Patent ID: 7621464

Claim:
A rotary drive motor for a sprinkler comprising: a turbine being capable of rotating at a substantially constant rate of rotation in response to water flow; and a transmission disposed in the housing and in communication with the turbine to convert the substantially constant rate rotation of the turbine as an input to a generally variable rotation rate of rotation output, the transmission having a first gear module comprising: a substantially constant drive gear rotated in response to the turbine; at least one planetary gear in engagement with and rotated by the substantially constant drive gear; a rotatable carrier plate having a variable rate of rotation about a central axis thereof and configured to be rotated about the central axis by the rotation of the at least one planetary gear; and the at least one planetary gear having a connection to the rotatable carrier plate that is arranged and configured to slide in a radial direction relative to the central axis of rotation such that when the connection is at a position closest to the central axis of rotation the rotatable carrier plate provides a maximum rotational speed output and when the connection is at a position furthest from the central axis of rotation the rotatable carrier plate provides a minimum rotational speed output.