Traveling sprinkler incorporating automatic water supply valve docking station

A docking station module for fluidly connecting a mobile irrigation apparatus to a stationary hydrant water supply valve mounted on a water supply pipe, the module comprising a hydrant valve actuator resiliently suspended from a frame for floating movement in at least three mutually substantially perpendicular directions relative to the hydrant water supply valve.

TECHNICAL FIELD

This invention relates to a traveling irrigation sprinkler, and particularly to a cart that is adapted to follow a water supply pipe, and that incorporates a docking station or module adapted to successively engage and actuate water supply valves located along the pipe.

BACKGROUND OF THE INVENTION

Traveling sprinklers that are adapted to follow an above-ground water supply pipe, and to engage in succession a number of water supply valves located along the pipe, are described in various prior patents, among them U.S. Pat. Nos. 3,575,200; 3,970,102; 3,984,052; and 4,240,461. There are other traveling irrigation machines known as “linear move” or “lateral move” machines that include large wheel-supported booms fitted with multiple sprinkler devices, where the drive tower is adapted to engage and actuate a forward supply valve before a trailing valve is disengaged so as to ensure continuous flow to the sprinklers supported on the machine. Representative examples are described in U.S. Pat. Nos. 4,442,976; 4,182,493 and 3,608,825.

The various machines described in the above patents have significant drawbacks and disadvantages, to the extent that there are few if any successful machines of this type on the market today. In fact, the most successful of the “linear move” machines are designed to draw water from a canal running alongside the field (see, for example, U.S. Pat. No. 5,080,290), or to utilize “drag hoses” that enable the machine to move from one end of the field to the other so as to eliminate the need for intermittent coupling to supply valves (see, for example, U.S. Pat. No. 4,350,295). The latter machines, however, also have drawbacks. For example, canal water is often dirty and can foul and clog the valves, sprinklers and other components. Drag hoses require constant attention and have to be relocated each time the machine reaches the end of a field.

In still other cases, complex mechanisms have been proposed for automatic docking with hydrants spaced along the length of a water supply pipe. One of the problems with these arrangements is that the hydrant risers must be held firmly in concrete, or welded onto steel pipe. In addition, alignment or docking mechanisms have been complex and costly to maintain. As a result, reliable docking under various conditions has proven to be an elusive goal. There remains, therefor, a need for a traveling sprinkler or irrigation device that moves into engagement, or docks with, and actuates, successive water supply valves located along a water supply pipe in a simple, cost-effective and reliable manner.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides, in its simplest form, a unique docking module or docking station for use with a single large-volume sprinkler on a wheeled cart that moves along an above-ground water supply pipe, and that successively docks with and actuates individual water supply valves in hydrants located along the pipe. Power to the cart drive wheels may be provided by a pair of conventional 12-volt batteries carried on the cart. A programmable logic controller (PLC), also carried on the cart, controls the movement of the cart, the speed of the cart, and both the docking and sprinkler operations.

The cart, in an exemplary embodiment, includes a frame supported on a pair of relatively large rear drive wheels and two pair of smaller front guide wheels that roll along the exposed pipe and thus guide the cart without the need for any separate steering mechanism.

The cart frame also supports a floating docking station or module that incorporates a water supply valve actuator. The docking station is adapted to engage and actuate the water supply valves in the hydrants located along the pipe. A dock stop limit switch and docking stop assembly are provided on the docking station for stopping the cart when proper alignment is achieved. The cart also supports the single, large-volume sprinkler that is in fluid communication with the water supply valve actuator.

In a first embodiment, the docking station includes a housing having a shroud with an open, inwardly tapering (in a direction opposite the direction of movement of the cart) forward end that serves to guide and align a hydrant valve actuator carried by the housing, to a position directly over a hydrant supply valve. The valve actuator includes an internal cylinder or plunger that is movable downwards into the supply valve to open the valve and allow water to flow through the plunger and through a flexible hose to the sprinkler. The sprinkler is combined with an associated control valve serving as an on/off valve for flow of water to the sprinkler nozzle.

The docking station is supported on the cart frame by means of a flexible suspension arrangement including a series of compressible tie-rods and elongated coil springs that allow the docking station housing to float, i.e., to move or flex in limited fashion in plural directions. Specifically, to ensure consistent and effective hydrant engagement, the docking station is arranged and supported so as to permit several degrees of movement as follows:

1. The docking station is resiliently suspended or hung from its supporting frame by elongated coil springs (or equivalents) extending vertically between the docking station and the cart frame to enable up and down or vertical movement, but also to facilitate front-to-back, side-to-side and compound movements, i.e., tilting and twisting movements.

2. Horizontally-oriented coil springs and/or spring-loaded, compressible tie rods (or equivalents) extend horizontally between the cart frame and docking station utilizing swivel or universal bushings to enable front-to-back horizontal movement, but also to facilitate the limited vertical, side-to-side and compound movements.

In order to further facilitate the docking operation, the hydrant itself is provided with a docking plate or flange adapted to be received and captured by the docking station. The flange, with a suitable hub, may be mounted on an existing hydrant incorporating a compatible valve, or it may be incorporated into a new water supply valve mounted on an otherwise conventional hydrant riser.

A pressure accumulator is also mounted on the cart frame and is used to supply water under pressure to the valve actuator and thereby cause the plunger to move down into the water supply valve to open the valve. The pressure accumulator is recharged with water from the supply pipe during a time delay for use with the next successive water supply valve.

In a second exemplary embodiment, the docking station assembly is designed for use with a cart adapted to be driven in either one direction, or in two opposite directions. The docking station per se in this embodiment is formed by a pair of housings sandwiched about a modified hydrant valve actuator. The two housings support multiple pairs of guide wheels adapted to engage a round plate or flange on each of the hydrants. The housings also support the docking stop assembly and related mechanical and electrical hardware for halting the movement of the cart and docking station when properly aligned with the hydrant valve, opening and closing the valve, and subsequently permitting the resumption of cart movement after an allotted sprinkling time has expired. The docking station in this embodiment has its own supporting frame that is, in turn, secured to the cart frame. The docking station or module is resiliently suspended, or hung, from its supporting frame in a manner generally similar to the first-described embodiment, but with additional vertically-oriented springs and replacement of the horizontally-oriented springs with additional tie rods. The supporting frame, in turn, supports a power supply, control panel and related hydraulic and electrical hardware as described in further detail below.

In addition to the docking station suspension mentioned above, this second embodiment may also incorporate an additional suspension feature. Specifically, the docking station and its supporting frame members may be movable as a unit laterally along a pair of rails fixed to the cart frame and extending perpendicularly to the path of movement of the cart so as to permit a wide range of lateral adjustment to accommodate a similarly wide range of hydrant misalignment situations.

