A cam follower uses a cam, usually a flat piece of tooled metal, and follower system to replicate a specific motion. As the cam is rotated, pressure is applied to the follower, which tracks the shape of the cam by its edge and translates the movement of the cam into a movement pattern. The cam follower operates on a very simple principle and can be applied to a wide number of tasks, because although basic, it is highly versatile. Cam follower systems are used in a wide variety of daily applications, including motor vehicles, moving lawn ornaments, and pumping devices.
Cam follower systems usually take the form of a rotating rod that turns the cam or cams and followers mounted above the cams. A follower with a pointed head will more accurately hold and replicate the motion of the cam, but it will also wear down and require replacement more quickly. Followers with broader heads will not wear down as easily, but some accuracy will be sacrificed. It is important that an external downward force be applied to the follower, to make sure that it retains smooth and even contact with the cam. Without a stabilizing downward force on the follower system, the follower may have a tendency to wobble or jitter, potentially causing a malfunction in the device being moved by the cam follower and wearing the follower down more quickly.
Most cams are made in simple shapes designed to create basic motions – the more complex the shape of the cam, the harder the follower must work to replicate the motion. Many cam follower systems take the shape of a teardrop or have a single jagged inset to create a specific motion. The cam follower systems used on motor vehicles to control the pistons, for example, usually have a teardrop shape that causes a sharp upward motion, or displacement, as the follower reaches the apex of the teardrop, causing the attached piston to fire.
In a motor vehicle, there are multiple cam follower systems, one for each cylinder, and they are offset so that all the pistons do not fire at once. The multiple systems can all be mounted on one camshaft, making the most use of the energy used to turn the shaft, rather than dedicating energy to each piston individually. In this case, damage to the cam follower could cause a misfire in the engine.