Section b lubrication
Friction causes heat and wear. In an engine, oil lubricates the moving parts and reduces the heat and the wear. The oil also collects any small particles of dirt or metal and carries them to the oil filter.
Some of the oil will leak out of the engine when it is used. The amount of oil in the engine will need checking regularly. The dipstick is used for checking the amount of oil. If there is not enough oil in the engine, friction between the moving parts will increase and the engine will quickly become damaged.
The oil in the engine will need changing about once every 5000 km. If it is not changed, it will become thin and full of impurities and it will not lubricate efficiently. The oil filter will also need changing regularly. If it is not changed, it will become blocked by particles of dirt and metal. If the filter becomes blocked, the oil will not flow around the engine and heat and wear will increase very rapidly.
Some parts of a car need greasing - usually about once every six months. Fifty years ago cars needed greasing every week. Modern vehicles need much less greasing. They only need greasing about twice a year. Cars in the future will probably need no greasing.
Exercise 5 Are these statements true or false? Rewrite them if they are false.
1. Oil lubricates and collects dirt.
2. The oil filter is used for changing the oil.
3. Particles of dirt and metal will damage the moving parts of an engine.
A. The amount of oil in an engine does not change.
5. If the amount of oil in an engine decreases, the friction will increase.
6. The dipstick shows the amount of damage in an engine.
7. The oil in an engine needs changing regularly but the oil filter does not need changing.
8. Grease lubricates.
9. Early cars needed more greasing than modern cars. 10. Cars in the future will need more greasing.
Exercise 6 Often, will does not refer to the future but indicates something that always happens. For example: Friction will cause heat and wear.
Rewrite this paragraph using will in each sentence.
Friction causes heat and wear. In an engine, oil lubricates the moving parts and reduces heat and wear. The oil also collects any small particles of dirt and metal and carries them to the oil filter.
Now rewrite these sentences using will.
1. At normal pressure, water boils at 100°C. It freezes at 0°C.
2. Lead melts at 327°C.
3. An electric current flows from negative to positive.
4. Non-ferrous metals do not corrode easily.
5. A hacksaw cuts metal.
6. Low pressure decreases the boiling point of water.
7. In an open container, a liquid evaporates slowly.
8. A dry cell supplies 1.5 V.
Section c engine lubricating system
The basic purpose of lubricating is to reduce both friction and wear to the minimum and to prevent the engine parts from water and dirt.
The parts of the automobile engine are either fastened together or they move within close limits of each other. In the latter case they require lubrication. Without proper lubrication there would be so much friction that heat would melt some of the parts, close up clearances and stick the parts.
Lubrication engineers are faced with a number of highly technical problems. In the first place, it is necessary to produce a lubricating oil which will properly lubricate metallic parts. The lubricating oil must prevent these metallic parts from rubbing one on the other. The lubricating oil must carry heavy loads while during this work. Special attention should be paid to such parts as piston and valves and the conditions of their operation. Pistons, valves and other reciprocating parts are known to be subjected to very high temperatures caused by the burning of the fuel in the combustion chambers of the engine cylinders or by the friction. Therefore, the lubricating oil for the above mentioned parts must be resistant to high temperatures.
The selection of oils having the right viscosity is of great importance too. A highly viscous oil film will withstand considerable pressure but it will set up a great fluid friction which will generate additional heat. A driver should remember the general rule for selecting a lubricating oil. The oil should be the one that will carry the load under the given operating conditions and have the lowest possible viscosity.
Let us consider the equipment which is to do the work of lubricating the engine. The oil from the oil pan is circulated to the various parts by an oil pump. A modern engine is also provided with an oil filter. The use of a filter lengthens the time between oil changes and prolongs the life of the engine. The oil. gauge is at the upper left-hand position above the flywheel. It is to register the amount of pressure being developed by the pump. If a driver regularly examines the state of oil in the oil pan and checks up the oil pressure the service life of the engine in his car will be much longer.
Exercise 7 Answer the following questions. You may choose the correct answer from those given in parenthesis)
1. Does the engine of any road vehicle require greasing? What is the purpose of greasing?
In what way can small particles of dirt and metal be removed?
What engine parts should be paid great attention to when greasing?
What does a driver have to do if he wants to prolong the service life of his car?
(1. He has to examine regularly the state of oil in the oil pan. 2. They can be removed with the help of oil, which carries them to the oil filter. 3. Yes, it does. 4. Pistons, valves and spark plugs. 5. The purpose of greasing is to reduce friction and wear.)