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Text 1
FUNDAMENTALS OF AUTOMOBILE
1. Basically, the automobile consists of four components:
1. The engine.
2. The framework, or support for the engine and wheels.
3. The power train, or mechanism that transmits the power from the engine to the wheels.
4. The body.
To these may be added the fifth component, the car-body accessories: the heater, lights, radio, and other devices that contribute to the convenience and comfort of the driver.
2. The Engine. The engine is the source of power that makes the wheels go around and the car move. It is usually referred to as an internal combustion engine because gasoline is burned within its cylinders, or combustion chambers. Most automobile engines have six or eight cylinders, although some four-, twelve-, and sixteen-cylinder engines are in use.
3. Fuel System. The fuel system is designed to store liquid gasoline and to deliver it to the engine cylinders in the form of vapor mixed with air.
4. Electric System. The electric current performs several jobs on the car. It cranks the engine, furnishes electric sparks at the spark plugs that ignite the compressed mixture in the cylinders, operates the radio and heater motor, supplies light for night driving, and operates gauges on the dash of the car that indicate charging rate, oil pressure, engine temperature, and the amount of fuel in the tank.
The electronic system consists of the storage battery, cranking motor, generator, regulator, distribution, ignition coil, and spark plugs as well as wires and switches that connect these various units. Lights, radio, heater, indicating gauges, and other electrically operated devices are usually considered as accessory devices, since are not absolutely necessary to the operation of the car.
5. Power Train. The power that the engine develops must be transmitted to the car wheels, so that the wheels will rotate and cause the car to move. The power train performs this job, providing in the process several different gear ratios between the engine crankshaft and wheels, so that the crankshaft may rotate approximately four, eight, or twelve times to cause the wheels to rotate once. The power train consists of a series of gears and shaft, which mechanically connect the engine shaft with the car wheels, and contains a clutch, transmission or change gears, a propeller or cardan shaft, and the final drive.
6. Clutch. The clutch permits the driver to connect the crankshaft to, or disconnect it from, the power train. Its main part is a friction disk pressed tightly by springs to the smooth face of the engine flywheel. The flywheel is attached to the end of the engine crankshaft, and when the clutch is engaged, the friction disk is held against the flywheel so that it revolves with the flywheel. When the clutch foot pedal is depressed the friction disk moves away from the flywheel face and stops revolving; when the foot pressure on the clutch pedal is removed, the springs again force the friction disk against the flywheel face, so that it once more rotates with the flywheel. The rotary motion is transmitted through the clutch and clutch shaft to the transmission gears and from there through the propeller shaft and the final drive on to the rear wheels.
7. Transmission. The transmission or change gears provide a means of varying the gear ratios of the engine crankshaft and the wheels. There are three main gear positions in the automobile transmission: low gear, second gear and high gear. Thus the engine crankshaft may turn four, eight, or twelve times for each wheel revolution (approximately). In addition, a reverse gear is provided that permits backing the car.
The varying gear ratios are necessary since the engine does not develop much power at low engine speeds: it must be turning at a fairly high speed in order to deliver enough power to start the car moving. Thus, on first starting, the gears are placed in low speed so that the engine crankshaft will turn approximately 12 times for each wheel revolution. The clutch is then engaged, so that power is applied to the wheels. Car speed increases with engine speed until the car is moving 5 or 10 miles per hour, at which time the engine crankshaft may be turning as many as 2.000 r. p. m. The clutch is then disengaged, the gears are shifted in second, and the clutch is again engaged. A still higher car speed is obtained as engine speed is again increased; the gears are then shifted in high, the clutch being disengaged and engaged for this operation as before.
Упражнение 1. Закончите предложения, пользуясь текстом.
1. It consists of a fuel …
2. Most automobile engines have …
3. The heater, lights, radio, and other devices contribute …
4. The electric current performs …
5. The power must be transmitted …
6. The clutch permits the driver …
7. The transmission or change gears provide …
Упражнение 2. Ответьте на вопросы по тексту.
1. What components does automobile consist of?
2. The engine is the source of power that makes the wheel go around and the car move, isn't it?
3. What is the fuel system designed for?
4. What jobs does electric system perform?
5. The clutch permits the driver to connect the crankshaft to, or disconnect it from, doesn't it?
6. What provides a means of varying the gear ratios?
7. Does the electric current perform several jobs?
8. Does the car speed increase with the engine speed or not?
Text 2
Упражнение 1. Прочитайте текст и ответьте на вопросы.
1. Какому абзацу текста соответствует рисунок 3?
2. В каком абзаце текста дано упрощенное описание работы четырехтактного д. в. с.?
3. Сколько рабочих циклов д. в. с. упоминается в тексте, в каком (каких) абзаце (абзацах)?
Рисунок 3
Engine
1. An engine produces power by burning air and fuel. The fuel is stored in a fuel tank. The fuel tank is connected to a fuel pipe. The fuel pipe carries the fuel to a fuel pump. The fuel pump is connected to the carburettor. The fuel pump pumps the fuel into the carburettor. In the carburettor the fuel is mixed with air. The fuel and air are drawn into the engine cylinder by the piston. Then the fuel and air are compressed by the piston and ignited by the spark plug. They burn and expand very quickly and push the piston down. Thus the power is produced. The burned fuel and air are expelled from the cylinder by the piston.
2. The flow of gases into and out of the cylinder is controlled by two valves. There is an inlet valve allowing fresh fuel mixture into the cylinder and an exhaust valve which allows the burnt gases to escape.
3. There are two basic engine operating cycles:
a) the four-stroke cycle;
b) the two-stroke cycle.
The complete four-stroke cycle comprises:
1) the induction-stroke (the piston moves downwards);
2) the compression stroke (the piston moves upwards);
3) the power stroke (the piston moves downwards);
4) the exhaust stroke (the piston moves upwards).
Notes:
a stroke: the distance travelled by the piston (upwards or downwards) in the cylinder
t. d. e. (top dead centre): the position of the piston at the top of the stroke
b. d. c. (bottom dead centre): the position of the piston at the bottom of the stroke
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