4th Class Power Engineering Part B 2025 – 400 Free Practice Questions to Pass the Exam

The main purpose of a flywheel in a steam engine is to dampen speed fluctuations. A flywheel serves as a mechanical device that stores kinetic energy when the system operates. As the steam engine goes through its power strokes, the flywheel helps to smooth out the irregular delivery of power by maintaining a more constant speed.

In steam engines, power is not produced evenly due to the cyclical nature of the steam's expansion and the reciprocating motion of the piston. This results in variations in speed, which can negatively affect performance and efficiency. The flywheel mitigates these fluctuations by providing a reservoir of energy; when the engine speeds up, the excess energy is stored in the flywheel, and when the engine slows down, the energy is released back into the system. This function is crucial for ensuring a steady output and improving the overall operation of the engine.

While options such as increasing fuel efficiency, increasing power output, and reducing vibrations can be seen in the broader context of mechanical system improvements, they do not accurately capture the primary role of the flywheel within the specific mechanics of a steam engine. The flywheel's design is fundamentally geared towards managing and optimizing the rotational speed of the engine rather than directly influencing fuel use or power levels.