Livestock head gates with improved ratchet-based lock, tensile and double over-center linkage designs, hydraulic / pneumatic conversion kit and conveniently replaceable wear blocks

Abstract

A livestock head gate features a ratchet-locked control linkage and drive assembly, relocatability of symmetrically designed components from one side of other head gate to another, one control linkage design imparting only tensile loads to the links during closure of the gate, another control linkage design using near over-centering of two drive links to maximize holding force, direct drive of the linkage at a front side of the ratchet via a slidably relocatable handle therebehind, a reversible pawl for extended wear life, concavely notched transition in the ratchet tooth profile to reduce edge wear on the pawl, optimized linkage geometry for reduced range of handle movement and increased gate openability within road-transportable equipment width constraints, easily replaceable wear blocks for guided constraint of hanging gate panels, and a hydraulic / pneumatic conversion kit and method for upgrading the head gate from manual drive to fluid-powered drive.

Description

[0001] LIVESTOCK HEAD GATES WITH IMPROVED RATCHET-BASED LOCK, TENSILE AND DOUBLE OVER-CENTER LINKAGE DESIGNS, HYDRAULIC / PNEUMATIC CONVERSION KIT AND CONVENIENTLY REPLACEABLE WEAR BLOCKS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates generally to livestock head gates in which a pair of gate panels are movable back and forth toward and away from one another on an overhead track, and more particularly to such livestock head gates where a control linkage of the gate employs a ratchet mechanism to automatically lock the gate against unintended opening.

[0004] BACKGROUND

[0005] Applicant’s prior U.S. Patent No. 9,963,673 discloses a heat gate with a pair of doors or gate panels rollingly suspended from an overhead track spanning across the top of an animal-receiving opening of the head gate, for synchronous movement of the gate panels toward one another to close the gate, and away from one another to open the gate, such that closure of the gate with an animal’s neck in the animal-receiving opening will force the gate panels against the opposing sides of the animal's neck to secure the animals head in a generally stationary position. In that patent, locking of the gate panels against opening movement from such a closed position was effected by way of spring loaded locking plates in upper roller carriages of the gate panels, which locking plates are spring tilted into locking positions that frictionally bite onto a round shaft that forms the track on which the gate panels roll back and forth via rollers of the roller carriages. A handle-operated control linkage for opening and closing the gate includes links that both impart movement to the gate panels, and release the locking action of such spring-tilted locking plates during an opening stroke of the linkage, so that the anti-opening locking action on the head gate is only released through intentional user-manipulation of the linkage’s operating handle.

[0006] Such frictional locking action imparted through tiltable lock plates acting on a roller support shaft is only one example of known anti-opening locking means for a livestock head gate however, of which some other known examples instead use a ratchet-and-pawl mechanism for the gate’s anti-opening locking action. Head gates using ratchet and pawl mechanisms for their anti-opening locking action can be seen, for example, in Australian Patent Application AU2019202901 by Neat Investments, Australian Patent Application AU2020203561 by Offsider Ag, and Australian Patent Application AU2015246063 by National Stockyard. Potential benefits of the ratchet and pawl approach to the anti-opening lock functionality of a head gate include that each engagement point between the ratchet and pawl defines a hard stopping point, as opposed to a “frictional bite” that may see some slight relaxation or slip in the opening direction before the “bite” takes full locking effect. As another benefit, the mechanical interaction between the ratchet teeth and pawl provides audible and tactile feedback to the operator during the closing of the gate, giving them a better feel of the degree of advancement of through the closing cycle and audible reassurance of the hard “lock” with each advancement of the pawl from one ratchet tooth to the next. In illustration of this, with a frictional lock, when the gate panels have reached contact with opposing sides of the animal’s neck, the human operator may continue pushing the operating handle in attempt to increase the pressure or holding force exerted on the animal, but there’s no audible or tactile feedback on whether the gate panels are actually moving any closer together to achieve such "tightening” on the animal. In contrast, the audible / tactile click of a pawl from one ratchet tooth to the next gives the operator feedback of a successful advancement of the gate panels in the closing direction.

[0007] The ratchet locked gate control linkages of the above cited prior art are of varying design, each employed in the somewhat different context of a particular respective style of head gate and chute on which they are used. These prior designs also appear to lack any means of adjusting the location of the operating handle of the head gate along the chute to enable operation of the head gate from a variety of different locations.

[0008] Accordingly, there remains room for alternative ratchet-based head gate designs more optimally suited for integration into Applicant’s particular livestock handling equipment, as well as room for general functional improvements in the field of head gate design as a whole.

[0009] SUMMARY OF THE INVENTION

[0010] According to a first aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; and a pawl carried on said hammer and biased, into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; and a drive shaft running longitudinally of the chute on a longitudinal axis about which said drive shaft is rotatable and on which said pivotal movement of the hammer is centered, said drive shaft being rotatably operable, via an operating handle, about said longitudinal axis to drive movement of the hammer in pivotal opening and closing directions corresponding, respectively, to the lateral opening and closing directions of the first and second gate panels.

[0011] Preferably said operator handle is slidably relocatable back and forth along said drive shaft.

[0012] According to a second aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels movable in a closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage comprising: a hammer pivotably supported laterally outward from the lateral center of the head gate toward one lateral extreme thereof for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels; and additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; wherein the linkage is configured to exert only tensile forces on the additional links thereof during closure of the head gate.

[0013] According to a third aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a pair of wear blocks each installed beneath a respective one of the gate panels at a respective outer side of an animal-receiving opening of the head gate that is selectively openable and closeable by movement of said gate panels in the lateral opening and closing directions, each wear block comprising a U-shaped block delimiting a channel through which a bottom end of the respective gate panel is slidable back and forth during movement thereof in the lateral opening and closing directions, and the wear blocks are fastened in place via removable fasteners that penetrate the wear blocks non-longitudinally, such that lateral withdrawal of said removable fasteners is enabled in presence of the gate panels without necessitating removal thereof.

[0014] According to a fourth aspect of the invention, there is provided a ratchet- locked device on a piece of livestock equipment, said device comprising: a rack having an arched array of ratchet teeth thereon; a hammer supported adjacent the stationary rack for relative pivotal movement between the rack and the hammer about a pivot axis lying orthogonally of a plane in which the ratchet teeth are arrayed; a pawl carried on said hammer and biased into engagement with the ratchet teeth of the rack in a locking position preventing movement of the hammer in one direction; wherein a tooth profile among the ratchet teeth of the rack has a working side at which contact thereof by a working surface of the pawl blocks movement of the hammer in said one direction, and a resting side against which a resting surface of the pawl rests when the working surface of the pawl is in abutting contact with the flat working side of a neighbouring tooth, the resting side and the working side of the neighbouring tooth are joined by a concavely radiused transition that forms a concavely recessed notch to accommodate non-contacting receipt of a corner of the pawl, at which the working and resting surfaces thereof intersect, when the working surface of the pawl abuts the working side of the neighbouring tooth.

[0015] In detailed embodiments set forth in the description that follows, the ratchet-locked device in which the novel tooth profile is employed is a head gate of a livestock chute, where the locking action of the pawl on the rack is employed to impart an anti-opening lock function to the head gate at all times other than during opening of the head gate, during which the pawl is disengaged from the rack by a release mechanism. Other livestock equipment on which the novel ratchet-locked device may be employed include ratchet-based locking of the squeeze panels of a livestock chute, locking of a head holder of a livestock chute, or ratchet-locked hoof trimming equipment.

[0016] According to a fifth aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed, said hammer being connected to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; a first drive link pivotally connected both to the hammer and to a far one of the gate panels situated furthest from the hammer; and a second drive link pivotally connected both to the hammer, at a location across the longitudinal pivot axis from where the first drive link connects to the hammer, and to a near one of the gate panels situated nearest to the hammer; and a pawl carried on said hammer and biased into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; wherein said first and second drive links are the sole components by which the pivotal movement of the hammer is converted into movement of the gate panels in the opening and closing directions.

[0017] According to a sixth aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage comprising: a first drive link for imparting motion to the first gate panel; and a second drive link for imparting motion to the second gate panel; wherein said first and second drive links, in a maximally closed state of the head gate, both achieve angular proximities within 15-degrees of respective overcenter reference axes, past which said first and second drive links would over-center.

[0018] According to a seventh aspect of the invention, there is provided a conversion kit for fluid-powered upgrade of a manually operated livestock head gate that comprises at least one of either a manually driven rocker arm or hammer that is pivotally supported on or adjacent an existing bolt-on component that is bolted to an existing bolting site on said head gate, said conversion kit comprising: a replacement rocker arm carried, by a supportive pivot shaft, on a bolt- on replacement rocker support bracket that is configured for selective bolted attachment to said existing bolting site in replacement of the existing bolt-on component formerly bolted thereto, said replacement rocker arm radiating in two opposing directions from said supportive pivot shaft, and further comprising a coupling shaft at a radial distance outward from said supportive pivot shaft; a fluid-powered cylinder having one end thereof pivotally coupled or couplable to the replacement rocker arm in journaled relation about said coupling shaft thereof; and a bolt-on cylinder support bracket to which an opposing end of the fluid- powered cylinder is pivotally coupled or couplable, and which is configured for bolted attachment to an existing structural component of the head gate at a predefined bolting location of distanced relationship from the bolt-on replacement rocker support bracket in a direction spaced radially outward from the supportive pivot shaft thereof.

[0019] According to an eighth aspect of the invention, there is provided a method of installing the kit recited in the preceding aspect of the invention, said method comprising:

[0020] (a) decoupling the manually driven rocker arm or hammer from two gate panels of the head gate;

[0021] (b) removing one or more unnecessary components of the head gate formerly needed for manual actuation but unnecessary for powered actuation, including at least the existing bolt on-component;

[0022] (c) bolting the bolt-on replacement rocker support bracket at the existing bolting site, and bolting the cylinder support bracket in place on the existing structural component at the predefined bolting location thereon, and if not already coupled between said brackets, coupling said fluid-powered cylinder therebetween, thereby replacing the one or more unnecessary components with the replacement rocker arm and the fluid-powered cylinder; and

[0023] (d) reestablishing an operational head gate control linkage, at least in part by installing a pair of links, each in a position pivotally coupled to the replacement rocker arm adjacent a respective end thereof, and pivotally coupled to a respective one of the two gate panels, such that extension and collapse of the fluid-powered cylinder is thereafter operable to pivot the replacement rocker arm in opposing directions and thereby open and close said two gate panels.

[0024] According to a ninth aspect of the invention, there is provided a ratchet- locked device on a piece of livestock equipment, said device comprising: a rack having an arched array of ratchet teeth thereon at a topside thereof; a hammer pivotably supported adjacent the rack for pivotal movement about a pivot axis lying orthogonally of a plane in which the ratchet teeth are arrayed; a pawl carried on said hammer and biased into engagement with the ratchet teeth of the rack in a locking position; wherein said pawl is biased into engagement with the rack by: gravitational force; and a bias spring whose position resides oppositely across a pivot point of said pawl from where said pawl engages the rack.

[0025] According to a tenth aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage operable to control movement of said first and second gates panels in said opening and closing directions; an operator handle coupled to said gate control linkage to manually impart driving movement thereto and thereby drive movement of said first and second gate panels; wherein said operator handle is swingable upwardly and downwardly through an operating range that measures no greater than 90-degrees between a fully open position of said handle corresponding to maximum distancing of the gate panels from one another in a fully open state thereof and a maximally closed position of the handle corresponding to closest achievable adjacency of the gate panels in a maximally closed state thereof.

[0026] According to an eleventh aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; and a pawl carried on said hammer and biased into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; wherein the overhead support track has a length, measured in the lateral opening and closing directions of the head gate, that exceeds a width, likewise measured in the lateral opening and closing directions of the head gate, of an exit opening that the head gate is operable to open and close, the longitudinal pivot axis of the hammer resides at a location between two opposing ends of the overhead support track.

[0027] According to a twelfth aspect of the invention, there is provided a livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; and a pawl carried on said hammer and biased, into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; a drive shaft running longitudinally of the chute on a longitudinal axis about which said drive shaft is rotatable and on which said pivotal movement of the hammer is centered, said drive shaft being rotatably operable, via an operating handle, about said longitudinal axis to drive movement of the hammer in pivotal opening and closing directions corresponding, respectively, to the lateral opening and closing directions of the first and second gate panels; wherein the stationary rack has a hole therein that serves as a rotational support for a rotatable component of a drive assembly to which the drive shaft belongs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Preferred embodiments of the invention will now be described in conjunction with the accompanying drawings in which: Figure 1 is a front right perspective view of a livestock chute with a head gate of a first embodiment of the present invention installed at an exit thereof and shown in a fully closed position, with the livestock chute shown in a substantially simplified form with minimal detail to avoid overcrowding and obstruction of the head gate details.

[0029] Figure 2 is an enlarged partial front right perspective view of the head gate of Figure 1 .

[0030] Figure 3 is an enlarged partial rear right perspective view of the head gate of Figure 1 .

