🔍 Key Concepts

• Location of label P relative to the cylinder liner and scavenge air space • Purpose of fittings that deliver oil in small, metered amounts to the cylinder wall on large low‑speed diesel engines • Differences between cooling water connections, air system valves, and lubricating devices on an engine cross‑section

💭 Think About

• Look at where the arrows for label P point: Are these parts on the air side, water jacket, or directly on the cylinder liner? What does that tell you about their function? • On a cross‑section of a large two‑stroke diesel, what kind of device is usually mounted in groups around the mid‑stroke area of the liner to protect it from wear and scuffing? • Compare the shapes: do they look like valve bodies in a pipe run, like spring‑loaded air check valves, or like small pumps/injectors aimed at the liner surface?

✅ Before You Answer

• Confirm whether the fittings at P appear to connect to the cooling water jacket or to small lines leading from a lubricator system. • Check if there is any passage from P into the scavenge air receiver; if not, they are unlikely to be air check valves or diffuser vanes. • Verify that the function associated with P would logically be to provide a thin film on the cylinder wall rather than move air or water.