Figure 11. Two Stroke Cycle Engine.

Principles of Internal Combustion Engines
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PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 1

in figure 11. Instead of placing the intake and exhaust ports in the combustion

chamber, they are placed in the cylinder wall. In this engine, the piston goes

through a power stroke every time it moves from top dead center to bottom dead

center. The downward stroke is also an intake and an exhaust stroke. As the

piston moves from bottom dead center back to top dead center, it is going through a

FIGURE 11. TWO STROKE CYCLE ENGINE.

(a) Downward Stroke (figure 12, view A, on the following page). The piston

begins the power stroke at top dead center. As the exploding fuel and air mixture

pushes the piston downward, it first covers the inlet port. This seals the

crankcase. As the piston continues downward, it uncovers the intake and the

exhaust ports. The pressure built up in the crankcase forces the fuel and air

mixture into the cylinder through the intake port. The top of the piston is shaped

to divert the mixture upward and away from the exhaust port. As the mixture enters

the cylinder, it displaces and pushes the burnt gases out through the exhaust port.