A Hydrodynamical Theory of Piston Ring Lubrication

It is shown that, making the assumption that oils as used in engine lubrication cannot stand absolute tension, and taking into account the observed tendency of the bearing faces of piston rings to wear into an uneven shape with the ``high'' point near the middle and a very gentle slope to each edge, Reynolds' theory of bearing lubrication can be extended to ring lubrication. A practical application of this extension is outlined and illustrated. Results of calculations, based on this extension, of ring clearance and wear under average working conditions are in substantial agreement with a number of observations.