Abstract: A self-propelled irrigation apparatus has a main pressurized irrigation liquid distribution pipe with its inner end pivotally supported at a central supply pipe and a plurality of radially extending distribution pipe sections which have swinging connections with each other, a mobile support at the outer end of a section, a liquid reaction spray motor for driving each mobile support, a diaphragm-operated "on-off" motor control valve connecting the motor to the distribution pipe, and a pilot valve selectively connecting a pressure control chamber at one side of the control valve diaphragm with either the pressurized irrigation liquid in the pipe or with a pressure relief opening in response to predetermined relative swinging movement of the pipe sections.