Njira yolumikizira ndodo ya crankili ndi magawo atatu: gulu la thupi, gulu la ndodo yolumikizira pisitoni ndi gulu la crankshaft flywheel. Makina olumikizira ndodo ndiye gawo lalikulu losuntha la injini kuti azindikire kuzungulira kwa ntchito ndikumaliza kutembenuza mphamvu.

Mu sitiroko mphamvu, izo otembenuka matenthedwe mphamvu pisitoni kwaiye ndi kuyaka kwa mafuta mu reciprocating zoyenda ndi crankshaft kasinthasintha mu makina mphamvu linanena bungwe mphamvu; mu zikwapu zina, zimatengera kusinthasintha kozungulira kwa crank ndi flywheel ndikuyendetsa pisitoni mmwamba ndi pansi kudzera pa ndodo yolumikizira kuti Pangani zinthu za ntchito yotsatira.

Ntchito yamakina olumikizira ndodo ndikupereka malo oyatsira, kusinthira kupanikizika kwa gasi pamwamba pa pisitoni mafutawo atawotchedwa mu torque ya crankshaft rotation, ndi mphamvu yotulutsa mosalekeza.

(1) Sinthani mphamvu ya gasi kukhala torque ya crankshaft;

(2) Sinthani mayendedwe obwerezabwereza a pisitoni mukuyenda mozungulira kwa crankshaft;

(3) Sinthani mphamvu ya kuyaka pamwamba pa pisitoni kukhala torque ya crankshaft kuti itulutse mphamvu zamakina kumakina ogwira ntchito.