Nka rotor ya feri ikozwe mubyuma, mubisanzwe iragora kandi iyo ihuye namabuye yumunyu, ingese (okiside) ikunda kwihuta.Ibi bigusigiye na rotor mbi cyane.
Mubisanzwe, ibigo byatangiye kureba uburyo bwo kugabanya ingese za rotor.Inzira imwe kwari ugukoresha Geometeri kugirango wirinde ingese.