In order to further facilitate the docking operation, a new hydrant design has been adopted for use with the docking station of this second embodiment. The hydrant may include a standard vertical pipe or riser fixed to the water supply pipe. At the upper end of the riser, a new valve housing is attached by any suitable means and incorporates a spring-loaded valve assembly. The upper end of the valve housing is formed with an exterior, round, horizontal flange or plate that cooperates with the docking station during capture of the hydrant. By making the flange round, the hydrant is easily approached and engaged from any direction. The valve itself projects above the top of the flange to facilitate alignment with the hydrant valve actuator on the docking station. Another alternative is the use of a conversion kit to render existing hydrants (with compatible valves) useable with the docking station.

The hydrant valve actuator carried by the docking station of this second embodiment includes a housing that incorporates a piston/cylinder, the piston portion of which is movable within an enlarged chamber in the actuator housing. “Extend” and “retract” cavities are formed on either side of (i.e., above and below) the piston portion (or simply “piston”) with the assistance of a pair of rolling diaphragms attached between the piston and the actuator housing. Briefly, water under pressure introduced into the “extend” diaphragm cavity will push the piston/cylinder downwardly such that the lower edge of the cylinder will engage the hydrant valve and push it downwardly away from the valve seat to open the valve. Water can then be supplied to the sprinkler on the cart via a flexible hose connecting the valve actuator to the sprinkler. When a pre-programmed sprinkling time has expired, water under pressure introduced into the “retract” cavity will drive the piston/cylinder upwardly and back into the hydrant valve actuator, closing the valve prior to movement to the next hydrant.

In both embodiments, the various operations of the carts and docking station(s) are controlled by an appropriately pre-programmed PLC carried by the cart frame, along with solenoids that control the various mechanical movements of the components as described in detail further herein.

The cart as described engages and follows an above-ground supply pipe. The cart can also be used with underground pipe, with only the hydrants visible, and with guidance provided by wire, GPS, etc. In such cases, the front guide wheels are modified to run on the ground rather than on the supply pipe itself. In addition, for carts capable of travel in opposite directions, two pairs of vertically-oriented, angled guide wings respectively mounted on the front and back of the docking station supporting frame, along with one pair of horizontally-oriented front and back guide wings, assist in “capturing” the hydrants projecting upwardly from the underground supply pipe. In this regard, the docking station itself is also operable in opposite forward and rearward directions of movement of the cart, with no change or adjustment in any of the component parts. For single direction carts, only front guide wings are required. In this regard, and for purposes of this application, any use of “front” or “forward,” etc. is intended to refer to the ends of the cart, docking station, etc. that lead in the direction of initial movement of the cart, i.e., along a path P1as shown inFIG. 1. Use of “back” or “rearward,” etc. is intended to refer to the opposite ends of the cart, docking station, etc. that trail in the movement along path P1.

Accordingly, in one aspect, the invention relates to a docking station module for fluidly connecting a mobile irrigation apparatus to a stationary hydrant water supply valve mounted on a water supply pipe, the module comprising a hydrant valve actuator resiliently suspended from a frame for floating movement in at least three mutually substantially perpendicular directions relative to the hydrant water supply valve.

In another aspect, the invention relates to a traveling sprinkler apparatus comprising a cart adapted for movement along a path defined by water supply pipe having a plurality of spaced hydrants thereon; a sprinkler mounted on the cart; a power source carried on the cart for moving the cart along the path; a docking station including a housing having a body portion and a valve actuator adapted for successively engaging the plurality of spaced hydrants, and for opening valves contained in the hydrants, the docking station resiliently suspended from the cart for substantially free-floating movement relative to the cart and to the hydrants; and a hose operatively connected between the valve actuator and the sprinkler.

In another aspect, the invention relates to an automatic traveling sprinkler comprising a cart including a cart frame; a plurality of wheels attached to the cart frame, including a pair of drive wheels for moving the cart between a plurality of water supply valves projecting upwardly from a water supply pipe; a power supply supported on the cart frame and operatively connected to the pair of drive wheels; a sprinkler mounted on the cart frame; a floating docking station resiliently suspended from the cart frame for movement in plural directions relative to the cart frame, the docking station supporting a valve actuator adapted to engage and open one of the water supply valves when the docking station has aligned the valve-actuating cylinder with the one water supply valve; and a hose extending between the valve-actuating cylinder and the sprinkler.

In another aspect, the invention relates to an automatic sprinkler comprising a wheeled cart having an electromechanical drive thereon for moving the cart along a path defined by a plurality of spaced water supply valves; a docking station mounted on the cart adapted to engage, successively, individual ones of the plurality of water supply valves, wherein the docking station supports a valve actuator having a plunger operable to open the water supply valve; and a pressure accumulator supported on the cart frame and arranged to supply the valve actuator with water under pressure.

In another aspect, the invention relates to automatic traveling sprinkler comprising a cart including a cart frame; a plurality of wheels attached to the cart frame, including a pair of drive wheels for moving the cart between a plurality of water supply valves projecting inwardly from a water supply pipe; a power supply supported on the cart frame and operatively connected to the pair of drive wheels; a sprinkler mounted on the cart frame; and a floating docking station resiliently suspended from the cart frame for limited movement in plural directions relative to the cart frame, the docking station supporting a valve-actuating cylinder adapted to engage and open one of the water supply valves when the docking station has aligned the valve-actuating cylinder with the one water supply valve; wherein the docking station includes a housing and a tapered shroud for guiding the docking station into alignment with the water supply valve; and wherein the docking station is resiliently suspended from the cart.

In still another aspect, the invention relates to an automatic traveling sprinkler comprising a cart; first means on the cart for moving the cart along a path defined by a water supply pipe; second means for engaging and actuating, successively, a plurality of water supply valves arranged along the pipe; a sprinkler mounted on the cart and in fluid communication with the second means; and third means mounted on the cart for controlling operation of the first and second means.

In still another aspect, the invention relates to a method of operating a water supply valve actuator carried on a mobile sprinkler apparatus having at least one sprinkler thereon comprising (a) moving the mobile sprinkler apparatus to a position where the water supply valve actuator is aligned directly over a water supply supported on a water supply pipe; (b) driving a valve actuator component downwardly into the water supply valve to open the water supply valve, using water under pressure stored in at least one pressure accumulator supported on the mobile sprinkler apparatus, thereby permitting water to flow to the sprinkler; (c) after a predetermined time interval, halting flow of water to the sprinkler and recharging the pressure accumulator with water from the water supply pipe; (d) withdrawing the valve actuator component from the water supply valve; and (e) moving the mobile irrigation apparatus to another water supply valve on the water supply pipe.

In still another aspect, the invention relates to a method of operating a water supply valve actuator carried on a mobile sprinkler apparatus having at least one sprinkler thereon comprising (a) moving the mobile sprinkler apparatus to a position where the water supply valve actuator is aligned directly over a water supply supported on a water supply pipe; (b) driving a valve actuator component downwardly into the water supply valve to open the water supply valve, using water in a pressure accumulator obtained from a previously opened water supply valve; and (c) before withdrawing the valve actuator component, recharging the pressure accumulator with water for use in opening the next water supply valve to be opened.

