Isihlungi sikawoyela yisihlungi esiklanyelwe ukususa ukungcola kuwoyela wenjini, uwoyela wokudlulisa, uwoyela wokugcoba, noma uwoyela osebenza ngamanzi. Uwoyela ohlanzekile kuphela ongaqinisekisa ukuthi ukusebenza kwenjini kuhlala kufana. Ngokufanayo nesihlungi sikaphethiloli, isihlungi sikawoyela singakhuphula ukusebenza kwenjini futhi ngesikhathi esifanayo sinciphise ukusetshenziswa kukaphethiloli.