工程机械专业英语-毕设论文外文翻译（翻译+原文）.doc

1、题 目： 工程机械专业英语 图3-2 弹簧离合器2.变速箱从其安装图，所有大批量生产的现代卡车所采用的阶梯变速箱可分为下列几类：1） 由控制类型：手动换档变速箱和自动换挡变速箱；2） 通过齿轮组合传动类型：固定轴式和行星式。自动换挡变速箱在最近得到越来越广泛的应用，手动换档变速箱可细分为：1）单范围变速；2）直接驱动变速器（汽车型）；3）多范围的变速。变速箱通常设计有四个或五个速度。单范围变速箱（图3 3a型）由两个轴 与离合器轴连接的传动齿轮轴1以及与减速器连接的主轴（驱动）3。滑动齿轮可以相啮合，齿轮4与齿轮5在主轴上硬性安装，从而提供不同的传动比。当在中立位置时，驱动齿轮轴和主轴不啮合而

2、没有运动，此时将是从发动机传动。这种类型的一个五速变速箱的安装。在变速箱直接驱动输入(驱动)轴可直接耦合到输出轴上，在这种情况下，变速箱不再作为一个减速器。这张图（图3-3b型）显示了包含有3轴的传动 传动齿轮轴1，通过恒定耦合的齿轮7连接到传动齿轮轴的副轴6以及主轴3。这是一个驱动齿轮轴的附加部分。滑动齿轮2以上的花键轴主要从事移动的传输，它配备了5档安装在副轴上。一旦齿轮2和齿轮8啮合将得到直接的驱动，这将来自传动齿轮轴的扭矩直接传输向主轴。从而使副轴的运行空闲。一个有5级直接驱动范围的变速箱被用于卡车。多范围的变速箱（图3 3c型）使得它有可能得到与齿轮的几对需要援助的齿轮比。虽然这些传

3、输效率更低，但是他们有一个更广泛的齿轮口粮，而且提供一个在所有的速度范围都容易逆转的能力，这是拖拉机上非常重要的特点。图3-3 变速箱3万能杆传动万向节传动应用于现代拖拉机和卡车（取决于安装图和机械设计），因此可能具有不同的结构9。这是两个半万向和全万向节传动轴的主要类型。一个半万向节是一个铰链连接，可用于传输之间小角度（最多5“）旋转轴的扭矩。这种接头主要被安装在拖拉机的离合器轴和变速箱主传动轴之间，主要是因为当拖拉机在不平坦的地面移动时，他们不准确了。半万向允许在拖拉机框架的安装上有一定的误差并且不会以任何方式恶化他的性能，这基本上简化了组装程序。这种类型的大多数接头以弹性橡胶金属套管的形

4、式设计（图3 4a的）。同样的设计用在离合器轴1上的拔叉2和拔叉5和通用接头花键轴6。有四个弹性橡胶套筒4的吊环3被安置在拔叉2至拔叉5之间。其他的高弹性联轴器的设计类似, 但它的前拔叉整体是由轴6制成，而后方拔叉被安全的装置在变速箱驱动轴的花键上。扭矩可以通过一个角度在由于橡胶套管的变形而产生稍微不一致的轴间传输。拔叉5与轴之间的滑动连接，使人们有可能改变轴的长度。一个完整的万向节可以在非常大的倾斜锐角（最大30 40 ）之间传递轴扭矩。它们被用在汽车变速器（图3 4b型），因为后轴悬架的弹簧使得轴偏差大大增加。图3-4 万能杆传动当一辆卡车走在崎岖不平的地面上时，普遍万向节的轴的长度是通过

5、拨叉2在花键轴上滑动来改变的。4主传动根据啮合的齿轮副数量卡车的主传动可能是一个单一的减速型（图3 5a型）或双减速型（图3 5b型），.中型和重型卡车的齿轮通常采用对数双减速型，从斜面驱动主传动，这给予了很高的传动比并且占据一个相对较小的体积，这对于给予了主传动箱（后轴）和地面之间足够的空隙来说非常重要。单减速型主传动被用在客运车和小负荷卡车上。5差速器当一辆卡车或轮式拖拉机在转弯，或者进入了一个不平坦的道路，或有不同车轮半径，不同的速度必须要传送给驱动车轮时，可以通过利用差速器来实现（图3 - 6a型） 。差速器分离的外壳由两个杯子1和4通过螺栓夹紧。左杯1提供给主传动上的从动齿轮7一个固

