Contact surface fatigue life for roller rack pinion system

A roller rack pinion (RRP) system, which consists of a rack-bar and a cam pinion, transforms a rotation motion into linear motion. The rack-bar has a series of roller train and meshes with the cam pinion. First, the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance have been proposed with the introduction of the profile shift coefficient. Then, the load stress factors are investigated under the variation of the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly with the increase of the profile shift coefficient.