Abstract
For the valve train with camshafts and roller followers, influences of the roller support bearing and the engine oil properties on the friction losses at the contact between cam and roller follower and the contacts of other elements in the valve train were examined by measuring the contact load and the friction force between the cam and the roller follower with a practical sized OHV valve train friction tester. The followings were made obvious. (1)The friction loss is smaller with the roller support of slide bearing than that of needle bearing. (2)When the viscosity of low-SAPS engine oils becomes low, the friction between cam and roller hardly changes but that from the other valve train elements slightly increases. (3)The friction loss becomes smaller with the low-SPAS engine oils lower in sulfur content.
