TITLE: GATE ASSEMBLY AND METHOD OF OPERATION

TECHNICAL FIELD

This invention relates to improvements in gates and door assemblies having substantially vertical hinge axes and relates more particularly, but not solely, to remotely operated farm gates.

The present invention also relates to methods for effecting the remote opening and closing of a gate, door or the like.

BACKGROUND TO THE INVENTION

Farmers, householders and many others have need for gates that can be opened and closed remotely in a simple and economic manner, for example from within a vehicle approaching and leaving the gate. However, because power cannot be laid onto most farm gates at reasonable cost or with reasonable reliability, the conventional methods of remote operation are unavailable. That is, a wide variety of automatic and semi-automatic gate and door actuators that is readily available on the market for city homes and businesses are impractical to use in many situations.

For the sake of brevity the following terminology will be adopted:

"Gate(s)" is intended to include 'door(s)" or other hinged closures in which the hinge axis is generally vertical. Gate is not intended to only indicate a farm, fence or perimeter style gate. "Gate assembly" is used herein to encompass a gate and its hinges along with all or portion of a remotely operable opening and closing mechanism.

"Hinge end" indicates the end of the gate proximal to the hinge axis.

"Hinge post" indicates the fixture to which the hinge end of the gate is hingedly attached. It may include portion of a door frame or a fixture such as a wall and does not imply, unless the context makes clear, an elongate post set in the ground.

"Latch end" indicates the end of the gate opposite the hinge end and which commonly - but not necessarily - carries or includes portion of a latch

mechanism. The use of 'latch end' is not intended, unless indicated otherwise, to limit the gates with which this invention is concerned to those that have latch means or which are latchable, whether the latch means operates to hold the gate open or closed. "Latch post", where provided, indicates the fixture to which the latch end of the gate closes. It may include portion of a door frame or a fixture such as a wall . and does not imply, unless the context makes clear, an elongate post set in the ground.

"Remotely operable" indicates means whereby a gate can be opened or closed without requiring the user to physically and directly handle the gate.

"Remote" does not imply that a user need be any particular distance from the gate to effect its operation.

OBJECTIVE OF THE INVENTION It is the general objective of the present invention to provide means to enable the remote opening and/or closing of a gate.

OUTLINE OF THE INVENTION

From one aspect, this invention comprises a method of effecting the opening and or closing of a gate by tilting the generally vertical hinge axis of the gate so that the weight of the gate enables the desired opening and/or closing action.

The tilting of the gate can be lengthwise; that is, so that the latch end of the gate is raised and the hinge axis is tilted away from the bottom of the hinge post, thereby imparting the potential energy to the gate necessary for it to swing open or closed under gravity. Lengthwise tilting of a closed gate will normally be substantially within or parallel to the plane of the gate posts. If desired, the hinge axis may also be titled sideways - that is, at an angle to the plane of the gate posts. Usually, the sideways tilting will be such that the top of the gate at the latch end is biased toward the intended direction of gate movement.

The raising of the latch end of the gate can be used to automatically unlatch the gate from either the open or closed position, and, it may also be used to impart an

initial 'kick' to the gate by making the latch end of the gate strike a cam or ramp to set the gate moving in the desired direction. This initial impetus can be increased where the latched gate is also tilted - or biased to tilt - sideways in the intended direction of movement as its latch end is raised. Thus, the gate may be automatically latched open or closed at it comes to rest at the stop post or latch post (respectively) and then released in the manner indicated, when desired.

Tilting of the gate may be effected by tilting means under the control of remotely operable actuator means that can be made conveniently accessible to the occupant of a vehicle - or could be operated by the weight of the vehicle on a tread plate let into the approach road. The gate may have hinge means comprising upper and lower hinge elements that define the hinge axis so that the tilting means allows tilting of the hinge axis to be effected by using the actuator means. For example, the hinge means may comprise upper and lower hinge elements that define a generally vertical hinge axis, the tilting means enables one hinge element to move relative to the other to cause the tilting of the hinge axis and the actuator means effects such relative movement in a controlled manner.

The actuator means can conveniently comprise a closed hydraulic circuit in which a slave cylinder moves a hinge element and the master cylinder is arranged at the remote location for operation by a hand lever, tread plate or other means.

