The two circular sections on both sides of the rotor represent the “volute”, that is the spiral casing where the fluid is forced before it reaches, through the nozzles, the rotor blades. The particular divergent shape of the rotor in its outlet part is called “hydrocone”; its aim is to use the remaining energy and give further acceleration to the fluid by making the most of the drop in pressure.

The light green sections show the regulating devices of the nozzles that adjust the machine power.