Patent ID: 8235357

Claim:
A valve gear comprising: a valve stem having a sliding surface; and a valve bush having a sliding surface, and slidably supporting said valve stem, wherein the entire valve stem is formed from a forged part made of a Ni-based superalloy, and the entire valve bush is formed from a cast part made of a Ni-based superalloy, wherein each of a surface roughness of said sliding surface of said valve stem in contact with said valve bush and a surface roughness of said sliding surface of said valve bush in contact with said valve stem is 10 μm to 100 μm in units of Rz; and wherein said valve stem and said valve bush are made of the same Ni-based superalloy wherein the Ni-based superalloy comprises Ni as a main constituent element and further comprises Cr in the range of 14 to 25 wt %.