Abstract:
A portable squeeze chute apparatus. The apparatus includes a chute having opposing sidewalls, an entrance end and an exit end. The sidewalls are selectively pivotable toward one another in order to inhibit lateral movement of an animal positioned in the chute. Movement of the sidewalls is actuated through a control chain which is connected to the sidewalls through a mechanical linkage. The control chain is selectively latched in position by a lock which is pivotally connected to the chute. The lock includes a tubular body through which the control chain passes. The tubular body includes a notch which selectively engages the control chain. A tailgate having interconnected door sections is mounted on the entrance end of the chute for selectively admitting an animal to the chute The tailgate and the sidewall squeezing mechanism include special mountings and bumpers which are adapted to reduce noise generated by operation of the apparatus.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to animal husbandry, and in particular to a portable apparatus for use in connection with treating livestock. 
     2. Description of the Related Art 
     In livestock operations it is frequently necessary to vaccinate, palpate, artificially inseminate, brand, dehorn, or otherwise treat the animals. In order to perform these tasks, the animals must be restrained. Permanent corrals constructed of steel pipe, wood or stone and having alleyways with headgates for holding the animals have long been used for this purpose. The capital investment required for building such permanent structures is often prohibitive, however. This is especially true among ranchers with decentralized operations where livestock are run on relatively small, isolated tracts of grazing land. Furthermore, many ranchers lease, rather than own, their grazing land and naturally wish to avoid making permanent, fixed improvements. 
     A solution to this problem is to provide portable livestock working equipment. Temporary corrals may be readily constructed using prefabricated, portable steel panels. Portable livestock working facilities mounted on wheels, such as that described in my previous Letters Patent, U.S. Pat. No. 4,829,936, may also be used. Either of these systems, however, must be used in conjunction with a portable animal restraining device such as a “squeeze chute.” 
     Squeeze chutes are well known and effective devices for restraining livestock while they are being treated. A squeeze chute combines a traditional “headgate,” which features a neck clamping means for restraining an animal&#39;s fore-and-aft movement, with a sidewall squeezing means for restraining the lateral movement of animals of varying sizes. Such squeeze chutes are of unitary construction and may be transported from one working location to another using a truck or trailer, or they may be equipped with retractable wheels so that they may be towed. 
     One problem with squeeze chutes which have been used heretofore is that their operation tends to produce a lot of noise, which can range from relatively low-amplitude background noise to relatively loud impact noises. This noise is stressful to animals and operators alike. Even the relatively low-amplitude background noises or “chatter” can contribute to stress, fatigue and the like. The sudden, high amplitude noises, such a those that might occur when gates or drop panels are slammed shut, can startle the animals and significantly increase their anxiety. Moreover, as frightened animals tend to struggle, they can further contribute to the noise levels by shaking the entire chute and exacerbate the stress-related problems. 
     One reason squeeze chutes have tended to be so noisy is that livestock handling systems are typically constructed with a certain amount of play, or with relatively loose tolerances at their connections. Such tolerances tend to reduce manufacturing costs and also tend to make such units better adapted for operation under the types of adverse conditions which they are likely to encounter in the field. 
     My previous Letters Patent, U.S. Pat. No. 5,331,923, which is herein incorporated by reference, addressed this problem by disclosing a hydraulically operated squeeze chute with noise reducing sleeve bushings and O-rings in many of its key joints. These bushings and O-rings help reduce noise by preventing metal-to-metal contact between the various parts of the chute. While hydraulic squeeze chutes are ideal for use in high volume livestock operations such as those found at sale barns, feedlots, veterinary clinics, and large ranches, they can be prohibitively expensive for smaller livestock producers. In addition, hydraulic chutes can be heavy and difficult to transport. 
     What is needed is a manually operated squeeze chute apparatus which is quiet, easily portable, economical, and which still provides working accessability to an animal confined therein while assuring relative safety and comfort for both the animal being worked and those working the animal. 
