What is the function of the flywheel in a manual transmission?

The flywheel plays a vital role in a manual transmission system by storing rotational energy. When the engine runs, the flywheel accumulates energy through its mass and rotation, allowing it to maintain a consistent engine speed. This stored energy helps smooth out the power delivery from the engine to the transmission, especially during transitions when the driver engages or disengages the clutch.

As the driver shifts gears, the flywheel supports the engine's inertia, helping to prevent stalling and ensuring a smoother power output, which is essential for optimal vehicle performance. Its function extends to aiding in the balance of the engine, ensuring vibrations are minimized. This capability is pivotal in ensuring a seamless driving experience.

The other options do not accurately describe the function of the flywheel. Engaging the clutch is a separate mechanism that works with the flywheel but does not define its purpose. Altering gear ratios relates to the transmission itself and not the flywheel's function. Cooling the transmission fluid is handled by other components in the system and is not connected to the flywheel's role.