Hydraulic operation this way is well adapted to locations where there is no external power supply for the operation of electrical pumps or other actuators. A lever or tread plate can be arranged on each side of the gate so that it can be operated both on approach and departure in either direction. The gate may be one-way (swinging to one side only) or it may be two-way (swinging to both sides).

The method may include the step of automatically latching the gate open or closed and of automatically releasing the latched gate so that it can swing to the opposite position. Latching may be effected by a drop-latch that operates between the latch end of the gate and the latch post and/or between the latch end of the gate and a stop post against which the gate rests when open. Additionally or

alternatively, it may be effected by a ramp-and-dip latch set in the road or near the bottom of the latch or stop post upon which the bottom portion of latch end of the gate rides up and by which it is located at the end of its swing. An additional cam surface, ramp, guide or the like may be located on the post that is near the ramp- and-dip latch so as to impart an impetus to the gate in the desired direction when the latch end of the gate is raised.

From another aspect, this invention comprises a gate assembly including: a gate having a latch end adapted for location near a latch post when the gate is closed and having a hinge end, hinge means for securing said hinge end of the gate to a hinge post so that the gate can swing about a substantially vertical hinge axis between an open position and a closed position, and tilting means operable on the hinge means to tilt the hinge axis relative to the vertical so as to bias the gate to swing to the open or closed position.

As already indicated, the hinge means can comprise an upper and a lower hinge element that together set or define the hinge axis and the tilting means is operable to vary the relative location of the upper and lower hinge elements to effect the tilting of the gate. Conveniently, the upper hinge element is self-aligning but otherwise substantially fixed in position relation to the hinge post while the lower hinge element is adapted to carry the weight of the gate and to be moveable relative to the hinge post and the upper hinge element. For example, the tilting means may include a slotted plate on which lower hinge element rests and by which it is guided for movement under the control of actuator means. Less conveniently, the upper hinge element can be moved by the actuator means relative to the hinge post instead. Alternatively the hinge elements may be substantially fixed relative to each other and may be moved conjointly by the actuator means to effect tilting of the hinge axis.

The actuator means is preferably remotely operable to drive the tilting means so as to permit remote operation of the gate. The actuator means can be mechanical, hydraulic or electrical. If external power is available, it could be a

motor driven actuator coupled to the tilting means and a switch arranged so as to be accessible to a driver sitting in a vehicle. Where external power is not available, convenient or affordable, the actuator means could - as already indicated - a closed circuit hydraulic or mechanical system with levers, tread plates or the like on one or both sides of the gate and operable by people or the passage of vehicles.

DESCRIPTION OF EXAMPLES Having portrayed the nature of the present invention, one particular example will now be described with reference to the accompanying drawings. However, those skilled in the art will appreciate that many variations and modifications can be made to the example without departing from the scope of the invention as defined by the following claims.

Brief Description of the Drawings

Figures 1A and 1 B are diagrammatic plan views of a one-way farm gate of the first example showing vehicles passing through.

Figures 1C and 1 D are diagrammatic plan views of a two-way farm gate of the second example showing vehicles passing through.

Figure 2 is perspective view of the one-way gate assembly of Figures 1A - 1 B.

Figure 3 is an enlarged perspective detail of the upper hinge element of the assembly of Figure 2.

Figure 4 is an enlarged perspective detail of the lower hinge element of the assembly of Figure 2.

Figure 5 is an enlarged plan detail of the lower hinge element of the assembly of Figure 2.

Figure 6 is an enlarged perspective detail of the catch mechanism of the gate assembly of Figure 2.

Figure 7 is an enlarged side elevation detail of the catch plate of the catch mechanism of Figure 6.

Figure 8A is a schematic perspective of the swing-through gate with a ground-mounted ramp latch, Figure 8B is a schematic plan view of a double-acting tilting latch plate also suitable for a swing-through gate, while Figure 8C is a schematic elevation of a latching stop post suitable for use with either the tow-way or the one-way gate assembly.

Figure 9 is a diagram showing the hydraulic actuator means employed in the gate assembly of the chosen example.

Figures 1A and 1 B indicate the operation of a one-way gate assembly 10, including gate 12, which provides the first example of the implementation of the invention. Figures 1C and 1 D indicate the operation of a two-way gate assembly 10a, including gate 12a, which forms the second example.

