In case of a sliding contact bearing, the bearing characteristic number is given by

(where, Z = Viscosity, N = Speed, P = Pressure):

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APPSC Lecturer (Polytechnic Colleges) Held on March 2020

Option 2 : \(\frac{{ZN}}{P}\)

CT 1: Indian History

18833

10 Questions
10 Marks
6 Mins

__Explanation:__

In the case of sliding contact bearing, several dimensionless numbers are used to understand the performance of bearing. Some of them are –

- \({\bf{Bearing}}\;{\bf{characteristic}}\;{\bf{number}} = \frac{{Z{N_s}}}{P}\)
**Bearing Modulus:**The value of Bearing characteristic number when the co-efficient of friction is minimum.**Sommerfeld number**: It is used to co-relate the working condition of a different machine which are operating under the same bearing. It is given by

\( {\rm{S}} = \left( {\frac{{{\rm{Z}}{{\rm{N}}_{\rm{s}}}}}{{\rm{P}}}} \right){\left( {\frac{{\rm{r}}}{{\rm{C}}}} \right)^2}\)

where Z = Absolute viscosity of the lubricant, Ns = Revolution per sec, P = Bearing pressure,

r = Radius of the shaft, c = Radial clearance of bearing and shaft and h_{o} = film thickness.

**Eccentricity ratio/Attitude:**It is the ratio of eccentricity to radial clearance.

\({\rm{e}} = \frac{{{\rm{eccentricity}}}}{{{\rm{radial\;clearance}}}} = \frac{{\left( {R - r} \right) - {h_o}}}{{\left( {R - r} \right)}} = 1 - \frac{{{h_o}}}{c}\)