[0031] Figure 4 is a front right perspective view of the livestock chute of Figure 1 , but with the head gate thereof in a fully opened position.

[0032] Figure 5 is an enlarged partial front right perspective view of the head gate of Figure 4.

[0033] Figure 6 is an enlarged partial rear right perspective view of the head gate of Figure 4.

[0034] Figure 7 is an isolated front right perspective view of a ratchet mechanism of the head gate of Figures 1 through 6.

[0035] Figure 8 is an isolated rear right perspective view of the ratchet mechanism of Figure 7.

[0036] Figure 9 is an isolated top front perspective view of the ratchet mechanism of Figure 7.

[0037] Figure 10 is an isolated top rear perspective view of the ratchet mechanism of Figure 7.

[0038] Figure 11 is a cross-sectional view of the isolated ratchet mechanism of Figures 7 through 10.

[0039] Figure 12 is an isolated front right perspective view of a toothed rack plate and associated pawl of the ratchet mechanism of Figures 7 through 11 .

[0040] Figure 13 is an enlarged front elevational view of the rack plate and pawl of Figure 12, but with the rack plate substantially cut away, except for an arched peripheral edge region thereof to illustrate a ratchet-tooth profile embodied thereat.

[0041] Figure 14 is an enlarged partial front right perspective view of the head gate of Figure 4, zoomed in on a lower fraction thereof to illustrate removable wear blocks thereof.

[0042] Figure 15 is an enlarged partial front right perspective view of the livestock chute of Figure 1 , also zoomed in on a lower fraction thereof to show the removable wear blocks thereof.

[0043] Figure 16 is a top front perspective view of a second embodiment of the head gate, showing the fully closed position thereof.

[0044] Figure 17 is another top front perspective view of the head gate of Figure 16, but showing the fully open position thereof.

[0045] Figure 18 is a front left perspective view of the livestock chute of Figure 1 illustrating replacement of manually driven head gate linkage componentry thereof, and an associated manual drive assembly thereof, with a bolt-on hydraulic conversion kit for converting the head gate from manual drive to hydraulic drive.

[0046] Figure 19 is an enlarged partial front left perspective view of the livestock chute of Figure 18.

[0047] Figure 20 is a partial front elevational view of the head gate of Figures 1 to 15, illustrating an achieved degree of over-center proximity of a drive link in a control linkage of the head gate, when the head gate is fully closed.

[0048] Figure 21 is a partial front elevational view of the head gate of Figures 16 and 17, illustrating an achieved degree of over-center proximity of two drive links in a control linkage of the head gate, when the head gate is fully closed.

[0049] Figure 22 is another partial front elevation view of the head gate of Figures 1 to 15 and 20, illustrating an angular operating range of an operating handle of the control linkage.

[0050] Figure 23 is another partial front elevation view of the head gate of Figures 16, 17 and 21 , illustrating an angular operating range of an operating handle of the control linkage.

[0051] DETAILED DESCRIPTION

[0052] With initial reference to Figure 1 , there is shown a livestock chute 10 as one example of a type of livestock equipment that may serve as an operating context for a head gate of the present invention. The livestock chute 10 is shown in a highly simplified form, showing mainly its structural framework, without other componentry thereof, so as not to detract from clear illustration of the inventive head gate, which is the subject of the present invention. The framework delimits an interior space of the chute, and also an entrance and exit thereto and therefrom. In addition to forming this skeletal structure of the chute, the framework also serves to support all of the omitted functional components of the chute, and the illustrated functional components of the inventive head gate. The framework includes a pair of longitudinal floor beams 12A, 12B lying horizontally in a longitudinal direction of the chute, a pair of longitudinal header beams 14A, 14B lying horizontally in parallel relation to the floor beams 12A, 12B in elevated relation thereover at a top header of the chute, and a set of four corner posts 16 each standing vertically upright from one of the floor beams 12A, 12B at an end or end-adjacent region thereof to perpendicularly interconnect same to the matching end or end region of one of the longitudinal header beams 14A, 14B, and thereby defining a respective one of four outer comers of the chute 10. The framework thus delimits an interior space of generally rectangular volume. A set of two or more cross-headers 18A, 18B span horizontally and perpendicularly between the two header beams 14, 14B at spaced apart locations therealong to maintain a squareness of the header. At each end of the chute, the floor beams 12A, 12B are likewise perpendicularly and horizontally connected by cross-sills 20A, 20B, the illustrated two of which are each situated at or closely adjacent a vertical plane occupied by a respective pair of the corner posts 16, to maintain a squareness of a ground-level floor structure composed of this combination of perpendicularly related floor beams 12A, 12B and cross-sills 20A, 20B. At each end of the chute, the two respective corner posts 16 and the respective one of the cross-sills 20A, 20B frame three sides of a respective rectangular opening through which entrance to, and exit from, the chute’s interior space is possible, thereby enabling traversal of an animal through said interior space from one opening to the other on a longitudinal pathway therebetween.

[0053] The framed opening at a first of these two ends of the chute is referred to herein as an entrance opening 22, through which animals are admitted into the interior space of the chute during use thereof, for example in controlled one-by-one fashion via a sliding gate (not shown) or other entrance gate installed in this entrance opening 22. The framed opening at the opposing second end chute is referred to herein as an exit opening 26 through which animals depart the interior space of the chute once having travelled therethrough on the longitudinal pathway from the opposing entrance opening 22. The first and second ends of the chute are thus also referred to as the rear entrance end 28 and the front exit end 30 of the chute, respectively, in relation to the travel direction in which animals move therethrough, travelling forwardly from the rear entrance end 28 of the chute toward the opposing front exit end 30 thereof. Departure of an admitted animal from the chute 10 through the exit opening 26 at the front end 30 thereof is controlled via the inventive head gate 32 that is the subject of the present application. As with the prior art, closure of this head gate 32 is performed while the animal attempts to pass through the exit opening 26 so that two movable gate panels of the head gate abut against opposing sides of the animal’s body, at the neck thereof, to help hold the animal in a position in which their head resides outside the chute 10, while the trailing remainder of their body is still inside the chute 10. The framed opening in which the animal’s neck resides in this closed state of the head gate is referred to generally as an animal-receiving opening of the head gate 32, which in the illustrated example of the head gate’s installation at the exit opening 26 of a chute 10, is synonymous with this exit opening 26. The chute 10 may be a squeeze chute that also features a pair of movable side walls (not shown), each normally residing in a non-working position situated generally within or closely adjacent a vertical plane bound by the one of the longitudinal floor beams 12A, 12B, the corresponding one of the longitudinal header beams 14A, 14B situated thereover, and the corresponding two corner posts 16 that interconnect that floor beam and header beam at a respective side of the chute. Via a squeeze control linkage (not shown), for example manually operable by a squeeze control lever installed externally on one side of the chute, the two side walls of such typical squeeze chute are selectively movable in an inward direction toward one another and into the interior space of the squeeze chute in order to constrict the width of the interior space and thereby squeeze against opposing sides of the trailing rear portion of the animal’s body inside the chute. Alternatively, the squeezing action of the side walls of such squeeze chute may be actuated hydraulically. The squeeze function cooperates with the head gate 32 to further constrain the animal in a stationary position for safe inspection and / or treatment thereof by a human operator from laterally outside the chute 10.

[0054] The head gate 32 features two movable gate panels 40A, 40B each suspended from a respective roller carriage 42A, 42B having a set of rollers therein that ride on a transverse roller support shaft 44 of the head gate 32, which lies perpendicularly transverse of the longitudinal floor beams 12A, 12B and the header beams 14A, 14B, and parallel to the cross-sills 20A, 20B and cross-headers 18A, 18B. The terms transverse and lateral are used herein to refer to horizontal directions of perpendicularly transverse relation to the horizontally longitudinal direction already defined above. The transverse roller support shaft 44 is mounted to a shaft-support bracket 46 that spans transversely across the two corner posts 16 of the exit opening 26 at front sides of these corner posts 16 that face outwardly from the interior space of the chute 10, and near top ends of these posts where the header beams 14A, 14B are attached thereto. In the illustrated example, the shaft-support bracket 46 resides at slightly lesser elevation than the top ends of the corner posts 16, for example with a top wall of the shaft-support bracket 46 at roughly equal elevation to undersides of the two header beams 14A, 14B. The two movable gate panels 40A, 40B can slide laterally toward and away from another in the transverse direction via rolling movement of their roller carriages 42A, 42B on the transverse roller support shaft 44, which thus serves as an overhead support track for the two gate panels 40A, 40B. In the Applicant’s own prior art referenced in the background above, it is these carriages 42A, 42B that also have spring loaded, tiltable locking plates therein for frictional biting thereof on the shaft 44 to lock the gate panels against movement in the opening direction, which spring- tilted, frictionally biting locking plates are omitted in the present invention in favour of a ratchet-based mechanism for imparting the anti-opening locking action to the two gate panels 40A, 40B. The ratchet-based mechanism features a stationary rack 48 mounted in a static position atop the shaft-support bracket 46 at or closely adjacent one of two laterally outer extremities thereof that respectively reach outwardly past the two corner posts 16 of the chute’s exit opening 26. The stationary rack 48 is embodied as a flat metal plate, and is thus also referred to herein as rack plate 48. The rack plate 48 has a convexly arcuate upper edge along which a set of ratchet teeth 50 are arranged in an arched array. The radial center point of the arcuate upper edge of the rack plate 48 and the arched array of ratchet teeth 50 embodied thereon is also the radial center of a circular hole 52 of the rack plate 48, and also the radial center of an arcuate guide slot 54 that resides between the circular hole 52 and the toothed upper edge of the rack plate 48.

[0055] For driving opening and closing movement of the head gate 32, an elongated drive shaft 56 of square cross-section runs longitudinally alongside the header of the chute 10 a short lateral distance outside the same one of the header beams 14A that is neighboured by the rack plate 48. A rear end of this drive shaft 56 is rotatably supported by a drive shaft support bracket 58 that projects laterally out from the header beam 14A near the rear entrance end 28 of the chute 14, whereby the drive shaft 56 is rotatable about its longitudinal axis L. Near an opposing front end of the drive shaft 56, the drive shaft 56 penetrates through the circular hole 52 of the rack plate 48, which is generally centered on the drive shaft’s longitudinal axis L. The drive shaft 56 thus passes from a rear side of the rack plate 48 that faces the rear entrance end 28 of the chute 10, to an opposing front side of the rack plate 48 that faces forwardly away from the rear entrance end 28 of the chute 10 and toward the opposing front exit end 30 of the chute 10.

[0056] The drive shaft 56 is of multi-piece construction, having a main shaft body 60 composed of a length of square metal tubing that embodies a vast majority of the drive shaft’s overall length, starting from the drive shaft support bracket 58 and spanning to close adjacency with the rack plate 48. A remainder of the drive shaft 56 is embodied by a removable end collar 62 that is composed of a shorter length of square metal tubing of slightly larger cross-sectional size than the main shaft body 60, and is fitted externally over a front end of the main shaft body 60, as can be seen in Figure 3. The end collar 62 is removably fastened to the main shaft body 60 at a short distance rearward from the rack plate 48 by a removable bolt fastener 64 penetrating through both drive shaft components 60, 62. Of these two drive shaft components 60, 62, it is the shorter end collar 62 that penetrates concentrically through the circular hole 52 of the rack plate 48, inside of which the rectangular drive shaft 56 is rotatable relative to the stationary rack plate 48, for purposes set forth further below. The rack plate 48 thus serves as a stationary metal bushing for rotational support of the drive shaft 56 near the front end thereof, in cooperation with the shaft support bracket 58 that rotatably supports the opposing rear end of the drive shaft 56.

[0057] The drive shaft 56 is part of an overall drive assembly that further includes an operator handle 66 having an elongated shank 68, a hand grip 70 at an actuation end of the shank, and a support channel 72 affixed to an opposing working end of the shank 68. This support channel 72 may made of a short length of metal tubing or 11- shaped channel (of which the latter is shown in the illustrated example) whose internal width is slightly greater than that of the main shaft body 60 of the drive shaft 56. The support channel 72 therefore fits over the main shaft body 60 of the drive shaft 56 to suspend the operator handle 66 therefrom, yet is slidable back and forth along the main shaft body 60 of the drive shaft 56 to enable longitudinal repositioning of the operator handle 66 therealong. Though not shown in the illustrated embodiments, a locking mechanism may optionally be included to enable selective locking of the operator handle 66 at a user-selected position on the main shaft body 60 of the drive shaft 56, for example using a wing-bolt engaged in a threaded bore penetrating into the interior of the support channel 72. The slightly larger end collar 62 of the drive shaft serves as a stop that limits forward sliding of the operator handle to a point shortly behind the head gate 32 and its ratchet mechanism.

