1. Thaum qhov tawm ntawm lub raj xa dej ntau dua los yog sib npaug ntawm qhov nyiaj them siab tshaj plaws ntawm qhov sib koom tes, yuav tsum nce cov pob qij txha ntxiv mus rau qhov pauv mus. Roj Hmab Txheej Txheem Loj Tshaj Tawm yog txwv tsis pub kho qhov sib txawv ntawm cov kav dej kom lub pob qij qis nyob rau hauv qhov kev txwv ntawm kev xa tawm thiab kev sib txawv, thiab nws tsis pub tshaj qhov txwv (Telescopic, xaav, deflection, lwm yam.
2. Lub raj dej uas siab tshaj plaws lossis tshem tawm dej tseg, lub raj xa dej yuav tsum tau muab khi rau ntawm lub khawb khawm, lub khib nyiab lossis khawm thaj khau, thiab cov leeg tsis tuaj yeem dais phaus thiab lub zog ntawm cov yeeb nkab, rub tawm cov khoom (lub peev xwm ntawm txoj kabmob yuav tsum muaj ntau dua cov yeeb nkab Axial zog).
