附 錄 A 一、英文原材料 Drive Axle All vehicles have some type of drive axle/differential assembly incorporated into the driveline. Whether it is front, rear or four wheel drive, differentials are necessary for the smooth application of engine power to the road. The drive axle must transmit power through a 90 angle. The flow of power in conventional front engine/rear wheel drive vehicles moves from the engine to the drive axle in approximately a straight line. However, at the drive axle, the power must be turned at right angles (from the line of the driveshaft) and directed to the drive wheels. This is accomplished by a pinion drive gear, which turns a circular ring gear. The ring gear is attached to a differential housing, containing a set of smaller gears that are splined to the inner end of each axle shaft. As the housing is rotated, the internal differential gears turn the axle shafts, which are also attached to the drive wheels. The differential is an arrangement of gears with two functions: to permit the rear wheels to turn at different speeds when cornering and to divide the power flow between both rear wheels. (1)The accompanying illustration has been provided to help understand how this occurs. The drive pinion, which is turned by the driveshaft, turns the ring gear. (2)The ring gear, which is attached to the differential case, turns the case. (3)The pinion shaft, located in a bore in the differential case, is at right angles to the axle shafts and turns with the case. (4)The differential pinion (drive) gears are mounted on the pinion shaft and rotate with the shaft. (5)Differential side gears (driven gears) are meshed with the pinion gears and turn with the differential housing and ring gear as a unit. (6)The side gears are splined to the inner ends of the axle shafts and rotate the shafts as the housing turns. (7)When both wheels have equal traction, the pinion gears do not rotate on the pinion shaft, since the input force of the pinion gears is divided equally between the two side gears. (8)When it is necessary to turn a corner, the differential gearing becomes effective and allows the axle shafts to rotate at different speeds. As the inner wheel slows down, the side gear splined to the inner wheel axle shaft also slows. The pinion gears act as balancing levers by maintaining equal tooth loads to both gears, while allowing unequal speeds of rotation at the axle shafts. If the vehicle speed remains constant, and the inner wheel slows down to 90 percent of vehicle speed, the outer wheel will speed up to 110 percent. However, because this system is known as an open differential, if one wheel should become stuck (as in mud or snow), all of the engine power can be transferred to only one wheel. Engineers searched diligently for ways to allow each driving wheel to operate at its own speed. Many ideas were tried with mixed results before the basic design for the present-day, standard differential was finally developed. The successful idea that is still used in principle today was to divide the engine power by dividing the axle in two-attaching each driving wheel separately to its own half-axle and placing in between, an ingenious, free-rotating pinion and gear arrangement. The arrangement was called the differential because it differentiates between the actual speed needs of each wheel and splits the power from the engine into equal driving force to each wheel. On/off road vehicles and other trucks required to haul heavy loads are sometimes equipped with double reduction axles. A double reduction axle uses two gear sets for greater overall gear reduction and peak torque development. This design is favored for severe-ser-vice applications, such as dump trucks, cement mixers, and other heavy haulers. The double reduction axle uses a heavy-duty spiral bevel or hypoid pinion and ring gear