A vehicle 11 approaching one-way gate assemblylO of the first example from the north stops at a first gate control station 14 (Figure 1A) and effects the opening of gate 12 in the direction indicated by arrow 15a from the closed position (indicated in continuous lines) to the open position (indicated in broken lines). After passing though the open gate way, south moving vehicle 11 stops at a second gate control station 16 (Figure 1 B) and effects the re-closing of gate 12 in the direction indicated by arrow 15b. Conversely, when vehicle 11 returns traveling north

(indicated in broken lines in Figures 1A and 1 B), it stops at station 16 (Figure 1A) to effect the opening of gate 12 in the direction of arrow 15b and, after passing northwards through the gate opening, stops at station 14 (Figure 1B) to effect the re-closing of gate 12 in direction of arrow 15b.

In this first example, control stations 14 and 16 are located centrally in road 17 (indicated by dot-dash lines) to the north and south of gate 12 (respectively) and are arranged so that an actuator mechanism can be operated by a driver through the window of a car or truck, or by bringing the vehicle to rest on a tread plate or the like. Stations 14 and 16 are far enough away from gate 12 to allow a towed trailer of a departing vehicle to clear the gate as it closes. Gate 12 is hinged from a fixed hinge post 18, latched closed to a fixed latch post 20 and preferably latched open to a fixed stop post 22.

In the second example (Figures 1C and 1 D), four control stations are provided each being located at the sides of road 17, two 14a and 14b to the north of gate assembly 10a and two, 16a and 16b to the south. Vehicle 11a approaching from the north (Figure 1C) stops at right hand control station 14a (assuming a right- hand-drive vehicle) and effects the opening of gate 12a away from the vehicle in the direction indicated by arrow 24a. After passing through the gate way, south traveling vehicle 11 b stops at station 16a (Figure 1C) and operates an actuator at that station to effect the closing of gate 12a. When a north traveling vehicle 11 b stops at station 16b (Figure 1 D) and operates the actuator at that station to effect opening of gate 12a to the north, again away from the vehicle as indicated by arrow 24b. After passing through the gate way, north traveling vehicle 11 b stops at control station 14b and actuates the re-closing of gate 12a. As with gate 12 of one-way assembly 10 of the first example, gate 12a of two-way gate assembly 10a is hinged from a fixed hinge post 18 and latched closed to a fixed latch post 20. However, two stop posts 22a and 22b are employed in the second example of Figures 1C and 1 D - one to the south and the other to the northth of hinge post 18 - to limit the opening of gate 12a and, if desired, to permit gate 12a to be latched open in either position.

It will be appreciated that the difference in number and location of control stations between the first and second examples is little related to the mode of gate operation but is, rather, determined by user needs and operational convenience.

We generally prefer the use of one-way gate assemblies because they are easier to install, adjust and maintain, and because two-way gate assemblies offer little operational advantage over one-way gate assemblies in most situations.

Figure 2 shows one-way gate assembly 10 in greater detail, gate 12 having a bent tubing peripheral frame 32 covered with welded wire mesh 34. The upper hinge element (which does not support the gate vertically) is generally indicated at 36, the lower hinge element at 38 (which carries the vertical weight of the gate) and a latch mechanism at 40. Hinge post 18, latch post 20 and stop post 22 (not shown in Figure 2) are conveniently formed from steel tubing set into concrete foundations (not shown).

Upper hinge element 36 (see Figure 3) comprises a threaded steel rod 42 passed through post 18 and formed with an upwardly facing hinge-pin 44 on its inner end. A bracket 46 having a hinge arm 48 extending therefrom is bolted to the hinge end 50 of gate frame 32, hinge arm 48 having a vertical hole formed therein to take hinge pin 44. This construction is quite conventional for a hinge element of a farm gate and allows upper hinge-pin 44 to self-align with the hinge axis set by lower hinge element 38.

Lower hinge element 38 is shown in the detailed views of Figures 4 and 5 and includes a steel sleeve 52 slidably and rotatably fitted on hinge post 18 and fixed in position (after adjustment) by a set screw or welding (not shown). Sleeve 52 carries a lower horizontally extending bracket 54 on which is mounted a first slave cylinder assembly 56 that includes a piston rod 58 having an end boss 59 that rotationally engages the lower end of a lower hinge pin 60. Sleeve 52 also carries a horizontally extending intermediate hinge-support plate 62 located higher than bracket 54 and having a slot 64 (Figure 5) that slidably receives hinge pin 60, which passes therethrough. Sleeve 52 carries an upper horizontally extending bracket 66 on which is mounted a second slave cylinder assembly 68 that has a piston rod 70 with a bearing bush 71 on its distal end that rotationally receives the hinge pin 60. Finally, like upper hinge element, lower hinge element 38 includes a bracket 72 that is bolted to the bottom portion of the hinge end 50 of gate frame

32 and carries a horizontally extending lower hinge arm 74 through which most of the weight of gate 12 is carried. A hole (not shown) is formed in the distal or hinge end of arm 72 through hinge pin 60 passes and within which it may be rigidly fixed.

