INTRODUCTION

This invention relates to the irrigation of race tracks.

BACKGROUND OF THE INVENTION

Grass horse racing tracks require regular watering. Conventional means of watering race tracks comprise fixed sprinklers positioned outside the tracks. Pop-up sprinklers within the race track are viewed as potentially dangerous to galloping horses. The outside sprinklers spray water over a large area but prove to be inefficient, especially in high winds. A known means of applying water to a grass track from a sprinkler positioned closer to the grass surface is to use a boom that is driven around the track. The problem with the boom arrangement is that the wheels of the boom over time compact the grass and growing medium. Similarly, booms tend to drag hoses over the track which can damage the grass and again compact the track. Compaction of a race track is a particular problem in horse racing because it is highly desirable that the going of the track is uniform and racing officials particularly wish to avoid strips of a track that are compacted to define a different going than the remainder of the track. The inefficiency of the existing sprinkling and irrigating equipment means that watering of grass race tracks has become a labour intensive and expensive exercise that uses an excessive amount of water, which in a dry continent such as Australia raises serious ecological concerns. Race tracks are conventionally 30m wide but there have been proposals to introduce 45m wide tracks. Tracks of this width cause further problems with existing sprinkler systems. It is these that have brought about the present invention.

SUMb-ARY OF THE INVENTION

According to one aspect of the present invention there is provided: an irrigator for race tracks comprising an elongate boom supported at either end by wheeled supports so that the boom extends over both sides of the track, vertically adjustable sprinklers spaced across the boom, means to drive at least one wheeled support, means to steer the irrigator, and guide means to guide the path of one set of wheels to dictate the path of the irrigator. Preferably, the sprinklers are fed from a water feed line that is either dipped into an open water channel surrounding the track or connected to a hose arranged to be attached to spaced hydrants positioned outside the track. In a preferred embodiment, the open water channel serves both as the guide means and a drainage channel for the race track. Preferably, the wheeled supports are driven and a speed controller varies the speed of the wheeled supports to cause a turning moment on demand. The guide means preferably controls the speed controller. In accordance with a further aspect of the present invention there is provided a method of irrigating a race track comprising: positioning an elongated boom sprinkler supported at either end by wheeled supports across the track with the wheeled supports outside either side of the track, attaching the boom sprinkler to a source of water, and guiding the boom sprinkler to circumnavigate the track while spraying water onto the track from a plurality of spaced sprinkler heads depending from the boom. DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example only with reference to accompanied drawings in which: Figure 1 is a plan view of a typical race track, Figures 2 and 3 are cross sectional views of drainage channels for use with the irrigator, Figure 4 is a plan view of part of the channel showing the water inlet, Figure 5 is a side elevational view of an irrigator spanning the racetrack, Figure 6 is an end elevation of one form of wheeled support for the irrigator, Figure 7 is a plan view of the wheeled support, Figure 8 is a cross sectional view taken along the lines AA of Figure 7, Figure 9 is a side elevational view of the wheeled support, Figure 10 is a partial plan view illustrating the irrigator when used with a hose, and Figure 11 is a end elevational view of a wheeled support of the irrigator when used with a hose.