In still another aspect, the invention relates to a hydrant for use on a water supply pipe adapted to supply water to a mobile irrigation apparatus, the hydrant comprising a substantially vertical riser adapted to be secured to the water supply pipe; a valve located in an upper end of the riser, adapted to be opened by a valve actuator on the mobile irrigation apparatus; and wherein a round, external flange plate is located proximate to the upper end of the riser, adapted to be engaged by the mobile irrigation apparatus.

In still another aspect, the invention relates to an automatic traveling sprinkler comprising a cart including a cart frame; a plurality of wheels attached to the cart frame, including a pair of drive wheels for moving the cart between a plurality of water supply valves projecting upwardly from a water supply pipe, and at least one pair of guide wheels adapted for engagement with the water supply pipe, the guide wheels mounted on a freely pivotable steering frame assembly; a power supply supported on the cart frame and operatively connected to the pair of drive wheels; a sprinkler mounted on the cart frame; and a floating docking station resiliently suspended from the cart frame for movement in plural directions relative to the cart frame.

The invention will now be described in detail in connection with the drawings identified below.

DETAILED DESCRIPTION OF THE INVENTION

With reference initially toFIGS. 1-5, the traveling sprinkler10generally includes a cart12; a pair of rear drive wheels14,16; two pairs of forward guide wheels18,20and22,24; a docking station26communicating with a single large-volume sprinkler28; a pair of 12-volt batteries30and32; and a programmable logic controller (PLC)34.

More specifically, the cart12is formed by a rectangular steel or other suitable metal (e.g., aluminum) frame13that includes parallel front and rear rails36,38connected by parallel side rails40,42welded together to form a rigid main frame subassembly (or simply, main frame). Vertical frame members44,46extending downwardly at the rear of the main frame support the drive wheels14,16via conventional stub axles48,50. The main frame is reinforced at the rear by angled rails52,54extending between the vertical frame members44,46and the side rails40,42. A crossbeam56extends between the vertical frame members44,46approximately midway along the vertical frame members44,46and in vertical alignment with the rear rail38. Vertical struts58,60and62extend between rear rail38and crossbeam56to provide additional support.

Vertical frame members64,66extend downwardly from the front rail36(spaced inwardly from the ends of the rail) and support the two pair of forward guide wheels18,20and22,24. More specifically, short frame components68,70are welded to the members64,66at about opposite 30° angles to horizontal, respectively, and support axially oriented wheel support rods72,74. Wheels18and20are supported via stub axles76,78at opposite ends of the support rod72, while wheels22,24are supported via stub axles80,81at opposite ends of the support rod74. Thus, the wheels18,20and22,24are also oriented, respectively, at about a 30° angle to horizontal. By so orienting the guide wheels, they are able to engage the main water supply pipe P from opposite sides thereof, thus enabling the cart10to follow the pipe.

The front end of the main frame is also reinforced. A crossbeam82extends between the side rails40,42slightly to the rear of the guide wheels20,24. Angled brace assemblies84,86extend between the crossbeam82and respective vertical frame members64,66. Additional support is provided by parallel members88,90that extend between the front rail36and crossbeam82, inside the brace assemblies84,86. A cross link92also extends between the vertical frame members64,66at the upper ends of the frame members. One additional crossbeam94extends between the side rails40,42midway between the front and rear of the main frame.

The sprinkler28is supported on a tripod frame including members96,98welded at the rear of side rails40,42and member100welded to the crossbeam82. Members96,98and100converge at, and are welded to a cylindrical pipe section102on which the sprinkler28is supported, as described further below. The tripod frame is reinforced by short braces104,106and108.

In connection with the further description of the docking station and related hardware, the various drawing figures have been simplified via omission of details for the sake of clarity and ease of understanding. For example, in some views, certain structure not necessary for understanding the text relating to these views has been omitted. In addition, wiring and other minor details that would otherwise clutter the drawings, but that are nevertheless well understood by those of ordinary skill in the art, have also been omitted from various figures.

The docking station or housing26is suspended from the cart12, generally in the middle of the main frame13, but below the main frame so as to facilitate alignment of the docking station26with a hydrant110on the pipe P. With further reference toFIGS. 6-11(simplified for ease of understanding), the docking station26includes a housing27with outer parallel side plates112,114, a back plate116, and an intermediate plate118that extends between the side plates112,114and is parallel to the back plate116. Note that inFIGS. 6-11, the docking station is facing in the opposite direction from that shown inFIGS. 1-3. For convenience and ease of understanding, arrows in FIGS.1and6-8show the direction of movement of the cart and hence, the docking station, along a path P1. Note also that inFIGS. 6,7and8, the side plate114has been removed to permit sight of the components inside the docking station housing27.

Within the housing27, there is a tapered shroud120secured to the side plates112,114and intermediate plate118by any suitable means (welding, bolts, etc.). The shroud120includes a top wall122, a bottom wall124and a pair of side walls126,128, all of which taper in a rearward direction to a horizontally oriented slot130that resembles a similarly shaped slot132in the back plate116. The plate118is also cut out to include a similar slot (not visible). The slots130,132are substantially T-shaped, and bottom wall124of the shroud120is split, leaving a wide opening in the center thereof to permit passage of the cart10and docking station26over and beyond each hydrant110on the pipe P as the cart travels along the pipe (seeFIG. 10). The slot130at the rear of the shroud is configured to receive the hydrant110and a substantially flat, rectangular docking plate or flange134fixed (by welding, for example) on the top of a vertical riser111of the hydrant110. The T-shaped slots132in plate116and similar slot in plate118are also sized and shaped to receive the generally similar T-shaped cross-sectional shape of the combined riser and docking plate134as also best seen inFIG. 10.

The intermediate plate118not only reinforces the housing27but also provides support, along with plate116, for the hydrant valve actuator136. A docking stop assembly138and dock stop limit switch140are also supported on the plate116. More specifically, the dock stop limit switch140is secured to the exterior surface of the plate116, adjacent the stem portion of the T-shaped slot132in the plate. A switch arm142is pivotally mounted in the switch box and a roller144is secured to the remote end of the arm. Roller144projects upwardly into the slot132and is located so as to be engaged by a forward edge148of the docking plate134(seeFIG. 7) as the docking station housing27moves over the riser111of the hydrant110.

The docking stop assembly138includes a pair of docking stops150,152mounted on a transverse shaft154for rotation with the shaft. The shaft154is journalled for rotation in bearing cages156,158,160and162fixedly mounted on the exterior surface of the plate116. The docking stops150,152are movable between an extended “stop” position as shown inFIGS. 6 and 7, and a retracted “go” position as shown inFIGS. 8-10. Rotation of the shaft154and hence docking stops150,152is controlled by a hydraulic actuator164mounted on the interior side of the plate112. An actuator rod166extending out of the actuator164is connected to one end of a first link arm168that is, in turn, connected at its other end to a pair of links170,172. Link172is pivotally secured to a pin housed in a roller174attached to intermediate plate118, while link170extends in a substantially opposite direction with its free end pivotally secured to a drive link178that is, in turn, fixed to the drive shaft154.

The operation of the docking stops150,152and dock stop limit switch140will be described further hereinbelow.

