Advanced Calculation Method of the Contact Stress in Roller Follower Valve Train Systems

The calculation of the contact stress between cam and cam follower is an important step in the valve train design process. Unacceptably high contact stresses result in excessive wear at the running surfaces.

The established analytical methods for calculation of contact stress are limited by assumptions. The Finite Element Analysis (FEA) offers an advanced tool with fewer limitations than the analytical equations. This paper compares these two calculation methods.

In a first step, the FEA is used to confirm the analytically calculated results with the standard Hertz equations. Then some special cases, which cannot be calculated by the standard equations, are investigated by FEA, like the limited width of one contact partner, or a non-circular roller profile.