資源目錄里展示的全都有預(yù)覽可以查看的噢，，下載就有,,請放心下載，原稿可自行編輯修改=【QQ：11970985 可咨詢交流】====================喜歡就充值下載吧。。。資源目錄里展示的全都有，，下載后全都有,,請放心下載，原稿可自行編輯修改=【QQ：197216396 可咨詢交流】==================== 本科生畢業(yè)設(shè)計（論文）外文翻譯 畢業(yè)設(shè)計（論文）題目： 外文題目：AUTOMOTIWE FINAL DRIVE 譯文題目：汽車主減速器 學(xué) 生 姓 名： 專 業(yè)： 指導(dǎo)教師姓名： 評 閱 日 期： AUTOMOTIWE FINAL DRIVE FINAL DRIVE A final drive is that part of a power transmission system between the drive shaft and the differential. Its function is to change the direction of the power transmitted by the drive shaft through 90 degrees to the driving axles. At the same time. it provides a fixed reduction between the speed of the drive shaft and the axle driving the wheels. The reduction or gear ratio of the final drive is determined by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear. In passenger vehicles, this speed reduction varies from about 3:1 to 5:1. In trucks it varies from about 5:1 to 11:1. To calculate rear axle ratio, count the number of teeth on each gear. Then divide the number of pinion teeth into the number of ring gear teeth. For example, if the pinion gear has 10 teeth and the ring gear has 30 (30 divided by 10), the rear axle ratio would be 3:1. Manufacturers install a rear axle ratio that provides a compromise between performance and economy. The average passenger car ratio is 3.50:1. The higher axle ratio, 4.11:1 for instance, would increase acceleration and pulling power but would decrease fuel economy. The engine would have to run at a higher rpm to maintain an equal cruising speed. The lower axle ratio. 3:1, would reduce acceleration and pulling power but would increase fuel mileage. The engine would run at a lower rpm while maintaining the same speed. The major components of the final drive include the pinion gear, connected to the drive shaft, and a bevel gear or ring gear that is bolted or riveted to the differential carrier. To maintain accurate and proper alignment and tooth contact, the ring gear and differential assembly are mounted in bearings. The bevel drive pinion is supported by two tapered roller bearings, mounted in the differential carrier. This pinion shaft is straddle mounted. meaning that a bearing is located on each side of the pinion shaft teeth. Oil seals prevent the loss of lubricant from the housing where the pinion shaft and axle shafts protrude. As a mechanic, you will encounter the final drive gears in the spiral bevel and hypoid design. Spiral Bevel Gear Spiral bevel gears have curved gear teeth with the pinion and ring gear on the same center line. This type of final drive is used extensively in truck and occasionally in older automobiles. This design allows for constant contact between the ring gear and pinion. It also necessitates the use of heavy grade lubricants. Hypoid Gear The hypoid gear final drive is an improvement or variation of the spiral bevel design and is commonly used in light and medium trucks and all domestic rear- wheel drive automobiles. Hypoid gears have replaced spiral bevel gears because they lower the hump in the floor of the vehicle and improve gear-meshing action. As you can see in figure 5-13, the pinion meshes with the ring gear below the center line and is at a slight angle (less than 90 degrees). Figure 5-13.