This invention relates to apparatus used for agricultural irrigation, and more specifically, to a linear water feed mechanism that automatically and successively engages and disengages spaced hydrants mounted on a water supply pipe extending alongside or through a field to be irrigated.
Mobile irrigation systems having elevated boom or truss assemblies carrying multiple sprinklers are typically of the center pivot-type or the linear- (or lateral-) move-type. In a center-pivot machine, the elevated truss assembly pivots about an upright standpipe that supplies water to the sprinklers attached to the truss assembly. In a linear-move machine, the elevated truss assembly is carried on mobile, wheeled towers that move the machine linearly along a path that is perpendicular to the elevated boom or truss. Typically, the linear-move machine travels from one end of a field to the other and back again, and sprinkling typically occurs in both directions.
While linear-move machines can irrigate more area than center-pivot machines by reason of the resulting rectangularly-shaped irrigation pattern, the linear-move machines have proven to be problematic in several respects. The most significant problem relates to the manner in which water is supplied to the machine. In some cases, the machine travels alongside an open ditch or canal from which water is continuously removed. Ditch water is typically filled with dirt and/or debris that can clog the sprinkler nozzles. In other cases, one or more hoses are dragged by the machine the length of the field, requiring one or more manual attachment/detachment procedures and attendant issues of hose management. 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 this arrangement is that the hydrant risers have had to be held firmly in concrete or welded onto steel pipe. Alignment mechanisms have been complex and costly to maintain. As a result, reliable docking under various conditions has proven to be an elusive goal, and we are unaware of any automatic docking mechanisms that have achieved a significant degree of commercial success to date.