What is a "main reduction gear" used for?

The main reduction gear is an essential component in marine propulsion systems, serving the critical function of reducing the rotational speed (RPM) of the engine to a suitable level for efficient propeller operation. In marine contexts, engines typically operate at higher RPMs for optimal performance and efficiency. However, propellers require a lower RPM to function effectively without generating excessive cavitation or vibration, which can compromise performance and damage the propeller or shaft.

By decreasing the engine's RPM to an appropriate level, the main reduction gear allows the propellers to turn at speeds that generate the necessary thrust for maneuvering the ship. This reduction in speed is vital for balancing power and efficiency, ensuring that the ship can operate smoothly and effectively across various sea conditions. Overall, the main reduction gear plays a pivotal role in the ship's propulsion system, significantly impacting its operational capabilities.