Revolutions of crankshaft to complete a cycle in four stroke engine - Basic Mechanical Engineering

Q.  In four stroke cycle engine, cycle is completed in ______
- Published on 01 Sep 15

a. two strokes of the piston
b. two revolutions of the crankshaft
c. three strokes of the piston
d. four revolutions of the crankshaft

ANSWER: two revolutions of the crankshaft


  • Sravanthi    -Posted on 12 Nov 15
    Four stroke cycle engine

    - It is an internal combustion engine in which piston completes four strokes such as intake, compression, power and exhaust.

    - This cycle is completed in four strokes of piston or two in two revolutions of crankshaft. Two stroke cycle engine completes its cycle in two strokes of piston or in one revolution of crankshaft.

    - Intake stroke begins at top dead center and ends at bottom dead center. In this stroke, piston pulls an air-fuel mixture into the cylinder through its downward motion and creates vacuum pressure.

    - During compression stroke, inlet and exhaust valves are closed and the piston compresses air-fuel mixture for the preparation of ignition during power stroke. This stroke begins at B.D.C. and ends at T.D.C.

    - The second revolution of power stroke starts when the compressed air-fuel mixture is ignited by the spark plug.

    - During the exhaust stroke, the exhaust valve is open and the piston returns from B.D.C to T.D.C. Hence, by completing these processes, two revolutions of the crankshaft are completed.

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