汽車實(shí)用英語(已整理)

1、.：.；Valves and Valve TrainThe valve gear of an internal combustion engine provides timely admission of the fresh charge into the cylinders and exhaust of spent gases from them. For this purpose the valves at definite moments open and close the intake and exhaust ports in the cylinder head, through w

2、hich the cylinders communicate with the intake and exhaust manifold.The valve gear is composed of timing gears, a camshaft, tappets, valves, spring with fasteners and valve guides.The timing gears in most engines are housed in a special case fitted at the front end of the engine. These are necessary

3、 to transmit rotation from the crankshaft to the camshaft, fuel injection pump shaft, and to oil pump and other mechanisms.The gears are made of steel and use helical teeth to reduce noise.Camshafts function is to open the engine valves positively and timely, in a definite sequence, and to control t

4、heir closing against the return action of the valve springs. The shaft is made integral with its cams and bearing journals. Each cam controls a single valve, either intake or exhaust. In some automobile engines, the camshaft is made integral with fuel pump eccentric wheel and oil pump drive gear. Th

5、e camshaft bearings are lubricated with oil supplied under pressure from the main gallery in the cylinder block.The tappets serve to transmit the force from the camshaft to the push rods. The tappets are small cylindrical bores receiving the push rods. They are made of cast iron or steel and located

6、 in the guides, which may be made integral with the cylinder block or removable as in the engine. When the engines operate, the tappets continuously rotate about their axes for uniform wear. The rotation is ensured by a convex surface of their bottoms and a slanted surface of the cams.The push rods

7、transmits the force from the tappets to the rocker and are made as steel stems with hardened tips or duralumin tubes with spherical steel tips press-fitted at. both ends. The push rod tips bear against the tappet hollow at one end against the spherical surface of rocker adjusting screw at other.The

8、rockers transmit the force from the push rod to the valve. The rockers are made from steel and are installed on a hollow fulcrum. A bronze bush is press fitted into the rocker hole to reduce friction. The hollow fulcrum is supported by standards on the cylinder head. Endplay of the rocker is prevent

9、ed by a coil spring.The rocker arm is a bell crank made of steel. At the middle of the rocker arm, there is a boss with a bore into which is pressed the bushing. A hardened curved pad is provided on the end of the rocker where it contacts the valve stem tip, while a threaded hole is machined in its

10、other end to receive the adjusting screw used to set the valve clearance, the clearance between the rocker contact pad and the valve stem tip, so that the valve will be tightly pressed against its seat when hot. The rocker arm freely oscillates about the rocker-arm shaft supported by a series of ped

11、estals or brackets, which are bolted to the top deck of the cylinder head.An engine valve is a device designed to open a passage when moving in one direction and to close it when moving in the opposite direction. Each cylinder of a four-stroke-cycle diesel or gasoune engine is commonly equipped with

12、 an intake valve and an exhaust valve. The purpose of the intake valve is to allow the air fuel mixture or air to enter the cylinder. After the combustion process has been completed, the burned gases are permitted to escape from the cylinder though the exhaust valve. To obtain sufficient valve area,

13、 some automobiles have two intake valves and two exhaust valves.A valve consists of a head and stem. The valve head has a narrow chamfer of 45 or 30 referred to as valve face. The valve face fits tightly against the seat, which is achieved by grinding.For better engine breathing, the inlet valve has

14、 a larger diameter than the exhaust one. As the valves are not equally heated in the running engine, they are made from different materials. The inlet valves are made from chromium steel, the exhaust valves are of silchrome heat-resistant steel.The cylinder stem of the valve has a recess at the uppe

15、r end for fastening the valve spring. The valve stems slide in the cast-iron or cerametallic valve guides.The valve spring provides the force necessary to close the valve and hold it tightly against its seat.Some engines use two springs on each valve, which reduce the size of the springs, improves t

16、heir reliability, and makes their operating conditions less arduous.Valve guide supports the valve stem and guides its movement so that the valve face remains perfectly concentric with the valve seat and fits it without any skewing. Replaceable valve guides are fabricated from cast iron or a cermets

17、 material and pressed in the cylinder head.To decrease oil penetration along the valve stem to the combustion chambers, the seating collars are fitted with rubber rings or the seats are provided with rubber caps. More uniform heating and wear of the valve are ensured with the valves rotating during

18、the operation of the engine. In general, there are two ways of rotating: one is free rotate the other is positive rotate.As the valve is opened, spring is compressed and its increasing load causes the flexible washer to flatten out and force balls down their ramps against the resistance offered by t

