A full numerical solution to the coupled cam-roller and roller-pin contact in heavily loaded cam-roller follower mechanisms

In cam-roller follower units two lubricated contacts may be distinguished, namely the cam-roller contact and roller-pin contact. The former is a nonconformal contact while the latter is conformal contact. In an earlier work a detailed transient finite line contact elastohydrodynamic lubrication model for the cam-roller contact was developed. In this work a detailed transient elastohydrodynamic lubrication model for the roller-pin contact is developed and coupled to the earlier developed cam-roller contact elastohydrodynamic lubrication model via a roller friction model. For the transient analysis a heavily loaded cam-roller follower unit is analyzed. It is shown that likewise the cam-roller contact, the roller-pin contact also inhibits typical finite line contact elastohydrodynamic lubrication characteristics at high loads. The importance of including elastic deformation for analyzing lubrication conditions in the roller-pin contact is highlighted here, as it significantly enhances the film thickness and friction coefficient. Other main findings are that for heavily loaded cam-roller follower units, as studied in this work, transient effects and roller slippage are negligible, and the roller-pin contact is associated with the highest power losses. Finally, due to the nontypical elastohydrodynamic lubrication characteristics of both cam-roller and roller-pin contact numerical analysis becomes inevitable for the evaluation of the film thicknesses, power losses, and maximum pressures.