拖拉机的分类外文文献翻译、中英文翻译、外文翻译

Classification of Tractors
The tractor is a wheeled or tracked self-propelled vehicle used as a power means for moving agricultural, road building, and other machines equipped with special tools, and also for towing trailers. The tractor engine can be used as a prime mover for active moving tools or starting farm machinery through the intermediary of the power takeoff shaft or belt pulley.
The uses of the tractor in agriculture are many, and so different types of tractors are needed to do different types of farm work.
Farm tractors are classified as follows.
AS TO PURPOSE, modern farm tractors are classed in three groups: general-purpose tractors (land utility), universal-row-crop (row-crop utility) tractors, and special-purpose tractors.
Land utility tractors are used for major farm operations common to the cultivation of most crops, such as tillage, digging, general cultivations, harrowing, sowing, and harvesting. The tractors are characterized by a low ground clearance, increased engine power, and good traction. Thanking to their wide tires or tracks enabling them to develop a high pull.
Universal-row-crop tractors are intended for row-crop work, as well as for many other field tasks. For this purpose, some row-crop utility tractors are provided with replac eable driving wheels of different tread widths-wide for general farm work and narrow for row-drop work, in order not to damage plants, the tractors have a high ground clearance and a wide wheel track that can be adjusted to suit the particular inter-tow distance.
Special-purpose tractors are modifications of standard land or row-crop utility tractor models and are used for definite jobs, and under
certain conditions. Thus, special tractors used to mechanize the cultivation of cotton have a single front whee l, swamp tractors are equipped with wide tracks enabling them to operate on marshy soils, and hillside tractors are designed to work on hillsides sloping at up to 16º.
AS TO THE DESIGN OF THE RUNNING GEAR，tractors are divided into crawler (track-laying) and wheeled types.
Crawler tractors are distinguished by a large ground contact area and therefore have a good track adhesion; they crush and compact the soil insignificantly. Such tractors show a high cross-country power and are capable of developing a high pull.
Wheeled tractors are more versatile and can be used for both field and transport work, but their traction is lower than that of crawler tractors.
Main Component Parts of tractor
The tractor is complex self-propelled machine consisting of separate interacting mechanisms and units that can be combined into certain groups.
Irrespective of particular design features, all tractors consist of engine, drive line, running fear, steering mechanism, working attachments, and auxiliary equipments.
THE ENGINE converts thermal energy into mechanical energy.
THE DRIVE LINE comprises a set of mechanisms which transmit the torque developed by the engine to the driving wheels or tracks and change the driving torque both in magnitude and direction. The drive line includes the clutch, flexible coupling, transmission (gearbox) and rear axle.
The clutch serves to disconnect the engine shaft from the transmission for a short period of time while the driver is shifting gears
and also to connect smoothly the flow of power from the engine to the driving wheels or tracks when starting the tractor from rest.
The flexible coupling incorporates elastic elements allowing to connect the clutch shaft and the transmission drive shaft with a slight misalignment.
The transmission makes it possible to change the driving torque and the running speed of the tractor by engaging different pairs of gears. With the direction of rotation of the engine shaft remaining the same, the transmission enables the tractor to be put in reveres.
The rear-axle mechanisms increase the driving torque and transmit it to the driving wheels or tracks at right angles to the drive shaft. In most tractors, the rear axle also comprises brakes.
In the wheeled tractor, as distinct from its crawler counterpart the drive line includes the differential which enables the driving wheels to revolve with different speeds when making turns of running over a ragged terrain, at which time the left-and right-hand wheels must travel different distances during one and the same time.
THE RUNNING GEAR is needed for the tractor to move. The rotation of the driving wheels (or the movement of the tracks) in contact with the ground is converted into translatory motion of the tractor.
THE STEERING MECHANISM serves to change the direction of movement of the tractor by turning its front wheels (in wheeled tractors) or by varying the speed of one of the tracks (in crawler tractors).
THE WORKING ATTACHMENTS of the tractor are used to utilize the useful power of the tractor engine for various farm tasks. They include the power takeoff shaft, drawbar (hitch device), implement-attaching (mounting) system, and belt pulley.
