USCG Exam PracticeDiesel engine principles (motor propulsion)
In a four-stroke diesel engine, the camshaft is geared to run at what speed relative to the crankshaft?
- A. One-quarter crankshaft speed
- ✓ Half crankshaft speedCorrect
- C. Equal to crankshaft speed
- D. Twice crankshaft speed
Why B is correct
In a four-stroke engine, each cylinder fires once every two crankshaft revolutions, so the camshaft is geared to run at half crankshaft speed to time the valves correctly. Running at any other ratio would mistime valve events relative to piston position.
Cited:DOE-HDBK-1018 Vol.1 §1-1