🔍 Key Concepts

• Wrist pin (piston pin) connects the piston to the connecting rod and is always the cylindrical pin through the small end of the rod. • Heat dam on a piston is usually a groove or recess located near the top ring area to reduce heat transfer to the skirt and rings. • In some large marine diesels, a piston carrier or skirt is the lower supporting part of a composite piston that the crown is bolted to.

💭 Think About

• Look closely at where arrow 15 is pointing in relation to the cylindrical pin (arrow 14) and the ring belt area. Is it pointing at a pin, a groove, or a structural lower piece of the piston? • Ask yourself which option describes a visible groove or recess, which describes a pin, and which describes a supporting lower section of the piston, then match that to what you see at label 15. • Compare the shape and position of part 15 to common textbook diagrams of a composite marine diesel piston: which part usually lies just below the crown and above the skirt or carrier?

✅ Before You Answer

• Verify that the wrist pin (piston pin) must be the long cylindrical pin running through the small end of the connecting rod. • Verify whether part 15 appears as a groove near the top ring land (heat dam) or as a separate structural piece between the crown and the skirt (piston carrier). • Confirm that a thrust washer is normally found near a rotating shaft or crankshaft, not inside the piston body itself, and see if anything in the illustration matches that.