—Types of final drives. This angle and the use of heavier (larger) teeth permit an increased amount of power to be transmitted while the size of the ring gear and housing remain constant. The tooth design is similar to the spiral bevel but includes some of the characteristics of the worm gear. This permits the reduced drive angle. The hypoid gear teeth have a more pronounced curve and steeper angle, resulting in larger tooth areas and more teeth to be in contact at the same time. With more than one gear tooth in contact, a hypoid design increases gear life and reduces gear noise. The wiping action of the teeth causes heavy tooth pressure that requires the use of heavy grade lubricants. Double-Reduction Final Drive In the final drives shown in figure 5-13, there is a single fixed gear reduction. This is the only gear reduction in most automobiles and light- and some medium-duty trucks between the drive shaft and the wheels. Double-reduction final drives are used for heavy- duty trucks. With this arrangement (fig. 5-14) it is not necessary to have a large ring gear to get the necessary gear reduction. The first gear reduction is obtained through a pinion and ring gear as the single fixed gear reduction final drive. Referring to figure 5-14, notice that the secondary pinion is mounted on the primary ring gear shaft. The second gear reduction is the result of the secondary pinion which is rigidly attached to the primary ring gear, driving a large helical gear which is attached to the differential case. Double-reduction final drives may be found on military design vehicles, such as the 5-ton truck. Many commercially designed vehicles of this size use a single- or double-reduction final drive with provisions for two speeds to be incorporated Figure 5-14.—Double-reduction final drive Two-Speed Final Drive The two-speed or dual-ratio final drive is used to supplement the gearing of the other drive train components and is used in vehicles with a single drive axle (fig. 5-15). The operator can select the range or speed of this axle with a button on the shifting lever of the transmission or by a lever through linkage The two-speed final drive doubles the number of gear ratios available for driving the vehicle under various load and road conditions. For example, a vehicle with a two-speed unit and a five-speed transmission, ten different forward speeds are available. This unit provides a gear ratio high enough to permit pulling a heavy load up steep grades and a low ratio to permit the vehicle to run at high speeds with a light load or no load The conventional spiral bevel pinion and ring gear drives the two-speed unit, but a planetary gear train is placed between the differential drive ring gear and the differential