Effects of micro-geometry features and profile error on elastohydrodynamic lubrication of helical gears

The paper presents the results of transient elastohydrodynamic lubrication (EHL) analyseis of a pair of helical gears over the meshing cycle. The test gears considered are being used as a basis for assessing changes in gear contact functionality in terms of profile errors. Their involute profiles are modified by tip relief and axial crowning which has been chosen to ensure that edge contact occurs during testing. The influence of tip relief on the EHL contacts is shown in terms of elevated contact stress and EHL film thinning. Results are also presented for analyses where profile deviations resulting from the manufacturing process, measured using a 2 mm diameter spherical probe in a gear testing measuring machine, were used to specify the gear flank geometry, including tip relief. These show the significant changes in elastohydrodynamic performance brought about by profile deviations