- For the ionic propulsion device, see Lifter (ionic propulsion device).
Piston engines
In piston engines, a lifter, cam follower , or tappet is a device that actuates a poppet valve through rocker arms and pushrods. Cam followers are needed to transfer the radial forces caused by the rotating cams on the camshaft to the engine block, leaving only an axial force on the pushrod.
Use of hydraulic lifters eliminates the need to regularly adjust the valve play, but can be inefficient. Solid lifters are used in performance applications.
In engineering, lifter has some unrelated meanings.