Definition
A rotating or sliding mechanical part shaped with one or more lobes (raised sections) that converts rotary motion into precise, timed linear motion in a follower riding against it. In aircraft engines, cams are used to open and close intake and exhaust valves at the correct moment in each cylinder's cycle.
Plain English
A specially shaped wheel or shaft with bumps on it. As it turns, the bumps push parts up and down at the right moments. In an engine, the bumps push the valves open and let springs close them again, all in the correct timing.
Context Anchor
Seen in aircraft engine maintenance, especially when studying valve operation, camshafts, and engine timing.
Derivation
From the Dutch word 'kam', meaning 'comb' — referring to the tooth-like or lobed profile around the rotating part. The shape of the lobes is what does the work.
Why Pilots Care
Cam lobes set the timing of valve opening and closing, which directly affects engine power, smoothness, and reliability. A worn or damaged cam lobe causes weak cylinders, rough running, and is a common reason for engine teardown.
Grounding Statement
Picture a turning metal shape with one high spot that gives another part a push each time the high spot comes around.
Intuition Check
Cam does not mean a camera or webcam here. In this maintenance context, it means a shaped engine part that turns or slides to move another part at the right time.
Example Sentence 1
As the camshaft rotated, each cam lobe pushed its lifter upward, opening the valve at the correct point in the cycle.
Example Sentence 2
Proper cam timing ensures the valves open and close in sequence with piston movement.