     SUMMARY OF THE INVENTION 
     An improved portable squeeze chute apparatus is provided for restraining a large animal while being worked, such as branding, vaccinating, artificially inseminating, de-horning or the like. The apparatus includes a chute having opposing sidewalls, an entrance end, an exit end, a base having a floor, and a superstructure. The sidewalls are connected to the superstructure such that each of the sidewalls is rotatable about an axis provided by a pair of generally horizontally oriented stub axles situated near the lower extremity thereof Upper portions of the opposing sidewalls are interconnected such that they can be synchronously pivoted about their respective axes to selectively allow and prevent lateral movement of an animal positioned in the chute. 
     The synchronous pivoting of the opposing sidewalls is manually controlled by means of a chain connected to a pivoting control rod which is in turn connected to the sidewalls. A squeeze latch is provided to retain the opposing sidewalls in a desired position. The lower extremities of the opposing sidewalls are adjustable so as to allow the chute to be widened or narrowed to fit animals of varying sizes. Each of the opposing sidewalls has a lower panel which is pivotable about a lower extremity thereof to provide access to lower portions of an animal positioned in the chute. A lower panel latching mechanism selectively retains the lower panel in a closed configuration. The lower panels have planar inner surfaces to avoid providing footholds for an animal positioned in the chute. Each of the opposing sidewalls also has an upper panel which is pivotable about a lower extremity thereof to provide access to upper portions of an animal positioned in the chute. An upper panel latching mechanism selectively retains the upper panel in a closed configuration. The upper panels generally comprise a plurality of vertically oriented, spaced apart bars such that persons working on an animal positioned in the chute can stand outside and reach therebetween. One or both of the opposing sidewalls may be fitted with side exit gates which pivot about a rear extremity of the sidewall and latch at a front extremity. Such side gates are useful for sorting animals or for releasing animals which may become entrapped in the chute. 
     The improved portable squeeze chute apparatus also includes an tailgate which is connected to the entrance end of the chute and adapted to selectively admit an animal to the chute and prevent the animal from exiting rearwardly from the chute one so admitted. The tailgate has a pair of cooperating opposing door sections which are interconnected such that they move transversely to the chute between open and closed positions. The tailgate door sections are connected to the chute by a parallelogram linkage and generally open upwardly and outwardly from the chute. Opening and closing of the tailgate door sections is manually controlled by manipulating a handle connected to pivoting control rod which is in turn connected to the door sections. The exit end of the chute provides a mounting place for a headgate with a neck clamp for restraining the fore and aft movement of an animal positioned in the chute. The present invention does not include such a headgate, but headgates are commercially available from many sources. Noise reducing bushings, O-rings, and bumpers are provided between a plurality of the moving parts to minimize noise fatigue of the user and to prevent unnecessarily agitating the animals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a portable squeeze chute apparatus embodying the present invention. 
     FIG. 1 a  is an enlarged cross-sectional view of a side exit gate hinge, taken generally along line  1   a — 1   a  in FIG. 1, showing the location of a noise reducing sleeve bearing. 
     FIG. 1 b  is an enlarged cross-sectional view of the squeezing mechanism control rod and a socket, taken generally along line  1   b — 1   b  in FIG. 1, showing the location of a noise reducing sleeve bearing. 
     FIG. 2 is a cross-sectional view of the portable squeeze chute taken generally along line  2 — 2  in FIG.  1 . 
     FIG. 2 a  is an enlarged fragmentary and partially cross-sectional view of a squeezing mechanism link and a sidewall top rail flange, taken generally along line  2   a — 2   a  in FIG. 2, showing the location of a noise reducing O-ring. 
     FIG. 3 is an enlarged and fragmentary perspective view of the squeeze chute apparatus showing a hinge for a lower panel. 
     FIG. 3 a  is an enlarged cross-sectional view of a lower drop panel hinge, taken generally along line  3   a — 3   a  in FIG. 3, showing the location of a noise reducing sleeve bearing. 
