Effect of gear misalignment on contact area: Theoretical and experimental studies

Abstract

Parallel and angular gear misalignments reduce effective contact area and increase contact stresses, which in turn accelerate gear surface fatigue failure. In the present study, experiments on gear tooth contact area by varying degree and extent of misalignment have been performed. Theoretical model to estimate contact area as a function of misalignment is proposed. A methodology to measure contact area using coordinate measuring machine (CMM) is also discussed.The results of effective contact area obtained from theoretical and experimental studies show good agreement. It is observed that in the case of axial and radial misalignments, the contact patch area reduces linearly in proportion to amount of misalignment while in case of angular misalignment it follows a non-linear behaviour. As far as the angular misalignment is concerned, the contact patch changes from rectangular to quadrilateral and finally to triangular shape depending upon angle of misalignment. At an angular misalignment of 9°, contact patch shifts from quadrilateral to triangular shape. Combined parallel and angular misalignments result in larger reduction in contact area as compared with individual axial, radial and angular misalignment.