Rotary sprinkler

A rotary sprinkler includes a body member (2) having an inlet (3) connectable to a source of pressurized liquid, and a chamber (10) communicating with the inlet (3); a distributor head (4) rotatably mounted on the body member (2); and a rotor (12) within the chamber (10) and having an outer rounded surface (12a) of a slightly smaller diameter than that of the adjacent inner surface of the chamber wall (11) to define a small clearance (14) between the rotor (12) and the chamber wall (11). The rotor (12) is rotatable with respect to the body member (2) by the passage of liquid through the chamber (10) via the inlet (3) and clearance (14), and is laterally movable to the inner surface of the chamber (10) and to roll around the inner surface. The rotor (12) is coupled to the distributor head (4) to rotate the distributor head (4), and includes a passageway (18) for passing liquid from the chamber (10) to the distributor head (4) to distribute liquid around the sprinkler during the rotation of the distributor head (4) by the rotor (12).