FAA Powerplant Written Practice Test

Which engine type includes cam roller, cam rings, and cam tracks as part of its valve operating mechanisms?

1. Piston engine

2. Radial engine

3. Turbojet engine

4. Wankel engine

The correct answer is: Radial engine

The correct answer is the radial engine, which features a unique design that incorporates cam rollers, cam rings, and cam tracks in its valve operating mechanism. In a radial engine, the cylinders are arranged in a circular pattern around the crankshaft, and each cylinder operates its own valve through a system that uses these cam components. The cam rings, which rotate with the crankshaft, guide the cam rollers as they move along specific tracks. This design allows for efficient operation of the valves, enabling synchronization with the piston's movement within each cylinder. This method of operation is essential for achieving optimal performance in radial engines, which are often used in aviation due to their power-to-weight ratio and reliability. Other engine types do not utilize cam rings and cam tracks in the same way. Piston engines typically have a more standard overhead camshaft configuration, while turbojet engines primarily focus on turbine mechanics and do not incorporate a valve mechanism driven by cam systems in the same manner. The Wankel engine, known for its rotary design, uses an entirely different method of valve control involving an eccentric rotor instead of traditional cams. This distinction highlights the radial engine's unique and complex valve operation mechanism that makes it essential for its design and functionality.