▁for ▁some ▁such ▁bear ings ▁to ▁have ▁near - zero ▁wear ▁if ▁operated ▁correctly . ▁ ▁They ▁can ▁be ▁broad ly ▁class ified ▁into ▁two ▁types : ▁fluid ▁dynamic ▁bear ings ▁( also ▁known ▁as ▁hyd rod ynamic ▁bear ings ) ▁and ▁hydro static ▁bear ings . ▁H ydro static ▁bear ings ▁are ▁extern ally ▁press ur ized ▁fluid ▁bear ings , ▁where ▁the ▁fluid ▁is ▁usually ▁oil , ▁water ▁or ▁air , ▁and ▁the ▁press ur ization ▁is ▁done ▁by ▁a ▁p ump . ▁H yd rod ynamic ▁bear ings ▁rely ▁on ▁the ▁high ▁speed ▁of ▁the ▁journal ▁( the ▁part ▁of ▁the ▁sh aft ▁rest ing ▁on ▁the ▁fluid ) ▁to ▁press ur ize ▁the ▁fluid ▁in ▁a ▁w edge ▁between ▁the ▁faces . ▁ ▁Fl uid ▁bear ings ▁are ▁frequently ▁used ▁in ▁high ▁load , ▁high ▁speed ▁or ▁high ▁precision ▁applications ▁where ▁ordinary ▁ball ▁bear ings ▁would ▁have ▁short ▁life ▁or ▁cause ▁high ▁noise ▁and ▁v ibration . ▁ ▁They ▁are ▁also ▁used ▁increasing ly ▁to ▁reduce ▁cost . ▁ ▁For ▁example , ▁hard ▁disk ▁drive ▁motor ▁fluid ▁bear ings ▁are ▁both ▁qui eter ▁and ▁che aper ▁than ▁the ▁ball ▁bear ings ▁they ▁replace . ▁App lications ▁are ▁very ▁vers atile ▁and ▁may ▁even ▁be ▁used ▁in ▁complex ▁geomet ries ▁such ▁as ▁leads cre ws . ▁ ▁The ▁fluid ▁bearing ▁may ▁have ▁been ▁invent ed ▁by ▁French ▁civil ▁engineer ▁L . ▁D . ▁Gir ard , ▁who ▁in ▁ 1 8 5 2 ▁proposed ▁a ▁system ▁of ▁railway ▁prop ulsion