🔍 Key Concepts

• Look closely at the number of pistons in each cylinder and whether there is a conventional cylinder head with valves on top. • Notice whether the engine uses ports in the cylinder wall plus a blower (typical of many two‑cycle diesels) or poppet valves in the head (typical four‑cycle). • Understand the difference between opposed-piston (two pistons in one cylinder moving toward each other) and opposed cylinder/boxer (two separate cylinders facing each other).

💭 Think About

• Count how many pistons you can see sharing the same central cylinder bore. Does one cylinder appear to have two pistons coming from opposite ends, or are there separate cylinders on each side? • Look for a valve train and cylinder heads: do you see intake/exhaust valves above each piston, or mainly ports in the side of the cylinder with air being forced in by a blower? • Given what you see, which combination of cycle (two vs four) and layout (opposed-piston vs opposed cylinder) best matches the drawing?

✅ Before You Answer

• Confirm whether there is one cylinder with two pistons moving toward each other, or two separate cylinders facing each other. • Verify if the gas exchange appears to be handled by ports and a blower (suggesting two-cycle) or by valves in cylinder heads (suggesting four-cycle). • Before choosing, double-check that your option’s wording matches both the cycle (two vs four) and the construction (opposed-piston vs opposed cylinder).