case. The internal gear of the planetary gear train is bolted rigidly to the bevel drive gear. A ring on which the planetary gears are pivoted is bolted to the differential case. A member, consisting of the sun gear and a dog clutch, slides on one of the axle shafts and is controlled through a button or lever accessible to the operator When in high range, the sun gear meshes with the internal teeth on the ring carrying the planetary gears and disengages the dog clutch from the left bearing adjusting ring, which is rigidly held in the differential carrier. In this position, the planetary gear train is locked together. There is no relative motion between the differential case and the gears in the planetary drive train. The differential case is driven directly by the differential ring gear, the same as in the conventional single fixed gear final drive. When shifted into low range, the sun gear is slid out of mesh with the ring carrying the planetary gears. The dog clutch makes a rigid connection with the left bearing adjusting ring. Because the sun gear is integral with the dog clutch, it is also locked to the bearing adjusting rings and remains stationary. The internal gear rotates the planetary gears around the stationary sun gear, and the differential case is driven by the ring on which the planetary gears are pivoted. This action produces the gear reduction, or low speed, of the axle DIFFERENTIAL ACTION The rear wheels of a vehicle do not always turn at the same speed. When the vehicle is turning or when tire diameters differ slightly, the rear wheels must rotate at different speeds. If there were a solid connection between each axle and the differential case, the tires would tend to slide, squeal, and wear whenever the operator turned the steering wheel of the vehicle. A differential is designed to prevent this problem. Driving Straight Ahead When a vehicle is driving straight ahead, the ring gear, the differential case, the differential pinion gears, and the differential side gears turn as a unit. The two differential pinion gears do NOT rotate on the pinion shaft, because they exert equal force on the side gears. As a result, the side gears turn at the same speed as the ring gear, causing both rear wheels to turn at the same speed. Turning Corners When the vehicle begins to round a curve, the differential pinion gears rotate on the pinion shaft. This occurs because the pinion gears must walk around the slower turning differential side gear. Therefore, the pinion gears carry additional rotary motion to the faster turning outer wheel on the turn.. Differential speed is considered to be 100 percent. The rotating action of the pinion gears carries 90 percent of this speed to the slowing mover inner wheel and sends 110 percent of the speed to the faster rotating outer wheel. This action allows the vehicle to make the turn without sliding or squealing the wheels. Figure 5-15.—Two speed final drive 汽車主減速器 主減速器 主減速器是在傳動軸和差速器之間的一個動力傳動系統(tǒng)的組成部分。它的作用是通過90°傳動軸改變傳給驅(qū)動軸的動力傳遞方向。