UNIT 5 Lecturer: Lang Van Thang ENGLISH FOR AUTOMOBILE ENGINEERING HOW IT WORKS Presentation Read the text and complete the Figure 5.1(Look at the words in italics in the text): Many cars have a fuel warning light. When the level of fuel (petrol) in the tank is very low, this light switches on and the driver can see that he needs more petrol. How does this light work? When the level of the fuel falls, the float moves downwards. When this happens, the arm also moves downwards and makes the lever touch an electrical contact. This switches on the fuel light in the car. When the driver sees the fuel warning light, he puts more petrol into the tank. This makes the fuel level rise and pushes the float upwards. When the float rises, it makes the arm move upwards and this causes the lever to move upwards also. The fuel warning light then switches off. Presentation Practice 1 Use the words in the Figure 5.2 to complete the passage below: Most cars use _________ to cool the engine. Water flows from the __________ through a system of water passages and _______ _______. A _____ _______ pushes the water round. This system is known as the cooling system. water radiator rubber hose water pump Practice 2 Use the description of the cooling system in Practice 1 to complete the description of the lubricating system; refer to Figure 5.3. Cars use _________ to lubricate the _________. Oil _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _____. oil engine flows from the sump through a system of oil passages and metal pipe. A oil pump pushes the oil round This system is know as the lubricating system Practice 3 Using Figure 5.2 to connect the sentences in the right order: Start: Most car engines are cooled by water._ _ _ _ _ _ _ _ _ . 1. The water flows around the engine to make the engine cool and the water is hot. 2. There are some stages in the cooling process. 3. The water pump pushes the water around the engine again. 4. The hot water enters the radiator through the top hose. 5. The cool water leaves the radiator through the bottom hose. 6. It flows down the lower tank through the radiator. 7. Here it is cooled by air. 8. Water is pumped from the engine to the top (receiving) tank where it spreads over the tops of the hoses. Practice 4 Look at this extract from a tour of a car factory and complete the text with the words below. Practice 4 Development 1 Read the text and label Figure 5.4. The two diagrams in Figure 5.4 show the pushrod and valve operation in one type of petrol engine. When the pistons move up and down in the cylinders, the connecting rods push the crankshaft round. This rotary movement also turns the crankshaft sprocket. The crankshaft sprocket drives the timing chain to turn the larger camshaft sprocket. The crankshaft to camshaft speed ratio is 2:1. The camshaft has two cams for each cylinder; there are therefore 8 cams in a 4-cylinder engine, i.e. one for each pushrod. Development 1 When the camshaft rotates, the cams raise and lower the cam followers to operate the pushrods. Each cam follower controls one pushrod. When the latter moves up, the top end of the pushrod operates the valve rocker. The rocker shaft does not move so when the pushrod raises one valve rocker arm, the one on the same rocker moves down to open the valve. This downward movement compresses the valve spring. When the cam moves past the highest point, the cam follower and the pushrod fall; the valve spring expands to close the valve. . UNIT 5 Lecturer: Lang Van Thang ENGLISH FOR AUTOMOBILE ENGINEERING HOW IT WORKS Presentation Read the text and complete the Figure 5. 1(Look. Practice 4 Development 1 Read the text and label Figure 5. 4. The two diagrams in Figure 5. 4 show the pushrod and valve operation in one type of petrol