Image Number 4 for United States Patent #7980488.
A rotary sprinkler includes: a shaft having a cam, the cam having a plurality of radially outwardly projecting cam lobes; a rotatable water distribution plate adapted to be impinged upon by a stream emitted from a nozzle causing at least the water distribution plate to rotate; a hesitator assembly including a stationary housing having a sealed chamber at least partially filled with a viscous fluid, with at least the cam and the cam lobes located within the chamber; a rotor ring located within the chamber in substantially surrounding relationship to the cam, the rotor ring loosely located within the chamber for rotation and translation, the rotor ring provided with at least two hesitator lobes projecting radially inwardly and movable laterally into and out of a path of rotation of the cam lobes, and a first plurality of radially outwardly projecting teeth selectively engageable with a second greater plurality of teeth provided on an inner wall of the housing; and wherein rotation of water distribution plate is slowed during intervals when one of the cam lobes engages and pushes past a respective one of the hesitator lobes, the cam lobe exerting both rotation and translation forces on the rotor ring, with one of the first plurality of teeth on the rotor engaging one of the second plurality of teeth on the housing wall.
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