the opposing sidewalls  20  and  20 ′ are moved outwardly. When the third lever  142  is pushed in the opposite direction, the aforementioned cycle is reversed, and the opposing sidewalls  20  and  20 ′ are moved inwardly.  
         [0079]    By pulling a fourth lever  166 , which is attached to a fourth valve  168 , hydraulic pressure is directed to a fourth cylinder  170 , causing the same to retract. The fourth cylinder  170  is coupled to an arm  172  that is attached to mounting shaft  50 . The retraction of the fourth cylinder  170  causes the mounting shaft  50  to rotate. As described previously, the neck stretchers  54  and  54 ′ pivot arcably with the rotation of mounting shaft  50 . Accordingly, as the fourth cylinder  170  retracts, neck stretchers  54  and  54 ′ extend arcably from the chute  10 . When the fourth lever  170  is pushed in the opposite direction, the aforementioned cycle is reversed, and the neck stretchers  54  and  54 ′ are retracted toward the chute  10 .  
         [0080]    By pushing a fifth lever  174 , which is attached to a fifth valve  176 , hydraulic pressure is directed to a fifth cylinder  80 , causing the same to retract. The fifth cylinder  80  is coupled to arm  72  that is hinged in mounting box  78 . As the fifth cylinder  80  retracts, arm  72  extends outwardly into the chute  10 . When the fifth lever  174  is pushed in the opposite direction, the aforementioned cycle is reversed, and the arm  72  is retracted inwardly.  
         [0081]    A sixth lever/valve assembly (not pictured) is provided as a spare that can be coupled to any of the cylinders in the event that one of the first through fifth lever/valve assemblies fails mechanically.  
         [0082]    It is contemplated that several motive systems, other than a hydraulic chain drive assembly, could be employed by the squeeze chute  10 . For example, the hydraulic pump, valves, and cylinders could readily be replaced with one or more electric or gas powered motors or pneumatic pistons that could be operated by the control panel  106 . Manual power, employed through pivoting or rotary lever arms could also be used in place of the aforementioned power sources.  
         [0083]    It is further contemplated that belts, comprised of nearly any material such as metal, rubber, plastic or other synthetic material, could be used in place of the aforementioned roller chains. Alternatively, a simple system of lever arms could be pivotally secured between the aforementioned power sources and the gates  16  and  18 , opposing sidewalls  20  and  20 ′, neck stretchers  54  and  54 ′, and immobilizing arm  70 , in place of the previously described roller chains and double sprockets. The opposing sidewalls  20  and  20 ′ could also be simultaneously operated without drive shaft  151 . In that instance, an additional power source such as a hydraulic cylinder, electric or internal combustion motor, or pneumatic piston, would be coupled with vertical roller chain  156 , or aforementioned alternative.  
         [0084]    In the drawings and in the specification, there have been set forth preferred embodiments of the invention and although specific items are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and proportion of parts, as well as a substitution of equivalents, are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims.  
         [0085]    Thus it can be seen that the invention accomplishes at least all of its stated objectives.