Conveniently, upper and lower hinge arms 48 and 74 are substantially coplanar with gate 12, the hinge axis defined by hinge pins 44 and 60 is substantially vertical when gate 12 is closed, and, upper hinge rod 42 and lower hinge-support plate 62 are angled on hinge post 18 at about 45 degrees to the opening side with respect to the plane of closed gate 12.

In this example, brackets 48 and 74, together with their respective hinge pins 44 and 60 comprise the hinge means of the gate assembly, slot 64 in support bracket 62 and the movable hinge bush 71 therein comprise the tilting means and slave cylinder assemblies 56 and 58 comprise portion of the actuator means, the remaining portion comprising master cylinders and levers (to be described) located at control stations 14 and 16.

The convenience of mounting the fixed portion of lower hinge element 38 on sleeve 52 will now be apparent to those skilled in the art. Not only does it allow lower hinge element 38 to be easily adjusted vertically but the rotational adjustment (around post 18) allows adjustment of gate travel and swing with respect to terrain. Moreover, by rotating sleeve 52 in the anticlockwise (or closing direction) by about ninety degrees, the gate can be made to open the other way, assuming that the location of upper hinge rod 42 is changed in a corresponding manner.

As will be seen from Figure 5, slave cylinder assemblies 56 and 58 are located on opposite sides of gate 12 and are arranged in opposition so that the extension of rod 58 will move hinge pin 60 and its roller bush 71 along slot 64 in one direction forcing the retraction of rod 70, while extension of rod 70 will move hinge pin 60 in the opposite direction along slot 64 and will cause the retraction of rod 58. It is important to note from Figure 5 that, in this example, slot 64 is arranged so as to

be at an angle of about 45° to the plane of gate 12 both when it is closed and when it is open. The position of the closed gate is indicated by hinge arm 74 shown in broken lines in Figure 5, arm 74 being aligned with the gate in this example. For the purpose of the present example, the hinge axis of the gate is preferably set up so that it is substantially vertical - ie, 'neutral' - when lower hinge pin 60 is located at the outer end of slot 64 and gate 12 is closed with the latch end of the gate at its lowest. ['Inner' and 'outer' indicate the gate's closing and opening directions or sides.]

To open gate 12, pressure is applied to slave cylinder 56 to move hinge pin 60 to the inner end of slot 64. This effects both the raising and outward tilting of the latch end of the gate causing gate 12 to tend to be biased to swing open under gravity until it strikes stop post 22. With gate 12 open and resting against stop post 22, pressurization of cylinder 68 will now raise the latch end of gate 12 causing the gate to be biased to swing closed under gravity, pressure on slave cylinder 56 having been relieved.

It will be appreciated by those skilled in the art that slave cylinder assemblies 56 and 68 can be of the single-acting or double-acting type and that one double- acting cylinder assembly could be substituted for the two slave cylinder assemblies. While old-style automobile brake cylinders could be used as the single-acting cylinder assemblies at minimal cost, double-acting cylinder assemblies are generally preferred to avoid the aspiration of air or water past the cup seals.

The latching mechanism 40 is illustrated in detail in Figures 6 and 7 and essentially comprises a substantially horizontal latch bar 80 pivotally attached to a gate frame member 82 near latch end member 84 of gate frame 32, latch bar 80 being arranged to extend beyond the latch end of gate 12 so that it can engage a catch plate 86 that is attached to latch post 20. The pivotal movement of latch bar 80 in the vertical plane is constrained by a guide or bracket 88 welded to the latch end member 84, guide 88 acting to prevent significant horizontal movement of latch bar 80 out of the plane of gate 12. Thus, as gate 12 swings shut, latch bar

80 is pivoted upwards by contact with a ramp surface 90 on catch plate 86 before dropping downward into a slot 92 formed by latch plate 86.

