Seti ya giya yozungulira, yomwe nthawi zambiri imatchedwa "magiya," imakhala ndi magiya awiri kapena kupitilira apo okhala ndi mano omwe amalumikizana kuti azitha kusuntha ndi mphamvu pakati pa mitsinje yozungulira. Magiyawa ndi ofunikira pamakina osiyanasiyana, kuphatikiza ma gearbox, ma transmission amagalimoto, makina amafakitale, ndi zina zambiri.
Ma seti a ma cylindrical gear ndi osinthika komanso ofunikira pamakina osiyanasiyana amakina, opereka mphamvu zoyendetsera bwino komanso kuyendetsa bwino ntchito zambiri.