Isiphethu segesi esilawulekayo, esikwaziwa nangokuthi isiphethu segesi esikhiyayo, isiphethu segesi esishintshayo, silawula ukushaywa ngokuvula nokuvala i-valve, ukuze i-stroke imiswe kunoma iyiphi indawo, futhi isetshenziselwa kakhulu amatafula, imibhede, amadeski, izihlalo. , izibani zopende kanye namanye ama-engeli, Lapho ukuphakama kudinga ukulungiswa. Ngokwamandla okukhiya, ingahlukaniswa ibe ukukhiya okunwebekayo kanye nokukhiya okuqinile, futhi ukukhiya okuqinile kungahlukaniswa kube ukukhiya ngokucindezela kanye nokukhiya kwe-tension ngokwezikhombisi-ndlela zokukhiya ezihlukene.