FAA Powerplant Written Practice Test

Cam roller, cam rings, and cam tracks are a part of the valve operating mechanisms of which engine type?

1. In-line engines

2. V-type engines

3. Radial engines

4. Rotary engines

The correct answer is: Radial engines

Cam roller, cam rings, and cam tracks are integral components in the valve operating mechanisms of radial engines. These elements are structured in such a way that they ensure efficient operation of the engine’s valves, allowing for precise timing in the opening and closing of the intake and exhaust valves. In radial engines, the cam mechanism is particularly crucial because of the arrangement of the cylinders, which radiate out from a central crankshaft. The cam rings serve to control multiple valves per cylinder in a synchronized manner as the engine rotates. This design enables better performance and reliability in the valve operation, aiding in the overall efficiency of the engine. The unique geometry and configuration of the components, such as cam rollers that move in conjunction with the cam tracks, are specifically engineered to accommodate the radial layout of the engine. Each cylinder's valve actuation is closely tied to the rotation of the crankshaft, making this setup distinct and more complex than what is seen in in-line or V-type engines, where the valve mechanisms typically employ different types of actuation. Understanding this context provides clarity on why cam roller, cam rings, and cam tracks are characteristic components of radial engine valve mechanisms.