[0058] While the operator handle 66 is longitudinally slidable on the main shaft body 60 of the drive shaft 56, it is rotationally locked thereto by the similarly sized and straight-sided shape profiles of the support channel’s interior and the main shaft body’s exterior. Accordingly, rotation of the elongated drive shaft 56 about its longitudinal axis L is performable via manual gripping of the operator handle 66, and swinging thereof about the longitudinal axis L. Swinging of the operator handle 66 in a downward closing direction drives closure of the head gate 32 in its lateral closing direction via a gate control linkage 74, and swinging of the operator handle 66 in an upward opening direction instead drives opening of the head gate 32 in its lateral opening direction via this same gate control linkage 74.

[0059] The gate control linkage 74 features a pivotably movable hammer 76 situated in close adjacency to the rack plate 48, and whose pivotal motion is centered about the longitudinal axis L of the drive shaft 56, which in turn is coincident with the center point of the circular hole 52 in the rack plate 48, as mentioned above. The hammer 76 is a dual-plate hammer assembly of two-sided relation to the rack plate 48, being composed of a front hammer plate 76A situated on the front side of the rack plate 48, and a rear hammer plate 76B situated on the opposing rear side of the rack plate 48. The two hammer plates 76A, 76B in the illustrated example are of matching shape to one another, each having a proximal inner end adjacent to which the end collar 62 of the drive shaft 56 penetrates orthogonally through the hammer plate 76A, 76B, specifically through circular holes therein of aligned relation to the circular hole 52 of the rack plate 48, such that the hammer is not rotationally locked to the drive shaft 56, and relative rotation is instead allowed to occur therebetween.

[0060] The hammer plates 76A, 76B radiate outwardly and unidirectionally away from the end collar 62 of the drive shaft 56 to an opposing distal outer end 80 of the hammer plate 76A, 76B. Each hammer plate 76A, 76B of the illustrated embodiment features a set of three coupling holes 82A, 82B, 82C therein near the plate’s distal outer end 80, of which the two respective sets of coupling holes in the two hammer plates 76A, 76B are of matching and aligned with one another. In each set, the coupling holes 82A, 82B, 82C are spaced from one another along a length dimension of the respective hammer plate 76A, 76B, as measured between the proximal and distal ends thereof in radial relation to the longitudinal axis L. Coupling hole 82A is the nearest of the three coupling holes to the longitudinal axis L, coupling hole 82C is the furthest of the three coupling holes from the longitudinal axis L, and coupling hole 82B is the middle distanced of the three from the longitudinal axis L. Each hammer plate 76A, 76B also features a release slot 84 therein that is situated at a mid-region of the hammer plate’s lengthwise span. This release slot 84 spans a short distance of arcuately circumferential or tangential relationship to the longitudinal axis L. Like the sets of coupling holes, the release slots 84 of the two hammer plates are of matching and aligned relationship with one another.

[0061] A pair of matching and aligned pawl-pivot holes in the hammer plates 76A, 76B accommodate receipt of a pivot pin 86 through the two hammer plates at a location whose radial distance from the longitudinal axis L is greater than that of the release slots 84 and the toothed arcuate edge of the rack plate 48, but is less than the radial distance from the longitudinal axis L to the closest coupling hole 82A. This pivot pin 86 passes through the two hammer plates 76A, 76B at a location radially beyond the perimeter of the rack plate 48, and in doing so, also passes through a pawl carrier 88 that resides between the two hammer plates 76A, 76B. This pawl carrier 88 carries a pawl 90 for engaging the ratchet teeth 50 of the rack plate 48 to impart the anti-opening locking action to the head gate 32, which locking action is automatically imparted at all times other than during opening of the head gate, as described in more detail below. The pawl carrier 88 of the illustrated example, like the hammer 76, is an assembly of dual-plate construction, having a front carrier plate 88A on the front side of the rack plate 48, and a rear carrier plate 88B on the opposing rear side of the rack plate 48. Each carrier plate 88A, 88B resides in a respective vertical plane situated between a vertical plane of the rack plate 48 and a vertical plane of a respective one of the hammer plates 76A, 76B. Also situated in the plane between each hammer plate 76A, 76B and the rack plate 48 is a respective hammer spacer 92A, 92B, visible in Figures 9-11 , whose thickness, measured axially of longitudinal axis L and orthogonally of the hammer plates, rack plate and carrier plates, may exceed a thickness of the respective carrier plate 88A, 88B to ensure that each carrier plate 88A, 88B can swing smoothly about the pivot pin 86 relative to the stationary rack plate 48 and relative to the hammer plates 76A, 76B. Each hammer spacer 92A, 92B features a circular hole therein of aligned relation to those in the rack and hammer plates 48, 76B, 76B to accommodate passage of the end collar 62 of the drive shaft 56 through the hammer spacers 92A, 92B.

[0062] The two carrier plates 88A, 88B are of matching elongated shape and aligned relation to one another, and a majority length of their matching shape is embodied by an inner portion of the carrier 88 that radiates inwardly toward the toothed arcuate edge of the rack plate 48 from the pivot pin 86 on which the carrier 88 is pivotably supported on the hammer plates 76A, 76B. In the illustrated example, a shorter outer tail portion of each carrier plate 88A, 88B instead radiates outwardly in a diametrically opposing direction from the pivot pin 86. The pawl 90 is a solid piece of metal stock attached to the two carrier plates 88A, 88B in sandwiched relation between the inner portions thereof. In the illustrated embodiment, this attachment is achieved through a combination of welding, and mated receipt of portions of the pawl 90 in holes of the two carrier plates 88A, 88B, for example, with two protruding stubs on each of the front and rear sides of the pawl engaged in two matching holes in each of the front and rear carrier plates 88A, 88B. With reference to Figure 12, the pawl 90 of the illustrated embodiment is an H-shaped steel block, with the four rectangular tips 90A of the H-shape engaged in four rectangular holes of the carrier 88, of which there are two such rectangular holes in each of the two carrier plates 88A, 88B. The rectangular center cross-stem 90B of the pawl’s H-shape is sandwiched between the two carrier plates 88A, 88B. This rectangular center 90B of the H-shape is the part of the pawl that engages with the rack plate 48, specifically at an inner working end 90C of the pawl 90 situated radially furthest from the pivot pin 86 of the pawl carrier 88. The pawl setup is a trailing pawl setup, where the working end 90C of the pawl that engages the rack plate 48 trails the pivot pin 86 of the pawl during the closure of the head gate.

[0063] In a fully closed state of the head gate 32, with the two gate panels 40A, 40B at their closest achievable relationship to one another minimizing the openness of the exit opening 26 of the chute 10 between the two gate panels 40A, 40B, and corresponding to contact, and more preferably to compressed interfering contact, of two resilient bumpers 94 mounted on inner edges of the two gate panels 40A, 40B, the pawl 90 engages the arched array of ratchet teeth 50 near a laterally outermost terminus thereof. In this state, and as best shown in the cross-sectional view of Figure 11 , the pivot axis of pivot pin 86 resides at a lesser elevation than the contacting engagement between the pawl 90 and the ratchet teeth 50, so that the pawl 90 angles upwardly toward the rack plate 48. This way, absent a release action performed on the pawl 90 via the operator handle 66 (in a manner described further below), any attempted opening of the head gate 32, which requires upward movement of the outer distal end 80 of the hammer 76, serves only to force the pawl 90 more aggressively into locked relation to the rack plate 48, owing to the pawl’s 90 inwardly inclined orientation at an upper inner quadrant of a coordinate reference frame centered on the pivot axis of pivot pin 86. Rising of pivot pin 86 about the longitudinal axis L with upward movement of the distal end 80 of the hammer 76 would correlate to laterally inward movement of the inner working end 90C of the pawl 90, which is blocked by the pawl’s engaged relation to the rack teeth 50.

[0064] In the fully closed position, but also throughout the operational range of the ratchet, the pawl 90 is gravitationally biased into engagement with the ratchet teeth 50 of the rack plate 48, whereby reliability of the anti-opening locking action is not dependent on, or at least not fully dependent on, a spring-biasing of the pawl 90, where a spring failure could otherwise defeat the anti-opening locking action of the ratchet mechanism. That said, and as demonstrated by the illustrated example, a bias spring 96 may nonetheless be included to supplement the gravitational bias of the pawl 90 into engagement with the rack plate 48. In the illustrated example, this bias spring 96 is a tension spring that has one end hooked around a cross-pin 98 of the pawl carrier 88 near the outer tail end thereof, while the other end of the spring 96 is hooked around a cross-pin 100 of the hammer 76 that spans perpendicularly between the hammer plates 76A, 76B near the distal outer end 80 thereof (though the spring is not illustrated in a stretched state hooked about this second cross-pin 100 in the drawings, owing to CAD modeling limitations under which the spring is instead shown in its collapsed state of insufficient length for such attachment to pin 100). Since the spring-engaged cross-pin 98 of the pawl carrier 88 is situated across the pawl carrier pivot pin 86 from the pawl 90, the upward pulling of the outer tail portion of the pawl carrier 88 toward the distal outer end 80 of the hammer 76 rocks the inner working end 90C of the pawl 90 downwardly, and thus into locking engagement with the ratchet teeth 50 of the rack plate 48, thus supplementing the gravitational bias of the pawl 90 downwardly about pivot pin 86 to further encourage engagement of the pawl 90 with the ratchet teeth 50.

[0065] Opening of the head gate 32 through manual lifting of the operating handle 66 of the drive assembly requires that the pawl 90 be lifted out of engagement with the ratchet teeth 50 of the rack plate 48. For such purpose, a release arm 102 is attached to the end collar 62 of the drive shaft 56 at a terminal front end thereof in front of the front hammer plate 76A. In the illustrated embodiment, affixation of the release arm 102 to the end collar 62 of the drive shaft 56 is achieved by a combination of welding, and mated receipt of four longitudinally projecting end-tabs on the four walls of the square-profiled end collar 62 in four matching slots 102A provided in the release arm 102, which slots 102A can be seen in Figure 9. Affixed to the removable end collar 62 of the assembled drive shaft 56, the release arm 102 is rotated therewith during any manually driven rotation of the drive shaft 56 via the operating handle 66. By contrast, the hammer plates 76A, 76B of the hammer are not rigidly affixed to the end collar 62 of the drive shaft 56, nor are the hammer plates 76A, 76B rigidly affixed to the release arm 102. Instead, a limited degree of rotation between the hammer 76 and the release arm 102 is permitted to occur about the longitudinal axis L of the drive shaft 56 for the purpose of enabling the release arm 102 to effect pivoting of the pawl carrier 88 and attached pawl 90 relative to the hammer 76 about the pawl carrier pivot pin 86. Such pivoting of the pawl carrier 88 by the release arm 102 in a release direction lifting the pawl 90 out of engagement with the ratchet teeth 50 of the rack plate 48 occurs specifically when the operating handle 66 of the drive assembly is lifted upward to open the head gate 32.

[0066] The release arm 102 radiates outward from its attachment to the terminal front end of the drive shaft 56 in a vertical plane parallel to that of the front hammer plate 76A, and radiates in the same general direction in which the hammer plates 76A, 76B radiate outward from the drive shaft 56. Near a distal outer end of the release arm 102, a release pin 104 projects longitudinally rearward from the release arm 102 through the release slot 84 in the front hammer plate 76A. as can be seen in Figure 7. A bottom edge of each carrier plate 88A, 88B of the pawl carrier 88 includes a contact segment 106 (Figs. 7 & 11 ) that spans across the release slot 84 in the respective hammer plate 76A, 76B. The contact segment 106 of the bottom edge of the front carrier plate 88A serves as an engagement point of the pawl carrier 88 for contact and lifting of the pawl carrier 88 by the release pin 104 of the release arm 102 that penetrates through the release slot 84 in the front hammer plate 76A. thus enabling intentional operator-driven opening of the head gate 32 from any fully or partially closed state. During closing of the head gate 32, downward pulling of the operator handle 66 of the drive assembly drives rotation of the release arm 102 on the drive shaft 56 about the longitudinal axis L in a locking direction moving the release pin 104 away from the pawl carrier 88 toward a first end of the release slot 84, with the result that the pawl carrier 88 is gravitationally biased (with optional spring-bias supplementation) into engagement with the ratchet teeth 50 of the rack plate 48. Continued pulling of the operator handle 66 with the release pin 104 engaged with this end of the release slot 84 drives the hammer 76, in synchronicity with the release arm 102, in a closing direction pivoting the distal outer end 80 of the hammer 76 laterally outward and downward about the longitudinal axis L. This acts to close the head gate via the control linkage 74, during which the pawl 90 is drawn outwardly over the arched array of ratchet teeth 50 in slipping fashion thereover.

[0067] On the other hand, during manual lifting of the operator handle 66 to open the head gate 32 from a fully or partially closed state in which the pawl 90 is engaged with the toothed arch of the rack plate 48, lifting of the operator handle 66 will initially pivot the distal outer end of the release arm 102 upwardly about the longitudinal axis L, relative to the hammer 76, thus lifting the release pin 104 upwardly into engagement with the contact segment 106 of the front carrier plate 88A of the pawl carrier 88, and thereby lifting the pawl 90 upwardly out of engagement with the ratchet teeth 50 of the rack plate 48, to a point at which the release pin 104 contacts a second end of the release slot 84 of the front hammer plate 76A. Once such contact is made, continued lifting of the operator handle 66 will drive the hammer 76, in synchronicity with the release arm 102, in an opening direction pivoting the distal outer end of the hammer 76 laterally upwardly and inwardly about the longitudinal axis L, during which the release- lifted pawl 90 clears the ratchet teeth 50 on the toothed upper arch of the rack plate 48, so that lifting of the unlocked hammer 76 opens the head gate 32 via the control linkage 74.

