Exam Question
(a) In a 4-Stroke engine, describe each of the four strokes of the engine. (5)
(b) Draw timing diagram of a complete cycle. (5)
(c) How each stroke is completed, in the engine with action of crank travel and valves. (6)
Class 4 (4th Engineer)
MEKM
📅 Apr 2025
Reference Answer
### (a) Description of the Four Strokes of a 4-Stroke Engine
A 4-stroke engine cycle, also known as the Otto cycle (for spark ignition) or Diesel cycle (for compression ignition), completes its power-producing cycle in four distinct piston movements, or strokes, over two complete revolutions of the crankshaft (720 degrees).
1. **Intake (or Suction) Stroke:**
* **Piston Movement:** The piston travels from Top Dead Center (TDC) to Bottom Dead Center (BDC).
A 4-stroke engine cycle, also known as the Otto cycle (for spark ignition) or Diesel cycle (for compression ignition), completes its power-producing cycle in four distinct piston movements, or strokes, over two complete revolutions of the crankshaft (720 degrees).
1. **Intake (or Suction) Stroke:**
* **Piston Movement:** The piston travels from Top Dead Center (TDC) to Bottom Dead Center (BDC).
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