Marginally lubricated

7 BearingAssemblyFluid LubricationThe minimum clearance required for journalbearings operating under hydrodynamicor mixed film conditions for a rangeof shaft rotational speeds and diameters isshown in Fig. 23 It is recommended thatthe bearing performance under minimumclearance conditions be confirmed by testingif possible.0.06Diametral clearance C D [mm]0.050.040.030.0250 45 40 35 30 252018151210Detail design requiredfor rubbing speedsabove 3 m/s0.010100Speed N [rev/min]1000Fig. 23:DX minimum clearances - bush diameters D i 10-50 mmAllowance for Thermal ExpansionFor operation in high temperature environmentsthe clearance should be increasedby the amounts indicated by Fig. 24 tocompensate for the inward thermal expansionof the bearing lining.Increase in minimum diametral clearance [mm]0.050.040.030.020.0100 20 40 60 80 100 120 140 160Environmental temperature T amb [°C]Fig. 24: Recommended increase in diametral clearanceIf the housing is non-ferrous then the bore ference fit to the bush, with a similar reductionin the journal diameter additional toshould be reduced by the amounts given inTable 6, in order to give an increased inter-that indicated by Fig. 24.24