This image showcases the Napier Deltic, an opposed-piston, valveless, two-stroke diesel engine, which was originally developed for marine and railway applications. The Deltic's unique triangular arrangement of three banks of cylinders sharing a common crankshaft at each apex made it a compact and powerful engine with high power-to-weight ratios. Its design allows for a high level of mechanical complexity and innovation, with each bank containing two pistons that face each other in a single cylinder, negating the need for cylinder heads and valves. The Deltic saw extensive use in British naval vessels and locomotives due to its durability and efficiency.