19、heir return springs .As the balls roll down, they turn through some angle the flexible washer, seating collar and valve spring together with the valve; when the valve is closed, the valve spring load decrease, the flexible washer deflects to acquire its initial conical shape and abutting against a s

20、houlder in housing, releases the balls which are then forced by their coil springs to return to their starting position.配氣機(jī)構(gòu) 內(nèi)燃機(jī)的配氣機(jī)構(gòu)保證新穎混合氣可以適時(shí)進(jìn)入汽缸，同時(shí)熄滅后的廢氣及時(shí)排出。為實(shí)現(xiàn)這一目的，氣門在一定的時(shí)辰翻開和封鎖汽缸蓋上的進(jìn)排氣道，汽缸經(jīng)過進(jìn)排氣歧管與進(jìn)排氣管相溝通。 配氣機(jī)構(gòu)由正時(shí)齒輪、凸輪軸、挺柱、氣門、帶有鎖緊安裝的彈簧和氣門導(dǎo)管組成。 大多數(shù)發(fā)動(dòng)機(jī)的正時(shí)齒輪裝在專門的殼體內(nèi)，正時(shí)齒輪殼體位于發(fā)動(dòng)機(jī)前端。必需運(yùn)用正時(shí)齒輪將曲軸的旋轉(zhuǎn)傳送

21、到凸輪軸，驅(qū)動(dòng)噴油泵軸、機(jī)油泵和其他的安裝。正時(shí)齒輪由鋼制成，采用螺旋狀齒以減少噪聲。 凸輪軸的功用是按特定的順序準(zhǔn)確適時(shí)地翻開氣門并經(jīng)過氣門彈簧的回位作用控制氣門的封鎖。凸輪軸與凸輪、軸頸制為一體。每個(gè)凸輪控制一個(gè)氣門:進(jìn)氣門或排氣門。有些汽車發(fā)動(dòng)機(jī)的凸輪軸也與驅(qū)動(dòng)燃油泵的偏心輪和機(jī)油泵的驅(qū)動(dòng)齒輪做成一體。缸體內(nèi)主油道的機(jī)油在壓力作用下到達(dá)凸輪軸軸頸提供光滑。 挺柱用來把凸輪軸的作用力傳送給推桿。挺柱為圓柱形小筒，里面插入推桿。挺柱資料為鑄鐵或鋼，定位于導(dǎo)管內(nèi)，挺柱導(dǎo)管可以是與缸體一體的或者是可裝配的。發(fā)動(dòng)機(jī)任務(wù)時(shí)，為使磨損均勻，挺柱總是繞其軸線旋轉(zhuǎn)。挺柱的旋轉(zhuǎn)是由挺柱凸起的下外表和凸輪傾斜

22、面所保證的。 推桿將挺柱傳來的推力傳給搖臂。推桿由頂部淬火的鋼柱或由兩端壓入配合的帶球形鋼頭的硬鋁控制成。推桿的兩端一頭支撐在挺柱的空腔內(nèi)，另一頭與搖臂調(diào)整螺釘端的球形外表配合。 搖臂把推桿的作用力傳送到氣門。搖臂由鋼制成，安裝于空心的樞軸。搖臂空內(nèi)裝有青銅襯套以減少摩擦。中空的搖臂軸經(jīng)過支架固定于汽缸蓋。搖臂上的螺旋彈簧防止產(chǎn)生軸向竄動(dòng)。搖臂是鋼制的雙臂杠桿。搖臂中部有一帶孔的凸臺(tái)，孔內(nèi)壓裝有襯套。搖臂的一端是經(jīng)過淬火的圓弧狀長臂，與氣門桿尾端接觸，而車有螺紋孔的另一端安裝有調(diào)整螺釘，用來調(diào)整搖臂與氣門桿尾端之間的氣門間隙，從而保證氣門在受熱后緊緊壓在氣門座上。搖臂可以繞搖臂軸自在擺動(dòng)，搖臂

