| 摘要 |
A direct-acting hydraulic tappet which includes a roller cam follower which is received in a plastic block mounted in a piston slidingly received within the tappet body. The plastic block includes upwardly extending fins which straddle the engine cam to maintain alignment of the roller with respect to the cam. The plastic block is formed to define an annular low pressure reservoir between it and a lower portion of the piston, and ports are formed in the bottom of the piston to permit oil flow between the annular reservoir and a high pressure chamber defined between the bottom of the piston and the bottom of the body. A check valve in the form of a flat disk is fixed to the piston in position to close the ports when the high pressure chamber is pressurized.
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