I-unit yokubamba-yokubheka-yokubuyisa (ekubizwa ngokuthi "umshini wokubuyisa okubamba") kuyindlela entsha yokubuyisa okwenziwe ukuthatha izidingo eziningi zokubuyisa kwesitripi, okuyinto ibambisana nemiphumela yomshini wokubuyisa okuyisikhombisa kanye nomshini wokubamba-yokubuyisa. Izimo zakhe zokusebenza kuyinto ukuthi isitripi isenza ukunyakaza okuphazamiseka phakathi kwesikhombisa sokubamba nokubheka kwesikhombisa esinjalo esinjalo. Kuyakwazi ukuthuthukisa izifo zezigaba ezintathu zesitripi, njengokubamba kwesikhombisa, isitsha sokukhanya kwesikhombisa nokubamba, futhi kuyadinga ukwethula ubunzima bokuyisikhombisa.