DESCRIPTION OF THE EMBODIMENTS

Figures 1 to 4 of the accompanying drawings illustrate a horse racing track such as the track T of Figure 1. The track T has a straight S that joins a back straight BS via a first bend Bl. The back straight BS then joins the straight S through a second bend B2. In this racetrack inner and outer rails (not shown) define the width of the track. The inner rail is often adjustable to spread wear. The inside or true position is usually kept for major meetings. On the interior of the inner side of the inner rail there is an open drain C that circumnavigates the track. This drain also extends along the first portion of the straight. A number of spaced gates G are positioned across the drain to provide access to the center of the track for vehicles, pedestrians, and other traffic. The track is any track that requires regular watering - i.e. all surfaces including grass, synthetic surfaces or dirt. The track also includes a drainage system, part of which is shown in Figures 2, 3 and 4. Figure 2 illustrates a drainage system which is independent of the channel C whilst Figure 3 illustrates a system where the drainage is integrated with the irrigation. In either case the channel C is positioned with its top level within which the drain extends to the top of a 250 to 300 mm root zone RZ. Beneath the root zone is about 100mm of gravel GR and then a 150mm drainage pipe D is positioned under the gravel. In Figure 2 the drainage pipe D communicates with the normal perimeter pipe drain PD. In Figure 3 the drainage pipe D feeds into the base of the channel C via a back flow prevention valve V. When the drain is being used as an irrigation drain the back flow device will prevent the irrigation from going back under the track. In each case the channel C is 650mm deep and usually 300mm wide. As shown in Figure 4 the water inlet WI feeds an enlarged top section via an inflow box 70 with a cistern style float valve 71. The base of the channel C has a 200mm drainage pipe DP controlled by a solenoid valve X. In the example of Figure 3 the water recycles to the channel C whilst a separate water supply is used in the example of Figure 2. The track T is shaped so that run off water tends to run into the channel C for collection. In this manner the racetrack is able to cater for heavy rain and avoid cancellation of meetings due to a water logged track by having a well drained profile in conjunction with a drain to a storage dam. Figures 5 to 10 illustrate embodiment of an irrigator 5 that is used to water the racetrack described above. The irrigator comprises, as shown in Figure 5, an elongate boom 10 that is approximately 30 to 50 metres in length. The boom 10 is supported at each end by wheeled towers 11 and 12, each tower is supported by wheels 13 and 14 that are positioned outside the running rails of the track with the inner wheel positioned adjacent the drainage channel C. The boom 10 is a bowstring truss comprising an arcuate pipe modular assembly 15 with a triangulated truss2 understructure comprising angle iron struts 16 and braces 18 with steel tensioning rods 19 underneath and downwardly extending sprinkler arms 17. The sprinkler arms support a plurality of sprinkler heads 20 positioned approximately 1600mm apart and vertically adjustable to be about 1200mm off the ground. Each spray head 20 includes a 360-degree head that spreads water droplets to a radius of between 7 and 10 metres. Adjacent the wheeled towers 11 and 12 the spray heads 20 are reduced to 180 degree spray heads to reduce the likelihood of water spraying onto the driving mechanism which is waterproof. The bowstring truss is a known irrigation mechanism that can span considerable lengths and yet is sufficiently light for transportability. As shown in Figures 6 to 8 each end of the boom 10 is supported by a wheeled tower 11, 12 that comprises a triangular metal frame 30, 31 that supports the trussed beam 15, 16 of the boom 10. Each frame 30 or 31 comprises an elongate beam 32 that is connected in a triangular array by two vertically extending channel sections 33, 34 to the ends of the arcuate beam 15, 16 that spans the boom 10. Opposite ends of the beam 32 support stub axles 35, 36 that each support a wheel 37. Each wheel 37 supports a large inflated tire and the wheels are mounted in line but fixed in a straight ahead direction. The wheels may be hinged to rotate their axes through 90° for towing purposes. As shown in Figure 9, the centre of the elongate beam 32 supports an electric motor 40 and main gearbox 41. The output of the main gearbox 41 is coupled through a helical spur gear 42 that drives two opposed drive shafts 43, 44 that are each interconnected through rubber block couplers 45, 46 to half shafts 47, 48 that drive each wheel 37. The half shafts 47, 48 are coupled to a secondary gearbox 49 through a worm gear (not shown) to impart rotation to each wheel 37. The drive to either wheel can be disconnected as necessary to allow for towing. Since both sides of the boom 10 are powered and the wheel sets of both sides point straight ahead a turning motion of the boom is caused by varying the speeds on the inner or outer sets of wheels to cause a slight dragging movement that causes the irrigator to steer due to the difference in the relative speeds of the wheels. The wheels of the inner drive set may also be slightly indexed via linear actuators controlled from the PLC. This reduces the skidding action associated with very tight bends in the racetrack. The variation in the relative speeds is controlled by a control arm 50 that extends laterally of the inner drive set to engage the wall of the drainage channel C as shown in Figure 7. The arm has a wheel 51 at one end and is pivotally connected to a springloaded switch 52 (Figure 8) that has left and right limit switches 53, 54. The inner end of the arm 51 is coupled to a cylindrical guide plate 55 that is mounted to rotate about a vertical axis to engage the switches 53, 54. When travelling in a straight line neither of the steering limit switches 53, 54 are activated. As the irrigator approaches a bend, the control arm 50 is pulled left or right causing the guide plate 55 to contact one of the steering switches 53, 54. The switches 53, 54 are linked to a PLC in the main control panel and the PLC then controls the appropriate variable speed to vary the speed of one wheel set in relation to the other. The variation in the speed of the wheels causes the irrigator to steer in the direction required until the steering limits are reset to the neutral position. The irrigator also includes an oversteer limit switch 56 that can be activated should the arm 50 be dragged clear of the channel C or should the irrigator steer so offline as to be liable to collide with the rails of the track. The oversteer limit switch 56 would shut down the irrigator and it would be necessary to then reset the irrigator before it could be used again. In a preferred embodiment shown in Figures 1 to 9 the watering jets are fed by a pump 60 that is mounted on the inner wheel set. The pump 60 in turn draws water from the channel C which has been prefilled with water to a predetermined height. In this manner the irrigator can be fed with water from the channel which also doubles as the mechanism for controlling the direction of the movement of the irrigator 5. There is no need for hoses and there