The crank haɗa sanda injiya ƙunshi sassa uku: ƙungiyar jiki, ƙungiyar sanda mai haɗa piston da ƙungiyar ƙwallon ƙafar crankshaft. The crank haɗa sanda inji shi ne babban motsi na inji don gane da aiki sake zagayowar da kuma kammala makamashi tuba.

A cikin bugun wutar lantarki, yana jujjuya fistan makamashi na thermal da aka samar ta hanyar konewar mai zuwa motsi mai jujjuyawa da jujjuyawar crankshaft zuwa makamashin injina don fitar da wutar lantarki; a cikin wasu bugun jini, ya dogara da jujjuyawar inertia na crank da ƙugiya kuma yana motsa piston sama da ƙasa ta hanyar haɗin haɗin gwiwa don Ƙirƙirar yanayi don aiki na gaba.

Ayyukan ma'auni na haɗin haɗin crank shine don samar da wuri don konewa, canza ƙarfin fadada gas a saman piston bayan an ƙone man fetur a cikin juzu'i na juyawa na crankshaft, da kuma ci gaba da fitar da wutar lantarki.

(1) Canja matsa lamba na iskar gas a cikin juzu'i na crankshaft;

(2) Canja motsi mai maimaitawa na piston zuwa motsi mai juyawa na crankshaft;

(3) Canja ƙarfin konewa a saman fistan a cikin juzu'i na crankshaft don fitar da makamashin injiniya zuwa injin aiki.