Latch assemblies of this general type are well known and commonly used on farm gates as they are simple and reliable in operation, but gates fitted with such latches are normally opened by the farmer manually lifting the latch bar while pulling the gate open. However, in this case latch plate 86 includes an upper projection having a downward and outwardly projecting cam face 93 which furnishes a useful function in this example. When the latch end 84 of closed gate 12 is lifted, to cause its opening under gravity as described above, latch bar 80 strikes cam face 93 forcing the upper portion of the latch end of gate 12 outwards (away from latch post 20) giving it an opening impetus to help start it on its downward swing to the open position.

It will be appreciated that a latch plate similar to latch plate 86 could be fixed to stop post 22 so that gate 12 is latched in the open position when latch bar 80 strikes the latch plate on the stop post. Gate 12 can then be automatically released by lifting and tilting its latch end 84 to bias it toward the closed position again, with cam face 93 again providing a useful initial impetus. An alternative stop post latch that performs much the same function will be described below with reference to Figure 8C.

It will also be appreciated that a different type of latch is needed for the two-way gate 12a of Figures 1C and 1 D. Such a latch may be set in the ground near latch post 20a and/or stop posts 22a and 22b, or it can be fixed to one or both posts. A schematic illustration of two-way gate 12a and a double sided ground-mounted ramp latch 94 is provided by Figure 8A. Ramp latch 94 has sloping ramp faces 96 on each side and a central upwardly facing groove 98 adapted to accommodate the bottom bar 33a of gate frame 32a near the latch end 84a of gate 12a. In this case, latch post 20a need only serve as a fence post since it does not interact with latch end 84a of gate 12a and does not support latch 94. Grooved latching ramps of this type are known in the art. As gate 12a swings toward the closed position, its bottom bar 33a will contact and ride up the leading ramp portion 96 of

latch ramp 94 until it drops into groove 98 where it will be held. The latch end of the gate will automatically be released when it is lifted and tilted by the tilting means, as described above. However, in the case of a two-way gate, the direction of opening will depend upon the way in which the hinge axis of the gate is tilted by the actuator means.

It will be appreciated by those skilled in the art that a ground mounted latch ramp can allow the upper portion of the gate to twist under pressure in such a way as to allow an animal to pass between latch end 84a of gate 12a and latch post 20a. If desired, one of a number of known automatic double latches can be employed to latch gate 12a to latch post 20a at a higher level. An example is the double - or two-sided - tilting latch assembly 81 illustrated in Figure 8B that is similar to a double latch commonly used for two-way garden gates. Here, latch assembly 81 is fixed to latch post 20a at any desired height and comprises two tilting striker plates 83a and 83b that are mounted so as rest in the horizontal position but to be free to tilt upwards about a horizontal axis 85. Each plate (83a or 83b) is shaped so that, when struck by the latch end 84a of a closing gate 12a from the respective side, it is lifted up to permit latch end 84a to pass and strike the blunt abutment face of the other plate (83b or 83a, respectively). The plate (83a or 83b) that has been lifted then drops down under gravity capturing latch end of gate frame 32a and preventing it from rebounding, both latch plates being shaped so that they are not lifted by an opening force on the closed gate.

A horizontal release bar 87 is attached to latch end 84a of gate 12a so that it is located just below and clear of latch plates 83a and 83b when the gate is closed. Upon activation of the tilting means to effect the opening of the gate, the latch end 84a of gate 12a is raised bringing release bar 87 into contact with the under side of catch plates 83a and 83b to tilt both plates upwardly and release latch end 84a of gate 12a for opening in either direction, as determined by the tilt direction.

It is of advantage to use the ramp latch 94 of the type shown in Figure 8A with the double catch plate assembly 81 of Figure 8B so that sagging or dropping of the latch end of the gate over time does not prevent proper action of release bar 87. It

is also of advantage to make groove 98 shallower and to mount a wheel or roller on the bottom frame member bar 33a of gate 12a so that wearing of that member by contact with the ramp is prevented.

An alternative hook-like latch plate 89 suitable for use with stop post 22, 22a or 22b will now be described with reference to Figure 8C. It can be used with both one-way and two-way gates. Plate 89 is conveniently profile cut from steel and strapped to stop post 22, 22a or 22b by straps 91 so that it is capable of vertical adjustment. It has a lower upwardly sloping lead-in ramp 95, a groove 97 and an upper cam face 99 that slopes upward and outward from the stop post above and over groove 97. The function of latch plate 89 will be described below with respect to one-way gate assembly 12 of the first example.