     FIG. 4 is an enlarged and fragmentary perspective view of the squeeze chute apparatus showing a latch for a lower panel and a hinge for an upper panel. 
     FIG. 4 a  is an enlarged cross-sectional view of an upper drop panel hinge, taken generally along line  4   a — 4   a  in FIG. 4, showing the location of a noise reducing sleeve bearing. 
     FIG. 5 is an enlarged and fragmentary perspective view of the squeeze chute apparatus showing a latch for a upper panel. 
     FIG. 6 is an enlarged and fragmentary perspective view of the squeeze chute apparatus showing the squeeze latch assembly. 
     FIG. 6 a  is a perspective view of the squeeze latch lock, as seen from the underside, showing the control chain capturing notch and noise reducing lining. 
     FIG. 6 b  is an enlarged cross-sectional view of the tailgate control rod and a mounting sleeve, taken generally along line  6   b — 6   b  in FIG. 6, showing the location of a noise reducing sleeve bearing. 
     FIG. 7 is a partial, rear view of the portable squeeze chute showing the tailgate assembly in the closed position. 
     FIG. 8 is a partial, rear view of the portable squeeze chute showing the tailgate assembly in the open position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
     The reference numeral  1  generally refers to a portable squeeze chute apparatus in accordance with the present invention as shown in FIGS. 1 through 6 b . The apparatus  1  includes a chute  3  which generally has an exit end  5 , an entrance end  7 , opposing sidewalls  9  and  11 , a base  13  having a floor  15 , and a superstructure  17 . 
     Sidewalls  9 , 11   
     Each of the opposing sidewalls  9  and  11  includes a frame  19  having a top rail  21 , a front upright  23 , a rear upright  25 , and a generally horizontally oriented bottom rail  29 . The bottom rail  29  of each of the sidewalls  9  and  11  is connected to the superstructure  17  such that each of the opposing sidewalls  9  and  11  pivots about an axis provided by a respective pair of generally horizontal stub axles  31 . Each of the stub axles  31  passes through an adjusting slot  33  in one of a pair of generally horizontally oriented axle-supporting members  35  such that the bottom rails  29  are spaced above the floor  15  to protect workers standing alongside the apparatus  1  from sideways kicking by the animal  37  positioned in the chute  3 . The spacing of the bottom rails  29  above the floor  15  also facilitates cleaning of the floor  15  of the apparatus  1 . The spacing between the bottom rails  29  can be adjusted to accommodate animals of varying sizes by relocating the stub axles  31  within the adjusting slots  33  of the axle-supporting members  35 . 
     The sidewalls  9  and  11  include a side exit gate  39 . The side exit gate  39  includes a gate frame  41  which fits inside the sidewall frame  19  of the respective sidewall  9  or  11 . The gate frame  41  includes a top rail  43 , a front upright  45 , a rear upright  47 , a crossrail  49  and a generally horizontally oriented bottom rail  51 . Hinge sleeves  53  are affixed to the rear upright  47  of the gate frame  41  and positioned concentrically about the rear upright  25  of the sidewall frame  19 , allowing the gate  39  to pivot about the upright  25 . Hinge bearings  55  are placed between the hinge sleeves  53  and the upright  25  for noise reducing purposes. The hinge bearing  55  is constructed of suitable material, such as nylon or polyethylene. 
     A latch  57  selectively holds the side exit gate  39  securely in its closed position. The latch  57  may include a hook  59  which is affixed to the front upright  23  of the sidewall frame  19 , and a latching member  61  which is pivotally connected to the gate frame  41 . 
     Each of the sidewalls  9  and  11  includes a lower panel  63  for accessing lower portions of the animal  37  positioned in the chute  3 . Each of the lower panels  63  has a generally planar inner surface to prevent the animal  37  positioned in the chute  3  from using available surface irregularities as a ledge to attempt to climb out of the chute  3 . 
