Isethi yegiya eliyisilinda, ngokuvamile elibizwa ngokuthi “amagiya,” liqukethe amagiya ayisilinda amabili noma ngaphezulu anamazinyo ahlanganayo ukuze adlulise ukunyakaza namandla phakathi kwamashafu ajikelezayo. Lawa magiya ayizinto ezibalulekile ezinhlelweni ezehlukene zemishini, okuhlanganisa ama-gearbox, ama-transmissions ezimoto, imishini yezimboni, nokunye.
Amasethi amagiya angama-cylindrical ayizingxenye ezihlukahlukene futhi ezibalulekile ezinhlobonhlobo zezinhlelo zemishini, ezihlinzeka ngokudluliswa kwamandla okuphumelelayo nokulawula ukunyakaza ezinhlelweni eziningi.