The operation of one-way gate assembly 10 of the chosen embodiment will now be described with reference to the schematic diagram of Figure 9 that depicts the basic hydraulic circuit of the assembly. For the sake of illustration, the hinge end of gate 12 has been shown in broken lines raised and tilted for closing to the left at 12b, raised and tilted for opening to the right at 12c and in a lowered central or neutral and substantially vertical position 12d when latched closed and abutting the latch post (not shown in Figure 9), the tilt angles being exaggerated. It will be appreciated that the tilting for closing to the left will occur when the gate 12 is open against stop post 22 rather than at latch post 20.

[For two-way gate operation, tilting of a closed gate as indicated at 12b will bias the gate to open to the left and that tilting a gate in the manner indicated at 12c after it has been opened the left will cause it to close to the right. The opening of the two-way gate to the right and its closing to the left will be the same as for the one-way operation as indicated above.]

Gate control station 14 comprises a foundation block or pillar 100 let into road 17 supporting an upstanding lever 102 for pivotal movement about a hinge pin 104, the lower extremity of lever 102 being connected to the piston rod 106 of a first master cylinder 108 that is fixed to pillar 100 and is operatively connected to first

slave cylinder 56 by a single hydraulic hose 109. Similarly, gate control station 16 comprises a foundation block or pillar 110 let into road 17 supporting an upstanding lever 112 for pivotal movement about a hinge pin 114, the lower extremity of lever 112 being connected to the piston rod 116 of a second master cylinder 118 that is fixed to pillar 110 and is operatively connected to second slave cylinder 68 by a single hydraulic hose 119. Though not shown for the sake of simplicity, a suitable hydraulic fluid reservoir can be connected to each master cylinder so as to ensure automatic bleeding of air and top-up of hydraulic liquid in the lines.

When vehicle 11 approaches control station 14, gate 12 is closed and latched in position 12d, lever 102 of station 14 is in position 102a and lever 112 of station 16 is in position 112a. When at control station 14 from the left, the driver of vehicle 11 moves control lever 102 from position 102a to that indicated at 102b, master piston rod 106 will be pushed into first master cylinder 108 and piston rod 58 will be pushed out of first slave cylinder 56 to raise latch end 84 of gate 12. Inward movement of the bottom hinge pin 60 will force piston rod 70 into second slave cylinder 68 and, in turn, result in second master cylinder 118 forcing its piston rod 116 out to move lever 112 from position 112a to position 112b. The raising of the latch end 84 of gate 12 causes latch bar 80 to strike cam face 93 of latch plate 86 moving latch end of gate 12 into position 12c and providing an opening impetus to the gate. Gate 12 then 'falls open' under gravity until bottom bar 33a of frame 32 strikes catch plate 89 on stop post 22 and is lifted by ramp 91 until it drops into groove 95. Release of lever 102 by the driver at control station 16 allows it to return to its original position under the weight of gate 12 so that the gate is also lowered onto catch plate 89.

When vehicle 11 reaches second control station 16 after passing though open gate 12, the driver moves lever 112 from position 112b back to 112a, raising latch end of gate 12 and tilting it to position 12a causing gate 12 to 'fall' towards latch post 20 (not shown in Figure 8) where it is latched closed. These actions result in gate 12 swinging shut, latch bar 80 re-engaging in catch plate 86 and first control lever 102 returning to position 102a. It will be clear that the gate can be re-opened

by operating second control lever 112 at second control station 16 just as readily as it can be re-opened from a further vehicle at first control station 14.

As already indicated, a two-way farm gate can always be made to open away from the operator so that the control station can be mounted on the right hand side of the road (for right hand drive vehicles) where it causes less obstruction, is less likely to be damaged and is more convenient to mount. Moreover, since the driver can approach the gate more closely when it opens away, the hydraulic lines between the hinge post and the control stations will be shorter than for the one- way gate.

While it will be appreciated by those skilled in the art that the semi-automatic gate assembly of the chosen example is well suited for on-farm installation and operation, being simple, economical, reliable and manually operable, it will also be appreciated that many alternations, additions and variations maybe effected to the chosen example without departing from the scope of the invention as defined by the following claims.

****************