THE CONTACT BREAKER AND THE DISTRIBUTOR

The contact breaker stops or breaks the flow of electricity in the primary coil. The distributor distributes the high voltage electricity to the sparking plugs.

The electricity from the primary coil flows through the centre of the distributor. This rod is turned by the camshaft. There are points in the contact breaker. The points can be opened so as to break the flow of electricity to the primary coil. The points are opened by a cam. They are closed by a spring.

The cam of a four-cylinder engine fits on the rod from the camshaft. It turns when the rod turns. Each corner of the cam presses on the contact breaker. This opens the points of the contact breaker. (A condenser stops any spark at these points) Now high-voltage electricity flows through the secondary coil to the distributor rotor arm.

The rotor arm is above the contact breaker cam. It is turned by the same rod from the camshaft. As the rotor arm goes round it touches points. Each of these leads to a sparking plug. Each time the arm touches a point the contact breaker points are also open. Then high-voltage electricity flows from the secondary coil to the rotor arm. From the rotor arm it goes to the sparking plug. This causes a spark.

Let us look at this again. The cam opens the points. The flow of electricity to the primary coil stops. High-voltage electricity flows in the secondary coil. It flows through the rotor arm to the sparking plugs. The cam turns. The points close. Electricity flows again into the primary coil. The rotor arm turns also. Contact with the sparking plug is broken. All this is controlled from the camshaft.

1. Complete the sentences with the active form of the verb in brackets:

1. It ……… (to get) dark. Shall I turn on the light?

2. You ……… (to make) a lot of noise. Could you be quieter? I ……… (to try) to concentrate.

3. The library ……… (to open) at 9 o’clock and ……… (to close) at 6 every day but weekends.

4. Bad driving ……… (to cause) many accidents.

5. The economic situation is very bad and it ……… (to get) worse.

6. Julia is very good at languages. She ……… (to speak) four languages fluently.

7. Don’t put the dictionary away. I ……… (to use) it.

8. Don’t put the dictionary away. I ……… (to need) it.

9. It was hard work carrying the bags. They ……… (to be) very heavy. I could hardly put them into the boot of my car.

10. When I was young, I ……… (to want) to be a bus driver.

Text 12

THE COOLING SYSTEM

When the engine is working, it gets hot. The heat comes from the explosion in the cylinders and from friction. How is it kept cool? This is usually done with water. The water flows from the radiator. It flows through holes in the cylinder block. The water enters the bottom of the block. When it is hot it rises to the top of the block.

From there it flows back into the top of the radiator. A small pump helps it to flow. The hot water from the engine flows slowly through the radiator. The air makes the water cool again. The flow of air is helped by a fan. The fan is moved by the crankshaft.

Some engines are cooled by air only, not by water.

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