Cam followers made of hardenable chilled cast iron are used for heavy-duty diesel engines. Although this material has generally high wear resistance, its scuffing resistance becomes insufficient under conditions in which high heat is generated between sliding surfaces with load increase due to the valve spring force intensification.
Hence, the authors attempted to develop a cam follower in which the sliding surface toward the cam is made of a sintered metallic material composed of nickel and tungsten-carbide for an excessively high load application. Sintering the material in a disk form, and bonding it diffusively with the primary cam follower body made of steel, are carried out simultaneously in the production process.
Test results on a rig and an actual engine demonstrate its high wear and scuffing resistance capability, even under intended severe load conditions. Wear of steel camshaft can also be remarkably reduced, compared with using former cam follower made of hardenable chilled cast iron, by controlling the powder size and surface roughness of the sliding surface of the sintered disk.