PURPOSE: To obtain an OHC type valve mechanism preventing the scuffing of the sliding faces by laying a surface layer of a soft metal or a solid lubricant on the sliding face of a cam shaft formed with a wear resistant sintered alloy or a rocker arm formed with high Cr cast iron.
CONSTITUTION: The cam shaft of an OHC type valve system is formed with a wear resistant sintered alloy consisting of, by weight, 2.5W7.5% Cr, 0.10W3.0% Mn, 0.2W0.8% P, 1.0W5.0% Cu, 0.5W2.0% Si, ≤3% Mo, 1.5W3.5% C, ≤2% impurities and the balance Fe, and the rocker arm is formed with high Cr cast iron contg. 24W30% Cr. A surface layer of a soft metal such as Pb, Sn, Zn or In, an alloy thereof or a solid lubricant such as MoS2 or graphite is laid on the sliding face of at least one of the cam shaft and the rocker arm. Thus, the fittability of both the parts is improved to prevent the scuffing of the sliding faces.
NAKAKOHARA TAKESHI
UEDA FUMIO
SATAKE SHIGERU
MURASE HIROYUKI
