Emarevs aphansi, ukunyakaza okuphindaphindayo kwamapistoni enjini kuhamba kancane, futhi amandla okudonsa ukudonsa ingxube kumasilinda ayancipha. Ngalesi sikhathi, i-valve yokungena idinga ukuvulwa isikhathi eside ngangokunokwenzeka, futhi lapho i-piston igijima endaweni ephansi efile futhi ingena ku-stroke yokucindezela, i-valve yokungena ivalwa ngaso leso sikhathi ukuvimbela igesi exubile ukuthi ingaphumi. Nakuba i-camshaft ene-cross-section "ebukhali" ivala i-valve yokudonsa ngokushesha, i-camshaft "ye-rounder" ithatha isikhathi eside ukuvala. Ngakho, nge-rpm ephansi injini idinga i-camshaft "ebukhali".

Emarev aphezulu, ipiston yenjini ibuyela ngokushesha, futhi amandla okudonsa ukudonsa ingxube kusilinda anamandla. Ngisho nalapho i-piston igijima ifike endaweni ephansi efile futhi isizongena ekucindezelekeni, igesi exutshwe izogcwala kusilinda ngalesi sikhathi futhi ayikwazi ukuphazanyiswa. Yebo yilokhu esikufunayo, ngoba uma okuningi kwengxube kungadonselwa ku-cylinder, khona-ke injini ingathola amandla engeziwe. Ngalesi sikhathi, sidinga ukugcina i-valve yokungena ivuliwe lapho i-piston ikhuphuka, futhi ungayivali okwamanje. Ikhamera ye-"rounder" manje isisendaweni yesehlakalo!

Ukuma kwesigaba sekhamera yenjini kuhlobene eduze nesivinini senjini. Ukukubeka kalula, kuma-revs aphansi sidinga i-camshaft "ebukhali"; kuma-revs aphezulu sidinga i- "rounder" camshaft.