Behaviour of point contact EHL films under pulsating loads

The effects of pulsating and impact loads on point contact EHL films are investigated by direct observations using the optical interferometry technique. The sudden increase of the load leads to a larger contact region and consequently, entraps a film, due to squeeze motion, at the inlet side corresponding to just outside the initial Hertzian contact circle. In unloading phase, the maximum film thickness is kept but the film thickness at the inlet periphery is reduced due to the occurrence of air bubbles. The entrapped and reduced films pass through the EHL conjunction approximately at the entrainment speed. The effects of the entrainment velocity and loading time and minimum load are also discussed.