▁frequencies ▁of ▁journal ▁bear ings ▁( s ometimes ▁called ▁con ical ▁or ▁rock ing ▁modes ). ▁ ▁It ▁is ▁very ▁difficult ▁to ▁make ▁a ▁mechanical ▁bearing ▁which ▁is ▁atom ically ▁smooth ▁and ▁round ; ▁and ▁mechanical ▁bear ings ▁de form ▁in ▁high - speed ▁operation ▁due ▁to ▁cent rip etal ▁force . ▁ ▁In ▁contrast , ▁fluid ▁bear ings ▁self - correct ▁for ▁minor ▁imper fe ctions ▁and ▁slight ▁de form ations . ▁ ▁Fl uid ▁bear ings ▁are ▁typically ▁qui eter ▁and ▁sm o other ▁( more ▁consistent ▁fr iction ) ▁than ▁rolling - element ▁bear ings . ▁ ▁For ▁example , ▁hard ▁disk ▁drives ▁manufact ured ▁with ▁fluid ▁bear ings ▁have ▁noise ▁ratings ▁for ▁bear ings / mot ors ▁on ▁the ▁order ▁of ▁ 2 0 – 2 4 ▁d B , ▁which ▁is ▁a ▁little ▁more ▁than ▁the ▁background ▁noise ▁of ▁a ▁quiet ▁room . ▁ ▁D riv es ▁based ▁on ▁rolling - element ▁bear ings ▁are ▁typically ▁at ▁least ▁ 4   d B ▁no is ier . ▁ ▁Fl uid ▁bear ings ▁can ▁be ▁made ▁with ▁a ▁lower ▁NR RO ▁( non ▁repeat able ▁run ▁out ) ▁than ▁a ▁ball ▁or ▁rolling ▁element ▁bearing . ▁This ▁can ▁be ▁critical ▁in ▁modern ▁hard ▁disk ▁drive ▁and ▁ult ra ▁precision ▁sp ind les . ▁ ▁T il ting ▁pad ▁bear ings ▁are ▁used ▁as ▁radial ▁bear ings ▁for ▁supporting ▁and ▁loc ating ▁sh aft s ▁in ▁compress ors . ▁ ▁Dis adv antage ▁ ▁Bear ings ▁must ▁maintain ▁pressure ▁to