Returning toFIGS. 1-5, the docking station26is suspended, i.e., hung, from the frame12by several suspension components including two pairs of tie rods180,182on one side of the housing27, and184,186on the other side of the housing27. Tie rods184,186extend between the vertical frame member66and the side plate112of the housing27. Tie rods180,182extend between the other vertical frame member64and the side plate114of the housing27. The docking station26is further supported by a first pair of elongated, generally horizontally-oriented coil springs188,190extending between side plates112,114and vertical frame members66,64, respectively. Springs188,190are located between each pair of tie rods180,182and184,186, respectively. A second pair of vertically-oriented elongated coil springs192,194extend between the cross brace94and the side plates112,114of the docking station housing27.

With this arrangement, the docking station26“floats” relative to the cart frame12for movement in at least three mutually perpendicular directions, i.e., vertical, horizontal front-to-back (and vice versa), and horizontal side-to-side. In addition, limited compound movements, i.e., tilting, twisting or swiveling and combinations thereof, are also possible by reason of the flexible nature of the vertically-oriented springs in combination with the tie-rod universal mounts or bushings196,198,200and202(FIG. 2). These multiple degrees of freedom of movement permit reliable and accurate docking with hydrants110even when the latter are out of alignment relative to the docking station.

As best seen inFIG. 9, the valve actuator136is supported between plates116and118in the docking station housing27. The valve-actuating cylinder136is connected to the lower end of the pipe section102by a flexible hose193(FIGS. 1-5) which feeds water from the hydrant110to the sprinkler28. Sprinkler28may be any conventional large-volume sprinkler, such as the Big Gun™ Series 75 or Series 100 available from the assignee, Nelson Irrigation Corporation. As such, the sprinkler28need not be described in detail, except to note that the sprinkler is rotatable about a vertical axis through various adjustable arcs, under the control of the PLC34. Other suitable sprinklers may be utilized however. A pressure control valve203is located at the base of the sprinkler28and controls the flow of water to the sprinkler. The control valve203may be of any suitable type, for example, the “800 Series Control Valve,” also available from Nelson Irrigation Corporation.

A pressure accumulator204is supported on the crossbeam94(by any suitable means) and is in fluid connection via hose205(FIGS. 2,12and13) with the valve actuator136as further described below. The pressure accumulator204may be of any suitable type, for example, a TEEL® precharged water well tank, Model No. 3P676C.

Turning toFIGS. 12 and 13, the valve actuator136includes a cylindrical actuator housing206having a reduced diameter upper housing portion208and a lower housing portion210, secured together about flange212by a plurality of bolts214or the like. The upper housing portion defines a chamber216having an internal diameter sized to receive a key cylinder or plunger218that has a radial flange220approximately midway along the length of the plunger, on which is seated an inner periphery of a rolling diaphragm222. The inner edge of the diaphragm is thus clamped between the flange220and an annular ring224, secured by screws226. The outer periphery of the diaphragm is clamped between the upper and lower housing portions208,210, thus establishing a sealed chamber228above the diaphragm. In this regard, the plunger218is sealed relative to chamber216via annular seal230. The plunger218is biased in an upward direction, to the position shown inFIG. 12by means of a coil spring232acting between the bottom wall234of the lower housing portion210and the radial flange220. The lower end of the plunger218is adapted to move downwardly upon pressurization of chamber228, with the flange220and ring224serving as a piston, through the housing and valve seal guide236into engagement with a water supply valve assembly238in the riser111. The valve seal guide is sized to receive the plunger218in a close-fit arrangement that precludes water escaping along the joined surfaces of the valve-actuating cylinder and the valve seal guide. Movement of the plunger through the valve seal guide236will unseat the water supply valve assembly238, including the tapered, annular seal ring239from its seat240(FIG. 13), against the bias of a pair of springs242,245to thereby open the valve as described further below. Seal ring239may be made of any suitable material, for example, a flexible Buna-Nitrile or similar material. The seal ring is sandwiched between a pair of support surfaces241,243which form part of the valve seal assembly238. Springs242and245are telescoped, one within the other, to provide the desired bias. Note also that water supply valve238includes a plurality of radially directed spokes or webs247that allow water to pass through the valve but also provide surfaces for engagement by the plunger218as it moves downwardly into the seal guide236.

A port244is provided at the upper edge of the upper housing portion208for a pressure sensor251(FIG. 14), and another port (not shown) is provided on the opposite side of the housing portion208for a key cylinder or plunger proximity switch249(FIG. 14), and a port fitting246is connected to the upper housing portion208, and specifically chamber228, establishing fluid communication with the pressure accumulator204(FIG. 3) via hose205. A vent valve248permits porting of the water in chamber228to atmosphere as described further below.

Returning toFIG. 5, the drive wheels14,16are powered by the pair of 12-volt batteries30,32that are supported in trays250,252(FIG. 1) fixed to the crossbeam56. The batteries30,32are connected to, for example, a conventional 0.5 HP axial drive motor and gearbox assembly254supported on the rear rail38. The gearbox is connected via chain256to a sprocket258on a drive shaft260that is journalled in bearings262,264fixed to the vertical frame members44,46. The wheels14,16are connected to the drive shaft via sprockets266,268on the ends of the drive shaft260and sprockets270,272on the stub axles via chains274,276, respectively. A conventional differential278interposed along the drive shaft permits the wheels14,16to rotate at different speeds, thus enabling the cart to move through curves as determined by the layout of the pipe P.

Note that there are no separate hydraulic drive systems in the illustrated embodiments. All movements and functions are carried out electrically in concert with applied water pressure derived from the water supply pipe. However, hydraulic drives, electromechanical drives, and the like may also be used.

The PLC34is programmed to control not only the cart movement, but also the operation of the docking station, valve-actuating cylinder and the sprinkler itself.

In use, and with reference not only toFIGS. 1-13but also to the system diagram inFIG. 14, a first necessary step is to be sure that safety buttons290,292,294and296(FIGS. 1-5,14) located at the four corners of the cart frame are pulled outwardly. This is a safety measure, in that the motor254cannot be started until these buttons are in the proper extended positions. Conversely, during operation, if any one of these buttons is depressed, the motor will switch off and the cart will stop. Once started, the traveling sprinkler10and specifically the cart12drives along irrigation pipe P, following path P1, using the four forward guide wheels18,20,22,24to follow the pipe. As the cart approaches a water supply hydrant110, the speed control limit switch280and its vertically oriented sensor wand282(FIGS. 1 and 2) is tripped which signals the PLC34to reduce the voltage to the drive motor254(FIGS. 5 and 14) from 24 volts to 12 volts by removing power from one of the two control relays R1and R2(FIG. 14). The voltage reduction results in a speed reduction of the cart. The PLC34also sends power to a control valve solenoid284(FIGS. 1 and 14) which ports water to the outer sleeve of the valve and thus closes the control valve203.

As the cart12drives forward, approaching the riser111and dock plate134, the docking stops150,152are down or extended in the “stop” position, ready to stop the cart when engaged by the plate or flange134(FIGS. 6 and 7). At this stage, the docking limit switch140is also in an untripped state.

