Mbali yapansi ya cylinder block yomwe crankshaft imayikidwa imatchedwa crankcase. Chikwamacho chimagawidwa kukhala chapamwamba chapamwamba ndi chocheperako. Kumtunda kwa crankcase ndi cylinder block zimaponyedwa ngati thupi limodzi. M'munsi crankcase ntchito kusunga mafuta mafuta ndi kutseka chapamwamba crankcase, choncho amatchedwanso poto mafuta. Chiwaya chamafuta chimakhala ndi mphamvu zochepa kwambiri ndipo nthawi zambiri chimasindikizidwa kuchokera kuzitsulo zopyapyala. Maonekedwe ake amadalira kamangidwe kake ka injini ndi mphamvu ya mafuta. Chophimba chokhazikika chamafuta chimayikidwa mu poto yamafuta kuti mupewe kusinthasintha kwakukulu kwamafuta akamayenda. Pansi pa poto yamafuta mumakhalanso ndi pulagi yothira mafuta, nthawi zambiri maginito okhazikika amayikidwa pa pulagi yamafuta kuti amwe tchipisi tachitsulo mumafuta opaka mafuta ndikuchepetsa kuvala kwa injini. Gasket imayikidwa pakati pa malo olumikizirana pamwamba ndi pansi kuti mafuta asatayike.

Crankcase ndiye gawo lofunikira kwambiri la injini. Imanyamula mphamvu yochokera ku ndodo yolumikizira ndikuisintha kukhala torque kuti itulutse mu crankshaft ndikuyendetsa zida zina pa injini kuti zigwire ntchito. Crankshaft imayendetsedwa ndi kuphatikizika kwa mphamvu ya centrifugal ya misa yozungulira, mphamvu yamagetsi yamagetsi yanthawi ndi nthawi komanso mphamvu yobwereranso, kotero kuti mayendedwe opindika amatha kupindika ndi kugwedezeka. Chifukwa chake, crankshaft imafunika kuti ikhale ndi mphamvu zokwanira komanso zolimba, ndipo pamwamba pa magaziniyo sayenera kuvala, kugwira ntchito mofanana, komanso kukhala bwino.

Crankcase idzawonongeka pakati pa mapeto aakulu a ndodo yolumikizira ndi magazini chifukwa cha mafuta odetsedwa ndi mphamvu yosagwirizana ya magazini. Ngati mafuta ali ndi zonyansa zazikulu komanso zolimba, palinso chiopsezo chokanda pamwamba pa magazini. Ngati kuvala kuli koopsa, kungathe kukhudza kutalika kwa pistoni mmwamba ndi pansi, kuchepetsa kuyaka bwino, ndipo mwachibadwa kumachepetsa mphamvu. Kuphatikiza apo, crankshaft imathanso kuyambitsa kuwotcha pamapepala chifukwa chamafuta osakwanira kapena mafuta ochepa kwambiri, omwe amatha kukhudza kubweza kwa pisitoni nthawi zambiri. Choncho, mafuta odzola a viscosity yoyenera ayenera kugwiritsidwa ntchito ndipo ukhondo wa mafutawo uyenera kutsimikiziridwa.