I nā haʻahaʻa haʻahaʻa, ʻoi aku ka lohi o ka neʻe ʻana o nā piston engine, a ua hoʻemi ʻia ka ikaika o ka huki ʻana i ka hui ʻana i loko o nā cylinders. I kēia manawa, pono e wehe ʻia ka valve intake no ka lōʻihi o ka hiki, a i ka wā e holo ai ka piston i ke kikowaena make lalo a komo i ka hahau hoʻoemi, ua pani koke ʻia ka valve intake e pale ai i ka kahe ʻana o ke kinoea hui. ʻOiai ʻo kahi pahu pahu me kahi ʻāpana "ʻoi aku" e pani koke i ka pahu komo, ʻoi aku ka lōʻihi o ka pani ʻana o ka pahu pahu "poʻe". No laila, ma ka rpm haʻahaʻa, pono ka ʻenekini i kahi camshaft "ʻoi".

I nā kiʻekiʻe kiʻekiʻe, ʻoi aku ka wikiwiki o ka piston o ka ʻenekini, a ʻoi aku ka ikaika o ka ikaika o ka huki ʻana i ka hui ʻana i loko o ka cylinder. ʻOiai ke holo ka piston i ke kikowaena make lalo a kokoke e komo i ka hahau hoʻoemi, e hoʻoulu ʻia ke kinoea hui ʻia i loko o ka cylinder i kēia manawa a ʻaʻole hiki ke hoʻopau ʻia. ʻOiaʻiʻo kēia ka mea a mākou e makemake ai, no ka mea, inā hiki ke huki ʻia ka hui ʻana i loko o ka cylinder, a laila hiki ke loaʻa i ka ʻenekini ka mana. I kēia manawa, pono mākou e wehe i ka valve intake i ka wā e piʻi ai ka piston, a mai pani i ka manawa. Aia ka "rounder" camshaft i kēia manawa!

ʻO ke ʻano o ka ʻāpana cam engine e pili pono ana i ka wikiwiki o ka ʻenekini. No ka maʻalahi, ma nā haʻahaʻa haʻahaʻa pono mākou i kahi camshaft "ʻoi"; i nā kiʻekiʻe kiʻekiʻe pono mākou i kahi camshaft "rounder".