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PART 3 The four-stroke cycle

Read the following passage carefully and write down a list of the missing words against their sentence numbers. Use the diagrams on page 94 to help you. These diagrams represent the four strokes in the cycle. They are not in the correct order and they are not named. Write down the names of the strokes represented.

23In the Four-stroke petrol engine there is a sequence, or cycle of evens which is completed in four strokes of the piston. 24The evens which take place in each stroke are as follows:

induction stroke 25With the open and the exhaust valve shut, the piston moves down the cylinder creating a partial vacuum. 26This partial vacuum draws in the atomized fuel from the into the cylinder.

compression stroke 27With both the inlet and exhaust valves closed, the moves up the cylinder, compressing the fuel mixture. 28Just before the end of the stroke, an electric spark across the points of the ignites the petrol and air mixture.

power stroke 29Both valves remain closed. 30During the tiny interval of time required for the flame to establish itself, the piston has reached its highest position in the . 31The gas generated by the burning fuel now expands rapidly, driving the piston down the cylinder. 32This downward push is converted into a rotary movement by the connecting rod and . 33A contained within the cylinder wall helps to conduct away the heat generated during this burning and thus keeps the engine cool.

exhaust stroke 34The exhaust valve opens but the inlet valve remains shut. 35The piston moves up the cylinder, pushing the exhaust gas out through the . 36With the completion of the exhaust stroke the cycle begins again.

Date: 2015-01-29; view: 1071

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