[0068] The operational range of the ratchet mechanism over which the release arm 102 and the hammer 76 are rotatable about the longitudinal axis L relative to the stationary rack plate 48 is limited by engagement of a guide pin 108 that penetrates longitudinally through the guide slot 54 of the rack plate 48 via aligned holes in the hammer plates 76A, 76B and the hammer spacers 92A, 92B, and also through a release arm spacer 92C that is similarly disposed between the front hammer plate 76A and the release arm 102 in the illustrated example. This guide pin 108 also penetrates through an aligned guide pin slot 110 in the release arm 92 that arcs a short angular distance around the longitudinal axis L at a radial distance therefrom lesser than that of the release pin 104. The guide pin slot 110 is substantially concealed by a washer in most of the figures, but is partially visible in Figure 9. This guide pin slot 110 permits the limited degree of relative pivoting between the hammer 76 and the release arm 102 that is necessary to disengage the pawl 90 from the rack plate 48 during opening of the head gate 32.

[0069] In an alternative embodiment (not illustrated), instead of being situated outside the hammer 76 and relying on a release pin 104 penetrating through a release slot 84 in the nearest hammer plate 76A, the release arm 102 may alternatively reside between the two hammer plates, i.e. between the rack plate 48 and one of the hammer plates, for direct interaction with the pawl carrier 88 inside the hammer 76. Such internal release arm may have a square hole therein by which this internal release arm 102 would be fitted over, and rotationally locked to, the end collar 62 of the drive shaft 56 for driven rotation thereby.

[0070] Attention is now turned to details of the first embodiment’s control linkage 74 whose movement is executed via user-executed drive of the hammer 76 via the operator handle 66 and release arm 102. Aside from the already described hammer 76 and associated release arm 102, the additional links of the control linkage 74 include a repositionable first drive link 112, a rocker arm 114, a connecting link 116, and a second drive link 118. The first drive link 112 has an outer end thereof pivotally coupled to the front hammer plate 76A of the hammer 76, and an opposing inner end pivotally coupled to a far one of the gate panels 40B situated furthest from the hammer 76, for example at an upper coupling point of a coupling plate 120B that stands upright from a front wall of this gate panel’s roller carriage 42B, whereby this upstanding coupling plate 120B places this upper coupling point above the roller support shaft 44 on which the gate panels 40A, 40B ride, and likewise above the shaft-support bracket 46 that carries the roller support shaft 44. The near gate panel 40A situated nearest to the hammer 76 has a matching coupling plate 120A on its roller carriage 42A, which is of matching shape and symmetrically mirrored orientation to the coupling plate 120B of the far gate panel 40B in the illustrated example.

[0071] The outer end of the first drive link 112 is selectively couplable to the front hammer plate 76A at any one of the three available coupling holes 82A, 82B, 82C, each of which imparts different characteristics to the closing stroke of the gate movement, specifically imparting a different degree to which the gate is maximally closeable i.e. the minimum achievable spacing between the gate panels 40A, 40B corresponding to the “fully closed” position of the hammer that reaches furthest laterally outward from the longitudinal axis L and corresponds to engagement of the pawl 90 and at outermost attainable point on the arched array of ratchet teeth 50 on the rack plate 48. Outermost coupling hole 82C furthest from the longitudinal axis L corresponds to maximum attainable closure of the gate with the two gate panels 40A, 40B at their closest achievable distance to one another in their closed state (for example, with their inner edges approximately 4-inches apart) with the bumpers 94 thereof in physical contact, which a user would select for working with calves, denoting a lower range of workable animal sizes. Middle coupling hole 82B corresponds to an intermediate attainable closure of the gate with the two gate panels at an intermediate closed-distance to one another at their closest achievable proximity to one another (for example, with their inner edges approximately 6-inches apart) with the bumpers 94 thereof thus now separated, which a user would select for working with cows, denoting a typical intermediate range of workable animals sizes. Innermost coupling hole 82A corresponds to a minimum attainable closure of the gate with the two gate panels at a furthest closed-distance to one another at their closest achievable proximity to one another (for example, with their inner edges approximately 8-inches apart), with the bumpers 94 thereof thus again separated, which a user would select for working with larger bulls, denoting a largest scale of a workable animal size range. Coupling of the outer end of the first drive link 112 to any selected one of the three user-selectable coupling points embodied by the three aligned pairs of coupling holes 82A, 82B, 82C in the hammer plates 76A, 76B is achieved by engagement of a removable locking pin 122 into the selected one of the front hammer plate’s three coupling holes 82A, 82B, 82C, through a corresponding pin lock hole in this outer end of the first drive link 112, and onward through the matching coupling hole 82A, 82B, 82C in the rear hammer plate 76B.

[0072] The rocker arm 114 is pivotally mounted atop the shaft-support bracket 46 at a location situated laterally across the gated exit opening 26 of the chute 10 from the ratchet mechanism and associated hammer 76, whereby the hammer 76 and the rocker arm 114 reside respectively adjacent two opposing lateral extrem ities of the head gate 32, for example as may be denoted either by the laterally opposing outer ends of the roller support shaft 44, or the laterally opposing outer ends of the shaft-support bracket 46 that carries same. The rocker arm 114 is pivotable about an axis parallel to the longitudinal axis L of the drive shaft 56, which as mentioned above, also denotes the pivot axis of the hammer 76 and the release arm 102. The pivot axes of the rocker arm 114 and the hammer 76, i.e. the two components of the linkage that are pivotably mounted to the framework of the chute 10 and head gate 32 at stationary pivot points, both reside within the length span of the roller support shaft 44, i.e. within the lateral measure of the overhead support track on which the gate panels 40A, 40B are movable back in forth in the lateral opening and closing directions. The head gate 32 is a curtainstyle head gate, where the gate panels 40A, 40B open and close via pure lateral displacement back and forth along the overhead support track, with no tilting of the gate panels about any longitudinal tilt axes, nor any swinging of the gate panels about upright swing axes, and whose gate panels are supported purely by roller-hung suspension thereof from the overhead track with no additional lateral support from the side, nor any bottom support from beneath.

[0073] This combination has not been seen previously among ratchet-locked head gate linkages, to which applicant attributes a newfound degree of attainable opening width by a ratchet-locked head gate, where in the fully open position, prototypes of this design have achieved an exit pass-through width of 800mm or 31 .5 inches, while keeping the head gate 32 within road safety constraints of a road transportable mobile chute. Another distinctive benefit associated with the novel ratchet and hammer setup described herein is an improvement to the angular operating range of the operating handle 66, measured between the handle position occupied in the fully open state of the head gate, and the handle position occupied in the maximally closed state of the head gate. In the present invention, the angular span of the handle’s operating range Ro is less than 90-degrees, more preferably less than 85-degrees, and optimally not more than 80-degrees, for example measuring 75 degrees in one particular embodiment represented by Figure 22. As shown in broken lines in Figure 22, the operator handle 66 occupies a position of at least initially downward inclination from the longitudinal drive shaft 56 in the fully open state of the head gate, making the operator handle easier to reach for a variety of operators of varying personal stature. In the maximally closed state of the head gate 32, shown in solid lines, the position occupied by the operator handle 66 is one that, in its initial hanging relation from the drive shaft 56, angles laterally inward toward the plane of the nearest side of the chute 10. As shown, the shank 68 of the handle 66 may be of a bent profile, whereby a distal segment 68B of the shank 68 nearest the hand grip 70 is obliquely offset from a proximal segment 68A of the shank 68 nearest to the support channel 72. As a result, the distal segment 68B angles laterally outward in its hanging relation from the inwardly angled proximal segment 68A of the operator handle’s fully closed position. This helps ensure no pinching risk for the operator’s hand between the handle 66 and the side of the chute 10 in the fully closed position. In the Figure 23 embodiment, the handle 66’ instead has an unbent straight shank 68’, but again has an angular operating range Ro under 90-degrees, preferably under 85-degrees, and measuring approximately 80- degrees in one particular embodiment represented in this figure.

[0074] The rocker arm 114 resides in front of the roller support shaft 44 and shaftsupport bracket 46, with its pivot axis above the shaft-support bracket 46, at equal elevation to the pivot axis L of the hammer 76 in the illustrated example, whereby a bottom half of the rocker arm 114 reaches downward from the top of the shaft-support bracket 46, at a laterally outward angle in the fully open state of the head gate 32, and at a laterally inward angle in the maximally closed state thereof, with the top half of the rocker arm thus reaching further upward from its pivotally mounted support on the shaftsupport bracket 46 at a laterally outward angle in the maximally closed state of the head gate 32, and at a laterally inward angle in the fully open state thereof. The connecting link 116 has an outer end thereof pivotally coupled to a bottom end of the rocker arm 114, and an opposing inner end pivotally coupled to the roller carriage 42B of gate panel 40B, for example at a lower coupling point provided on the same coupling plate 120B to which the first drive link 112 is pivotally coupled. The second drive link 118 has an outer end thereof pivotally coupled to the top end of the rocker arm 114, and an opposing inner end pivotally coupled to the gate panel 40A nearest to the hammer 76, at the upper coupling point of its coupling plate 120A, thereby mirroring the coupling point of the first drive link 112 to the other gate panel 40B. This linkage design requires only a singular link 112 of directly interconnected relationship between the hammer 76 and the far gate panel 40B situated furthest therefrom.

[0075] During closure of the head gate 32 from its fully open state, the first drive link 112 pulls the far gate panel 40B toward the hammer 76 and thus toward the near gate panel 40A. The pulling of the far panel 40B pulls the connecting link 116 toward the near gate panel 40A and the hammer 76, which in turn pulls the bottom end of the rocker arm 114 in the same direction, laterally inward toward the lateral center of the head gate 32. This pivots the rocker arm 114 in a direction swinging its top end laterally outward, i.e. away from the hammer 76 and gate panel 40A. This pulls the second drive link 118 away from the hammer 76, and thereby pulls the gate panel 40A toward the rocker arm 114 and gate panel 40B, thus closing the two gate panels 40A, 40B toward one another. Since both drive links 112, 118 and the connecting link 116 are all being pulled during this gate closure movement of the linkage 74, all such links are subjected to only tensile forces during closure of the gate, thus taking advantage of the maximum load handling capability of these steel links, whose tensile loading capacity and service life exceed those associated with compressive loading. In the maximally closed position (that corresponding to any of the three user-selectable coupling points 82A, 82B, 82C for the repositionable first drive link 112), the laterally inward force exertable on the animal by the gate panels 40A, 40B is at its maximum to provide optimal holding pressure on the animal. With reference to Figure 20, this is attributable to design of the linkage 74 such that first drive link 112 acquires an orientation of near, but not quite, in-line relation to an over-center reference axis Aoc spanning from the longitudinal axis L (the pivot axis of the hammer 76) to the selected coupling point 82A,82B, 82C of the hammer 76 where the outer end of the first drive link 112 is coupled. The over-center reference Aoc axis denotes a crossover point past which the first drive link would become over-centered under continued pivoting in the same gateclosing direction, which would have the effect of fully locking the head gate from opening (even under release of the ratchet mechanism). Such near approach to the over-center reference axis Aoc imparts a maximizing effect to the applied holding force to the animal as the gate reaches it maximally closed state.

[0076] In the illustrated embodiment, the first drive link 112 has a slightly arced shape, and so measure of the first drive link’s angulation relative to the over-center reference axis Aoc is measured using a straight drive-link reference axis ADL spanning from the first drive link’s pivotal coupling point on the hammer 76 to the first drive’ link’s pivotal coupling point on the coupling plate 120B of gate panel 40B. In preferred embodiments, the first drive link 112 reaches an angular proximity PA within 15-degrees of the first drive link’s over-center reference axis Aoc, with the illustrated embodiment being one in which the first drive link 112, when connected to coupling point 82C for full gate closure, achieves an angular proximity of 12.55-degrees to the over-center reference axis Aoc in the fully closed position.

