I use to erect/repair/move center pivot irrigation systems back in Nebraska during the summer while in high school. The standard system was 1/4 long and could go longer or shorter. Longest one I worked on was 1/2 mile long.
One option on these systems was that they can be moved. We installed a lot of these in fields that were 1/2 mile wide x 1 mile long with 2 wells, each centered on an end. The drive shafts at each tower could be disconnected and the wheels rotated parallel with the system. Farmer would rotate wheels, disconnect the center pivot from power and well, hook up a tractor much larger than I currently own /forums/images/graemlins/wink.gif, and the 'tow' the system to the other well head in the field.
It was a fun job in late July - 7ft tall corn, 105 degrees, 75% humidity. Let's just say I was in much better shape back then -- now I just keep telling my wife, "Round is a shape. "
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