Magiya ndi chimodzi mwazinthu zofunika kwambiri pa gearbox.Magiya ndi zida zamakina zomwe zimathandiza kusinthasintha liwiro ndi torque ya masamba opota mu tiller.Mu bokosi la gear, magiya amagwirira ntchito limodzi kuti atumize mphamvu kuchokera ku shaft yolowera kupita ku shaft yotulutsa, kuwonjezereka kapena kutsika liwiro laulimi wabwino.