Agricultural sprinkler systems are quite popular and often very necessary in agricultural operations in many areas of the United States as well as in certain foreign countries. A very popular type of irrigation system which is commonly used is a center pivot system in which a long horizontally disposed sprinkler boom or pipe extends outwardly from a well. A large motor and pump supply water to one end of the pipe and force the water through it. At various locations along the pipe there are exit ports to allow a certain amount of the water to exit.
A sprinkler head is operably connected to each exit port to spray the water or distribute it as it exits the horizontal pipe. Typically the exit ports are on the top side of the horizontal pipe so as to alleviate problems with sediment (e.g., sand, mineral deposits, scale, etc.) plugging the exit ports.
There are a number of different types of sprinkler heads which are commercially available for use on such horizontal sprinkler systems. Different types of sprinkler heads produce different types of spray patterns for the water as it exits the supply pipe.
One type of sprinkler head produces a particularly desirable type of spray pattern in which the water simulates rainfall with large drops. For example, this type of sprinkler head is commercially available from Senninger Irrigation Co. and is referred to as a Wobbler. It includes a head portion which rotates and wobbles at the same time when used on a sprinkler irrigation system. This type of head produces a very uniform water pattern which virtually eliminates compaction of soil and run-off of excess water which often results when using other types of sprinklers which allow numerous droplets of water to strike the ground at the same spot in rapid succession.
The main disadvantage associated with the use of these wobbler heads is that they cause severe vibration of the sprinkler apparatus. On certain brands of center pivot sprinklers this vibration can become harmonious and travel back and forth throughout the apparatus. Within several hours a truss component can fatigue and break, allowing a span of lateral pipe to fall and destroy portions of the apparatus and certain of the crops below it.
Some agricultural irrigation systems have very long spans of horizontal sprinkler pipe and may utilize more than 100 sprinkler heads. Thus, vibration caused by the sprinkler heads is especially dangerous when it becomes harmonic. Even if it does not become harmonic, long-term vibration can cause metal fatigue and failure of various components.
There has not heretofore been provided a safe, effective, easy-to-use, and reliable means for avoiding the vibration caused by sprinkler heads on large agricultural sprinkler systems.
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