Cov ntaub ntawv npog manhole sib txawv zoo li ntau hom "tus neeg saib xyuas":
Cam khwb cia hlau: Ib qho - txheej txheej txheem tuaj yeem nqa tau kwv yees li 5 tons, thaum ob npaug - txheej txheej txheej txheem tuaj yeem ncav cuag 20 tons.
Cov ntaub ntawv sib xyaw: 50% sib dua, thaum tseem tuav lub load -cov kabmob muaj peev xwm ntawm 8-10 tons.
Hlau: Tshwj xeeb los tiv thaiv-slip textured tsim, haum rau thaj chaw uas muaj qhov chaw siab tshaj.
