Patent ID: 7624935

Claim:
A sprinkler comprising a stationary nozzle arranged to emit a stream of water directly to atmosphere, a water distribution plate and diffuser plate assembly located downstream of said nozzle, said assembly comprising a shaft mounted in a housing for rotation relative to the housing; a water distribution plate fixed to one end of said shaft, said water distribution plate formed with at least one drive groove adapted to receive the stream emitted to atmosphere by the nozzle and to rotate said water distribution plate and said shaft relative to said housing; a sleeve received over a portion of said shaft, said sleeve mounting a diffuser plate adjacent said water distribution plate, at one end of said sleeve; said shaft and said sleeve supported by plural bearings enabling said sleeve and said diffuser plate to rotate relative to said water distribution plate and said shaft; and wherein at least one of said shaft and said sleeve mounts a rotor located in a first chamber at least partially filled with a viscous fluid to thereby slow rotation of a respective one of said water distribution plate and said diffuser plate.