Four strokes. One continuous cycle.A cutaway petrol engine illustrates intake, compression, power and exhaust. The piston drives a crankshaft through a connecting rod. Two camshafts rotate at half crankshaft speed. Pause or scrub the twenty-second loop to inspect the mechanism. WORKING PRINCIPLES MECHANICAL SERIES / 001 THE FOUR-STROKE PETROL ENGINE Four strokes. One continuous cycle. Fuel becomes motion, one stroke at a time. 01 THE CURRENT STROKE Intake The piston moves down, drawing in a fresh mixture of petrol and air. INTAKE OPENEXHAUST CLOSED 2 crankshaft turns / 1 complete cycle SINGLE-CYLINDER CUTAWAY Fuel + airBurnt gasCamshafts½ crankshaft speed Intake valve Exhaust valve Spark plug Piston Connecting rod Crankshaft Fresh chargeCombustionExhaust gas 000° / 720° SLOW STUDY → RUNNING SPEED 00.0 / 20 s