2. Read and translate the text.

HOW THE ENGINE IS WATER-COOLED?

The majority of engines are cooled by means of water. The cylinder head, the combustion chamber and the valve seats are surrounded by hollow spaces known as water jackets. They are filled with water. These jackets are connected by pipes to the top and to the bottom of the radiator. The radiator is mounted at the front of the car. There are two circulating methods: pump and thermo-syphon. In the pump system, the pump is placed in the bottom water passage. It is driven by the engine and forces the cooled water into the jackets. It forces the heated water to the top of the radiator where it is cooled again.

In the thermo-syphon system of water cooling there is no pump. The system is based on the fact; that hot water is lighter than cold water and has a tendency to rise. So when the water in the jackets of a thermo-syphon cooled engine gets hot, it rises to the top and enters the radiator through the upper pipe. Here it is cooled and goes to the bottom of the radiator and from there back to the jackets. The circulation is entirely automatic and continues as long as there is a difference in temperature between the water in the radiator and that in the jackets. There is a variety of designs in the structure of the radiators The two main types are tubular and honey comb type.

In the tubular type а series of flat vertical tubes connect two tanks. The honey comb type is built up of short tubes placed horizontally. Their ends are soldered together, making a labyrinth of narrow spaces between the tubes. These spaces are filled with cooled water. Tubes of various shapes are used round, square, hexagonal. A cock is placed at the lowest point of the radiator to drain off water when it is necessary. Behind the radiator a fan is provided to blow cool air on the tubes containing water. It is driven by a belt from a pulley on the crankshaft.