Wear Characteristics of a Roller Follower Variable Valve Timing System

This study investigates the wear characteristics of a variable valve timing (VVT) system used to vary the phasing of the inlet valve events on a medium speed marine diesel engine.

The running-in properties of critical components within the system are examined.

The effect of surface finish and surface hardness upon wear is examined. It was found that in order to prevent excessive wear between the roller and tappet follower then the roller should be harder than the tappet. Tappet and roller hardness values of 60 and 70 Rockwell Hardness ‘C’ (HRC) respectively were found to be satisfactory.