     Each of the lower panels  63  is generally connected to the respective side gate bottom rail  51  of the respective side exit gate  39  by a plurality of hinge mounts  65 , each having a pivot axle  67  and a hinge sleeve  69 , such that each of the lower panels  63  pivots about a respective, generally horizontal axis. Each of the hinge mounts  65  generally includes a hinge sleeve bearing  71  disposed between the respective pivot axle  67  and the respective hinge sleeve  69 , as shown in FIG. 3 a , such that noise is substantially reduced during operation of the apparatus  1 . 
     At least one latch  73  is adapted to selectively latch the respective lower panel  63  in a closed configuration, as shown in FIG.  4 . Each of the latches  73  generally includes a casing  75 , a pinion  77 , a latch sleeve  79 , and an engaging member  81 . The latch sleeve  79  is constructed of suitable material, such as nylon or polyethylene, and is disposed between the casing  75  and the pinion  77  for noise reducing purposes. The engaging member  81  is connected to a distal end  83  of the pinion  77 . 
     The pinion  77  is retained within the casing  75  by a bolt  85  and a washer  87 . An O-ring  89  is positioned between the washer  87  and the top of the casing  75  for noise reducing purposes. The O-ring  89  is constructed of suitable material, such as nylon or polyethylene 
     For each of the latches  73  for the lower panels  63 , the casing  75  is secured to the side gate crossrail  49  of the side exit gate  39 . A latch roller  91 , constructed of nylon or polyethylene or other suitable material, is rotatably attached to an upper extremity of the lower panel  63 . The latch roller  91  facilitates latching of the lower panel  63  and reduces noise during operation of the apparatus  1 . 
     As the lower panel  63  is closed, the engaging member  81  engages the latch roller  91 . The bottom surface of the engaging member  81  is tapered such that latching is facilitated by urging the pinion  77  upwardly. The engaging member  81  has an protruding ledge  93  which provides a gripping surface for easily disengaging the latch  73 . 
     Each of the sidewalls  9  and  11  also generally includes an upper panel  95  for accessing upper portions of the animal  37  positioned in the chute  3 . Each of the upper panels  95  has a plurality of generally vertically oriented bars  97 , which are sufficiently spaced apart such that a worker can reach between the adjacent pairs of the bars  97 . Each of the upper panels  95  is connected to the respective side gate crossrail  49  of the respective side exit gate  39  by upper panel hinge mounts  99 , such that each of the upper panels  95  pivots about a respective, generally horizontal axis near the lower extremities thereof. The upper panel hinge mounts  99  generally comprise a cylindrically-shaped hinge sleeve  101 , a cylindrically-shaped hinge sleeve bearing  103 ,and a cylindrically-shaped pivot axle  105 . The hinge sleeve  101  and pivot axle  105  are generally constructed of steel or other suitable material, and the sleeve bearing  103  is generally constructed of nylon or polyethylene or other suitable material to reduce noise during operation of the apparatus  1 . Hinge spacers  107  are generally connected between the crossrail  49  and the pivot axle  105  to provide spacing therebetween and to define locations for the hinge sleeve  101  and the sleeve bearing  103  along the pivot axle  105 , as shown in FIG.  4 . 
     For some applications, each of the upper panels  95  may comprise a plurality of sections  109  spaced edge-to-edge along each side of the animal  37  positioned in the chute  3 . The sections  109  may have various widths and may include from one of the vertical bars  97  to the number required to make up an upper panel  95 . At least one of the latches  73  is connected to the side gate top rail  43  for each of the sections  109  and is adapted to selectively latch the respective section  109  in a closed configuration. Each of the latches  73  for the upper panels  95  generally includes an upper panel latch roller  111 , constructed of nylon or polyethylene or other suitable material to facilitate latching the upper panel sections  109  and to reduce noise during operation of the apparatus  1 . 