As the cart continues its forward travel, the docking plate or flange134is captured by the docking station shroud120which guides the docking plate134toward the docking stops150,152and the dock stop limit switch140. The docking plate134engages the roller144and trips the dock stop limit switch140after passing through the docking station shroud120, and the limit switch signals the PLC34to stop the forward movement of the cart12by removing power from the other of the two control relays. The cart12then coasts forward until the docking stops150,152are engaged by the docking plate134, bringing the cart12to a stop (seeFIG. 7).

After a time delay, the PLC34sends a signal to the main water on/off control solenoid286(FIGS. 3 and 14) which ports water under pressure from the pressure accumulator204to the valve actuator136in the docking station housing27. As a result, the plunger218moves downwardly past the valve seal guide236nested in the riser111and opens the valve assembly238(seeFIGS. 12 and 13), pushing the valve ring off the valve seat240(FIG. 13). After a valve proximity switch249(FIG. 14) senses the valve to be open, and a pressure sensor251(FIG. 14) senses adequate pressure, the PLC34begins the pressure accumulator recharging time delay. This time delay allows sufficient time for system water pressure to recharge the pressure accumulator204through a check valve253(FIG. 14) in the hose205. This ensures that the pressure accumulator204will be fully charged for engagement with the next water supply valve. After the time delay, the PLC removes power from the sprinkler control valve solenoid284which ports water from the outer sleeve of valve203to atmosphere, allowing the control valve203to open. Water now flows freely from the hydrant110to the sprinkler28for irrigation.

The sprinkler28runs for a programmed amount of time. Once that time has expired, the PLC34will remove power from the main water on/off control solenoid286(FIGS. 3 and 14) to vent water to atmosphere from the valve actuator136via vent248(FIGS. 12 and 13). This removes the downward force on the “piston”220,224and diaphragm222, so that springs242,245in the riser valve assembly238and spring232in valve actuator136force the valve actuator plunger218back up into the valve actuator136to the position shown inFIG. 12, closing the valve and thus shutting off the flow of water through the valve. The PLC34also sends a signal to the docking stop control solenoid288, causing water to be ported to the hydraulic actuator164, to extend the actuator rod166, thereby moving the three linkages168,170and172. The movement of these linkages rotates the drive link178clockwise and, since the drive link is attached to the docking stops150,152via the drive shaft154, the stops150,152are raised out of the path of the docking plate, to the “go” position shown inFIG. 8.

Once the pressure sensor251and valve actuator proximity switch249sense no pressure and full plunger retraction, the sprinkler cart12is free to continue to the next riser. The PLC34energizes one of the power relays R1and R2so that the motor254will move the cart at slow speed, using only 12 volts, for a programmed amount of time and then, after the cart has cleared the riser and docking plate, the PLC will energize the second of the two power relays R1and R2so that the motor254is connected to 24 volts. The cart12is now back to full speed. As the docking plate134continues to pass over the docking station limit switch roller144(FIGS. 8 and 9), the limit switch arm142is pushed out of the way.

When the docking plate134has cleared the docking station limit switch140, the switch arm142is returned to the untripped position via an internal torsion spring. Following a programmed time delay to ensure that the docking plate134has cleared the docking station limit switch140, the PLC34removes power from the dock stop control solenoid288(FIG. 3) to vent water from the hydraulic actuator164to atmosphere. As a result, the hydraulic actuator rod166is forced to retract by an internal spring, moving the three link mechanism (168,170,172) so as to rotate the drive link178, drive shaft154and docking stops150,152in a counterclockwise direction. The docking stops150,152are now back in position to engage the next hydrant along the supply pipe, as shown inFIG. 6.

It will be appreciated that the invention as described may be modified in several ways. For example, the cart guide wheels18,20,22and24could be made to rotate about horizontal axes and to run on the ground if the pipe P is located below ground. In that case, the cart12could also incorporate magnetic, electrical or other means enabling the cart to follow buried pipe to the risers. The docking operation would otherwise remain substantially as described. A wire guide or GPS system could also be employed to guide the cart12to the various risers in any desired sequence. In addition, sprinkler28may be modified for control by the PLC34in terms of throw radius, arc of coverage, etc. It will be appreciated that the PLC34may be programmed to vary the sprinkling time at each riser and/or to skip certain risers. In addition, the sprinkler itself may be replaced by a relatively small, transverse boom or truss assembly, also supported on the cart, and to which several smaller sprinklers are attached.

In accordance with a second exemplary embodiment, and with reference toFIGS. 15-30, the docking station300is carried by its own supporting frame302that, in turn, may be adapted to be rigidly secured to the cart frame13. The supporting frame302includes a pair of inverted U-shaped subassemblies304,306that are connected at their upper ends by frame members (not shown) located below rails488,490. The U-shaped subassemblies could be fixed between, for example, crossbeam82and another crossbeam (not shown) that would be located rearward of crossbeam94, at a location that accommodates the length of the U-shaped subassemblies. For cart applications where the pipe is underground, and where the cart is adapted for movement in opposite directions, lateral movement of the docking station to enable capture of a misaligned hydrant is also enabled by front and rear pairs of substantially vertical guide wings. Specifically, a forward pair of guide wings312,314is fixed to respective forward ends of subassemblies304,306and extend forwardly of the docking station300, flaring outwardly in the forward direction. A rearward pair of guide wings316,318is fixed to respective rearward ends of subassemblies304,306and extend rearwardly of the docking station300, also flaring outwardly but in the rearward direction. The role played by the guide wings312,314and316,318in assisting the capture of the hydrant flange is explained further below. For a cart that moves along an above-ground pipe, the guide wings may be omitted.

The docking station300includes a pair of identical housings320,320′ (one shown inFIGS. 15,17and18) on either side of, i.e., sandwiched about, a hydrant valve actuator assembly322(FIG. 19). Since the housings320,320′ are identical to one another, only one need be described in detail. As best seen inFIG. 17(interior side) andFIG. 18(exterior side), housing320includes a main body portion324with two pairs of oppositely directed flanges326,328and330,332, each flange pair supporting between them a respective generally hourglass-shaped V-track roller334,336for rotation about a vertical axis defined by pivot pins or bolts338,340. The main body portion324of housing320also supports two pair of vertically aligned guide wheels342,344and346,348for rotation about horizontal axes350,352,354and356, respectively. The pairs of guide wheels are supported axially between the V-track rollers334,336, on the inner side of the housing320. An additional pair of idler rollers358,360may be mounted on each housing, but they are merely optional, not required. An elongated channel357, with its open side facing inwardly, is secured to the inside of the housing320, as best seen inFIGS. 17,18and22-24, thus providing a slot or groove for receiving the docking flange364. A side guide wheel359(FIG. 18) is mounted on the outside housing320for rotation about a vertical axis, and protrudes through an opening in the housing320and channel357, also to be engaged by the docking flange. Thus, when housings320,320′ are assembled on either side of the valve actuator assembly322, a passageway or docking space362(FIG. 24) is defined by the two laterally opposed pairs of V-track rollers334,336at the front and back of the docking station, the four pairs of laterally opposed guide wheels (342,344) and (346,348) located axially between the two pairs of V-track rollers, and the opposed channels357. This passageway362is located below the valve actuator322, and is sized and shaped to receive the round docking flange364(FIGS. 26-29) on the hydrant366as also described further below.