23、軸經(jīng)過一系列支座支撐，支座用螺栓固定于汽缸蓋上外表。 發(fā)動(dòng)機(jī)氣門向某一萬向運(yùn)動(dòng)時(shí)開啟-通道，而它向相反方向挪動(dòng)時(shí)那么封鎖此通道。四行程汽油機(jī)或柴油機(jī)的每缸普通都裝有進(jìn)氣門和排氣門。%氣門的作用是使空氣燃油混合氣進(jìn)入汽缸。熄滅過程完成后廢氣經(jīng)過排氣門排出汽缸。為了獲得足夠的充氣面積，有些發(fā)動(dòng)機(jī)采用兩個(gè)進(jìn)氣門和兩個(gè)排氣門。 氣門由頭部和桿身組成。氣門頭部相對(duì)于氣門平面之間存在45?；?0。的錐角。經(jīng)過研磨使氣門平面與氣門座嚴(yán)密貼合。 為使發(fā)動(dòng)機(jī)更好地?fù)Q氣，進(jìn)氣門(頭部)直徑大于排氣門。在發(fā)動(dòng)機(jī)任務(wù)時(shí)由于進(jìn)、排氣門受熱不均等，因此它們采用不同的資料制成。進(jìn)氣門采用鉻鋼，排氣門采用耐熱硅鉻鋼。 圓柱氣

24、門桿身的上部有一凹槽用來固定氣門彈簧。氣門桿身在鑄鐵或金屬陶瓷氣門導(dǎo)管內(nèi)運(yùn)動(dòng)。 氣門彈簧提供氣門封鎖時(shí)所需求的作用力，保證氣門與氣門座嚴(yán)密貼合。 有些發(fā)動(dòng)機(jī)的每個(gè)氣門裝有兩根彈簧，可以減小所運(yùn)用的彈簧大小，添加可靠性，使任務(wù)更平穩(wěn)。 氣門導(dǎo)管支撐氣門桿身，對(duì)其運(yùn)動(dòng)起導(dǎo)向作用，以保證氣門X閉時(shí)能準(zhǔn)確地與氣門座貼合而不產(chǎn)生偏移。可裝配式氣門導(dǎo)管采用鑄鐵或金屬陶瓷資料制成，壓入汽缸蓋上的(氣門導(dǎo)管。 為防止機(jī)油從氣門桿滲進(jìn)熄滅室，在氣門導(dǎo)管上裝有橡膠環(huán)或橡膠皮碗。發(fā)動(dòng)機(jī)任務(wù)時(shí)經(jīng)過氣門的旋轉(zhuǎn)可以使氣門獲得更均勻的受熱和磨損。通常有兩種實(shí)現(xiàn)氣門旋轉(zhuǎn)的方式：自在旋轉(zhuǎn)和強(qiáng)迫旋轉(zhuǎn)。 當(dāng)氣門開啟時(shí)，彈簧被緊縮，

25、彈力添加，將彈性墊圈壓平，迫使鋼球抑制回位彈簧的阻力沿斜坡滾動(dòng)。當(dāng)鋼球滾下時(shí)，帶動(dòng)彈性墊圈、氣門彈簧與氣門一同轉(zhuǎn)過一個(gè)角度;當(dāng)氣門封鎖時(shí)，氣門彈簧彈力減小，彈性墊圈變形為原來的圓錐狀，支撐于殼體的支撐板，鋼球在回位彈簧作用下回到原來位置。Engine Cooling SystemThe purpose of the cooling system is to keep the engine at its most efficient operating temperature at all speeds under all driving conditions. As fuel is burne

26、d in the engine, about one-third of the heat energy in the fuel is converted into power. Another third goes out through the exhaust pipe unused, and the remaining third must be handled by the cooling system. This means that the engine can work effectively only when the heat energy is equally handled

27、 so as to keep the engine temperature in balance:So, the temperature is quite essential for an engine to produce power. No engine can work well without suitable operating temperatures. If the engine runs too hot, it may suffer from pre-ignition, while the air-fuel charge is ignited prematurely from

28、excessive combustion chamber temperature. Viscosity of the oil circulating in an over heating engine is reduced. Hot oil also forms varnish and carbon deposits may be drawn into the combustion chamber where it increases HC emission. This also causes poor performance and premature wear, and may even

29、result in engine damage. Whats more, the behavior of the metals at excessively high temperature also differs from that at normal temperatures. If the engine runs too cold, the fuel will not vaporize properly. If liquid fuel reaches the cylinders, it will reduce lubrication by washing the oil from th

30、e cylinder walls and diluting the engine oil. This causes a loss of performance, an increase in HC emissions, and premature engine wear. For these reasons, a cooling system of some kind is necessary in any internal combustion engine.There are generally two different types of cooling system: water-co

31、oling system and air-cooling system. Water-cooling system is common. The cooling medium, or coolant, in them is either water or some low-freezing liquid, called antifreeze. A water-cooling system consists of the engine water jacket, thermostat, water pump, radiator, radiator cap, fan, fan drive belt