[0077] Among others, one novel aspect of the forgoing design is that because the drive shaft 56 passes through the stationary rack plate 48 to connect directly to the front hammer plate 76A to which the first drive link 112 is connected, the exertion of the drive force to the hammer 76 from the user-rotated drive shaft 56 occurs on the same front side of the rack plate 48 where the gate control linkage 74 resides, thus minimizing the potential for twisting loads on the linkage 74. At the same time, the inclusion of two matching hammer plates 76A, 76B on opposing sides of the rack plate 48 contributes to a reversibility of a near entirety of the gate control (the drive assembly, the ratchet mechanism, and the linkage), by which the gate control is relocatable from one side of the head gate 32 to the other. To do so, links 112, 116 are unbolted and removed, rocker arm 114 and a rocker arm support bracket 126 on which the rocker arm is pivotally carried are likewise removed, by unbolting this support bracket 126. Likewise, the end collar 62 and affixed release arm 102 are unbolted from the main shaft body 60 of the drive shaft 56 and from the rocker 76, respectively, and are pulled off the terminal front end of the main shaft body 60 together with the release arm spacer 92C, thus extracting these components from the rack plate 48 and the hammer 76. Such removal also enables removal of the hammer 76 and its spacers 92A, 92B from the rack plate 48, and decoupling of the main shaft body 60 from the drive shaft’s rear support bracket 58. The drive shaft support bracket 58 is unbolted from the header beam 14A, and also removed.

[0078] The rack plate 48 is unbolted from an upstanding mounting bracket 124A on the top wall of the shaft-support bracket 46 just outside the header beam 14A, and is relocated to a matching mounting bracket 124B of symmetrically mirrored relation to the first mounting bracket 124A at a location adjacent the opposing lateral extremity of the shaft-support bracket 46 just outside the other header beam 14B, from which the rocker support bracket 126 was unbolted. In its relocation from one side of the head gate 32 to the other, the rack plate 48 is simply flipped into a reverse orientation, where its previous front-facing side is now its rear-facing side, so that the arched array of ratchet teeth 50 resides in mirrored symmetry to where this arched tooth array previously resided on the original side of the head gate 32. While the illustrated embodiment uses the shaft-support bracket 46 as an overhead structural component on which the mounting brackets 124A, 124B define symmetrically mirrored bolting sites for selective relocation of the stationary rack 48 from one side of the head gate 32 to the other, the particular structural componentry of the head gate 32 used for such purpose may vary.

[0079] The hammer 76, from which the first drive link 112 has been unpinned, is likewise flipped around, and placed back over the repositioned and reoriented rack plate 48, together with the hammer plate spacers 92A, 92B, so that the former front hammer plate is the now the rear hammer plate, and vice versa. The drive shaft support bracket 58, having been decoupled from the main shaft body 60, is also reversed in its orientation, and bolted to header beam 14B at a predefined bolting location of symmetrically mirrored relation to that where it was previously bolted to header beam 14A, and the main shaft body 60 is recoupled to the now-front side of the reoriented and reinstalled drive shaft support bracket 58, with the operator handle 66 first being removed, flipped around and reinstalled on the main shaft body 60 to achieve mirrored symmetry of its originally installed location at the new location of the relocated drive shaft.

[0080] The only new component required to complete the reversed installation of the drive assembly, ratchet mechanism and hammer of the control linkage at the new side of the head gate 32 is a replacement end collar 62 and affixed release arm 102, which unlike the other components relocated in the preceding paragraph, is not reversible owing to the necessary offset angulation between the guide pin slot 110 and the release pin hole in the release arm to allow the limited degree of angular rotation between the release arm 102 and the hammer 76 necessary to release the pawl 90 from the ratchet plate 48. The replacement end collar 62 and release arm 102 combination (not illustrated separately, owing to its simply mirrored relation to that which is illustrated) are reinstalled onto the relocated main shaft body 60 of the drive assembly through the relocated and reoriented rack plate 48 and hammer 76, in combination with the original release arm spacer 92C.

[0081] First drive link 112 is recoupled to the front hammer plate of the relocated hammer 76, and this time coupled to the coupling plate 120A of gate panel 40A. The rocker arm 114 and its rocker support bracket 126 are moved over to, and bolted to, the mounting bracket 124A to which the rack plate 48 was originally bolted. The second drive arm 118 is recoupled to the top end of the relocated rocker arm 114, and this time also coupled to the upper coupling point of coupling bracket 120B on gate panel 40B, and the connecting link 116 is recoupled to the bottom end of the relocated rocker arm 114, and this time coupled to the lower coupling point of coupling bracket 120A on gate panel 40A. The drive assembly, ratchet mechanism and control linkage are thereafter operable in the same fashion described before, but now from the second side of the head gate to which the drive assembly and ratchet mechanism were relocated in mirrored symmetry to their prior locations.

[0082] All of the links within the gate control linkage 74, including the hammer 76, the first drive link 112, the rocker 114, the connecting link 116 and the second drive link 118, reside and pivot within vertically upright working planes of parallel relationship to one another, and pivot about longitudinally horizontal axes of parallel relationship to one another, Avoided are any horizontally oriented scissor linkages or the like, such as those found among some of the prior art designs cited above, and only a singular one of these links, namely the first drive link 112 spans from the ratchet mechanism to the far gate panel 40B.

[0083] Looking more closely at the rack plate 48 and the pawl 90 in Figures 12 and 13, the ratchet teeth 50 cooperate with a squared off shape of the inner working end 90C of the pawl 90. The shape profile of each tooth, referring to the shape thereof as viewed in any plane parallel to the flat faces of the rack plate 48, has a flat working side 128A at which contact thereof by a flat working surface 128B of the pawl blocks opening of the head gate when the pawl is engaged with the rack plate 48. The shape profile of each tooth also has a flat resting side 130A against which a flat resting surface 130B of the pawl 90 gravitationally rests when the flat working surface 128B of the pawl is in abutting contact with the flat working side 128A of a next tooth of neighbouring relationship in an inboard direction of the arched array, referring to a direction of increasing proximity to a laterally innermost terminus of the arched array of teeth. The working side and resting side of each tooth are joined by a convexly rounded apex of the tooth.

[0084] The pawl 90 terminates in the flat working surface 128B at the inner working end 90C of the pawl, and the flat resting surface 130B lies orthogonally of the flat working surface 128B, and intersects therewith at a ninety-degree corner edge 132A of the pawl. The flat working side 128A and the flat resting side 130A of a singular ratchet tooth 50 are oriented at slightly less than ninety degrees to one another, so that a slightly greater than ninety-degree angulation exists between the resting side of the 130A tooth and the working side 128A of the next tooth to afford some clearance for pawl movement. The resting side 130A of each tooth 50 and the working side 128A of the next tooth are joined by a concavely radiused transition 134 that forms a concavely recessed notch 136 to accommodate non-contacting receipt of the pawl’s corner edge 132A when the working surface 128B of the pawl abuts the working side 128A of the next tooth. The radiused transition 134 is positioned and sized such that the planes of the working and resting sides 128A, 130A joined by the radiused transition 134 intersect within the empty space of the notch 136, and not at a location within the bounds of the ratchet plate 48. This way, the corner edge 132A of the pawl 90 doesn’t make physical contact with the rack plate 48 in the pawl’s engaged positions therewith, thus improving the wear life of the pawl 90.

[0085] The working surface 128A of the pawl 90, at a terminus thereof opposite the corner edge 132A, terminates at another ninety-degree corner edge 132B where the working surface 128A intersects orthogonally with a second alternative resting surface 130C of parallel relation to the first resting surface 130B. A height of the working surface 128B of the pawl, measured from corner edge 132A to corner edge 132B, is at least twice an effective working height of each ratchet tooth, as measured from the top end of the flat working side 128A of the tooth (where the rounded apex begins) to the plane of the resting side 128B of a preceding tooth in the array (that which neighbours the tooth in an outboard direction of increasing proximity to a laterally outermost terminus of the arched array). The result is that the pawl 90 can be flipped upside down from an initial installation orientation in which resting surface 130B is used to seat against the rack plate 48, with corner edge 132A received in the rounded notches 136 of the rack plate 48, to an inversely flipped orientation in which resting surface 130C is instead used to seat against the rack plate with corner edge 132B now received in the rounded notches 136 of the rack plate 48. In each such installable orientation, a different respective half of the working surface 128B of the pawl is used for abutting contact with the working sides 128A of the ratchet teeth 50. This reversibility of the pawl 90 doubles the effective wear life thereof. In the illustrated embodiment, where the pawl 90 is welded to pawl carrier 88, this inversion of the pawl orientation to make use of its alternative resting surface 130C is achieved by inversion of the pawl carrier 88 on which the pawl 90 is permanently affixed. Such inversion of the pawl carrier 88 is easily performed by removal of the pivot pin 86 that couples the pawl carrier 88 to the hammer 76, flipping over the of the pawl carrier 88 and affixed pawl 90, and re-pinning of the reoriented pawl carrier 88. In the illustrated embodiment, each carrier plate 88A, 88B has a symmetric shape of matching perimeter profile at its top and bottom edges, for identical interaction with the release pin 104 in either installed orientation, and identical behavioural characteristics in either installed orientation.

[0086] Turning away from the control linkage design and the ratchet-based locking thereof, the inventive head gate 32 also includes a novel approach to the mounting and removability of replaceable wear pieces for constraining the bottom ends of the suspended gate panels 40A, 40B of the curtain-style head gate 32 to prevent deflection thereof forwardly or rearwardly in the longitudinal direction of the chute 10. With reference to Figures 14 and 15, the head gate 32 includes a pair of wear blocks 140A, 1406 each installed beneath a respective one of the gate panels 40A, 40B at a respective outer side of the exit opening 26 of the chute 10. Each wear block 140A, 1406 comprises a U-shaped block delimiting a channel through which a bottom end of the respective gate panel 40A, 40B is slidable back and forth during movement thereof in the lateral opening and closing directions. In the illustrated embodiment, each gate panel 40A, 40B is of a skeletal form composed of a horizontal bottom bar 142 of square or rectangular metal tubing from which a plurality of upright bars 144, likewise formed of metal tubing, stand vertically upward at horizontally spaced positions from one another along the bottom bar 142. The internal channel width of each U-shaped wear block 140A, 140B slightly exceeds the width of the bottom bar 142 of the respective gate panel to accommodate sliding passage of the bottom bar 142 of the respective gate panel 40A, 40B back and forth through the open inner channel of the U-shaped wear block 104A, 1406. In Applicant’s prior head gates, separate front and rear wear plates for each gate panel 40A, 40B were separately fastened in place in front of and behind the respective gate panel using longitudinally oriented bolt fasteners, and required removal of the gate panels 40A, 40B in order to unfasten and remove the wear plates when replacement thereof became necessary.

[0087] The novel U-shaped wear blocks 140A, 1406 of the present invention are instead secured in place via laterally oriented bolt fasteners 146, for example in a quantity of two bolt fasteners 146 per wear block 140A, 1406, one penetrating laterally through an upright front leg 148 of the U-shaped block 140A, 140B that resides in front of the bottom bar 142 of the respective gate panel 40A, 40B, and another penetrating laterally through an upright rear leg 150 of the U-shaped block 140A, 140B that resides behind the bottom bar 142 of the respective gate panel 40A, 40B. To enable such lateral fastening of the wear blocks 140A, 1406, the present embodiment employs two mounting brackets 152A, 152B, each standing upright at an outer side of a respective one of the chute’s two longitudinal floor beams 12A, 12B at protruding end segments thereof that project forwardly beyond the two corner posts 16 of the chute 10 that frame the two opposing sides of the exit opening 26. In the illustrated example, where the corner posts 16 reside at least partially outward from the floor beams 12A, 12B, the brackets 152A, 152B are affixed to the outsides of the corner posts 16, and the brackets 152A, 152B have in-turned lower flanges 154 that abut in bracing contact against outer sides of the protruding end segments of the longitudinal floor beams 12A, 12B. These in-turned lower flanges 154 maintain a slight outward offset from the longitudinal beams 12A, 12B of a main upper wall of the bracket 152A, 152B whose height reaches upwardly beyond the topsides of the floor beams 12A, 12B. It is these main upper walls of the brackets 152A, 152B that have bolt holes therein to accommodates the bolted attachment of the wear blocks 140A, 140B above the floor beams 12A, 12B. In the illustrated example, the U-shaped wear blocks 140A, 1406 are mounted in slightly elevated relation to the topsides of the floor beams 12A, 12B, and likewise in slightly elevated relation to the cross-sill 20A that spans between the floor beams 12A, 12B at a position underlying the wear blocks 140A, 1406. Bolt holes in the wear blocks 140A, 140B may have slot-shaped cross-sections of elongated height relative to their width, to allow for height adjustable mounting of the wear blocks 140A, 140B on the brackets 152A, 152B, or such slot-shaped elongation may instead be applied to the bolt holes in the brackets 152A, 152B to which the wear blocks 140A, 1406 are fastened. Each installed wear block 140A, 1406 resides in front of a respective one of the corner posts 16.

