Qhov tseeb, ib nrab ntawm cov yeeb nkab yog tib yam li cov yeeb nkab semi-rov qab siab, tab sis cov pa tawm txoj kab uas hla yog loj dua li ib nrab rov qab siab yeeb nkab: qhov pib torque qis dua ib nrab rov qab siab, tab sis qhov nruab nrab-rau-siab. ceev torque loj dua. Txuas qhov sib txawv ntawm qhov tso pa tawm mus rau lub tsheb tso lub qhov, Ntxiv ib sab raj.
Thaum ib lub yeeb nkab qhib tag, lwm cov yeeb nkab yog kaw tag nrho. Piv nrog rau ib leeg-valve variable tso tawm, nws muaj lub suab zoo dua. Thaum qhov qhib yog 1/3, lub suab nyhuv yog ntau dua ib leeg-valve Qi yog qhov zoo ib yam. Lub suab tuaj yeem hloov mus rau thiab tawm, thiab cov pa tawm tuaj yeem hloov qhov loj ntawm lub suab. Cov pa tawm yog tswj los ntawm lub valve kom ua tiav lub suab zoo tshaj plaws thiab kev ua haujlwm zoo.