32、 and necessary hoses.A water-cooling system means that water is used as a cooling agent to circulate through the engine to absorb the hot and carry it to the radiator for disposal. The engine is cooled mainly through heat transfer and heat dissipation. The heat generated by the mixture burned in eng

33、ine must be transferred from the iron or aluminum cylinder to the water in the water jacket. The outside of the water jacket dissipates some of the heat to the air surrounding it, but most of the heat is carried by the cooling water to the radiator for dissipation. When the coolant temperature in th

34、e system reaches 90 C, the thermostat valve open fully, its slanted edge shutting off the shorter circuit so that the coolant circulates through the longer one: water-pump-cooling jacket -thermostat -radiator top -tank -radiator core -bottom tank -pump.Water pumps have many designs, but most are the

35、 centrifugal type. They consist of a rotating fan, or impeller, and seldom are of the positive displacement type that uses gear or plungers. Many water pumps have a spring-loaded seal to avoid leakage of water around the pump shaft. Some V-type engines have a pump on each cylinder block.The radiator

36、 is a device designed to dissipate the heat which the coolant has absorb from the engine; it is constructed to hold a large amount of water in tubes or other passages which provide a large area in contact with the atmosphere.The radiator usually mainly consists of the radiator core, radiator bottom

37、tank, and radiator top tank. Radiator cores are of two basic types, the fin and tube type (fins are placed around the tube to increase the area for radiating the heat) and of the ribbon cellular or honey comb type. The popular fin and tube type of radiator core has the advantage of fewer soldered jo

38、ints and is therefore a stronger construction. It consists of a series of parallel tubes extending from the upper to the lower tank. The honeycomb type core consists of a large number of narrow water passages made by soldering pairs of thin metal ribbons together along their edges. These tubes are s

39、eparated by fins of metal ribbon, which help dissipate the heat.The radiator cap serves not only to prevent the coolant from splashing out the filler opening, but also to prevent evaporation of the coolant.The fan is designed to draw cooling air through the radiator core. The fan is usually mounted

40、on an extension of the water pump shaft and is driven by a V-belt from a pulley mounted on the front end of the crankshaft. Usually the same belt drives the alternator, and belt tension is adjusted by swinging the alternator on its mounting.An air-cooling system contains a centrifugal fan, thermosta

41、t, fan drive belt, radiator fin, baffle plates, air control ring, etc. An air-cooling system means that air is used as a cooling agent to circulate through the engine to carry the heat away from the moving parts. When the engine is running, force air is directed over and through the fins to dissipat

42、e the heat. In order to regulate the engine temperature by controlling the volume of cooling air, a thermostat is installed inside the metal housing which encloses the engine.The thermostat unit is connected to an air control ring. As the engine becomes hotter, the control ring opens wider to admit

43、more air, and closes when the engine is cold. With the ring closed, air circulation is restricted, and a cold engine warms up more rapidly. Rapid warm-up is one of the characteristics of air-cooled engine, since they do not have heat water in cylinder jackets and radiator.The engine cooling system a

44、ctually is a temperature-regulation system. For a late-model engine, the cooling system must maintain a temperature that is high enough for efficient combustion but not so high that the engine will be damaged. The two jobs of the cooling system are to carry excess heat away from the engine and maint

45、ain uniform temperature through the engine. These requirements are very critical for an engine with electronic controls that must maintain precise air-fuel ratios for economy and emission control.發(fā)動(dòng)機(jī)冷卻系統(tǒng) 冷卻系統(tǒng)的功用是保證發(fā)動(dòng)機(jī)在任何行車條件、任何車速堅(jiān)持最有效的任務(wù)溫度。燃料在發(fā)動(dòng)機(jī)中熄滅，約三分之一的熱能轉(zhuǎn)化為動(dòng)力，還有三分之一的熱能從排氣管排出，剩下的三分之一熱能由冷卻系統(tǒng)來處置。這就