6、定凸缘。其内部包含带有四个锥齿轮3（行星齿轮），在差速齿轮销上旋转自如的星形轮2。这颗行星小齿轮同车轴5上的齿轮6啮合。主传动上的从动齿轮7将旋转传输到差速器箱，从而传输到差速齿轮和行星齿轮。当卡车笔直的行驶在光滑的路面并且驱动轮的半径相同的时候，由车轴带动旋转的驱动轮执行相同数量的旋转。当他们与差速齿轮一起转动时，行星齿轮固定器，也就是轴齿轮将他们的速度调整为相等。通过这样差速器箱，车轴及其齿轮，驱动车轮都以同样的速度转动，同销连接的刨床小齿轮将没有运动。图3-5 卡车主传动；1-锥齿轮 2-驱动齿轮柄 3-齿圈 4-斯珀车道齿轮 5-从动齿轮6-主传动箱 7-齿轮轴当卡车在转弯时，或出于某

7、种原因或其他的，轮子中的一个车轮和车轴对应齿轮开始旋转缓慢时，同差速齿轮一起旋转的行星齿轮将开始在轴齿轮上减速运动。这些行星齿轮开始围绕其轴（差速齿轮销上的）旋转，从而增加了其他轴齿轮的转速和相应的驱动轮速度。这种差速器在所有条件下均匀地将扭矩在轴齿轮之间分配。这有时会阻碍一辆卡车的前进。如果有一个车轮，例如，在泥泞地面，冰地或雪地，地面抓地力差将会导致车轮打滑。由于差速器将扭矩均匀的分配在了车轮之间，第二轮的牵引动力也将由于太弱而不足以推动汽车行驶更远。当打滑的车轮以2倍速度旋转时，卡车将停止前进。这样差速器将增加路面上的打滑和滑移以及在湿滑路面上急转弯时的打滑和滑移。为了消除这一缺点，一些

8、现成的公路车（越野车，自卸车，卡车）的设计带有自锁差速器。联锁如图（3 - 6B型）。当套管8移动到左边，它将差速器杯同车轴5连接起来以防止2个车轴的一半转向彼此相对。由于车轴齿轮不能把比差速器箱慢，因而行星齿轮在他们的轴上保持静止而差速器本身已被锁定。当移动到右边套管将释放锁定装置。3.4汽车转向齿轮（图3-7）一辆卡车或轮式拖拉机通过方向盘转向。方向盘在驱动程序的2. Transmission BoxIn terms of their gearing diagrams, the stepped transmission boxes employed in all mass-produced

9、 modern trucks can be classified as follows;1) by the type of control:manual-shift transmission and power-shift transmission2) By the type of gear train: fixed axis and planetary.In recent time the power shift transmission are increasingly applied, manual shift transmission may be subdivided;1) sing

10、le-range transmission;2) direct drive transmission (automobile type);3) multi-range transmission.Transmission boxes are usually designed with four or five speeds.Single-range transmission boxes (Fig. 3-3a) consist of two shafts drive gear shaft 1 connected with the clutch shaft and main (driven) sha

11、ft 3, linked with the final drive. Sliding gear can be meshed. with gear 4 or gear 5 which are rigidly fitted on the main shaft, providing thereby different gear ratios. In the neutral position, when the gears on the drive gear shaft and the main shaft are out of mesh no motion will be transmitted f

12、rom the engine.A transmission box of this type with five speeds is installed.In transmission boxes with a direct drive the input (driving) shaft can be coupled directly to the output shaft, in which case the transmission box no longer acts as a reduction gear. The diagram in Fig. 3-3b) shows that th

13、e transmission contains three shafts drive gear shaft 1, lay shaft 6 coupled by constant-mesh gear 7 to the drive gear shaft and main shaft 3.which is a continuation of the drive gear shaft.Sliding gear 2 moving over the splines of the main shaft engages the transmission as it comes in mesh with gea

14、r 5 fitted on the lay shaft. A direct drive is obtained as soon as gear 8 engages gear 2 and this will transmit torque directly from the drive gear shaft to the main shaft. In this ease the lay shaft runs idle. A five-range transmission box with a direct drive is used in trucks.Multi-range transmiss

15、ion boxes (Fig. 3-3c) make it possible to obtain the required gear ratio with the aid of several pairs of gears. Although these transmission are less efficient, they have a wider range of gear rations and provide for an easy reversal at all speeds, a very important feature in tractors.3. Universal-J

16、oint DriveUniversal-joint shafts employed in modern tractors and trucks perform several functions (depending on the gearing diagram and the machine design) and, as a result may have a different construction9. These are two main types of shafts with semi-and full universal joints.A semi-universal joi

