| 摘要 |
A rocker arm in an internal combustion engine is pivotably supported by a fixed fulcrum retainer with a rocker key operatively positioned therebetween. The rocker arm and fulcrum retainer each have a concave, semi-cylindrical bearing surface and the rocker key has a pair of spaced apart, opposed convex, semi-cylindrical bearing surfaces, the concave, semi-cylindrical bearing surfaces and associate convex, semi-cylindrical bearing surfaces having radii ratios on the order of 1.7:1 to 3:1 and preferably 2:1 whereby to effect substantial rolling contact of these elements relative to each other. In addition, the rocker arm is preferably of U-shaped configuration as defined by a base with side walls depending from opposite sides thereof. A roller follower is operatively and rotatably positioned between the side walls at one end of the rocker arm, with the roller follower having an outer peripheral surface of a diameter whereby the outer peripheral surface is in rolling contact with the base and an associate element of the valve train at this end of the rocker arm. A roller support shaft is operatively associated with the side walls and with the roller follower to loosely retain the roller follower in unit assembly with the rocker arm. |