     Squeezing Mechanism  113   
     A squeezing mechanism  113 , as shown in FIGS. 1 and 2, interconnects the sidewalls  9  and  11  such that the sidewalls  9  and  11  synchronously pivot about respective axes to selectively allow and prevent lateral movement of the animal  37  positioned in the chute  3 . The mechanism  113  includes a control rod  115  rotatably secured in a pair of opposing sockets  117  as shown in FIG.  1 . Each of the sockets  117  is fixedly secured to a respective one of a pair of overhead crossbars  121  and  123  of the superstructure  17 . Noise reducing sleeve bearings  119 , constructed of an appropriate material such as polyethylene, are disposed between the rod  115  and the respective ones of the sockets  117  as shown in FIG. 1 b.    
     The squeezing mechanism  113  also includes a pair of elongate linkage flanges  125  and a control flange  127 . A pair of sidewall top rail flanges  129  are fixedly secured to each of the sidewall top rails  21  and extend radially outwardly therefrom. The control flange  127  and the linkage flanges  125  are fixedly secured to the rod  115  such that each extends radially outwardly from the rod  115 . Links  131  pivotally connect each of the flanges  125  to the sidewall top rail flanges  129 , as shown in FIGS. 1 and 2. O-rings  89  are installed for noise reducing purposes between the links  131  and the linkage flanges  125 , as well as between the links  131  and the sidewall top rail flanges  129  (FIG. 2 a ). 
     One end of a control chain  133  is connected to the control flange  127 ; the second end of the control chain  133  is equipped with a yoke  135  and a handle  137 . By manually applying pressure to the handle  137 , the operator causes tension on the control chain  133  and thereby causes the control rod  115  to rotate within the sockets  117 . Rotation of the control rod  115  causes the linkage flanges  125  to act upon the sidewall top rail flanges  129  through the links  131  and thereby pulls the top rails  21  of the sidewalls  9  and  11  closer together, restricting the lateral movement of the animal  37  positioned in the chute  3 . 
     A squeeze latch assembly  139  is provided to lock the control chain  133  in place once the sidewalls  9  and  11  are in their desired position, thereby retaining the sidewalls  9  and  11  in said position until the squeeze latch  139  is released by the operator. The squeeze latch assembly  139  includes a squeeze latch lock  141 . 
     The squeeze latch lock  141  includes a tubular portion  143  and a pair of mounting flanges  145  which are fixedly secured to the tubular portion  143 . The tubular portion  143  has a Y-shaped notch  147  cut into its lower lip. The mounting flanges  145  are pivotally mounted to the superstructure  17  of the chute  3  in such a manner that the tubular portion  143  is perpendicular to the longitudinal axis of the chute  3  and in alignment with the control flange  127  of the squeezing mechanism  113 . The control chain  133  passes through the tubular portion  143  of the squeeze latch lock  141 . 
     Because of its pivotal mounting, the squeeze latch lock  141  is free to rotate up and down, matching the tilt of the tubular portion  143  to the angle of the control chain  133 , and allowing the control chain  133  to travel freely through the tubular portion  143 . By pulling the handle  137  downwardly and inwardly, the operator can cause a link of the control chain  133  to engage the notch  147  and thereby lock the sidewalls  9  and  11  in position. To release the control chain  133 , the operator need only pull the handle  137  downwardly and outwardly. 
     The squeeze latch assembly  139  also includes a noise reducing lining  149 FIG. 6 a ). The lining  149  prevents metal-to-metal contact between the control chain  133  and the inner surface of the tubular portion  143 . The lining  149  consists of a tubular member, which may be made of nylon, polyethylene or other suitable material, which is affixed concentrically within the tubular portion of the squeeze latch lock  141 . The lining  149  has a Y-shaped notch  151  matching the Y-shaped notch  147  of the tubular portion  143  of the squeeze latch lock  141 . 
     Tailgate Assembly  153   
     A tailgate assembly  153  (FIGS. 7 and 8) is connected to the entrance end  7  of the chute  3  to selectively admit livestock to the chute  3  and to prevent said livestock from backing out of the chute  3  once admitted thereto. The tailgate assembly  153  generally comprises a frame  155 , door sections  157  and  159 , and a control mechanism  161 . The tailgate frame  155  has a base  163 , upright side rails  165  and  167 , and a generally horizontal top rail  169 . Door sections  157  and  159  have door frames  171  with upright inner rails  173 , and generally planar door panels  175 . The tailgate assembly  153  is moveable between a closed position (FIG. 7) and an open position (FIG.  8 ). 
