What are the two distinct types of pistons mentioned?

The two distinct types of pistons referred to are trunk and crosshead pistons. Trunk pistons are commonly used in two-stroke engines where the piston itself carries the connecting rod directly, which simplifies the design and reduces the number of components. This feature allows for a more compact engine design, making it suitable for various applications, including smaller engines.

On the other hand, crosshead pistons are used in larger, more complex engines, particularly those with larger stroke lengths, such as in marine propulsion systems. In a crosshead piston arrangement, the piston connects to a crosshead that slides along guides. This design is beneficial in reducing the side loads on the piston, which can prolong the lifespan of the cylinder walls and improve operating efficiency.

Understanding these two piston types is essential for various marine engineering applications, as it highlights how different designs can impact engine performance, efficiency, and maintenance considerations.