You are assigned to a river push boat fitted...

Question 1 of 2707066636eef28f7522a1c51f6e8

You are assigned to a river push boat fitted with main propulsion diesel engines operating on the cycle represented in the polar timing diagram shown in the illustration. What combustion cycle event has a duration of 103°? Illustration MO-0206

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Question 1 of 27070

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🔍 Key Concepts

• Identify where 0° TDC and 180° BDC are on the polar timing diagram and how crank angle relates to each stroke of a two-stroke diesel. • Look carefully at the sector marked 103° and note which valve or port events bound that sector (between which two labeled points it lies). • Recall which part of the cycle occurs between end of fuel injection/combustion and the point where scavenging or exhaust begins.

💭 Think About

• On a uniflow-scavenged two-stroke diesel, what is happening to the piston and gases immediately after combustion at TDC until the first opening of either exhaust valves or intake ports? • Which stroke(s) of a four-stroke engine are combined into a single downward or upward movement in a two-stroke design like the one shown? • Does the 103° span occur while valves and ports are mostly closed, or while they are open for gas exchange? What does that tell you about which named event it represents?

✅ Before You Answer

• Confirm on the diagram exactly where fuel injection begins and ends relative to 0° TDC. • Trace piston travel from TDC through 103° of crank rotation and see whether intake ports or exhaust valves are open during that interval. • Match that closed‑valve interval to the listed options: Intake, Exhaust, Power, Compression.