Abstract: A sluice gate for controlling the discharge of water through a gateway in a flood irrigation system mounted with stub axles defining a hinge axis upstream of the gateway, and comprising a closure element mounted for swing movement about that axis and able to swing from a lower position wherein it blocks the gateway to an upper position wherein it allows water to flow through the gateway, a chamber integral with the closure element, a filler opening through which water from the upstream side of the gateway may enter the chamber, a drain opening that is larger than the filler opening through which water may drain from the chamber to the downstream side of the gateway, and a battery powered solenoid valve, having an actuator responsive to a radio signal from a remote water sensor, controlling the flow of water from the chamber through the drain opening.

Abstract: A variable ratio epicyclic drive transmission comprises a drive shaft (10), a driven shaft (11), a sun wheel (12) fixed on the driven shaft (11), a stationary outer ring member co-axial with said shafts, a planet carrier (15) fixed to the drive shaft (10) and three planet wheels (19) swing mounted on said carrier and in engagement with said ring member. The ring member comprises an almost complete, but broken, substantially circular loop of chain (14) engaged by said planet wheels (19) and supported by a contractile iris structure permitting the diameter of the loop to be varied while maintaining its circularity.