     The door sections  157  and  159  each include a door stop  177 . The door stops  177  are positioned to make contact with the respective tailgate frame side rails  165  and  167  when the door sections  157  and  159  are in their fully open position. Each door stop  177  includes a bumper  179  which is made of a sound deadening material such as rubber, neoprene, or other suitable material, and is designed to reduce noise by cushioning the impact between the door stops  177  and the tailgate frame side rails  165  and  167 . 
     Each of the door sections  157  and  159  are connected to the tailgate frame  155  by means of a pair of parallel links  181 . The links  181  have first ends which are pivotally connected to the respective upright inner rail  173  of the door section  157  or  159  and second ends which are pivotally connected to mounting flanges  183  on the tailgate frame  155 . 
     A pair of noise reducing bumper stops  185  are positioned between each door section  157  and  159  and the respective tailgate frame side rail  165  or  167 . The bumper stops  185  are fixedly secured to the side rails  165  and  167  to prevent the door sections  157  and  159  from impacting the tailgate frame  155 . The bumper stops  185  can be made of rubber, neoprene or other suitable energy absorbing material. 
     The tailgate control mechanism  161  (FIG.  1 )includes a control rod  187  which has a handle  189  which extends radially outwardly therefrom. The handle  189  may include a pivot joint  191  which allows the handle  189  to be folded out of the way when not in use. The control rod  187  also includes an elongate linkage flange  193  which is fixedly secured to the control rod  187  such that each extends radially outwardly from the control rod  187 . The control rod  187  is rotatably mounted to the superstructure  17  of the chute  3  by means of control rod sleeves  195 . A control rod sleeve bearing  197  is located between each control rod sleeve  195  and the control rod  187  for noise reduction purposes. The control rod sleeve bearing is constructed of nylon or polyethylene or other suitable material. 
     The tailgate control mechanism also includes a pair of links  199  (FIGS.  7  and  8 ). Each of the links  199  connects the elongate linkage flange  193  to an upper extremity of a respective door frame inner rail  173 . As the control rod  187  is rotated by means of the handle  189 , the door sections  157  and  159  pivot on the parallel links  181  and are moved upwardly and outwardly to their open position. 
     Headgate Assembly  200   
     The exit end  5  of the chute  3  is adapted for the mounting of a headgate assembly  200  having a neck clamp which is adapted to selectively abut opposing sides of the neck of the animal  37  as it is positioned in the chute  3 , and thereby selectively control the fore-and-aft movement of the animal  37 . Headgate assemblies of various types are well known in the livestock equipment industry, and many different designs are commercially available. The headgate assembly  200  can be any one of these known, preexisting, or commercially available headgates. 
     Noise Reduction System  201   
     The squeeze chute apparatus  1  includes a noise reduction system  201 , which includes a sleeve-pivot subsystem  203  for suppressing noise at various pivotal connections between chute components. 
     More specifically, the rod  115  and the sockets  117  of the squeezing mechanism  113  are separated by noise-reducing sleeve bearings  119  (FIG. 1 b ). The sleeve bearings  119  can comprise a suitable material for reducing noise and friction, such as polyethylene, nylon, or any other suitable material. 
     The sleeve-pivot subsystem  203  is also located at the pivotal connections between the upper drop panel  95  and the side gate crossrail  49  of the respective side exit gate  39 , as shown in FIG. 4 a . Such pivotal connections include pivot axles  105  which are mounted on the crossrails  49  by spacers  107 . Outer, metal hinge sleeves  101  extend between respective pairs of spacers  107 , and hinge sleeve bearings  103  are positioned between the outer metal hinge sleeves  101  and the axles  105  for permitting relatively quiet and low-friction rotation therebetween. The sleeve bearings  103  can comprise polyethylene, nylon or some other suitable material, and can extend coextensively with the metal hinge sleeves  101  between respective pairs of spacers  107 . 
