Question

When the lubrication is arranged so that rubbing surfaces are separated by a fluid film, and the load on the surfaces is carried entirely by the hydrostatic or hydrodynamic pressure in the film, it is known as

(a) boundary lubrication

(b) viscous lubrication

(c) solid lubrication

(d) none of the mentioned

I have been asked this question during an online interview.

My question is based upon Limiting Angle of Friction topic in chapter Friction of Machine Kinematics

Answer 1

The correct answer is (b) viscous lubrication

Easiest explanation: When the lubrication is arranged so that rubbing surfaces are separated by a fluid film, and the load on the surfaces is carried entirely by the hydrostatic or hydrodynamic pressure in the film, it is known as viscous lubrication.

When the rubbing surfaces are separated from each other by a very thin film of lubricant it is known as boundary lubrication.