同時，它提供了一個固定的減速，該值介于傳動軸和驅(qū)動輪軸的速度之間。 主減速器的減速和齒輪傳動比取決于環(huán)形齒輪齒數(shù)和小齒輪齒數(shù)?？蛙嚨臏p速在3:1到5:1之間，卡車是在5:1到11:1之間。計算后軸傳動比要數(shù)每個齒輪上的齒數(shù)。然后把小齒輪的齒數(shù)插入環(huán)形齒輪的齒數(shù)。例如，如果小齒輪有10齒，齒圈有30(30除以10)，后軸比率將3:1。生產(chǎn)廠家在安裝后軸傳動比時要考慮到性能和費用之間的協(xié)調(diào)?？蛙嚻骄谋嚷适?.50:1 更高軸比，例如4。11:1，將增加加速度和動力但會降低燃油經(jīng)濟性。發(fā)動機將不得不突然進攻一個更高轉(zhuǎn)速保持一個能與之匹敵的速度。 較低級軸比如3:1，將減少加速度和拉動力但是將會增加燃油里程。發(fā)動機將突然進攻一個降低轉(zhuǎn)速而維持同一速度。 主減速器的主要元件包括連接到傳動軸上的小齒輪，和一個被啰嗦或是鉚釘固定在差速器殼上的斜齒輪或者是圓柱齒輪。為了保持輪齒之間準(zhǔn)確，正確的接觸，齒圈，差動總成被安裝在一定的方位。主動小錐齒輪由二對圓錐滾子軸承支撐，安裝在差速器上。這個小齒輪軸跨式組合安裝。意味著那是一個能被定位在每個小齒輪齒側(cè)的軸齒。油封是為了防止?jié)櫥瑒?，小齒輪軸，軸凸出的部分泄漏 弧齒錐齒輪 具有彎曲的輪齒的弧齒錐齒輪同小齒輪，齒圈在同一中心線。這種主減速器形式被廣闊使用在卡車上，偶爾用在年長的汽車上。這個設(shè)計允許環(huán)形齒和小齒輪之間建立不斷地聯(lián)系。它也因此有必要用高等級滑潤劑。 雙曲面齒輪 雙曲面齒輪減速器是一個改進或變異的盤旋斜角設(shè)計，常用在輕型和中型卡車以及所有國內(nèi)的四輪驅(qū)動汽車上。雙曲面齒輪已經(jīng)取代了弧齒錐齒輪，因為他們降低了汽車底板上的凸起，改善輪齒嚙合行動。正如你看到的在5-13圖中，小齒輪軸線在中心線的下方，在一個輕微角度(少于90°)。 這個角度和用的重（大）的輪齒可以保證被傳遞的功率增加同時保持環(huán)形齒的大小和容積不變。這種齒型設(shè)計類似盤旋斜角然而包括一些蝸輪的特征。這個保證驅(qū)動器角的減小。雙曲線齒輪輪齒有一個更顯著的彎曲和陡峭的角，導(dǎo)致了在大齒輪輪齒地區(qū)更多的輪齒在同時接觸。在不止一個輪齒在同時接觸的情況下，一個雙曲線設(shè)計能夠增加齒輪的壽命和減少齒輪噪音。輪齒的縱向滑動會引起很大的壓力，所以要使用高等級的潤滑油。 雙級主減速器 在圖5-13所示的主減速器中，有一個獨立的固定減速齒輪。這個獨一無二的減速齒輪常用在大多數(shù)汽車和輕型和中型卡車的傳動軸和車輪之間。 雙極主減速器被用在重型卡車上。有了這種安排（圖：5-14）我們就沒必要用一個大直徑的環(huán)形齒輪來使其獲得必要的齒輪減速。第一級齒輪減速是通過一個小齒輪，齒圈作為單固定齒輪減速來實現(xiàn)的主減速器。提到圖5-14，我們注意到那個次要小齒輪被安裝在主環(huán)形齒輪軸上。第二級齒輪減速是通過被安裝在主環(huán)形齒輪軸上的次要小齒輪驅(qū)動被附屬在差動器里面的一個大的螺旋齒輪實現(xiàn)的。雙級主減速可在軍用汽車上發(fā)現(xiàn)，例如5噸卡車上。許多這種尺寸的商用汽車設(shè)計使用單級或雙級主減速器同規(guī)定的雙速結(jié)合在一起。 雙速主減速器 雙速或者是兩傳動比的主減速器常常被用來補充另一個傳動元件的齒輪，常用在單驅(qū)動軸的汽車上。（圖5-15）操作者選擇這個軸的范圍或者是速度可以通過一個按鍵安裝在傳輸?shù)淖兯贄U上或者是一個連鎖的杠桿。 雙速減速器擁有兩個齒輪比來驅(qū)動汽車以適用多種多樣的負(fù)荷和道路狀況。例如，一輛汽車有一個雙速單元，一個五速傳輸，那么就有十種不同的前進速度可供使用。這個單元提供一個足夠高的齒輪齒數(shù)比來保證拉重負(fù)荷徒級行駛，和一個低的比率以允許車輛在輕載或者是空載的情況下以高速來運行。 常規(guī)螺旋小傘齒輪，齒圈驅(qū)動雙速單位，但一個行星齒輪系被放置在差速器傳動齒輪和差速器殼之間。內(nèi)齒輪行星齒輪系被用螺絲定在硬性斜角傳動齒輪。有一個環(huán)，在這個環(huán)上行星齒輪是回轉(zhuǎn)的，這個環(huán)被釘在差速器殼上。一個成員，它的組成包括太陽輪 和一個爪形離合器，滑動在其中的一個半軸上，通過一個按鍵或者是連接到操作者那里的杠桿被控制。 當(dāng)在高的范圍，相嚙合的太陽齒輪同在環(huán)上的內(nèi)齒攜帶行星齒輪，從左邊的調(diào)整環(huán)上脫離接觸爪形離合器，這個環(huán)硬性固定在差速器殼上。在這個位置上，星系齒輪系被鎖在一起。在差速器殼和在行星傳動軸里的齒輪之間沒有相對運動。差速器殼由差速器環(huán)齒輪直接驅(qū)動，在常規(guī)的單級主減速器也是同樣的。 當(dāng)在轉(zhuǎn)換到低的范圍，太陽齒輪從嚙合的狀態(tài)滑離，和環(huán)一起驅(qū)動行星齒輪。爪形離合器和左邊的調(diào)整環(huán)構(gòu)成了一個剛性連接。因為太陽輪也是爪形離合器的一部分，它業(yè)被鎖在調(diào)整環(huán)上，保持靜止。內(nèi)齒輪使行星齒輪繞著靜止的太陽輪旋轉(zhuǎn)。差動器殼通過行星齒輪被安裝在樞軸上的環(huán)來驅(qū)動。這個動作將產(chǎn)生齒輪減速或者是低速的軸。 不同動作 一輛汽車的后輪不是總是用同一種速度在行駛。當(dāng)汽車在轉(zhuǎn)彎或者是當(dāng)輪胎直徑不同時，汽車的后輪們必須以不同的速度運轉(zhuǎn)。 如果在每個軸和差速器殼之間都有一個固體連接，那么輪胎將傾向于滑動、發(fā)出尖銳的噪聲、以及每當(dāng)操作者轉(zhuǎn)動方向盤的時候磨損。一個差速器就被設(shè)計用來防止這樣的問題。 直線行駛 當(dāng)汽車在直線行駛是，齒圈，差速器殼，差速器小齒輪和差速器邊緣齒輪像一個單元一樣運轉(zhuǎn)。兩個差速器小齒輪不在一個小齒輪軸上運轉(zhuǎn)，因為他們施加相等的力量到變齒輪上。結(jié)果，兩半軸齒輪與環(huán)形齒輪同一速度運轉(zhuǎn)，導(dǎo)致兩個車輪用同一速度運轉(zhuǎn)。 轉(zhuǎn)彎 當(dāng)車輛按曲線行駛，差動齒輪旋轉(zhuǎn)在小齒輪軸。發(fā)生這種情況四因為小齒輪齒輪必須繞這慢轉(zhuǎn)差速器側(cè)齒輪旋轉(zhuǎn)。因此，在轉(zhuǎn)彎時，小齒輪會帶動差速器旋轉(zhuǎn)運動來使外轉(zhuǎn)向輪運動速度快。 差動的速度被認(rèn)為是百分之百。小齒輪的旋轉(zhuǎn)運動將會把百分之九十的這個速度帶該運動緩慢的內(nèi)輪，把百分之一百一的速度傳遞給運動較快的外輪。這個動作會使汽車在轉(zhuǎn)彎的時候無滑動或者是這輪無噪聲。