| 摘要 |
A valve operating system in an internal combustion engine includes a switchover pin which is movable between an associatively operating position where adjacent ones of rocker arms are operated in association with each other, and an associative-operation releasing position where the associative-operation is released, the switchover pin receiving at axially opposite ends thereof a hydraulic pressure force acting toward the associatively operating position and a spring force acting toward the associative-operation releasing position, a cylindrical roller shaft which is fixed to one of the adjacent rocker arms. and into which the switchover pin is slidably fitted in response to the movement thereof toward the associatively operating position, and a roller rotatably carried on the roller shaft to come into rolling contact with a cam provided on a camshaft. In this valve operating system, at least one of axially opposite end surfaces of the roller shaft foamed of a maternal harder than that of the one rocker arm, which receives the switchover pin, protrudes from a side surface of the one rocker arm. Thus, a wear powder can be prevented from entering into the roller shaft, thereby ensuring the smooth switching-over operation of the switchover pin.
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