     As noted above, the lower drop panels  63  are pivotally connected to respective side gate bottom rails  51  of the respective side exit gate  39  by hinge mounts  65 , each having a pivot axle  67  and a hinge sleeve  69 , such that each of the lower drop panels  63  pivots about a respective, generally horizontal axis. Hinge sleeve bearings  71 , which can comprise polyethylene, nylon, or other suitable material, are located between respective pivot axles  67  and hinge sleeves  69 , as shown in FIG. 3 a.    
     The sleeve-pivot subsystem  203  is also employed at the pivotal connections of the tailgate control mechanism  161 . Noise reducing sleeve bearings  197  are used to separate the tailgate control rod  187  from the control rod sleeves  195 . Use of the sleeve bearings  197  prevents metal-to-metal contact between the control rod  187  and the sleeve  195 , thereby reducing friction and diminishing the noise which would likely occur if the tailgate control mechanism  161  were operated without the sleeve bearings  197  in place. 
     The sleeve-pivot subsystem  203  is also used on the side exit gates  39  where bearing sleeves  55  are disposed between hinge sleeves  53  and the rear uprights  25  of the sidewall frames  19 . 
     A second noise reduction subsystem  205  comprises a plurality of captured latch roller assemblies  91  and  111 , each located at a respective drop panel  63  or  95 . As shown in FIGS. 4 and 5, each captured latch roller assembly  91  or  111  is captured between a respective latch assembly  73  and the side exit gate frame  41 , and the upper ends of the drop panels  63  and  95  are thus restrained. The inclusion of the plastic latch roller assemblies  91  and  111  prevents metal-to-metal contact in these locations and noise caused by the closing of the upper panels  95  and the lower panels  63  is thus suppressed. Moreover, with the panels  63  and  95  in their closed positions, the latch rollers  91  and  111  function to suppress chatter at the secured upper ends of the panels  63  and  95 . If not silenced in this manner, such connections could be a considerable source of noise or chatter, i.e., as the animal  37  in the chute  3  moves about and as the sidewalls  9  and  11  are manipulated. 
     The noise reduction system  201  further includes a latch sleeve subsystem  207  which comprises multiple latch sleeves  79 , each located within a respective latch casing  75  and receiving a respective latch pinion  77  which is axially slidable therein along a generally vertical axis. The latches  73  are thus considerably quieter in operation because metal-to-metal contact is avoided by the interposing latch sleeves  79  so that latching and unlatching procedures involve metal-to-plastic contact only, which can be relatively quiet. Moreover, the latch sleeves  79  also cushion the latch casing  75  and pinions  77  from contact when subjected to lateral forces, for example forces which are transmitted through the drop panels  63  and  95  and into the latch assemblies  73 . Absent such latch sleeves  79 , the noise level associated with such lateral forces could be considerable. 
     Still further, the noise reduction system  201  includes a noise reducing squeeze latch subsystem  152 . A sleeve or lining  149 , which may be made of nylon, polyethylene, or other suitable material, is disposed within the tubular portion  143  of the squeeze latch lock  141 . The lining  149  prevents metal to metal contact between the control chain  133  and the inner surface of the tubular portion  143  as the control chain  133  is pulled through the tubular portion during operation of the squeezing mechanism  113 . 
     The noise reduction system  201  also includes an O-ring subsystem  209  comprising a plurality of O-rings  89  mounted on top of each respective latch pinion  77  by a bolt  85  threadably received by the respective pinion  77  and clamping the O-ring  89  in place by means of a washer  87 . The O-ring subsystem  209  suppresses noise as the latches  73  open and close by cushioning the tops of the casings  75  and the respective pinions  77 . Moreover, the O-rings  89  tend to suppress chatter which might otherwise be caused by relative movement between the washer  87 , casing  75 , and pinion  77  of each latch  73 . 
