Valve lifter

[1] The cylindrically shaped component that presses against the lobe of a camshaft and moves up and down as the cam lobe rotates. Most valve lifters have an oil-lubricated hardened face that slides on the cam lobe. So-called "roller lifters," however, have a small roller in contact with the cam lobe — thereby reducing the friction between the cam lobe and the lifter. Also called "valve follower" or cam follower.
[2] A tool that compresses valve springs for removal and replacement. See also hydraulic valve lifter