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1、UNIT 3 Lubrication and Cooling System,PART 1 Technical and Practical Reading,Passage A Lubrication System,The engine lubrication system is designed to deliver clean oil at the correct temperature and pressure to every part of the engine. The job of the lubrication system is to distribute oil to the
2、moving parts to reduce friction between surfaces which rub against each other. The lubrication system mainly consists of oil pump, engine oil, oil filter, oil screen and oil pan. See figure 3-1.,Figure 3-1,Oil Pump,An oil pump being the heart of the system is located in the oil pan on the bottom of
3、the engine. The pump is connected by a worm gear to either the crankshaft or the camshaft. In this way, when the engine is turning, the oil pump is pumping.,Most oil pumps have two small gears that mesh with each other. A pressure-regulator valve in the pump is used to prevent the lubrication system
4、 from reaching too high a pressure. The oil pump pulls oil up from the oil pan and makes the engine oil circulate through the engine. See figure 3-2.,Figure 3-2,Engine Oil,Engine oil is often referred to as the lifeblood of an automobile engine. An engine running without oil will be just like a huma
5、n without blood. See figure 3-3.,Figure 3-3,Engine oil has several important jobs in the engine. First, it must be circulated between moving engine parts to prevent metal-to-metal contact. Without oil, metal-to-metal contact produces wear. Oil between moving parts allows them to move easily, with le
6、ss friction. The lower the friction of an engine, the more power it can develop.,The circulating oil also cools the engine by carrying heat away from hot engine components, and cleans or flushes dirt and deposits off the engine parts. Finally, oil circulated on the cylinder walls seals the rings, im
7、proving the engines compression.,Oil Filter,If engine oil is the lifeblood of an automobile engine, then the oil filter is the liver. Like the liver, the oil filter takes in dirty oil and removes the particulates and crud. This engine damaging crud remains trapped in the filter media and the oil fil
8、ter returns the clean oil back into the engine.,In addition to providing essential engine lubrication oil, this is also important for scrubbing the inside of the engine clean. Changing the oil and filter on a regular interval gives the engine a fresh transfusion for longer life. See figure 3-4.,Figu
9、re 3-4,Oil Screen,The oil pump pulls oil up from the oil pan through the oil screen. The oil screen collects any large particles of dirt so that the oil entering the pump is fairly clean. The pump then directs the oil through an oil filter, which strains any remaining dirt out of the oil, as the oil
10、 entering the engine lubrication passages should be clean. See figure 3-5.,Figure 3-5,Oil Pan,So long as engines require engine oil for them to run smoothly, engines will be equipped with oil pans to act as storage for such engine oil. Therefore, the main function of the oil pan is to store the engi
11、ne oil before it is pumped back again to the various engine parts. See figure 3-6.,Most engine oil pans have baffles that help control the flow direction of the oil, bringing it close to the oil pump for easier circulation. Oil pans are often made from thin steel sheet with a coat of alloy materials
12、 that allow the engine oil to cool faster. Further, most oil pans are equipped with magnetic drain plugs that not only allow the exit of old oil out of the pan, but also attracts the metal fragments that mixes with the oil.,Tow methods are used to circulate oil through an engine: pressure and splash
13、. In modern engine designs, these two methods are often combined. Pressure is developed by the oil pump, which delivers oil to the filter for cleaning before it is sent to the camshaft and valve train components at the top of the engine. Other components are lubricated by splashing oil and by a net-
14、work of passages.,New Words,lubricate lu:brikeit v. 润滑，涂油 distribute distribju(:)t v. 分配，散布 filter filt n. 筛选，滤波器，过滤器 reduce ridju:s v. 减少，分解，减低 circulate s:kjuleit v. 循环，流通（使）流传 lifeblood laifbld n. 鲜血，活力源泉，生命线 flush flF v. 冲洗 dirt d:t n. 污垢，泥土 deposit dipCzit n. 沉淀, 沉积物 liver liv n. 肝脏,particulate
15、 ptikjulit n. 微粒子，微粒，微尘 crud krd n. 杂质，掺和物，脏东西 scrub skrb v. 用力擦洗 baffle bfl n. 折流板（或挡板） transfusion trnsfju:n n. 输血，输液 trapped trpt adj. 收集的，截留的 interval intvl n. 间隔 drain drein n. 排水，排水管 fragment frgmnt n. 碎片，破片，断片 splash splF n. 溅的水，污点,Phrases and Expressions,lubrication system 润滑系统 oil pump 机油泵，
16、油泵 engine oil 机器润滑油 oil filter 机油滤清器 oil screen 滤油网 worm gear 蜗轮传动装置，蜗轮 pressure regulator valve 压力调节阀，调压阀 filter media 滤料，过滤介质 drain plug 放油塞，排泄螺塞,EXERCISE 2,Translate the following phrases into Chinese or English. 1. lubrication system 2. 机油滤清器 3. oil screen 4. 压力调节阀 5. filter media 6. 机器润滑油 7. oil pump 8. 放油塞/排
