What is the function of a cam in mechanical systems?

• A. To convert rotary motion into linear or oscillatory motion.
• B. To store energy.
• C. To reduce friction.
• D. To increase speed.

Answer: (A)

The function of a cam is to convert rotary motion into linear or oscillatory motion. As the cam—a shaped surface on a rotating element—turns, it pushes against a follower connected to another part. The follower’s movement follows the cam’s contour, producing a controlled up-and-down or back-and-forth displacement. The specific motion of the follower, including its position, speed, and acceleration, is determined by the cam profile, which is why cams can precisely time and shape motions in mechanisms such as valves, lifters, or actuators.

This differs from simply storing energy (that’s the role of springs or flywheels) or reducing friction (solved by lubrication and bearing design). It also isn’t about increasing speed directly (that’s achieved with powertrains or motors). The cam’s unique purpose is to impose a predetermined motion on the follower through its shaped surface.