Patent ID: 8167270

Claim:
A valve gear comprising a bearing having a sliding surface against a valve shaft, wherein: the bearing has a plasma powder building-up welded layer (X) made of a heat-resistant cobalt-based alloy on the sliding surface against the valve shaft; the valve shaft has a plasma powder building-up welded layer (Y) made of a heat-resistant cobalt-based alloy on a sliding surface thereof against the bearing; the welded layer (X) formed on the bearing comprises: a first welded layer formed on the surface of the bearing, having a dilution ratio of 15 to 25%; and a second welded layer formed on the first welded layer, having a dilution ratio of 50% or less of the dilution ratio of the first welded layer; and the welded layer (Y) formed on the valve shaft comprises: a third welded layer formed on the surface of the valve shaft, having a dilution ratio of 15 to 25%; and a fourth welded layer formed on the third welded layer, having a dilution ratio of 50% or less of the dilution ratio of the third welded layer.