I-worm shaft iyisici esibalulekile ku-gearbox wezikelemu, okuwuhlobo luka-gearbox oqukethe igiya lezikelemu (elibuye laziwe ngokuthi yisondo lezikelemu) nesikulufu sezikelemu. I-worm shaft iyinduku eyicylindrical okugxunyekwe phezu kwayo isikulufu sesikelemu. Ivamise ukuba nentambo ye-helical (isikulufu sezikelemu) esisikwe endaweni yayo.
Izikelemu zezikelemu ngokuvamile zenziwe ngezinto ezifana nensimbi, insimbi engagqwali, noma ithusi, kuya ngezidingo zohlelo lokusebenza zamandla, ukuqina, nokumelana nokugqokwa. Akhiwe ngendlela efanele ukuqinisekisa ukusebenza kahle kanye nokudluliswa kwamandla ngendlela efanele ku-gearbox.