[0088] To remove the wear blocks 140A, 140B when replacement thereof is warranted, the head gate 32 is fully opened, and the bolt fasteners 146 are removed. The inner ends of the bolt fasteners 146 are especially easy to access in the fully open state of the head gate 32, but alternatively may be accessed with the gate closed, for example with particular access to the bolts at the rear legs 150 of the wear blocks being achieved from inside the chute 10 if not easily accessed from outside the closed head gate 32. The outer ends of the bolt fasteners 146 are always accessible from outside the chute 10 regardless of the open or closed state of the head gate 32. With the head gate open, and the fastener bolts 146 removed, each U-shaped wear block 140A, 140B is easily slid out from under the bottom bar 142 respective gate panel 40A, 40B in a laterally inward direction toward the lateral center of the head gate 32. A new replacement wear block can be easily slid into place under the open gate panel 40A, 40B, and bolted into place against the bracket 152A, 152B, thereby accomplishing convenient and easy replacement of the wear blocks 140A, 1406, without removal of the gate panels 40A, 40B. Figures 16 and 17 show a second embodiment of the head gate 32’ (in isolation from the chute framework). This second embodiment shares a similarly configured drive assembly and ratchet mechanism described above for the first embodiment, but differs in terms of the design of the control linkage 74’, where the dualplated hammer 76’, instead of projecting in a singular direction from drive shaft 56 now takes the form of a double-ended rocker-hammer that projects in two directions from the drive shaft 56. Once again, a first drive link 112’ has one end thereof pivotally coupled to the hammer 76’ near a first end 80 thereof toward which the release arm 102 extends from the drive shaft 56, which first end of the hammer 76’ once again points upwardly in the fully open state of the head gate 32, and points laterally outward in the maximally closed state thereof. An opposing end of the first drive link 112’ is again pivotally coupled to the roller carriage 42B of the far gate panel 40B to impart a pulling movement thereto during closure of the head gate 32’. However, this embodiment omits the rocker arm 114 and the connecting link 116 at the opposing side of the head gate 32, and instead features a second drive arm 118’ of shorter length than that of the earlier embodiment. An outer end of this second drive arm 118’ is pivotally coupled to a second end of the hammer 76’ that resides across the longitudinal axis L from the first end thereof. An inner end of this second drive arm 118’ is pivotally coupled to the roller carriage 42A of the near gate panel 40A. In this embodiment, the far gate panel 40B is once again pulled closed via first drive link 112’, but the near gate panel 40A is now pushed closed via second drive link 118’, thus lacking the benefit of both drive links being in tension, like the earlier embodiment.

[0089] Once again of the links within the gate control linkage 74’, this including the hammer 76’, the first drive link 112’, and the second drive link 118’, reside and pivot within vertically upright working planes of parallel relationship to one another, and pivot about longitudinally horizontal axes of parallel relationship to one another, thus again avoiding any horizontally oriented scissor linkages or the like. In this embodiment, each gate panel 40A, 40B has only a singular link connected thereto, whereby the first and second drive links 112’ and 118’ are the sole components by which the pivotal movement of the hammer is converted into movement of the gate panels in the opening and closing directions.

[0090] This illustrated second embodiment lacks repositionability of the first drive link 112’ to attain different closing stroke characteristics, but, with reference to Figure 21 , retains a linkage geometry where first drive link 112’ gets angularly close to an inline position of angularly coincident relation its over-center reference axis Aom just as the maximally closed state of the head gate 32’ is reached, in order to maximize the holding force exertable on an animal. The over-center reference axis Aom of first drive link 112’ runs from the longitudinal axis L to the coupling point at which first drive link 112’ is coupled to the hammer 76’, and the first drive link 112’ reaches an angular proximity PAI within 15-degrees of its over-center reference axis Aom in preferred embodiments, which proximity more particularly measures 14.95 degrees in the case of the illustrated linkage geometry. In this embodiment, both gate panels 40A, 40B actually benefit from such near-proximity of their respective drive links 112’, 118’ to their respective overcenter reference to optimize the holding force of the head gate in a substantially balanced manner, as the second drive link 118’ in this setup also nears its respective over-center reference axis Aoc2, which runs from the longitudinal axis L to the coupling point of second drive link 118’ to the hammer 76’. This drive link 118’ likewise reaches an angular proximity PA2 within 15-degrees of its over-center reference axis, which proximity more particularly measures 13.5 degrees in the case of the illustrated linkage geometry. Like the first embodiment, the linkage geometry of this embodiment achieves a notable extent of gate openability, with an exit pass-through width of 750mm or 29.5 inches, while keeping the head gate 32 within road safety constraints of a road transportable mobile chute.

[0091] Figures 18 and 19 illustrate optional replacement of a fraction of the linkage componentry from the first embodiment of Figures 1 through 15 with a hydraulic conversion kit 160, whose installation is accompanied by removal of the ratchet mechanism and the drive assembly, both of whose functionality is rendered unnecessary by the installation of the hydraulic conversion kit. The conversion kit 160 includes a replacement rocker arm 162 carried, by a supportive pivot shaft 164, on a bolt-on replacement rocker support bracket 166; a bolt-on cylinder support bracket 168; and a hydraulic cylinder 170, which in the installed state of the conversion kit has one end pivotally coupled to the cylinder support bracket 168, and the other end pivotally coupled to the replacement rocker arm 162. The replacement rocker arm 162 may be installed in place of the manually driven rocker arm 114 of the manually driven gate control linkage of the first embodiment, at the same predefined bolting site defined by the upstanding mounting bracket 124B atop the shaft-support bracket 46 of the head gate, or may instead be installed in place of the ratchet plate 48 and hammer at the opposing side of the head gate. The support shaft 44 and gate panels 40A, 40B are omitted in Figures 18 and 19 to avoid illustrative overcrowding of the figure, but in actual practice will remain in place during installation and use of the hydraulic conversion kit 160.

[0092] The replacement rocker support bracket 166 of the illustrated embodiment is simply a flat plate having a set of bolt holes 172 therein of matching quantity and layout to those found in the existing rocker support bracket 126 of the first embodiment, which is likewise embodied purely as a flat plate in the illustrated example. In the illustrated example, there are four such bolt holes 172, of which three are used in any given installation of the replacement rocker arm 162, of which there are two possibilities: installation thereof to the left side of the exit opening 26 of the chute 10 (as shown) at mounting bracket 124B, or installation thereof to the right side of the exit opening 26 of the chute at the other matching, but mirrored, mounting bracket 124A. Each mounting bracket 124A, 124B is L-shaped, with an upright leg of the bracket standing upright in adjacency to a respective one of the corner posts 16 and header beams 14A, 14B, and a lateral leg of the bracket spanning laterally outward from the upright leg toward the nearest lateral extremity of the head gate (e.g. nearest end of the shaft support bracket 46 or roller support shaft 44). The upright leg of each mounting bracket 124A, 124B has two bolt holes 172A therein for alignment with two holes 172 in a corresponding end of the bolt-on support bracket 126, 166 of either the manually driven rocker arm 114 or replacement rocker arm 162. The lateral leg of each mounting bracket 124A, 124B features a singular bolt hole 172B near an outer end thereof of distal relation to the upright leg of the bracket, for alignment with a third one of the four bolt holes 172 in the given bolt-on support bracket 126, 166. The ratchet plate 48 has three bolt holes therein of matching layout to the three bolt holes of each mounting bracket 124A, 124B for bolted attachment of the rack plate to either mounting bracket 124A, 124B.

[0093] The supportive pivot shaft 164 penetrates through the replacement rocker support bracket 166, and thus has a front half 164A that is of protruding relation from a front side of the replacement rocker support bracket 166 to rotatably carry the replacement rocker arm 162 in front of the installed replacement rocker support bracket 166, and in front of the shaft support bracket 46, so that the working position of the replacement rocker arm 162 matches that of the manually driven rocker arm 114 of the first embodiment. The supportive pivot shaft 164 also has a rear half 164B that is of protruding relation from a rear side of the replacement rocker support bracket 166 to rotatably carry a crank arm 174 that radiates in one direction from the rear half 164B of the supportive pivot shaft 164. In contrast, the replacement rocker arm 162 radiates in two opposing directions from the front half 164A of the supportive pivot shaft 164, about which the replacement rocker arm 162 is pivotable in equivalency to the manually driven rocker arm 114 of the first embodiment. A coupling shaft 176 is removably installable in a position spanning between the crank arm 174 and the replacement rocker arm 162 at a radial distance outward from the supportive pivot shaft 164, adjacent an outer end of the crank arm 174 and somewhere situated intermediately along a top half 162A of the replacement rocker arm 162 between the supportive pivot shaft 164 and a top end of the replacement rocker arm 162. It will be appreciated that, unless explicitly indicated otherwise, the term “half” is used herein in a general sense, to mean one of two constituent parts or fractional portions, without necessarily meaning that each of the two halves denotes a fifty percent measure of the overall whole. In operation of the hydraulically driven head gate, the crank arm 174 moves in synchronicity with the replacement rocker arm 162 and braces the coupling shaft 164 near a rear end thereof.

[0094] The hydraulic cylinder 170 has one end thereof, particularly the ram end thereof in the illustrated example, journaled around the coupling shaft 176 between the replacement rocker arm 162 and the crank arm 174, while the other end of the hydraulic cylinder 170, particularly the cylinder end thereof in the illustrated embodiment, is journaled around a cross-pin 178 of the cylinder support bracket 168. This cross-pin 178 spans between upright front and rear walls 168A, 168B of this channel-shaped cylinder support bracket 168, whose bottom wall 168C is bolted to the top wall of the shaft support bracket 46 at a predefined pair of bolt holes therein, of which a matching such pair of bolt holes 180 can be situated across the lateral center of the head gate in symmetric relation to the pair at which illustrated cylinder support bracket 168 is mounted. This way, the cylinder support bracket 168 is installable in either one of two symmetrically mirrored positions on either side of the head gate’s lateral center, just like the replacement rocker arm 162 that can be mounted at either of the head gate’s two mounting brackets 124A, 124B. Each bolt hole pair 180 in the shaft support bracket 46 thus denotes a respective predefined bolting location on a structural component of the head gate where the cylinder support bracket 168 can be conveniently and easily installed in bolted fashion, just like the replacement rocker support bracket 166 can be conveniently and easily installed in bolted fashion to either one of two symmetrically mirrored bolting sites embodied by mounting brackets 124A, 124B.

[0095] The replacement rocker arm 162, and its associated replacement rocker support bracket 166, supportive pivot shaft 164, coupling shaft 176 and crank arm 174 collectively denote a hydraulically-driven bolt-on replacement rocker assembly that is substitutable for the manually-driven rocker assembly denoted by the manually driven rocker arm 114 and rocker support bracket 126 of the first embodiment. Accompanied by the bolt-on installation of the cylinder support bracket 168 at a distance radially further from the supportive pivot shaft 164 than the coupling shaft 176, and by coupling the two ends of the hydraulic cylinder 170 to the removable coupling shaft 176 of the replacement rocker assembly and the removable cross-pin 178 of the cylinder support bracket 168, the hydraulic cylinder 170 is extendable and retractable to hydraulically drive pivotal motion of the replacement rocker arm 162 in opposing directions about its supportive pivot shaft 164, in matching relation to the manner in which the manually driven rocker arm 114 of the first embodiment was manually driven through the operator handle 66, drive shaft 56 and hammer 76 of the first embodiment. The removability of the coupling shaft 176 from the replacement rocker arm 162 is illustrated by way of a bolted end plate 182A to which one end of the coupling shaft 176 is affixed, and which is removably bolted to the front side of the replacement rocker arm 162, though removable engagement of the coupling shaft 176 may be achieved in varying ways. Cross-pin 178 of the cylinder support bracket 168 is likewise removable, for example by another such bolted end plate 182B removably fastened to the front upright wall 168A of the bracket 168. The removability of the coupling shaft 176 and the cross-pin 178 by which the two ends of the cylinder 170 are journaled into operating relation to the replacement rocker arm 162 and the cylinder support bracket 168 enables the hydraulic cylinder 170 to be flipped around depending on whether the hydraulic kit is installed on the left or right half of the head gate 32.

[0096] To install the hydraulic conversion kit 160 on an existing chute 10 on which the manually driven head gate control linkage (manual linkage, for short) and drive assembly of the first embodiment was previously installed, the installer decouples (unbolts) the first drive link 112 from gate panel 40B, and likewise decouples (unbolts) the second drive link 118 and the connecting link 1 16 from the existing manually driven rocker arm 114. The existing rocker arm support bracket 126 is then unbolted from its mounting bracket 124B on the shaft support bracket 46, and removed entirely from the head gate 32, together with the existing manually driven rocker arm 114. Optionally, all the componentry (ratchet mechanism, drive assembly) associated with the manual drive of the existing manually driven rocker arm 114 may also be removed entirely from the head gate 32 and chute 10, in the manner described earlier in relation to movement of the ratchet mechanism and drive assembly from one side of the head gate 32 and chute 10 to the other.