46、意味著只需當(dāng)熱能被平衡地控制，堅(jiān)持發(fā)動(dòng)機(jī)溫度平衡，發(fā)動(dòng)機(jī)才干有效地任務(wù)。 因此，溫度對(duì)于發(fā)動(dòng)機(jī)產(chǎn)生動(dòng)力來說是至關(guān)重要的。假設(shè)沒有適宜的任務(wù)溫度，發(fā)動(dòng)機(jī)就不能正常任務(wù)。假設(shè)發(fā)動(dòng)機(jī)過熱，過高的熄滅室溫度會(huì)過早點(diǎn)燃混合氣，機(jī)油黏度會(huì)下降，熱機(jī)油也會(huì)構(gòu)成機(jī)油氧化膜，熄滅室會(huì)構(gòu)成積碳，添加HC排放。過熱還會(huì)呵斥發(fā)動(dòng)機(jī)性能下降、早期磨損，甚至導(dǎo)致發(fā)動(dòng)機(jī)損壞。再者，金屬資料在過高溫度和正常溫度下的性能是截然不同的。假設(shè)發(fā)動(dòng)機(jī)溫度過低，燃油汽化不好。假設(shè)液態(tài)燃油進(jìn)入汽缸，燃油將沖刷缸壁的機(jī)油、稀釋機(jī)油而降低光滑效果。這也將導(dǎo)致發(fā)動(dòng)機(jī)性能下降、HC排放添加、發(fā)動(dòng)機(jī)早期磨損?；谶@些緣由，內(nèi)燃機(jī)必需有某種方式的冷

47、卻系統(tǒng)。 通常有兩種方式的冷卻系統(tǒng):水冷系統(tǒng)和風(fēng)冷系統(tǒng)(汽車發(fā)動(dòng)機(jī))普遍采用水冷系統(tǒng)。其中的冷卻介質(zhì)或冷卻液為水或某些低凝點(diǎn)液體，被稱為防凍液。水冷系統(tǒng)由發(fā)動(dòng)機(jī)水套、節(jié)溫器、水泵、散熱器(水箱)、散熱器蓋、風(fēng)扇、風(fēng)扇驅(qū)動(dòng)皮帶和必要的軟管組成。 水冷系統(tǒng)是指以水作為冷卻劑在發(fā)動(dòng)機(jī)內(nèi)循環(huán)吸收熱量，然后到水箱散熱。發(fā)動(dòng)機(jī)的冷卻主要經(jīng)過熱量的交換和耗費(fèi)?；旌蠚庀绠a(chǎn)生的熱量必需從鑄鐵或鋁制汽缸傳送到水套中的水。水套外側(cè)將部分熱量發(fā)散到周圍的空氣中，但大部分熱量經(jīng)過冷卻液到達(dá)水箱進(jìn)展散熱。當(dāng)冷卻液溫度到達(dá)g0C時(shí)，節(jié)溫器完全翻開，節(jié)溫器傾斜邊緣封鎖小循環(huán)，冷卻液大循環(huán)流動(dòng):水泵+冷卻水套+節(jié)溫器+散熱器

48、進(jìn)水室+散熱器心部+散熱器出水室+水泵。 水泵的設(shè)計(jì)各異，但多數(shù)采用離心式。水泵由旋轉(zhuǎn)的葉輪組成，少數(shù)容積式水泵采用齒輪或柱塞。許多水泵帶有彈性密封件，防止水泵軸周圍漏水。一些V型發(fā)動(dòng)機(jī)兩側(cè)缸體都有水泵。 散熱器用于分發(fā)由冷卻液所吸收的發(fā)動(dòng)機(jī)的熱量，因此散熱器的構(gòu)造保證水管內(nèi)可以包容大量的水，并且保證盡量大的散熱面積。 散熱器通常由心部、上儲(chǔ)水室和下儲(chǔ)水室組成。散熱器心部有兩種根本類型:管片式(散熱片位于水管周圍以添加散熱面積)和管帶式或蜂窩型。常見的管片式散熱器心部優(yōu)點(diǎn)是焊接點(diǎn)少，因此強(qiáng)度高。管片式心部由一系列從上儲(chǔ)水室延伸至下儲(chǔ)水室的平行水管組成。蜂窩型心部由大量的窄的水道組成，每對(duì)細(xì)金屬

