| 摘要 |
A bucket tappet is provided for direct-acting valve gear having a body portion formed of a light weight material having a thermal expansion suitable for use in an aluminum engine head. The body of the tappet is formed with a tubular wall, an inner tubular hub and a transverse web joining and supporting the hub within the outer tubular wall. An hydraulic lash adjusting piston/plunger assembly formed of steel is received within the tubular hub. The leakdown control surfaces within the lash adjuster are formed on the mating interfaces between the steel piston and plunger. The body of the tappet has a cam face member formed of hardened material, preferably iron base, received thereover transversely of the outer tubular portion and retained thereon for providing a cam contacting surface. The inner tubular hub has the end adjacent the cam face closed by portions of the body for forming a portion of the hydraulic reservoir in conjunction with a cavity formed in the hydraulic piston. The outer periphery of the light weight body has a hardened surface adapted for wear-resistant sliding contacting with a guide bore formed in the aluminum engine head.
|
