Piv cov hniav txiav ua los ntawm pob zeb thiab asphalt los ntawm kev sib txuas, qhov loj ntawm cov hniav, RPM, qhov tob ntawm kev txiav thiab kev siv ntub lossis qhuav, nrog rau cov ntaub ntawv tau txheeb xyuas thiab cov kauj ruam xaiv ua tau.
Ib tus neeg muab khoom siv hauv kev tsim kho vaj tse rau 30 xyoo.
Lus