[0097] The bolt-on replacement rocker support bracket 162 in then bolted in place, for example to mounting bracket 124B from which the original manually-driven rocker assembly was removed, or alternatively to the mounting bracket 124A from which the ratchet plate 48 was removed, if so removed with the rest of the ratchet mechanism and drive assembly, and the cylinder support bracket 168 is bolted to whichever of the two available bolting locations 180 resides in operational relationship (nearest, in the illustrated example) to the selected mounting bracket 124A, 124B at which the replacement rocker support bracket 162 is installed. If necessary, depending on the selected left or right installation and the already-installed orientation of the hydraulic cylinder 170 on the cylinder support bracket 168, the hydraulic cylinder 170 may need to be removed from the cylinder support bracket 168, via extraction of removable cross-pin 178, and flipped around. In the illustrated embodiment, cylinder support bracket 168 is non-reversible, owing to its rear wall 168B being taller than its front wall 168A so that the rear wall hangs down from the topside of the shaft support bracket 46 to abut against a rear wall thereof to resist forwardly oriented load exertions on the bracket 168, hence the included removability of the cross-pin 178 to enable reversal of the hydraulic cylinder 170, though in other embodiments, the cylinder support bracket 168 as a whole may instead be reversibly installable according to left hand or right hand installation of the replacement rocker arm 162. The properly oriented cylinder 170 is then coupled to the replacement rocker arm 162 via the removable coupling shaft 176.

[0098] Though not shown in Figures 18 and 19, a workable gate control linkage is then reestablished, in now hydraulically driveable fashion, which in the illustrated example of the left-handed installation of the replacement rocker arm 162, is achieved by coupling (bolting) existing drive link 118 of the right gate panel 40A to the top end of the replacement rocker arm 162, and coupling (bolting) existing connecting link 116 of the left gate panel 40B to the bottom end of the replacement rocker arm 162, so that replacement rocker arm 162, when hydraulically driven by cylinder 170, pulls on gate 40A and pushes on gate 40B during closing, and pulls on gate 40B and pushes on gate 40A during opening. On the other hand, if the replacement rocker arm 162 were instead installed in right-handed fashion at mounting bracket 124A where the rack plate 148 of the ratchet mechanism used to reside in the former manually driven setup, drive link 118 would be relocated from gate panel 40A to gate panel 40B and connected to the top end of the replacement rocker arm 162, and connecting link 116 would be relocated from gate panel 40B to gate panel 40A, and connected to the bottom end of the replacement rocker arm 162. The illustrated example in Figure 18 also illustrates optional mounting of a hydraulic control station 184, hosting at least one user-operable valve control lever 186 for operating hydraulic cylinder 170 and any other hydraulic components of the chute 10 (head holder, squeeze, etc.), at the right side of the head gate 32 and chute 10 from which the ratchet mechanism and drive assembly were removed, which may be particularly beneficial when the opposing side of the head gate 32 and chute 10 is occupied by other operational componentry of the chute 10, for example related to operation of the squeeze panels thereof (not shown), if so equipped. On the other hand, it will be appreciated that the hydraulic control station 184 may alternatively be installed elsewhere.

[0099] The bolt-on hydraulic conversion kit 160 enables quick and easy changeover of the head gate from manual drive to hydraulic drive via simple unbolting of existing linkage, ratchet and drive components, and likewise simple bolted installation of the conversion kit 160, whether done in a shop setting, or even in the field, given the lack of welding required to install the kit, and the lack of need for any grinding or other destructive removal of previously welded or other comparably permanent componentry. Associated hydraulic componentry (pump, hoses, etc.) necessary for the operation of hydraulic cylinder 170 from hydraulic control station 184 are not shown, but such equipment and appropriate interconnection thereof with the illustrated hydraulic cylinder 170 and hydraulic control station 184 are well known in the art, and may be installed and routed at varying locations on the chute 10. While the illustrated example described above is a hydraulic conversion kit featuring a hydraulic cylinder 170, the kit may alternatively be a pneumatic conversion kit employing a pneumatic cylinder instead.

[0100] Since various modifications can be made in the invention as herein above described, and many apparently widely different embodiments of same made, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims

CLAIMS:1 . A livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; a pawl carried on said hammer and biased into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; and a drive shaft running longitudinally of the chute on a longitudinal axisabout which said drive shaft is rotatable and on which said pivotal movement of the hammer is centered, said drive shaft being rotatably operable, via an operating handle, about said longitudinal axis to drive movement of the hammer in pivotal opening and closing directions corresponding, respectively, to the lateral opening and closing directions of the first and second gate panels.

2. The head gate of claim 1 wherein said drive shaft is coupled to the hammer on a same side of the stationary rack at which at least one of the additional links is also coupled thereto.

3. The head gate of claim 2 wherein said same front side of the stationary rack is a front side thereof that faces outwardly away from an exit end of a piece of livestock equipment on which the head gate is installed, and the operating handle is situated on an opposing rear side of the stationary rack that faces an opposing entrance end of said livestock equipment.

4. The head gate of claim 3 wherein said shaft comprises a main shaft body on which said operating handle is slidably relocatable, and an end component that is mated with an end of said main shaft body and passes through the plane of said stationary rack to the front side thereof.

5. The head gate of any preceding claim wherein said operator handle is slidably relocatable back and forth along said drive shaft.

6. The head gate of any preceding claim wherein the stationary rack has a hole therein that serves as a rotational support for a rotatable component of a drive assembly to which the drive shaft belongs.

7. The head gate of claim 6 wherein said rotatable component is the drive shaft, and said drive shaft and said hole in the stationary rack have different cross- sectional shapes in the plane of said stationary rack.

8. The head gate of claim 7 wherein the cross-sectional shape of the hole in the stationary rack is a circle.

9. The head gate of any preceding claim wherein said drive shaft possesses a non-circular cross-section.

10. The head gate of any preceding claim wherein an angular operating range of said handle, measured between a fully open position thereof corresponding to maximum distancing of the gate panels from one another and a maximally closed position of the handle corresponding to closest achievable adjacency of the gate panels to one another, is less than 90-degrees.11 . The head gate of claim 10 wherein the angular operating range of the handle is less than 85-degrees.

12. The head gate of any preceding claim wherein the hammer is a two- sided hammer having two sides that reside on respective opposing sides of the stationary rack, and the pawl is pivotally supported on the hammer between the two sides thereof.

13. The head gate of any preceding claim wherein the gate panels are supported solely by suspension thereof from the overhead support track.

14. The head gate of any preceding claim wherein the overhead support track has a length, measured in the lateral opening and closing directions of the head gate, that exceeds a width, likewise measured in the lateral opening and closing directions of the head gate, of an exit opening that the head gate is operable to open and close.

15. The head gate of any preceding claim wherein the longitudinal pivot axis of the hammer resides at a location between two opposing ends of the overhead support track.

16. The head gate of any preceding claim wherein, in a fully open position of the gate panels at a furthest attainable distance from one another along the overhead support track, a pivot point of the pawl resides at an elevation below a point of physical engagement between said pawl and the ratchet teeth of the stationary rack.

17. The head gate of any preceding claim wherein the pawl is selectively repositionable in either one of two different working orientations that are both of operable relationship to the stationary rack to engage a different combination of surfaces of said pawl with the stationary rack.

18. The head gate of claim 17 wherein said pawl has a working surface for abutting working sides of the teeth to block opening movement of the head gate when the pawl is engaged with the stationary rack, and said working surface of the pawl is neighboured by two possible resting surfaces each arranged for resting contact with resting sides of teeth in a respective one of the two different working orientations.

19. The head gate of claim 18 wherein the working surface has a height measured between said two possible resting surfaces that is at least twice an effective working height of the teeth so that the two different working orientations each correspond to abutment of a different respective half of the working surface with the working sides of the teeth.

20. The head gate of claim 18 or 19 wherein the working surface of the pawl lies perpendicularly of the two possible resting surfaces thereof.

21. The head gate of any one of claims 18 to 20 wherein each resting surface meets the working surface at a right-angle corner edge of the pawl.

22. The head gate of any one of claims 17 to 21 wherein the pawl is mounted to a pawl carrier, and said pawl carrier is pivotally coupled to the hammer, and said pawl carrier is selectively removable and replaceable in a different orientation toreorient the pawl between said different working orientations.

23. The head gate of claim 22 wherein said pawl carrier comprises two carrier plates residing on opposing sides of the stationary rack and between which the pawl is mounted.

24. The head gate of claim 23 wherein each carrier plate has at least one hole therein in which a mating portion of the pawl is received to dictate a proper alignment of the pawl on the pawl carrier.

25. The head gate of any one of claims 22 to 24 wherein the hammer comprises a pair of hammer plates between which the stationary rack resides, each carrier plate of the pawl carrier resides between respective planes of the stationary rack and a respective one of the hammer plates.

26. The head gate of claim 25 comprising a pair of spacers each respectively disposed between the stationary rack and one of the hammer plates.

27. The head gate of claim 25 or 26 wherein a release arm for imparting the release action to the pawl resides outside the pair of hammer plates.

28. The head gate of claim 26 wherein a release arm for imparting the release action to the pawl resides outside the pair of hammer plates, and a third spacer resides between said release arm and an adjacent one of the hammer plates nearest thereto.

29. The head gate of claim 27 or 28 wherein the release arm carries a release pin that penetrates a slot in one of the hammer plates to impart said release action to the pawl.

30. The head gate of claim 29 wherein the release pin penetrates only said one of the hammer plates, and the other of the hammer plates has a matching slot therein for the purpose of enabling reversed mounting of the hammer plates and thestationary rack at an opposing side of the head gate.

31. The head gate of any one of claims 1 to 24 wherein the hammer comprises a pair of hammer plates between which the stationary rack resides, and the hammer plates have symmetrically mirrored features that enable relocation and reversed installation of the hammer plates and the stationary rack from the installed position adjacent the one lateral extreme of the head gate to a relocated position adjacent an opposing lateral extreme of the head gate.

32. The head gate of claim 30 or 31 wherein an overhead structural component of the head gate comprises symmetrically mirrored bolting sites thereon between which the stationary rack is selectively relocatable and at each of which the of the stationary rack is mountable by bolted attachment.

33. The head gate of any one of claims 1 to 26 and 31 comprising a pawl release operably associated with the pawl to impart the release action thereto when actuated, wherein the drive shaft is coupled to the pawl release and operable, when rotated in a rotational direction corresponding to the pivotal opening direction of the hammer, to actuate the pawl release.

34. The head gate of any one of claims 1 to 31 and 33 wherein an overhead structural component of the head gate comprises symmetrically mirrored bolting sites thereon at which the stationary rack is selectively relocatable from the installed position adjacent the one lateral extreme of the head gate to a relocated position adjacent an opposing lateral extreme of the head gate.

35. The head gate of any preceding claim wherein at least one of the additional links is a repositionable link for which there are provided a plurality of user- selectable coupling points at which said repositionable link can be selectively coupled to the hammer to modify an available movement range for the gate panels duringclosure of the head gate, whereby modification of this movement range enables optimization of the head gate for different size ranges of livestock animal.

36. The head gate of claim 35 wherein the plurality of user-selectable coupling points comprise a plurality of differently positioned coupling holes among which a locking pin is selectively engageable in any one of said coupling holes to lock the repositionable link thereat.

37. The head gate of any preceding claim wherein a tooth profile among teeth of the stationary rack has a working side at which contact thereof by a working surface of the pawl blocks opening of the head gate, and a resting side against which a resting surface of the pawl gravitationally rests when the working surface of the pawl is in abutting contact with the flat working side of a neighbouring tooth, the resting side and the working side of the neighbouring tooth are joined by a concavely radiused transition that forms a concavely recessed notch to accommodate non-contacting receipt of a corner of the pawl, at which the working and resting surfaces thereof intersect, when the working surface of the pawl abuts the working side of the neighbouring tooth.

38. The head gate of any preceding claim wherein each of said additional links resides, and is constrained to movement within, an upright working plane parallel to a working plane of the hammer.

39. The head gate of any preceding claim wherein said additional links are pivotable about axes parallel to the longitudinal axis on which the pivotal movement of the hammer is centered.

40. The head gate of any one of claims 1 to 39wherein the gate control linkage includes a rocker arm pivotally mounted a location situated laterally across an animal-receiving opening of the head gate from of the hammer and adjacent anopposing lateral extreme of the head gate, wherein the additional links comprise a first drive link coupled to the hammer and to a far one of the gate panels situated furthest from the hammer, a connecting link coupled to the far one of the gate panels and to the rocker arm, and a second drive link coupled to the rocker arm and to a near one of the gate panels situated nearest to the hammer, whereby during closure of the head gate, the first drive link pulls the far one of the gate panels toward the hammer and toward the near one of the gate panels, the far one of the gate panels pulls the connecting link toward the near one of the gate panels, which in turn pivots the rocker arm, which in turn pulls on the second drive link, and thereby pulls the near one of the gate panels toward the rocker arm and the far one of the gate panels, whereby said first and second drive links and the connecting link are all in tension during closure of the head gate.41 . The head gate of any one of claims 1 to 39 wherein the linkage is configured to exert only tensile forces on the additional links thereof during closure of the head gate.

42. A livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage comprising: a hammer pivotably supported laterally outward from the lateral center of the head gate toward one lateral extreme thereof for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels; andadditional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; wherein the linkage is configured to exert only tensile forces on the additional links thereof during closure of the head gate.