     O-rings  89  are also employed for noise reducing purposes at pivotal connections in the various operating linkages of the squeeze chute apparatus  1 . For example, O-rings  89  are used in the squeezing mechanism  113  to separate the links  131  from the linkage flanges  125  and the sidewall top rail flanges  129 . O-rings  89  may be used in the tailgate control mechanism  161  between the linkage flange  193  and the links  199 , as well as between the links  199  and the door frame inner rails  173 . Similarly, O-rings  89  may be disposed between the parallel links  181 , the door frame inner rails  173 , and the mounting flanges  183 . 
     Lastly, the noise reducing system  201  includes a bumper stop subsystem  211 , which involves placing bumper stops made of a suitable energy absorbing material such as rubber or neoprene between metal parts to prevent them from impacting each other and producing noise. The bumper stop subsystem  211  is generally employed between the door sections  157  and  159  and the tailgate frame  155  to prevent the door sections  157  and  159  from colliding with the tailgate frame  155 . 
     Noise reducing bumper stops  185  are positioned between the door sections  157  and  159  and the respective tailgate frame side rail  165  or  167  to prevent the metal parts from impacting each other when the tailgate assembly  153  is operated, or when the animal  37  positioned in the chute  3  jars the door sections  157  and  159 . Similarly, door stop bumpers  179  are attached to the door stops  177  of the door sections  157  and  159  to prevent the metal door stops  177  from impacting the tailgate frame side rail  165  and  167  when the door sections  157  and  159  reach their fully open positions. 
     The cumulative effect of the noise reduction system  201  is to considerably suppress the operating noise, which can range from relatively low-amplitude background noise to relatively loud impact noises in chutes which are not equipped with such noise reduction systems. Stress on animals and operators alike can be decreased by reducing operating noises of all types. Even the relatively low-amplitude background noises or “chatter” can contribute to stress, fatigue and the like. The sudden, high amplitude noises, such a those that might occur when the drop panels  63 ,  95  are slammed shut, can startle the animals and significantly increase their anxiety. Moreover, as frightened animals tend to struggle, they can further contribute to the noise levels by shaking the entire chute and exacerbate the stress-related problems which can accompany a squeeze chute lacking such a noise reduction system. 
     The noise reduction system is particularly important for livestock handling systems which are typically constructed with a certain amount of play, or with relatively loose tolerances at their connections. Such tolerances tend to reduce manufacturing costs and also tend to make such units better adapted for operation under the types of adverse conditions which they are likely to encounter in the field. Although a portable squeeze chute apparatus embodying and employing the present invention would be feasible with relatively tight tolerances and might even be preferable in some respects, the noise reduction system  201  is particularly well adapted for applications involving relatively loose tolerances which can withstand the relatively severe and adverse operating conditions which can often be encountered in livestock handling operations. 
     Collectively, the use of noise-abating tubing, O-rings, and bumper stops as described above and as depicted herein can be employed at approximately seventy locations for avoiding metal-to-metal contact thereat and suppressing noise. These locations include: the side exit gate hinge bearings  55 ; the lower panel hinge mount sleeve bearings  71 ; the panel latch sleeves  79 ; the panel latch O-rings  89 ; the lower panel latch rollers  91 ; the upper panel hinge sleeve bearings  103 ; the upper panel latch rollers  111 , the squeezing mechanism socket sleeve bearings  119 ; the squeezing mechanism O-rings  89 ; the squeeze latch lock lining  149 ; the tailgate door stop bumpers  179 ; the tailgate bumper stops  185 ; and the tailgate control rod sleeve bearings  197 . More or fewer such connections could be equipped with such plastic sleeves and O-rings in chutes with different configurations embodying the present invention. 
     The portable squeeze chute apparatus of the present invention is adaptable for use with animals of various sizes, including but not limited to bovine, equine, swine, and other livestock. 
     It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.