| 摘要 |
A valve actuating assembly for opening and closing a valve includes a cam mounted on a camshaft and enclosed by a pair of rotary cam guides each of which includes a roller channel having an outer race for receiving opposed ends of a roller that extends transversely from the lowermost end of a valve lifter disposed between the cam guides with the lifter being mounted to a connecting rod. The lifter has a radius at the lowermost end for engagement with the cam during certain engine phases, and the connecting rod is pivotally attached to a rocker arm, and the rocker arm attached to a valve. A valve spring mounted on the stem of the valve extends and compresses coincident with the rotation of the cam guides and contact of the roller ends with the outer races of the cam guides thereby actuating the lifter to open and close the valve with positive force and wherein the point of contact for valve opening and closing transfers between the engagement of the roller ends with the outer races and the radius against the cam during the various engine phases with the valve spring holding the valve in the closed position during certain phases through the exertion of positive force.
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