43. The head gate of claim 42 wherein the gate control linkage includes a rocker arm pivotally mounted at a location situated laterally across an animalreceiving opening of the head gate from the hammer and adjacent an opposing lateral extreme of the head gate, and the additional links comprise a first drive link coupled to the hammer and to a far one of the gate panels situated furthest from the hammer, a connecting link coupled to the far one of the gate panels and to the rocker arm, and a second drive link coupled to the rocker arm and to a near one of the gate panels situated nearest to the hammer, whereby during closure of the head gate, the first drive link pulls the far one of the gate panels toward the hammer and toward the near one of the gate panels, the far one of the gate panels pulls the connecting link toward the near one of the gate panels, which in turn pivots the rocker arm, which in turn pulls on the second drive link, and thereby pulls the near one of the gate panels toward the rocker arm and the far one of the gate panels.

44. A livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away fromone another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a pair of wear blocks each installed beneath a respective one of the gate panels at a respective outer side of an animal-receiving opening of the head gate that is selectively openable and closeable by movement of said gate panels in the lateral opening and closing directions, each wear block comprising a U-shaped block delimiting a channel through which a bottom end of the respective gate panel is slidable back and forth during movement thereof in the lateral opening and closing directions, and the wear blocks are fastened in place via removable fasteners that penetrate the wear blocks on-longitudinally, such that lateral withdrawal of said removable fasteners is enabled in presence of the gate panels without necessitating removal thereof.

45. A ratchet-locked device on a piece of livestock equipment, said device comprising: a rack having an arched array of ratchet teeth thereon; a hammer supported adjacent the rack for relative pivotal movement between the rack and the hammer about a pivot axis lying orthogonally of a plane in which the ratchet teeth are arrayed; a pawl carried on said hammer and biased into engagement with the ratchet teeth of the rack in a locking position preventing movement of the hammer in one direction; wherein a tooth profile among the ratchet teeth of the rack has a working side at which contact thereof by a working surface of the pawl blocks movement of the hammer in said one direction, and a resting side against which a resting surface of the pawl rests when the working surface of the pawl is in abutting contact with the flat working side of a neighbouring tooth, the resting side and the working side of theneighbouring tooth are joined by a concavely radiused transition that forms a concavely recessed notch to accommodate non-contacting receipt of a corner of the pawl, at which the working and resting surfaces thereof intersect, when the working surface of the pawl abuts the working side of the neighbouring tooth.

46. The device of claim 45 wherein said device is a livestock head gate further comprising first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; wherein: said rack is a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon; the pivot axis lies orthogonally of the lateral opening and closing directions of the gate panel; said hammer is connected to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; and the locking position of the pawl prevents opening of the head gate absent input of a release action to said pawl.

47. A livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening directionmoving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed, said hammer being connected to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer; a first drive link pivotally connected both to the hammer and to a far one of the gate panels situated furthest from the hammer; and a second drive link pivotally connected both to the hammer, at a location across the longitudinal pivot axis from where the first drive link connects to the hammer, and to a near one of the gate panels situated nearest to the hammer; and a pawl carried on said hammer and biased into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; wherein said first and second drive links are the sole components by which the pivotal movement of the hammer is converted into movement of the gate panels in the opening and closing directions.

48. The head gate of any one of claims 1 to 39 wherein: the additional links comprise a first drive link pivotally connected both toQ7 the hammer and to a far one of the gate panels situated furthest from the hammer, and a second drive link pivotally connected both to the hammer, at a location across the longitudinal pivot axis from where the first drive link connects to the hammer, and to a near one of the gate panels situated nearest to the hammer; and said first and second drive links are the sole components by which the pivotal movement of the hammer is converted into movement of the gate panels in the opening and closing directions.

49. The head gate of claim 47 or 48 wherein said first and second drive links, in a maximally closed state of the head gate, both achieve angular proximities within 15-degrees of respective over-center reference axes, past which said first and second drive links would over-center.

50. A livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage comprising: a first drive link for imparting motion to the first gate panel; and a second drive link for imparting motion to the second gate panel; wherein said first and second drive links, in a maximally closed state of the head gate, both achieve angular proximities within 15-degrees of respective overcenter reference axes, past which said first and second drive links would over-center.51 . A conversion kit for fluid-powered upgrade of a manually operated livestock head gate that comprises at least one of either a manually driven rocker armor hammer that is pivotally supported on or adjacent an existing bolt-on component that is bolted to an existing bolting site on said head gate, said conversion kit comprising: a replacement rocker arm carried, by a supportive pivot shaft, on a bolt- on replacement rocker support bracket that is configured for selective bolted attachment to said existing bolting site in replacement of the existing bolt-on component formerly bolted thereto, said replacement rocker arm radiating in two opposing directions from said supportive pivot shaft, and further comprising a coupling shaft at a radial distance outward from said supportive pivot shaft; a fluid-powered cylinder having one end thereof pivotally coupled or couplable to the replacement rocker arm in journaled relation about said coupling shaft thereof; and a bolt-on cylinder support bracket to which an opposing end of the fluid- powered cylinder is pivotally coupled or couplable, and which is configured for bolted attachment to an existing structural component of the head gate at a predefined bolting location of distanced relationship from the bolt-on replacement rocker support bracket in a direction spaced radially outward from the supportive pivot shaft thereof.

52. The kit of claim 51 wherein the supportive pivot shaft comprises a front half protruding from a front side of the replacement rocker arm and a rear half protruding from an opposing rear side thereof, from which rear half a crank arm radiates outward from the supportive pivot shaft and connects to the coupling shaft in bracing support thereof.

53. A method of installing the kit of claim 52 or 53 comprising:(a) decoupling the manually driven rocker arm or hammer from two gate panels of the head gate;(b) removing one or more unnecessary components of the head gateformerly needed for manual actuation but unnecessary for powered actuation, including at least the existing bolt on-component;(c) bolting the bolt-on replacement rocker support bracket at the existing bolting site, and bolting the cylinder support bracket in place on the existing structural component at the predefined bolting location thereon, and if not already coupled between said brackets, coupling said fluid-powered cylinder therebetween, thereby replacing the one or more unnecessary components with the replacement rocker arm and the fluid-powered cylinder; and(d) reestablishing an operational head gate control linkage, at least in part by installing a pair of links, each in a position pivotally coupled to the replacement rocker arm adjacent a respective end thereof, and pivotally coupled to a respective one of the two gate panels, such that extension and collapse of the fluid-powered cylinder is thereafter operable to pivot the replacement rocker arm in opposing directions and thereby open and close said two gate panels.

54. The method of claim 53 wherein the head gate comprises an existing rocker arm support on which the manually driven rocker arm is pivotably carried at said existing bolting site prior to step (b), and the existing bolt-on component removed in step (b) comprises said existing rocker arm support, and the one or more unnecessary components removed in step (b) includes the manually driven rocker arm carried on said existing rocker arm support.

55. The method of claim 53 wherein the head gate comprises an existing ratchet mechanism that includes a bolt-on ratchet-toothed rack that, prior to step (b), is mounted at said existing bolting site, and is neighboured in pivotable adjacency by the hammer, and the existing bolt-on component removed in step (b) comprises said bolt- on ratchet-toothed rack, and the one or more unnecessary components removed instep (b) includes the hammer.

56. The method of claim 53 wherein: prior to step (b), the head gate comprises: an existing rocker arm support on which the manually driven rocker is pivotably carried at a first existing bolting site; and an existing mechanism that is situated across the head gate from the existing rocker arm support at a second symmetrically mirrored bolting site of symmetrically mirrored relation to said first existing bolting site, and through which said existing rocker arm was manually driveable; the existing bolt-on component removed in step (b) is either said existing rocker arm support, or a stationary functional component of said existing mechanism; and the existing bolting site at which the bolt-on replacement rocker arm is installed in step (c) is one of either said first existing bolting site or said second symmetrically mirrored bolting site.

57. The method of claim 56 wherein said existing mechanism is a ratchet mechanism, and the stationary functional component of said existing mechanism is a bolt-on ratchet-toothed rack that, at least prior to step (b), is neighboured in pivotable adjacency by the hammer, on which a pawl is carried for engagement with said bolt-on ratchet-toothed rack.

58. The method of claim 56 or 57 wherein the existing bolt-on component removed in step (b) is said existing rocker arm support, and the existing bolting site at which the replacement rocker arm support is bolted in step (c) is the first existing bolting site.

59. The method of claim 56 or 57 wherein the existing bolt-on componentremoved in step (b) is said stationary functional component of said existing mechanism, and the existing bolting site at which the replacement rocker arm support is bolted in step (c) is the second existing bolting site.

60. The method of any one of claims 56, 57 and 59 wherein said existing mechanism comprises a drive shaft running longitudinally alongside a chute and on which an operator handle is disposed for manual actuation of said existing mechanism.

61. The method of any one of claims 56, 57, 59 and 60 comprising installing a hydraulic control station at a location situated to a same side of the head gate at which said existing mechanism resided prior to step (b).

62. The livestock head gate of any one of claims 1 to 41 wherein the pawl is spring biased by a bias spring whose position resides oppositely across a pivot point of said pawl from where said pawl engages the stationary rack.

63. The livestock head gate of claim 62 wherein said bias spring is a tension spring exerting a pull force.

64. The device of claim 45 or 46 wherein the pawl is spring biased by a bias spring whose position resides oppositely across a pivot point of said pawl from where said pawl engages the rack.

65. The device of claim 64 wherein said bias spring is a tension spring exerting a pull force.

66. A ratchet-locked device on a piece of livestock equipment, said device comprising: a rack having an arched array of ratchet teeth thereon at a topside thereof; a hammer pivotably supported adjacent the rack for pivotal movement about a pivot axis lying orthogonally of a plane in which the ratchet teeth are arrayed; a pawl carried on said hammer and biased into engagement with theratchet teeth of the rack in a locking position; wherein said pawl is biased into engagement with the rack by: gravitational force; and a bias spring whose position resides oppositely across a pivot point of said pawl from where said pawl engages the rack.

67. The device of claim 66 wherein said bias spring is a tension spring exerting a pull force.

68. A livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; and a gate control linkage operable to control movement of said first and second gates panels in said opening and closing directions; an operator handle coupled to said gate control linkage to manually impart driving movement thereto and thereby drive movement of said first and second gate panels; wherein said operator handle is swingable upwardly and downwardly through an operating range that measures no greater than 90-degrees between a fully open position of said handle corresponding to maximum distancing of the gate panels from one another in a fully open state thereof and a maximally closed position of the handle corresponding to closest achievable adjacency of the gate panels in a maximally closed state thereof.

69. The livestock head gate of claim 68 wherein said operating rangemeasures no greater than 85-degrees.

70. The livestock head gate of claim 68 wherein said operating range measures no greater than 80-degrees.

71. The livestock head gate of claim 68 wherein said operating range measures no greater than 75-degrees.

72. A livestock head gate comprising: first and second gate panels; an overhead support track from which the first and second gate panels are suspended and on which the first and second gate panels are displaceable back and forth in a lateral closing direction moving toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and a lateral opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directions under driven movement of said hammer;a pawl carried on said hammer and biased into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; wherein the overhead support track has a length, measured in the lateral opening and closing directions of the head gate, that exceeds a width, likewise measured in the lateral opening and closing directions of the head gate, of an exit opening that the head gate is operable to open and close, the longitudinal pivot axis of the hammer resides at a location between two opposing ends of the overhead support track.

73. A livestock head gate comprising: first and second gate panels movable in a closing direction toward one another, and toward a lateral center of the head gate, to achieve a closed state bracing a livestock animal between said first and second gate panels, and an opening direction moving away from one another, and away from said lateral center, to an open state releasing said livestock animal from between said gate panels; a stationary rack mounted at an installed location situated laterally outward from the lateral center of the head gate toward one lateral extreme thereof, said stationary rack having an arched array of ratchet teeth thereon at a topside thereof; a gate control linkage comprising: a hammer pivotably supported adjacent the stationary rack for pivotal movement about a longitudinal pivot axis lying orthogonally of the lateral opening and closing directions of the gate panels and orthogonally of a plane in which the ratchet teeth are arrayed; additional links by which the hammer is linked to the first and second gate panels to effect movement thereof in the opening and closing directionsunder driven movement of said hammer; and a pawl carried on said hammer and biased, into engagement with the ratchet teeth of the stationary rack in a locking position prevent opening of the head gate absent input of a release action to said pawl; a drive shaft running longitudinally of the chute on a longitudinal axis about which said drive shaft is rotatable and on which said pivotal movement of the hammer is centered, said drive shaft being rotatably operable, via an operating handle, about said longitudinal axis to drive movement of the hammer in pivotal opening and closing directions corresponding, respectively, to the lateral opening and closing directions of the first and second gate panels; wherein the stationary rack has a hole therein that serves as a rotational support for a rotatable component of a drive assembly to which the drive shaft belongs.

74. The livestock head gate of claim 73 wherein said rotatable component of the drive assembly is said drive shaft.

75. The livestock head gate of claim 73 or 74 wherein said drive shaft possesses a non-circulator cross-section.

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