23 Phrases and Expressions 起,连同………一起 g with与……道,以及,除………之外 ate压盘压力板,压板 oupled with与…连接,与……联同 he fitted to装配到……上,安装到………,配合 a release yoke分离叉 contml linkage控制杆系,操作杆系 with the aid of借助于,用,通过 thermal- insulation gasket隔热衬垫,绝热垫圈 let out放出,放大 Notes The transmission of power through the clutch is accomplished by gradually bringing one or more rotating drive members connected to the engine crankshaft into contact with one or more driven members connccted to the transmission input shaft 经过离合器的动力输出主要是由与发动机曲轴相连的一个或多个驱动元件与一个或多个 动力输人轴相联的被驱动元件相接触形成的。 bringing为动名词短语,做介词by的宾语; mating现在分词短语作定语; driven过去分 词作定语修饰 members; connected to…过去分词作定语修饰 members 2. The springs spaced around the circumference between the pressure plate and the clutch cover lamp the: driven disk between the pressure plate and the flywheel 沿压盘和离合器之问的圆周均匀分布的弹簧夹住压盘与飞轮之间的从动盘。 spaced arounD-…为分词短语,作定语修饰 springs Unit Two Automobile transmission As we know, an engine can generate only limited torque at low speeds. Driving condition is very complicated and this required the tractive effort and speed vary in a large scope. And without sufficient torque,moving a heavily loaded vehicle from a standing start is impossible. In any engine, the crankshaft always rotates in he direction. If the engine transmitted its power directly to the drive axies, the wheels could be nly in one direction Given a leve an automobile without a transmission could be made to move by accelerating the engine and engaging the clutch. However, a start under these conditions would be slow, noisy and comfortable. In addition, it would place a tremendous strain on the engine and driving parts of the So in order to get smooth starts and have power to pass and climb hills, a power ratio must be provie to multiply the torque and tuming effor of the engine. Also required is a speed ratio to avoid the need
24 fur extremely high engine rpm at high road speeds. The transmission is geared to perform thesc functions A trans nission is a speed and power changing device installed at some point between the engine and driving wheels of the vehicle. It is designed fur changing the torque transmitted fron the engine crankshaft to the propeller shaft, reversing the vehicle movement and disengaging the engine from the drive line for a long time at parking or coasting. A higher torque should be applied to the wheels to set an automobile in notioN OT IN/: uphill with a full load that to keep it roLling after it gets under way on level stretches of the road. when inertia is high and tractive resistance is low. To meet these variable torque requirements special gear boxes are used. Such gear boxes are called fixed-ratio transmissions. Fig. 2-2) e Fig 2-2 Automobile transmissio I--exgistant-mesh gear 2-input shaft 3--splines 4-geaur 5-gear rir 6-cover with gear shift mechanisn 7-olput shaft 8-reverse gear cluster -axle 10--hosing 11-sliling gears 12--idler shaft The transmission consists of a housing, an input shaft and gear, an output shaft and gear, an idler shaft, a reverse gear, a cluster of gears and a gear shift mechanism The housing is cast of iron which has upper and side covers and bores for the installation of shafts The bottom and side walls are provided with holes for filling and draining oil s. The input shaft is made of steel integral with the driving gear and the rim. The front end of the input aft is installed on the bearing in the hwre of the crankshaft, while the rear end rotates in the bore of the front wall of the housing. The input shaft is arranged so that only the driving gear and the rim are accom- modated inside the housing while the splined portion of the shaft protruding from the transmission caries the hub of the clutch driven disk. The output shaft is splined and rests with its front end on a roller bear- ng installed in the bore of the input shaft. The other end of the output shaft rotates in a ball bearing in the transmission housing wall. The output shaft splines carry the shiding gears. The output shaft is coaxial with the input shaft The idler shaft carries a cluster of gears of different sizes. The cluster is mounted in the roller bear dle or, together with the shaft, on bearings in the ho all bores The idler shaft con-
25 stantly rotates with the input shaft because their gears are in constant mesh. The reverse gear rotates on ar axle secured in the holes of the bousing walls The gear shift mechanism is designed for engaging gears, setting thern neutral and engaging th e speed. The speeds are changed by shifting the gears or sleeves along the output shaft. The 如四如p两m the top cover. The shift lever is arranged on the cover or on the bracket of the lever suppl. of for ward speeds there are three, four and five-speed transmissions. 