A ƙananan revs, motsi mai juyawa na pistons na injin yana da hankali, kuma ƙarfin tsotsa don zana cakuda a cikin silinda yana raguwa. A wannan lokacin, ana buƙatar buɗaɗɗen bawul ɗin ci har tsawon lokacin da zai yiwu, kuma lokacin da piston ya gudu zuwa tsakiyar matattu kuma ya shiga cikin bugun jini, bawul ɗin shan yana rufe nan take don hana haɗaɗɗun iskar gas ɗin fita. Yayin da camshaft tare da sashin giciye na "kaifi" yana rufe bawul ɗin ci da sauri, camshaft na "rounder" yana ɗaukar tsawon lokaci don rufewa. Don haka, a ƙananan rpm injin yana buƙatar "kaifi" camshaft.

A babban revs, piston na injin yana yin sauri da sauri, kuma ƙarfin tsotsa don zana cakuda a cikin Silinda yana da ƙarfi. Ko da fistan ya gudu zuwa ga matattu cibiyar kuma yana gab da shiga cikin bugun jini, gauraye gas zai shiga cikin silinda a wannan lokacin kuma ba za a iya katsewa ba. Tabbas wannan shine abin da muke so, domin idan yawancin cakuda za'a iya jawowa cikin silinda, to injin zai iya samun ƙarin iko. A wannan lokacin, muna buƙatar ci gaba da buɗe bawul ɗin ci lokacin da piston ya tashi, kuma kada a rufe shi na ɗan lokaci. "Rounder" camshaft yanzu yana kan wurin!

Siffar sashin cam ɗin injin yana da alaƙa sosai da saurin injin. Don sanya shi a sauƙaƙe, a ƙananan revs muna buƙatar "kaifi" camshaft; a high revs muna bukatar "rounder" camshaft.