II lubricating system

Active Vocabulary to Text B, I

NOTES

I COOLING SYSTEM

OF THE INTERNAL COMBUSTION ENGINE

THE BASIC SYSTEMS

TEXT B

As the fuel burns heat is produced and the temperature in the combustion chamber is very high. Some¹ of the heat goes into useful power, some is lost through the exhaust gases and some must be removed by a cooling system. The cooling system of the modern engines is based on the forced circulation method. Around the cylinder and the cylinder head there is a water jacket connected to a radiator by two tubes. Between the radiator and the water jacket there is a pressure pump used for continuous² circulation of the coolant in the cooling system. A fan behind the radiator removes the heat from the coolant. A thermostat controls the flow of the coolant from the radiator to the water jacket and back and regulates its temperature. The coolant in the water jacket removes heat from the hottest parts of the engine. Temperature for proper³ cooling is about 85^оC. It is necessary to look after the temperature of the coolant.

When the engine is overcooled the required structure of the explosive mixture is upset.

Heat is lost and the efficiency of the engine lowers. The friction is great and the cylinder walls and piston rings are quickly worn.

When the engine is overheated, its parts expand; friction increases and the pistons are wedged. The engine operation cycle is broken. The oil vaporizes and burns. Both overcooling and overheating causes the damage of the engine.

¹some - некоторая часть

²continuous - постоянный

³proper - нормальный

useful - полезный	control - регулировать
lose/lost, lost/ - терять	flow - поток
water jacket - водяная рубашка	remove - отводить
efficiency - экономичность	expand - расширять
tube - труба, патрубок	wedge - заклинивать
cool - охлаждать	coolant - охладитель
vaporise - испаряться	radiator - радиатор
cause - вызывать	thermostat - термостат
break /broke, broken/ - нарушать

1. Answer the questions.

1. Which devices does the cooling system include?

2. What is the scheme of the circulation in the cooling system?

3. What is the function of thermostat?

4. What happens when the engine is overcooled?

5. How does overheating affect the engine operation?

2. Describe the work of the cooling system.

To reduce the friction between the working parts that are never completely smooth¹, and to absorb some heat one should use different oil lubricants. The most common type of lubrication is the combination of the force feed method² and splash lubrication. Oil is circulated and distributed within the engine by a gear type oil pump.

It maintains the sufficient³ pressure to supply oil in proper⁴ quantities to all moving parts. The oil from the oil pan is sucked into the oil passage and delivered to the oil pump. Then it is forced into the oil filters. There it is cleaned from particles and supplied to the main bearings of the crankshaft, to the connecting rod bearings, to the camshaft bearings and to the cylinder block units, valve mechanism and other parts requiring lubrication.

As a result a thin oil film is produced on the working surfaces that keeps them apart⁵. In this way friction and wear are reduced and the engine parts are cooled, cleaned and washed by the lubricant.

If one uses less lubricant than is required, the engine overheats, the bearings may melt and the piston is jammed in the cylinders. With too much lubrication the excess⁶ oil leaks into the combustion chamber and burns there. It results in snuff on the chamber walls and on the valves. If the meter shows no oil pressure one must stop the engine at once and check it.

Possible reasons may be the following:

1) the oil pipe-lines or the pump drive are damaged;

2) the bearings melt.

Further engine operation is impossible. It needs repairing. When the oil pressure lowers you must check the pipelines and oil filters and wash them if it is necessary, cool the oil or change it. If the gasket between the oil pan and crankcase or the crankshaft bearing seals are damaged the engine must be repaired at a service station.

If the oil pressure is too high you must:

1) warm up the engine at low revolutions because the oil may be thickened;

2) clean the oil pipe-lines⁷ because they may be obstructed with particles and dirt.

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