The friction in automotive engines is mainly caused by three components: th
e engine bearings, the piston-ring assembly and the valve train. In order t
o improve reliability and performance and to reduce fuel consumption, manuf
acturers have to reduce engine friction. To do this a better understanding
of these components is necessary. In this paper, the valve train is studied
for a direct-acting system. A transient elastohydrodynamic lubrication ana
lysis is developed. The model includes the variation in the radius of curva
ture of the cam, the variation in the hydrodynamic velocity and the variati
on in the load. The film thickness is calculated as a function of time and
space. In order to reduce the computing time, multi-grid and multi-level mu
lti-integration techniques are used. Results show squeeze-film effects and
ejection of lubricant on hydrodynamic speed reversion.