49、帶的兩端焊接起來就構(gòu)成了水道;這些水管經(jīng)過金屬散熱片隔開以利于散熱。 散熱器蓋不僅防止冷卻液從加水口濺出，也防止冷卻液蒸發(fā)。 風(fēng)扇把冷空氣吸進(jìn)散熱器心部。風(fēng)扇通常安裝在水泵軸的延伸處，曲軸前端的一皮帶輪經(jīng)過v形皮帶驅(qū)動(dòng)風(fēng)扇。這根皮帶普通也驅(qū)動(dòng)交流發(fā)電機(jī)任務(wù)，皮帶的張緊度經(jīng)過在支座上擺動(dòng)發(fā)電機(jī)的位置來進(jìn)展調(diào)整。 風(fēng)冷系統(tǒng)包括離心式風(fēng)扇、節(jié)溫器、風(fēng)扇驅(qū)動(dòng)皮帶、散熱片、導(dǎo)流板、空氣控制罩等。風(fēng)冷系統(tǒng)運(yùn)用空氣作為冷卻劑，空氣在發(fā)動(dòng)機(jī)內(nèi)循環(huán)流動(dòng)，帶走運(yùn)動(dòng)部件的熱量。當(dāng)發(fā)動(dòng)機(jī)任務(wù)時(shí)，空氣流經(jīng)散熱片進(jìn)展散熱。為了經(jīng)過控制冷卻空氣的體積來調(diào)理發(fā)動(dòng)機(jī)的溫度，圍繞在發(fā)動(dòng)機(jī)周圍的金屬殼體內(nèi)裝有節(jié)溫器。 節(jié)溫器與空氣

50、控制罩相連。發(fā)動(dòng)機(jī)溫度升高時(shí)，空氣控制罩開度添加，以進(jìn)入更多空氣;發(fā)動(dòng)機(jī)冷卻后，空氣控制罩封鎖，空氣的循環(huán)便停頓，這樣冷機(jī)可以迅速走熱。由于風(fēng)冷發(fā)動(dòng)機(jī)沒有水套和散熱器，因此迅速熱機(jī)是其特點(diǎn)之一。 發(fā)動(dòng)機(jī)冷卻系統(tǒng)本質(zhì)是溫度調(diào)理系統(tǒng)。新型發(fā)動(dòng)機(jī)的冷卻系統(tǒng)使發(fā)動(dòng)機(jī)堅(jiān)持在足以獲得高效熄滅的高溫下任務(wù)，但又不致?lián)p壞發(fā)動(dòng)機(jī)。冷卻系統(tǒng)的兩項(xiàng)任務(wù)就是帶走過度熱量和維持發(fā)動(dòng)機(jī)一定的任務(wù)溫度。這些要求對(duì)于保證準(zhǔn)確空燃比、追求好的燃油經(jīng)濟(jì)性和良好排放的電控發(fā)動(dòng)機(jī)而言是非常關(guān)鍵的。Engine Lubrication SystemAn automobile could not move itself without

51、the aid of friction. However, excessive friction in the engine would mean rapid destruction. Of course, we cannot eliminate friction, but we can reduce it to a considerable degree by the use of lubrication oil so that the automobile can move smoothly with proper friction.The engine lubrication is ma

52、inly conducted by the lubrication oil, which has several functions in the lubricating system : first of all, the oil forms a protective coating on the metal surface and prevents a metal to metal contact, thus reducing friction and minimizing wear. Secondly, as the oil is fed to the various moving pa

53、rts of the engine, it absorbs and carries the heat away from the engine parts. Thirdly as the oil circulates through the moving parts of the engine, it tends to wash off dirt away from the engine parts. Finally, the oil absorbs shocks between bearings and other engine parts, and forms a good seal be

54、tween piston ring and cylinder walls.Engine lubricating systems are divided into two types: splash, pressure feed. In the splash lubricating system, there are dippers on the lower parts of the connecting rod bearing caps; these dippers enter oil trays in the oil pan with each crankshaft revolution.

55、The dippers splash oil to the upper parts of the engine. The oil is thrown up as the oil sprays, which provides adequate lubrication to valve mechanisms, cylinder walls, piston rings and bearings.The splash system of lubrication is a simple method and only works successfully if the oil in the sump i

56、s maintained at the correct level, neither too high nor too low, and the engine is kept horizontal.Pressure or forced lubrication is used in practically all engines apart from simple lubrication and splash lubrication, and is characterized by the oil being fed under pressure from a pump to the major

57、ity of engine parts, especially to main bearings and connecting rod bearings.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

58、 the engine. Other components are lubricated by splashing oil and by a network of passages, or galleries.The lubricating system, no matter what type, has the job if supplying adequate amounts of oil to all moving engine parts so that the oil can do the various jobs. In some heavy-duty engines, where

59、 the oil has a harder and hotter job to do, oil cooler is included in the lubricating system. The oil cooler has a radiator much like the cooling system radiator, through which the oil passes; this cools the oil. All engines have some sort of level indicator, which usually consists of a dipstick, or

60、 oil lever stick, that enters the crankcase from the side of the block. To check the oil lever in the open pan, the dipstick can be pulled out and the height of the oil on the stick noted. Oil can then be added if the oil lever is too low for adequate engine protection.In general, the lubrication sy