17、nt is a hinged link which can be used to transmit torque between shafts rotating at a small angle (up to 5). Such joints are installed mainly in tractors between the clutch shaft and the transmission box primary shaft because they come out of alignment when the tractor moves over uneven ground. Semi

18、-universals allow for a certain inaccuracy in the arrangement of units mounted on the tractor frame without deteriorating in any way their performance and essentially simplify the assembly procedure.Most joints of this type are designed in the form of tan elastic rubber metal coupling (Fig. 3-4a). S

19、imilarly designed forks 2 and 5 are fitted onto the splines of clutch shaft 1 and universal-joint shaft 6. Ring 3 with four elastic rubber sleeves 4 is accommodated between forks 2 and 5.The other elastic coupling is designed similarly, but its front fork is made integral with shaft 6 while the rear

20、 fork is secured on the splines of the transmission-box driving shaft.Torque can be transmitted at an angle and with the shafts somewhat out of line due to deformation of the rubber sleeves, The sliding joint between fork 5 and the shaft makes it possible to change the length of the shaft. A full un

21、iversal joint transmits torque between shafts inclined at very acute angles (up to 3040). They are used in automobile transmissions (Fig.3-4b) because the spring-loaded suspension of the rear axle gives rise to a considerable increase in the misalignment of the shafts.When a truck travels over rough

22、 ground the length of the universal-joint shaft is changed by fork 2 slipping over the shaft splines.4. Final DriveThe final drives of trucks may be of a single-reduction (Fig.3-5a) or double-reduction type (Fig.3-5b) depending on the number of the gear pairs in mesh.Medium and heavy-duty trucks usu

23、ally employ double-reduction bevel-spur final drives, which give a high gear ratio and occupy a relatively small volume, which is extremely important for giving adequate clearance between the final drive housing (rear axle) and the road.Single-reduction final drives are employed in passenger cars an

24、d trucks of small load-car-rying capacity.5. DifferentialWhen a truck or a wheel tractor makes a turn, goes over a bumpy road or has different wheel radii, different speeds have to be imparted to the driving wheels, This can be done by means of a differential shown in Fig.3-6a). The split housing of

25、 the differential consists of two cups 1 and 4 clamped by bolts. Left cup 1 is provided with a flange to which driven gear 7 of the final drive is attached. The interiors of the housing contain spider 2 with four bevel gears (planet pinions) 3, rotating freely on the spider gear pins. The planet pin

26、ions are meshed with gears 6 of axle shafts 5.Driven gear 7 of the final drive transmits rotation to the differential housing and thereby to the spider gears and the planet pinions. When the truck moves straight over a smooth road and the driving wheels have the same radii, both driving wheels rotat

27、ed by axle shafts perform an equal number of revolutions. As they rotate together with the spider gears, the planet pinions clinch, as it were, both the axle shaft gears and turn them at the same speed. In this way the differential housing, axle shafts and their gears, and both the driving wheels ro

28、tate at the same speed, there being no rotation of the planer pinions relative to the pins.When the truck makes a turn or when, for some reason or other, one of the wheels and the corresponding gear of the axle shaft begin to rotate slower, the planet pinions rotating together with the spider gears

29、begin to run over on the axle shaft gear with the retarded motion. The satellites begin to revolve around their axles (on the spider gear pins), increasing thereby the rotational speed of the other axle shaft gear and the corresponding driving wheel. Under all conditions such differential will distr

30、ibute torque evenly between the axle shaft gears. This sometimes will hinder the progress of a truck. If one of the wheels, for example, goes over liquid mud, ice or snow, the poor grip in the ground will result in the wheel slipping.Since the differential distributes the torque between the wheels e

31、qually, the traction power on the second wheel will also become too weak to propel the automobile farther on. The truck will stop, while the skidding wheel will rotate at double the speed. In this way a differential increases slipping and skidding on route and on sharp turns on slippery roads. To el

32、iminate this shortcoming, some off-the-road trucks (cross-country vehicles, dump, trucks) are designed with a self-locking differential.The interlock is shown in Fig.3-6b). When sleeve 8 is moved to the left, it connects one of the differential cups with axle shaft 5 preventing the two halves of the

33、 axle shaft from turning relative to each other. Since the axle shaft gear cannot turn slower than the differential housing, the planet pinions remain stationary on their axles and the differential itself is locked. When moved to the right the sleeve will release the locking device.3.4 Truck Steering Gears (Fig.3-7) A truck or a wheel tractor is turned by a steering wheel. Steering wheels in the drivers9教师评语教师签名：2011年03月11日. .此处忽略！