Describe a four-stroke cycle, draw it with crank positions, and explain scavenging in that cycle?

flowchart TD
    A[Induction] --> B[Compression]
    B --> C[Power]
    C --> D[Exhaust]
    D --> A

• Cycle name: four-stroke because it completes one thermodynamic cycle in four piston strokes
• Strokes: induction, compression, power, exhaust
• Duration: two crank revolutions
• Gas exchange: valve-operated
• Scavenging in 4-stroke: gas exchange during exhaust and induction with valve operation
• Importance of scavenging: clears burnt gases, admits fresh air, gives cleaner gas exchange than two-stroke
• Engine use: medium-speed trunk-piston diesels