An experimental study of diesel engine cam and follower wear with particular reference to the properties of the materials

The main objective of this paper is to study and experimentally quantify the cam and follower wear mechanisms of a diesel direct valve-gear. Camshafts are made of nodular cast iron, surface hardened, ion nitrided and nitrosulphurized, and those made of grey chilled cast iron are mated with followers made of chilled grey cast iron and hardened steel. The investigation was carried out on a laboratory bench equipped with an engine head with a camshaft, followers and systems creating the conditions necessary for a routine run of the valve gear. Cam wear was defined by comparing the profile lifts of the cams. The height of the followers was measured using a coordinative measuring machine and a perpendicular optimeter. The rotational speed, valve displacement and the torque required by the valve gear were measured. Camshaft C9 and the thimble shaped followers with regulating plates F6 were also examined in a diesel engine. The effects of the materials the kinematic pair was made of, heat treatment and thermochemical treatment, the cams' own stresses at the moment-of-friction value, as well as the extent and nature of element wear, were analysed. (C) 2000 Elsevier Science S.A. All rights reserved.