'The gear shift mechanism is mounted cn The transmission gears are shifted by means of a gear shift mechanisin. The gear shift mechanist consists of a lever, shift rails, shift forks, retainers, locks and a reverse speed safety device. The shift lever mounted on the transmission cover has a spherical bulb housed in a socket in the eover boss. a pin keeps the lever against rotation. The cover drillings accommodate shift rails which carry the shift forks and shift blocks with slots. The lower end of the lever enters the slots of the shift blocks. The forks fit into the rooves of the sliding gears and synchronizer sleeves. To change a speed, the upper end of the lever is slid to a certain position, the lower end of the lever moves the shift block and the latter pushes the shift rail with the fork and gear until the required speed is engaged. Retainers keep the gears in the engaged or The retainer consists of a ball and a spring accommodated in a channel drilled in the transmission cover. The shift ruil has slots whose number is equal to that of speeds engaged by the given shift, plus one slot for neutral When the transmission is in gear or in neutral, the ball is forced into the slot to lock the shift rail move the shift ruil when changing gear, the force applied to it must be sufficient to push the ball out of the slot During a gear change, the lower end of the lever may stop between two shift blocks and move two shift rails simultaneously, thereby engaging two speeds at once. As the output shaft cannot rotate at two different speeds simultaneously, this will result in breaking the gear teeth, Simultaneous engagement of wo gears is prevented by locks, The locks are made in the form of balls of bars located in a horizontal channel between the shift rails. The shift rails have recesses which align with the channel of the locks when the shift rails are in the neutral position. The length of the lock bar plus the diameters of two balls is equal to the distance move any of the shift rails beforu a part of the bull or the end of the bar snaps into the recess of the other shift rail thus locking the latter New words ratio n.比,比率 particular adj.特殊的,特别的,个别的 形势,情況,环境 accelerateυ.加速,增加速度,促进 noisy adj.有噪声的,有干扰的,嘈杂的 uncomfortable adi,不舒适的,不方便的
tremendous a.巨大的,非常的,惊人的 strain v.;n.拉紧,紧张;应变,变形 ooth ad.光滑的,平坦的,平稳的 multiply v,增加,成倍地增加,乘 extremely ad,极端,极其,非常 coasting n,滑行,惯性运转,滑行距离 stretch n,一段路程,距离,路段 variable a.易变的,反复不定的,不同的 overall ac包括一切的,全面的,所有的 product n.产物,产品,成品 intermediate ad.中间的,中等的,居中的 installation n.安装,装配,设备,设置 dint.排出,排水,排放 spline眈t,开键槽于,用花键连接 coaxial ad.共轴的,共心的,同轴的 constantly adv.不变地,经常地,继续不断地 retainer n.导圈,保持架,夹持 channel n,通道,孔道,槽 simultaneously adw.同时地,一齐地,同时发生地 align v,使成一行,排成一行,成一线 snap 2,咬住,抓住,卡断 Phrases and Expressions tuming effort of the engine发动机转动力 propeller shaft汽车传动轴,万向节轴 drive line动力传动系统,驱动系统 be applied to施加于,应用于 under way行进中 tractive resistance牵引阻力 齿轮传动系 as many times as是……的许多倍 idler shaft惰轮轴 a cluster of gears齿轮组 synchronizer sleeves同步器啮合套 gear shift mechanism换挡机构 reverse speed safety device倒挡速度安全装置 Notes A higher torquc should bc applicd to the wheels to set an automobile in motion or move uphill
27 with a full load than to keep it olling after it gets under way on level stretches of the road. when inertia is high and tractive resistance is low 当惯性大、牵引力小的时候,应对4轮施加…个比在一般半路上行进时还要大的转矩使 汽车全负荷运转或全负荷爬坡 2. The input shaft is arranged so that only the driving gear and the rim are accommodated inside the housing while the splined portion of the shaft protruding from the transinission carries the hub of the clutch driven disk 输入轴这样布置以便只有主动齿轮和齿圈安装在笔体内,而伸出变速器外的轴的花键部 分用來支承离合器从动盘(花键)较。 Unit Three Steering System The direction of the automobile under way is changed by tuming the front wheels with the aid of the steering system. The steering systerm ineludes a steering gear and a steering control linkage. ' The rotation of the steering wheel is imparted to the: levers and rods of the linkage by which the steerable wheels are turned The steering column with the steering wheel is installed in the drivers cab. Its upper part is se- ed to the instrument board by a clamp, and the lower end is attached through bushings to the steering There are: Iwo types uf the steering system: manual steering system and power steering system the manual steering system, there are the worm and mller type and the recirculating ball and worm In the wum and roller type, an hourglass-shaped wom gear is attached to the input shaft. The threads of the wurn gear are meshed with the threads of a sector gear, commonly called a roller. The sec- tor gear transfers the rotary motion of the worm gear input shaft to the output shaft. The output shaft is splined to the pitman arm, which translates the rotary motion of the shaft to linear motion. Movement in the pitman arm is transmitted through a drag link to the steering arm and knuckle and thus to the wheels In the recirculating ball gears, the input shaft of this type of steering gear is also connected to a worm gear, but the worm gear in a recirculating ball type unit is straight. Mounted on the worm gear is a ball nut. The hall nut has interior spiral groves that mate with the threads of the worm gear. The ball mut also has exterior gear teeth on one side. These teeth mesh with teeth on a sector gear and shaft gea, V n the grooves between the ball nut and the worn gear are ball bearings. The ball nut and the wom are: ball bearings. The ball bearings allow the worm gear and ball nut to mesh and move with little friction. When the steering wheel is turned, the input shaft will rotale the worm gear. The ball bearing will transmit the turning forme from the worm gear to the ball nut, causing the ball nut to move up and down the worm gear. Ball retum guides are connected to each end of the ball nut grooves. These allow the ball bearing to circulate in a continuous loop As the ball nut moves up or down on the wonn gear, it causes the sector gear to rotate which urn,causes the pitman am to swivel back and forth. This Inmotion is transferred to the steering arm and