Wannan tsarin tsarin injin nau'in nadi uku na simmetrical, abin nadi a cikin simmetric na tsakiya guda biyu Matsayin da ke ƙarƙashin abin nadi yana motsawa a tsaye ta cikin tsutsa tsutsa da uwar siliki, Na ƙasa biyu Rollers suna jujjuyawa ta hanyar fitar da kayan rage kayan aiki da ƙananan rollers Gear mesh, don samar da juzu'i don Rubutun nadi. Rashin lahani na inji shine lankwasawa ƙarshen farantin yana buƙatar amfani da wasu na'urori.