Question 7 MODE02 - Assistant MODU Engineer

The Correct Answer is B. **Explanation for Option B (piston rings):** The terms "barrel face," "taper face," "grooved," and "chrome plated" all specifically describe common design features, cross-sectional profiles, and surface treatments applied to **piston rings** in diesel engines. These variations are engineered to optimize sealing, oil control, and wear resistance between the piston and the cylinder liner under different operating conditions (e.g., "taper face" aids in scraping oil, "barrel face" ensures rapid seating and better conformity, and "chrome plated" significantly improves wear life). **Explanation for Incorrect Options:** * **A) pistons:** Pistons are large, complex assemblies. While they have features like crowns, skirts, and ring grooves, they are not themselves categorized by terms like "barrel face" or "taper face." Their primary types are usually defined by material (e.g., aluminum, steel) or structure (e.g., trunk piston, crosshead piston). * **C) piston skirts:** The piston skirt is the lower section of the piston that guides it in the cylinder. Its descriptions usually relate to shape (e.g., elliptical, full skirt) or clearance, not specialized ring-like profiles such as "barrel face" or "taper face." * **D) cylinder liners:** Cylinder liners are the sleeves inserted into the cylinder block. They are typically categorized by features such as wet or dry type, or by their material (e.g., cast iron, hardened steel), not by the terms listed, which describe small, specialized seating surfaces.