combination for the first reduction. The second reduction is accomplished with a wide-faced helical spur pin-ion and gear set. The drive pinion and ring gear function just as in a single reduction axle. However, the differential case is not bolted to the ring gear. Instead, the spur pinion is keyed to and driven by the ring gear. The spur pinion is in turn constantly meshed with the helical spur gear to which the differential case is bolted. Many heavy duty trucks are equipped with two rear drive axles. These tandem axle trucks require a special gear arrangement to deliver power to both the forward and rearward rear driving axles. This gearing must also be capable of allowing for speed differences between the axles. Two axle hub arrangements are available to provide support between the axle hub and the trucks wheels: the semi-floating type axle and the fully floating type axle. Of the two ,the semi-floating is the simplest, cheapest design to incorporate ,but the fully floating axle is more popular in heavy-duty trucks. In the semi-floating type axle, drive power from the differential is taken by each axle half-shaft and transferred directly to the wheels. A single bearing assembly, located at the outer end of the axle, is used to support the axle half-shaft. The part of the axle ex-tending beyond the bearing assembly is either splined or tapered to a wheel hub and brake drum assembly. The main disadvantage of this type of axle is that the outer end of each axle shaft must carry and support the weight of the truck that is placed on the wheels. If an axle half-shaft should break ,the trucks wheel will fall off. Drive axle operation is controlled by the differential carrier assembly. A differential carrier assembly consists of a number of major components. These include: 1. Input shaft and pinion gear 2. Ring gear 3. Differential with two differential case halves, a differential spider ,four pinion gears ,and two side gears with washers. This differential assembly fits between the axle shafts, with the shafts being splined to the differential side gears. The parts of the differential carrier are held in position by a number of bearings and thrust washers. The leading end of the input shaft is connected to the drive shaft by a yoke and universal joint. The pinion gear on the other end of the input shaft is in constant mesh with the ring gear. The ring gear is bolted to a flange on the differential case. Insied the case, the legs of the spider are held in matching grooves in the case halves. The legs of the spider also support the four pinion gears. In addition ,the case houses the side gears ,which are in mesh with the pinions and are splined to the axle shafts. When the drive shaft torque is applied to the input shaft and drive pinion, the input shaft and pinion rotate in a direction that is perpendicular to the trucks drive axles. The drive pinion is beveled at 45 degrees and engages the ring gear, which is also beveled at 45 degrees, causing the ring gear to revolve at 90 degrees to the drive shaft. This means the torque flow changes direction and becomes parallel to the axles and wheels. The drive shaft must also be able to change in length while transmitting torque. As the rear axle reacts to road surface changes, torque reactions and braking forces, it tends to rotate for-ward or backward, requiring a corresponding change in the length of the drive shaft. In order to transmit engine torque to the rear axles, the drive shaft must be durable and strong. An engine producing 1 000 pound-feet of torque, when multiplied by a 12 to t gear ration in the transmission, will deliver 12 000 pound-feet breakaway torque to the drive shaft. The shaft must be strong enough to deliver this twisting force to a loaded axle without deforming or cracking under the strain. Drive shafts are