Gear drive sprinkler

This invention relates generally to irrigation sprinklers of the type having a rotary driven spray head mounted at the upper end of a pop-up riser. More particularly, this invention relates to an improved irrigation sprinkler having a gear drive transmission for rotatably driving the pop-up spray head, and incorporating an improved reverse mechanism for quickly and easily setting the sprinkler for part-circle spray head rotation between a pair of individually adjustable end trip stops, or for continuous full circle rotation. The reverse mechanism further provides improved resistance to vandal-caused damage such as attempted forced rotation of the spray head beyond one of the end trip stops. An improved gear drive sprinkler has a pop-up spray head adapted for adjustable part-circle or full circle operation to deliver irrigation water over a selected terrain area. The sprinkler includes a pop-up riser; a gear drive transmission mounted within the riser includes a water-driven turbine for rotatably driving a speed reduction gear train, which in turn rotatably drives the spray head. A reverse assembly includes an upper trip unit defining an individually adjustable pair of end trip stops, and a lower shift mechanism including a shiftable director plate having first and second sets of angularly oriented jet nozzles for respective alignment with turbine jet ports for respectively driving the water-driven turbine and the gear train in a forward-drive or a reverse-drive direction. The upper trip is coupled to the director plate by an elongated trip rod which shifts the director plate between forward-drive and reverse drive positions. An adjustment cam can be manipulated to disable at least one of the end trip stops to permit spray head rotation through continuous full circle revolutions.