Abstract

Within the scope of this work, the friction in the lubricating gap between elliptical contact of two surfaces operating under full-film lubrication was experimentally and simulatively investigated. The experimental examination of fluid friction was carried out on a twin-disc-machine by varying the load and slide-to-roll-ratio at constant hydrodynamic velocity and oil inlet temperature. As results, traction curves are obtained which show the change of the coefficient of friction or the shear stress respectively as a function of the slide-to-roll-ratio. From measurements, the maximum shear stress is obtained, which is used for the numerical determination of traction curves. To this end, the EHL theorieis is used, taking into account the pseudoplastic and the viscoelastic behaviour of the lubricant. In this work, two gear oils based on polyalkylene glycol were used as examples of lubricants used in modern worm gearboxes.