CONSTRUCTIONAL FEATURES

OF MODERN TRACTORS

Farmers are the principal users of tractors. That is why tractor development is closely¹ connected with agricultural operations. Engineers and designers constantly have to improve the models of tractors. Agriculture needs powerful machines that can provide efficient performance, easy operation, total quality and reliability and long service. Modern tractors are to be constructed with certain features. The basic parts of a tractor are the frame, the traction mechanism, the efficient power unit, the transmission power system, the steering unit, and the working and auxiliary devices.

The frame carries numerous parts that form the tractor. The frame must be rigid² to fix all the units on their places. To prevent tractor parts from damage three-point suspension is commonly used. Two points of the suspension are attached to the rear axle and one point is fitted to the middle of the front axle.

The traction mechanism of a tractor may be of two types: pneumatic wheels or tracks. Tracks are more reliable on heavy, sandy or hilly lands where wheels don't provide perfect adhesion with the soil.

The power unit includes a powerful diesel or petrol engine in which fuel is converted into mechanical energy. Unlike³ a car engine tractor engine is low-speed. The engine may be air-cooled or water-cooled, the latter⁴ being more popular. To lubricate the engine, the force feed method is used.

The transmission system consists of a clutch, mechanically operated gear mechanism, shafts, axles, differential and drives. The function of this system is to transmit the power produced by the engine to the driving speeds of the tractor, operating in different conditions. The transmission system should be compact and reliable.

The steering unit causes the tractor to move, change speed and direction. The working equipment consists of a PTO-shaft, a pulley, a hydraulic system to mount mechanisms, a three-point linkage to control implements. The auxiliary⁵ equipment includes a cab and an operator's seat, heating system; light and sound control devices, etc. One has to know all parts of a tractor and keep them in order to use it with the highest efficiency.

NOTES

¹closely - тесно

²rigid - жесткий

³unlike - в отличие от

⁴latter - последний

⁵auxiliary - вспомогательный

Active Vocabulary to Text В

EXERCISES

1. Translate the following words into English.

Определенные черты, сельскохозяйственные работы, постоянное улучшение, ходовая часть, трех точечная подвеска, эффективный и надежный трактор, полная сцепка, метод принудительной смазки, основные части трактора, рабочие и вспомогательные приспособления, многочисленные части, гусеницы, песчаная почва, двигатель, низкоскоростной, валы, оси, передачи, система отопления.

2. Agree or disagree with the statements using:

It's right; it will do; sure; I don't think so; I'm of a different opinion.

1. Tractors are more often used for military purposes than for farm jobs.

2. Modern tractors have a power unit, transmission system, steering unit, working and auxiliary equipment.

3. The frame must be rigid.

4. Three-point suspension is attached to the front and rear axles.

5. Pneumatic wheels can be replaced by two tracks.

6. Tractors are always equipped with diesel engines.

7. Shafts, axles, drives, gears and a clutch are the parts of the transmission system.

3. Read the description of devices or systems and name them.

a) a rigid device to carry numerous parts that form a tractor;

b) a device that prevents tractor parts from damage;

c) devices used to support the frame;

d) a device in which fuel is converted into mechanical energy;

e) a system that transmits power from the engine to the driving wheels;

f) a system that provides non-friction operation of the engine parts;

g) a system that controls the temperature of the engine;

h) a system that helps to mount implements.

4. Add some more facts to make the following statements more precise and complete.

1. The design of a tractor is connected with its function.

2. The basic parts of a tractor are a frame, an engine and working equipment.

3. The frame carries numerous parts of the tractor.

4. Three-point suspension is used on the tractor.

5. The traction mechanism is of two types.

6. The tractor has a power unit.

7. The function of the transmission system is to transmit the power.

8. Working and auxiliary equipment include a hydraulic system to mount implements.

5. Describe some parts of a tractor:

a) the frame;

b) the power unit;

c) the transmission system.

TEXT C

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