Also fixed to the housings320,320′ are a pair of optional, substantially horizontally-oriented guide wings366,368(FIGS. 15 and 16), also for use when the pipe370is underground. The guide wings366,368may be secured to the housings320,320′ by means of bolts or any other suitable means. Wing366projects outwardly and upwardly in a forward direction, while wing368projects outwardly and upwardly in a rearward direction. These wings work in concert with guide wings312,314and316,318to align the docking station300with the hydrant366. The vertically-oriented wing pairs312,314and316,318are designed to be engaged by the hydrant flange364when the hydrant366is misaligned in a lateral direction, causing the docking station300to move laterally in a direction dependent upon which of the guide wings is engaged. The horizontally-oriented wings366,368are especially designed to assist in adjustment of the docking station300to a hydrant366that is slightly higher than a desired optimum height, i.e., when the docking flange364is higher than the passageway or docking space362. Thus, when wing366, for example, engages a hydrant flange364, it will cause the docking station300to crawl upwardly over the flange364so that the flange can be engaged by the V-track rollers334,336. The V-track rollers334,336will also cam the docking station300in a direction that brings the docking station to a position where the flange364is located in the center of the V-track rollers as best seen inFIGS. 22-24. Note that the profile at the narrow center of the V-track rollers334,336complement the rounded profile of the peripheral edge of the flange364.

It will be understood that for carts adapted only for movement in a forward direction, only the forward wings are required, and for carts guided by an above-ground supply pipe, all of the guide wings may be omitted.

With reference now especially toFIGS. 22-26, the housings320,320′ and valve actuator322of the docking station300also support a pair of docking stops372,374on the forward and rearward ends, respectively, of the docking station. For carts adapted to move in only a forward direction, the forward docking stop372and associated linkages and drive may be omitted.

The rearward docking stop374is controlled by a similar linkage and actuator arrangement as forward docking stop372, but is supported on the opposite side of the docking station300, as best seen inFIG. 26. Note that the forward and rearward stops and their associated linkage and drives are mirror images of one another, with an actuator376mounted on each side of the docking station300, i.e., one actuator is mounted on the housing320and the other actuator is mounted on the opposed housing320′. For convenience and clarity, and with the exception of stops372,374themselves, the links, shafts and bearing supports for each stop have the same respective reference numerals.

The forward docking stop372is in the form of a vertically-oriented bar combined with a horizontally-oriented proximity sensor378at its lower end. The stop372is pivotally supported by two sets of parallel links380,380′ and382,382′. The upper set of links380,380′ is pivotally attached at a forward end to the upper end of stop372via a pivot pin, and at a rearward end to end384of a shaft386. The lower set of links382,382′ is pivotally attached at a forward end to the lower end of the stop372and at a rearward end to a clevis388(FIG. 19) secured to the housing of the valve actuator322. In this regard, the pivot pin or bolt (not shown) extends through holes390,390′ in the clevis. This parallel linkage arrangement allows the stop372to move essentially vertically up and down between lowered (stop) and raised (go) positions upon rotation of shaft386.

Shaft386is supported within a journal bearing392in an extended side394of the clevis388, and in a bearing stand396on the housing320. The free end of the shaft386adjacent the stand396mounts a clevis398for pivoting movement upon rotation of the shaft. A forward end of an adjustable link arm400is pivotally mounted within the free end of the clevis398. The rearward end of the link arm400is pinned to a forward end of a second link arm402via pin404. The rearward end of the second link arm402is pivotally mounted in a clevis406(via pin408) also supported on the housing. Adjacent the forward end of the second link arm (i.e., adjacent pin404), a right angle arm410is pivotally attached to a rigid connecting link412fixed to an output shaft414of the hydraulic actuator376. When the shaft414is extended, link402will pivot in a counter-clockwise direction, thereby pulling the first link400upwardly and rearwardly. This movement causes the clevis398and thus shaft386to rotate in a counter-clockwise position. As a result, the parallel linkage comprised of link sets380,380′ and382,382′ will also rotate in the same direction, raising the stop372to a retracted or “go” position. Retraction of output shaft414will have the opposite effect, i.e., lowering the stop372to an extended or “stop” position. Operation of the docking stops372,374will be described in detail further below.

As in the first-described embodiment, the docking station300itself is suspended or hung from its supporting frame302so as to allow the docking station to “float” to a limited extent in essentially any direction to facilitate capture of the hydrant. Specifically, and with reference again toFIGS. 15 and 16, the docking station300is resiliently suspended from its supporting frame302by means of four coil springs (two shown at416,418inFIG. 15) extending vertically between eyebolts (or other suitable points of attachment) secured to the inside surfaces of the horizontal members420,421of the inverted U-shaped subassemblies304,306and eyebolts (or similar)422(seeFIG. 17) on respective upper surfaces of housings320,320′. In the exemplary embodiment, one pair of springs is attached to the top of housing320, and the other pair of springs is attached to the top of housing320′, such that the four coil springs are arranged in a generally rectangular pattern. These springs permit spring-biased up and down movement of the docking station, and also permit limited side-to-side, front-to-back, and compound movements, i.e., tilting, and twisting and/or swiveling movements.

A first pair of spring-loaded, compressible tie rods424,426(FIG. 15) is secured substantially horizontally between the rearward vertical member428of the U-frame subassembly304, and the housing320via universal bushing mounts430,432and434,436(FIGS. 15,18), while a second pair of similar tie rods (one shown at438) is secured in a similar orientation between the rearward vertical member of the other U-frame subassembly306and housing320′, utilizing similar bushing mounts (not shown). Note that additional bushing mounts (unnumbered) are available on the housings320,320′ (FIG. 18) to provide other optional mounting arrangements. For each tie rod, and as best seen inFIG. 15, a “piston”440is movable within the tie rod against a bias established by internal springs. Such tie rods are well known to those skilled in the art. The use of universal bushing mounts430,432and434,436with the tie rods, permits some degree of side-by-side, up and down and compound movements, in concert with the vertically-oriented springs416,418, etc. Note also that the compressible tie rods (compressible in two opposite directions) also serve as shock absorbers in that they accommodate a limited degree of “over travel” by the cart during docking.

With this arrangement, the docking station300“floats” relative to its supporting frame302(and to a hydrant366) for movement in at least three mutually perpendicular directions, i.e., vertical, horizontal front-to-back (and vice versa), and horizontal side-to-side. In addition, limited compound movements, i.e., tilting, twisting and/or swiveling and combinations thereof, are also possible by reason of the flexible nature of the vertically-oriented springs in combination with the tie-rod universal mounting arrangements. These multiple degrees of freedom of movement permit reliable and accurate docking with hydrants366even when the latter are out of alignment relative to the docking station300.