is a degree of recycling of the water in the drainage channel. The pump 60 is electrically driven to pump water to an overhead pipe 61 that is supported by the boom 10 and provides water at the sprinkler heads 20 at low pressure. A diesel motor 65 is carried by the inner wheel set that is in turn coupled to a small generator 66 that provides the electrical power that drives the both the electric motors 41 that drive each wheel set and the water pump 60. The steering arm 50 that locates in the water channel C is removable and can be positioned to the opposite end of the wheel set as shown in Figure 4 if the irrigator 5 is to move in the opposite direction. The irrigator 5 has an in built computer that is coupled to a panel to control a variety of parameters such the rate of water delivery, height of spray heads, speed of movement of the irrigator and steering controls. It is also very important that the irrigator waters the track evenly and thus adjustments have to be made to rate of delivery of water by the spray heads 20 as the irrigator moves around corners. The spray heads 20 are split into banks one of which operates when the irrigator is travelling in a straight line and the other of which operates when the irrigator is circumnavigating a corner to ensure even application on the bends. Spray packages are specifically designed for each radius turn. In this embodiment the irrigator is designed to be fully automatic so that by appropriate programming of the control panel the irrigator 5 will travel around and around the track until the desired degree of watering has been completed. The more sophisticated control and diagnostics of the irrigator include control of all the machine functions through use of a touch screen that includes a digital setting of water application rates. The apparatus includes a complete engine protection system and systems that monitor and shut down in the event of an end of run, low water pressure, oversteer error, electric motor overload, structural overstress, emergency stop, low engine oil pressure, engine overheat. It is further understood that the system could include a remote shut down that can be activated by mobile phone or SMS. Furthermore report of machine status and faults can be transmitted via mobile phone or SMS. Further sophistications include an integrated hose wind up system for the embodiment shown in Figures 10 and 11 that incorporates a hose. It is also understood that the system can include a dual limit switch protection at the end of the run with each switch operating entirely on separate control circuits for added safety. Emergency stop buttons could be located on the end of each unit and an emergency stop/safety landyard could be positioned around the hose reel mechanism. Further safety features include the provision of an uninterrupted power supply to provide back up control in case of engine failure and to allow SMS reporting. The apparatus would also include manual override of drive controls via hand held pendant. The software and hardware are designed as off the shelf components that facilitate simple updates. The irrigator will then automatically switch off. As shown in Figure 6, a four metre lane is required between the true position running rail IR and the open channel C. A two metre lane is required outside of the outside rail OR. For tracks up to 35 metres wide the wheels run outside of both the inside and outside running rails . A four metre area is required on the outside of the inside rail and a two metre area is required on the outside of the outside rail. The irrigator 5 can be constructed to service tracks up to and even exceeding 50m in width. However the outside tower wheel will travel on the turf, on the outside of tracks that are wider than 35m. As it is not pulling a hose it will exert minimal ground pressure on the turf, certainly less than normal tractors used for mowing etc. If racing horses were ever out that wide, the travel position for the wheel could be varied if it was necessary to resolve any perception of potential track bias. However the load will be only 5psi(33.5kPa) and can be reduced to 1.2psi(6.7kPa) . It is suggested that this negligible load, which is less than foot traffic is better than having a much larger track span model. Some tracks eg Flemington Racecourse in Melbourne, Australia have a major chute joining the course proper and this could result in a double watering. If necessary this can be addressed by the manual control of sets of sprinklers to control output. In the embodiment shown in Figures 10 and 11 water is not drawn from an irrigation channel C on the inside of the track but the irrigator 5 and boom 10 are fed from a hose H that connects the inside wheel set to one of a plurality space hydrants HY that are spaced around the track T approximately 380 metres apart as shown in Figure 8. The hydrant which is positioned on the extreme inside of the roadway that joins the track to the track center. The irrigator has the same powered steering mechanism as in the first embodiment except that a control arm 20 is now located against the inside of the inner running rail IR. The control arm 80 sends a signal to the wheel set to start the irrigator around the track. When the irrigator has transcribed the desired path it then stops so that an operator can disconnect the hose from one hydrant and connect it to the second hydrant. Figure 10 shows the start and finish positions for this transfer. This is a more labour intensive form of the irrigator but is required when the terrain of the racetrack makes it impossible to install an open drainage channel that can carry the supply of water. The irrigator has been designed to be as efficient as possible by water conservation and reduction in labour. In the fully automated model the irrigator can be used at night without supervision. The positioning of the sprinkler heads and the design of the low pressure system is such as to provide water droplets of the required size to duplicate rain and reduce the likelihood of the water being blown away. The fact that the open guidance channel serves as a drainage channel also ensures a degree of recycling of the water to further reduce and optimize water consumption. It is also possible to use recycled waste water as the irrigation medium. Since the device is designed to run entirely externally of the track there is no compaction of the track surface caused by tyred wheels or hoses being dragged along the track surface. The computer control watering also ensures an even distribution of water which ensures that the track has consistent going from the inside rail to outside rail for the whole of the circuit of the track. The method further includes the step of using the water channel to guide the boom as it circumnavigates the track. - li ¬

lt is understood that other forms of navigating the irrigator are also envisaged such as the use of global positioning systems or underground wires positioned to provide a current that is picked up by sensors on the wheel sets to steer and control the passage of the irrigator. Although in the preferred embodiment the wheels of each wheeled tower are fixed in a single direction it is understood that they could be mounted with a capacity to turn about a vertical axis to improve the steerability and maneuverability of the irrigator. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.