Kev lag luam thawj cov khoom siv hydraulic thiab cov cuab yeej siv hydraulic siab heev, kev tsim cov khoom siv pob khawm sib xyaw, tag nrho rau kev nrhiav qhov zoo tshaj plaws. Ib-nres los ua ke Rhiav, ua tau zoo heev los ua ke ntawm zoo meej hinges. Tag nrho cov kev ntim khoom zaum kawg yuav tsum dhau kev siv tshuab, kev tshuaj xyuas phau ntawv ntawm cov qauv tsim nyog.