The hydrant valve actuator assembly322includes a lower housing442provided with a pair of attachment flanges444,446(FIG. 19) by which the valve actuator assembly322is secured between the housings320,320′. Specifically, the assembly322and housing320via bolts extending through holes460and462in attachment flange444and holes350and354in guide wheels342,344that extend into the housing320. Dowel pins (not shown) extending between holes456,458in angled ribs448,450and holes452,454in the attachment flange444may be used to align the attachment flange with the housing. The assembly322is secured to housing320′ in an identical manner.

The valve actuator assembly322also includes intermediate and upper housing portions464,466that, combined with lower housing442, enclose the valve actuator, as also described further below. A flexible hose468(FIGS. 15 and 16) connects the actuator assembly322to the sprinkler on the cart.

With reference now toFIGS. 20 and 21, an additional upper box frame470may be mounted on the supporting frame302. This upper frame may support a pair of pressure accumulators472,474and a control panel or box476housing the PLC469. Pressure accumulators472,474are arranged in parallel and are used to supply water under pressure to the valve actuator322, and are similar to the pressure accumulator204described above. The use of a pair of pressure accumulators is particularly useful for larger systems that utilize higher capacity water supply valves and valve actuators. If desired, the pair of 12-volt batteries30,32described earlier could be relocated to the upper frame270along with the component control solenoids. As best seen inFIG. 20, a solenoid bank may be arranged below the relocated control box476and the solenoids supported on, for example, a cross member477of the upper frame470. Thus, the solenoids are supported below but connected between the control box476and various controlled components such as the dock stop actuators376, the valve actuator322and the main water control valve203(FIGS. 1 and 14). More specifically, for this embodiment, solenoids471and473control the flow of water to and from the valve actuator322. Solenoids475and477control the movements of docking stops372,374and solenoid479controls the main water control valve203.

Another optional suspension feature may include the addition of two pairs of roller mounting flanges478,480and482,484(FIG. 21) to the supporting frame302, each flange pair mounting two rollers486(four total shown inFIG. 16) such that the supporting frame302is movable laterally, in a direction perpendicular to the path P1along a pair of pipes or rails488,490fixed between, for example, cart side rails40,42(FIG. 1). This arrangement provides a lateral adjustment feature for the docking station300relative to the cart (and hydrants) as described further herein. As best seen inFIGS. 20 and 21, a first pair of horizontally-oriented coil springs492,494are connected between the side rail40and vertically-oriented brackets on the top of the inner U-shaped subassembly306, while a second pair of horizontally-oriented coil springs496,498extend between the inner side rail42and vertically-oriented brackets on the top of the outer U-shaped subassembly304. This arrangement maintains the docking station300(described below) in a generally centered position along the rails488,490(between cart frame side rails40and42), but also permits reciprocatory spring-biased movement of the docking station300in opposite directions along the rails488,490. With this feature, the docking station300is able to accommodate various degrees of misalignment of any one or more of the hydrants366, and is particularly useful when the supply pipe is underground and not available as a guidance mechanism.

Turning now toFIGS. 27 and 28, a hydrant or water supply valve366is shown extending upwardly from the supply pipe370. One or more riser footings500may be used to stabilize the hydrant. The hydrant includes a vertical riser502on which a valve housing504including the integral docking flange364is secured in telescoping relationship. The valve housing504encloses and supports a water supply valve assembly506in a generally vertical orientation. The valve housing504is formed with a lower opening508with an adjacent, interior shoulder510by which the housing504is supported on the upper edge512of the riser502. The manner in which the valve housing504is secured is within the skill of the art and may include threaded attachment, welding or other suitable means.

The upper end of the housing504supports a valve cup514formed with an external shoulder516that permits the cup514to be seated on the valve housing504, with a smaller diameter lower portion518telescoped into the valve housing. A flexible annular seal520is seated in a groove formed in the interior of the cup. The valve assembly or simply “valve”506also includes an elongated stem assembly522with an annular Buna-Nitrile (or other suitable material) valve seal524sandwiched between upper and lower valve seal supports526,528. The lower support528is counterbored to create a spring recess530(FIG. 27). A stem532is attached to the upper support526by threaded engagement of bolt534. The bolt534accesses the lower support528by means of a bore in the upper support526. The stem532extends downwardly and through a guide spider536fixed near the lower end of the valve housing. A pair of coil springs538,540extend between the spring recess530and the hub542of the guide spider536, thereby biasing the valve assembly506upwardly to a normally closed position, with valve seal524engaged with annular seat544at the lower end of cylinder514. The upper support526is also formed as a spider, with three radial webs546(2 partially shown) extending radially outwardly to the interior wall of the cup514, thus permitting flow out of the hydrant while also providing an engagement interface for the hydrant valve actuator piston/cylinder as described further below.

As already mentioned, the hydrant valve actuator assembly322includes a three-part housing including the upper housing portion466, the intermediate housing portion464and the lower housing portion442, joined together at flanged interfaces548,550by bolts or other suitable means (not shown). Relatively large diameter portions of the upper and lower housing portions446,442in combination with the intermediate portion464create an enlarged interior chamber552axially between upper and lower smaller-diameter internal, cylindrical bores554,556.

A unitary piston/cylinder558is slidable within the housing, with the piston or flanged portion560confined to movement within the enlarged chamber552. An upper cylindrical part562of the piston/cylinder558slides within the upper internal bore554while a lower cylindrical part564slides within the lower internal bore556. A first rolling diaphragm566is fixed between the upper end of the piston560and radial flanges568,570at the interface548between the upper and intermediate housing portions466,464. Similarly, a second rolling diaphragm572is fixed between the lower end of the piston560and the radial flanges574,576at the interface550between the intermediate and lower housing portions464,442. This arrangement creates an “extend” cavity578above the diaphragm566and a “retract” cavity580below the diaphragm572for fluid acting on opposite sides of the piston560.

Fluid seals (O-rings or the like)582,584are located in respective upper and lower housing portions466,442to prevent fluid leakage from chamber552along the internal bores554,556. A spring586is located between an interior shoulder588at the lower end of the lower housing section442(formed by a counterbore in the lower internal bore556) and the lower side of the piston560to normally bias the piston-cylinder560in an upward direction, to the retracted position shown inFIG. 27. A first port590is provided in the upper portion of the housing for introduction/exhaustion of fluid into or from the extend cavity578and a second port592is provided in the lower housing section442for introducing/exhausting fluid into or from the retract cavity580.

The operation of a two-directional cart is described below, with the cart as shown inFIGS. 1-5modified as necessary for use with an underground supply pipe. As the cart is driven forward in the direction of path P1(FIG. 1), the forward docking stop372is in the up or go position, while the rearward docking stop374is in the lowered or stop position (FIG. 22).