constructed of high-strength steel tubing to provide maximum strength with minimum weight. The diameter of the shaft and wall thickness of the tubing is determined by several factors maximum torque and vehicle payload, type of operation, road conditions, and the brake torque that might be encountered. One-piece ,two-piece ,and three-piece drive shafts are used, depending on the length of the drive line. Each end of the drive shaft has a yoke used to connect the shaft to other drive line components. The yoke might be rigidly welded to the shaft tube or it might be a spline, or slip yoke. The tube yokes are connected through universal joints to end yokes on the output and input shafts of the transmission and axle. A typical slip joint consists of a hardened, ground splined shaft welded to the drive shaft tube that is inserted into a slip yoke that has matching internal splines. The sliding splines between a slib joint and a permanent joint must support the drive shaft and be capable of sliding under full torque loads. The propeller shaft is generally hollow to promote light weight and of a diameter sufficient to impart great strength. Quality steel, aluminum, and graphite are used in its construction. Some have a rubber mounted torsional damper. The universal yoke and splined stub (where used) are welded to the ends of a hollow shaft. The shaft must run true, and it must be carefully balanced to avoid vibrations. The propeller shaft is often turning at engine speeds. It can cause great damage if bent, unbalanced or if there is wear in the universal joints. As the rear axle moves up and down, it swings on an arc that is different from that of the drive line. As a result, the distance between transmission and rear axle will change to some extent. When the propeller shaft turns the differential, the axles and wheels are driven forward. The driving force developed between the tires and the road is first transferred to the rear axle housing. From the axle housing, it is transmitted to the frame or body in one of three ways: 1. Through leaf springs that are bolted to the housing and shackled to the frame. 2. Through control or torque arms shackled to both frame and axle housing. 3. Through a torque tube that surrounds the propeller shaft which is bolted to the axle housing and pivoted to the transmission, by means of a large ball socket. 二、中文翻譯 驅動橋 汽車傳動系統中驅動橋和差速器有許多形式。無論是前輪、后輪還是四輪驅動，差速器都是必要的，以便使發動機的功率充分的發揮到路面上。 驅動橋必須通過一個 90角傳遞動力。以傳統的后輪驅動汽車為例， 動力由前置引擎傳到大致在一條直線上的驅動橋，然后動力必須經過一個直角傳遞給驅動車輪。 這一過程是通過一個小齒輪傳遞到一個齒圈上而完成的。該齒圈連接到差速器殼，殼里面裝有一組小齒輪，小齒輪與帶有花鍵的每個軸的軸端相聯接，由橋殼的旋轉，從而差速齒輪帶動軸轉動，這個軸同時連接的就是驅動車輪。 圖示為一個典型驅動橋的組成 差速器齒輪具有兩個基本的功能：在轉彎時允許后輪以不同的速度轉動并將動力分配到兩后輪。 （ 1）提供的說明是為了幫助理解這一過程是如何實現的。軸帶動小驅動齒輪在齒圈上旋轉。 （ 2）該齒圈與差速器殼相連 ，并帶動殼旋轉。 （ 3）差速器殼內設有一小孔，放置一個小齒輪軸，該小軸與差速器成直角，并隨殼體轉動。 （ 4）差速行星齒輪驅動裝在小軸上的齒輪，使軸轉動。 （ 5）差速器邊上的齒輪（驅動齒輪）與小齒輪嚙合，并與做在一體的差速器殼和齒圈一起轉動。 （ 6）一側帶花鍵的齒輪與兩軸端配合，隨橋殼旋轉。 （ 7）當兩車輪具有相同的驅動力的時候，小齒輪（行星齒輪）在其軸架（行星架）上不旋轉，輸入到小齒輪上的力平均分配給兩端的齒輪。 （ 8）當需要轉彎時，差動齒輪開始起作用，能夠實現兩端的半軸以不同的速度旋轉。 由于內側車輪速度 減慢，同側的花鍵軸齒輪也變慢，行星齒輪作為平衡杠桿，保持兩邊的輪齒負荷相等，同時允許兩邊的半軸以不同的的速度旋轉。如果汽車的行進速度保持不變，內側車輪的速度將減低 90%。外側車輪的速度將增加到 110%。但是，因為系統有差速器，所以一旦有一個車輪轉速保持不變（如在泥或雪地），那么 所有的發動機功率 將全部 轉移到 另外的 一個車輪。 工程師們努力地尋找方法使每個驅動輪都按照自己的速度運行。在如今標準的差速器被最終發明出來之前，許多想法被交叉嘗試。目前在理論上非常成功的、一直沿用到今天的想法是通過把車軸分離成對稱的兩部分 。每一個半軸都連接到分離的驅動輪上，然后中間安放一個獨立的自由旋轉的小齒輪和其它兩個齒輪來分離來自發動機的動力。這個結構被稱為差速裝置。因為這種裝置能提供給每個車輪實際所需要的速度并且把來自發動機的動力分成相同的驅動力作用給每個車輪。許多卡車有時需要裝備雙級減速驅動橋來拖拽重物。雙級減速驅動橋使用兩套減速齒輪來降低速度使轉矩達到峰值。這種設計是非常受優待的例如自卸式卡車、混凝土攪拌車和其它重型貨車。 雙減速車橋采用了重型的螺旋錐齒輪或準雙曲面齒輪和環行齒輪配合從而進行第一級減速。第二級減速是通過寬面的螺旋柱 形直齒輪及其它齒輪組的配合完成的。主動小齒輪和環行齒輪在 單級減速橋 上運行，而差速器箱沒有被環形齒輪鎖死，相反，環形齒輪能將柱形直齒輪鍵入并驅動，柱形直齒輪就可以依次不斷地與差速器箱中的螺旋正齒輪相嚙合。 許多重型載貨汽車都配備了兩個后驅動橋，這種平衡懸架軸的卡車需要一種特殊的齒輪配置方法來解決后驅動橋上的向前與向后的傳動。這些齒輪必須要考慮到車軸間的轉速差。兩個車軸軸轂的排列為軸轂和車輪間提供了有力的支持。在 半浮動式軸 與 全 浮動式軸 中， 半浮動式軸 的設計較簡單、價格便宜的，而全 浮動式軸 多受歡迎于重型卡車中。 對 于半浮動式軸，來自差速器的動力施加與兩個半軸，并直接傳遞到輪子上。一個單軸承組（位于軸承外端）被用于支撐半軸。軸端外延到軸承組上