A.C. Smith

SOME NOTES ON THE APPLICATION OF ELASTO‐HYDRODYNAMIC THEORY TO GEAR LUBRICATION: PART TWO

The effectiveness of the oil film between the gear teeth will, of course, depend on the magnitude of the asperities. In this respect distinction must be made between the initial state of the gears and that after running‐in. Individual measurements of surface roughness show considerable variation between nominally similar gears, but there is a fairly well defined relationship between typical values and gear quality, as indicated below. Roughness is here expressed in micro‐inches CLA (centre line average), i.e., arithmetical average of the departure of the profile both above and below a centre line of appropriate curvature.