As the cart continues to move in a forward direction, the hydrant flange364and docking station300are initially roughly aligned, if necessary, by the interaction of the flange364with the front guide wings312,314and front guide wing366. Assuming the hydrant flange364and docking station300are not in substantial alignment during the initial contact, the vertically-oriented front guide wings312,314(and/or the horizontally-oriented forward guide wing366) will be engaged by the stationary hydrant flange364, causing the docking station300to move laterally along the rails488,490to a generally laterally aligned position, while engagement with wing366will cause the docking station300to move upwardly as the docking station continues to move toward the hydrant. The flange364will then be engaged by the forward pair of V-track rollers334,336the tapered surfaces of which further center the flange364relative to the docking station so that the flange is located at the smallest-diameter portion of the V-track rollers, as best seen inFIG. 24. In other words, the V-shape of the spinning rollers334,336allows the free-floating docking station300to crawl around the hydrant flange364until they are aligned. The hydrant flange364then slides between guide wheels342,344,346,348and into the side guide channel members357which capture the hydrant flange364in substantially the same plane as the docking station.

In an alternative arrangement, a power-assist feature may be added to facilitate lateral movement of the docking station on the rails488,490upon engagement of the hydrant flange364with one or the other of guide wings312,314and366. This would function in a manner similar to power brakes or power steering in a vehicle, and could employ oil hydraulics, water hydraulics, pneumatics, or electric motors to move the docking station along the rails488,490.

With further reference also toFIG. 30, as the hydrant flange364is captured by the docking station300, the cart12continues forward travel until the hydrant flange364engages the rearward docking stop374. More specifically, when the docking stop proximity switch375(part of the stop) is tripped (for example, when the flange364is within a few millimeters of the stop), it signals the PLC469in the control panel box476to stop the forward movement of the cart. At this point, the cart “coasts” into engagement with the docking stop374. The hydrant flange364is now fully captured by the docking station300, and the cart is in position to connect to the water supply valve. Depending on the normal operating speed of the cart, a second proximity switch may be used “upstream” of the switch375for the purpose of effecting a reduction in speed of the cart as it approaches the hydrant, as described in connection with the first embodiment. If desired, the speed control feature of the first-described embodiment may be employed here as well.

When the docking station300is fully aligned with the hydrant water supply valve housing504, only the flange364is engaged with the docking station. In other words, the docking station self-aligns with the flange364, the alignment determined by the docking stop374, the laterally opposed and axially spaced pairs of guide wheels342,344and346,348, and the opposed, horizontally-oriented channel members357and associated side-guide wheels359on the interior sides of the housings320and320′. Note that in the fully aligned position, the docking flange364is located between and axially spaced from the forward and rearward V-track rollers334,336.

The PLC469now sends a command to port water from the pressure accumulators472and474through the extend on/off control solenoid valve471to the extend diaphragm cavity578in the actuator assembly322. At the same time, the main water retract on/off solenoid valve473vents water from the retract cavity580. The water force in the extend cavity578overcomes the force of spring586and pushes the lower cylinder part564down into the hydrant valve housing504. The cylinder part564eventually travels through the valve cup514, and as the cylinder continues its downward movement, the valve seal524is pushed off the valve seat544to thereby open the valve. After extend on/off control solenoid471has been signaled by the PLC, a time delay allows sufficient time for system water pressure to recharge both pressure accumulator tanks472,474(as needed). After the time delay, the PLC469sends a command to solenoid479to open the control valve203so that water is then free to flow via the valve through the piston-cylinder558to the sprinkler28.

After the sprinkler has run for the programmed amount of time, the PLC469sends a command to solenoid479to close the control valve203to prevent water from draining out of the sprinkler. The PLC469then sends a command to vent water from the “extend” cavity578through the main water extend on/off control solenoid valve471to atmosphere. This removes the downward force on the rolling diaphragm566. At the same time, the PLC469sends a command to port water to the “retract” cavity580through the main water retract on/off control solenoid valve473. The springs586and diaphragm572now push the piston-cylinder558back up into the actuator housing to the position shown inFIG. 27. As the piston-cylinder558retracts, the valve seal assembly506is pushed upward by the valve springs538,540until the valve seal524seats on the valve seat544and shuts off water flow. When a proximity switch596senses the actuator piston-cylinder558is retracted, the PLC469initiates forward movement of the cart to the next hydrant. To initiate such forward movement, water is first ported through the solenoid477that operates hydraulic actuator376. The hydraulic actuator376extends its output shaft414to thereby raise the stop374out of the path of the flange364to the retracted or “go” position. The cart then begins to drive forward to the next hydrant. When the docking station is disengaged from the hydrant flange, the springs492,494and496,498will return the docking station to its centered position along trolley rails488,490. Following a programmed time delay to ensure that the docking station300has cleared the hydrant, the PLC sends a command to solenoid477to port water from the hydraulic actuator376to atmosphere. The hydraulic actuator rod414is forced to retract by an internal spring, rotating the docking stop374to its extended or “stop” position. The dock stop374is now in position to stop the docking station at the next hydrant. It will be appreciated that dock stop372will operate in the same manner when the cart travels in the opposite direction. Thus, stop372is always retracted when the cart travels along path P1, and stop374is always in the retracted position when the cart travels along opposite path P2.

In the above-described embodiments, water from the irrigation pipes is used as a hydraulic drive fluid. A closed hydraulic system employing standard hydraulic fluids, a pump, reservoir, and filter could also be employed. A water glycol fluid is currently under consideration. A pneumatic system could also be used employing a compressor, filter and reservoir. An electric jack screw or actuator could also connect to the valve actuator and be used to drive it up and down into the hydrant valve.

The hydraulic control lines that feed the “extend” and “retract” cavities on the valve actuator assembly can have in-line orifices to provide flow rate control in and out of their respective cavities. This will control how fast the valve will turn on and off. By controlling valve opening and closing speed, water hammer will be kept to a minimum.

With reference now toFIG. 31, the two pair of forward guide wheels594,596and598,600are mounted on a steering frame assembly602that is, in turn, secured to the cart frame604by means of a pivot bearing606. This arrangement allows the steering frame assembly and guide wheels to freely pivot about the pivot bearing, facilitating movement of the cart about sharp curves in the water supply pipe. In addition, each pair of guide wheels594,598and596,600are secured to respective brackets602,604which are, in turn, pivotally secured via pins or bolts606,608to steering frame assembly components610,612. The guide wheel pairs are thus free to pivot about the pins or bolts606,608to accommodate surface irregularities in the supply pipe.

In this embodiment, the docking station614is suspended from the cart frame by four vertically-arranged coil springs (not shown) as described above. Alternatively, the vertically-oriented springs could extend between the docking station614and a pair of laterally-spaced parallel rods (not shown) extending rearwardly from the steering frame assembly component615. The tie rods616,618extend from the docking station bushing mounts620,622to similar mounts624,626on the steering frame assembly component610. An additional horizontally-oriented coil spring627extends from the eyebolt628on the docking station to a similar eyebolt630on the steering frame assembly component610. This same suspension modification appears on the opposite side of the docking station as well. This arrangement results in a spring-biased directional change in the docking station as the cart wheels pivot about the pivot bearing606.

Finally, the invention is not limited to crop irrigation. For example, the traveling sprinkler may also be used to suppress dust in grain storage, road projects and the like. It may also be used for chemical leaching operations, as well as for fire prevention and/or suppression.