THE TRACTOR AUXILIARIES include the driver’s cab with a spring-mounted seat and heating and ventilation equipment, hood, lighting equipment, tell tales (indicators), horns, etc.
The Clutch
The clutch is located in the power train between the engine and the transmission. The clutch allows the driver to couple the engine or to uncouple the engine from the transmission while he is shi fting gears or starting the tractor moving from rest.
Modern tractors use friction clutches, ones employing friction forces to transmit power. The friction surfaces in such clutches are provided by discs, whose number depends on the magnitude of torque to single- and double-disc clutches.
Clutch driving disc (pressure plate) is connected to the engine flywheel, while driven disc is mounted on transmission clutch (input) shaft. The driven disc has splines in its hub that match splines on the input shaft. The disc is tightly clamped between the pressure plate and the flywheel by a series of coil springs, called the pressure springs held between the clutch cover and the pressure plate. Owing to the friction forces arising between the friction surfaces of the fl ywheel, driven disc, and pressure plate , torque transmission input shaft. In this position, the clutch is engaged.
The clutch is operated by the clutch linkage which passes on the movement of clutch pedal to clutch release (throw-out) bearing. When the driver steps on the pedal, the clutch linkage, which includes an operating rod and a release fork, forces the release bearing inward (to the left). As the release bearing moves left, it pushes against the inner ends of three release levers. When the inner ends of three release levers are pushed in by the release bearing, the outer ends of the levers move the pressure plate to the right, compressing pressure springs. With the spring pressure off the driven disc, spaces appear between the disc, the flywheel, and the pressure plate. Now the clutch is disengaged (released), and the flywheel can rotate without sending power through the driven disc. When the clutch pedal is released, the pressure springs
force the pressure plate to the left. The driven disc is agai n clamped tightly between the flywheel and the pressure plate. The driven disc must again rotate with the flywheel. In this position, the clutch is engaged. The initial slipping of the driven disc, which occurs until the disc is fully clamped between the f lywheel and the pressure plate, tends to make the engagement smooth. The clutch described above is known as the spring-loaded dry friction type.
Propeller Shaft and Universal Joint
The propeller shaft is a drive shaft to carry the power from the transmission to the rear-wheel axels. It connects the transmission main, or output shaft to the differential at the rear axels. Rotary motion of the transmission main shaft is carried by the propeller shaft to the differential, causing the rear wheels to rotate.
The propeller-shaft design must take two facts into consideration. First, the engine and transmission are more or less rigidly attached to the car frame. Second, the rear-axle housing (with wheels and differential) is attached to the frame by springs. As the rear wheels encounter irregularities in the road, the springs are compressed or expanded. These change the angle of drive and the distance between the transmission and the differential, and the propeller shaft should take care of these two changes. That is to say, as the rear axle housing, with differential and wheels, moves up and down, the angle between the transmission output shaft and propeller shaft changes. The reason why the angle increases is that the rear axle and differential move in a shorter than the propeller shaft. The center pointer of the axle-housing is rear-spring or control-arm attachment to the frame. In order that the propeller shaft may take care of these two changes, it must incorporate two universal joints to permit variations in the angle of drive. There must be a set of slip joint to make the propeller shaft change.
The propeller shaft may be solid or hollow, protected by an outer tube or exposed. Some applications include bearings at or near the center of the propellers which are supported by a center bearing and coupled together by universal joints.
A universal joint is essentially a double-hinged joint consisting of two y-shaped yokes, one on the driving shaft and the other on the driven shaft, and across-shaped member called the spider. The four arms of the spider, known as trunnions, are assembled into bearings in the ends of the two shaft yokes. The driving shaft causes the spider to rotate, and the other two trunnions of the spider cause the driven shaft to rotate. When the two shafts are at an angle to each other, the b earings in the yokes permit the yokes to swing around on the trunnions with each revolution. A variety of universal joints have been used on automobiles, but the types now in most common use are the ball-and-trunnion joints.
A slip joint consists of outside splines on one shaft and matching internal splines in the mating hollow shaft. The splines cause the two shafts to rotate together but permit the two to move endwise with each other. This accommodates any effective change of length of the propeller shaft as the rear axles move toward or away from the car frame.
拖拉机的分类
拖拉机是一种轮式或履带式的自走式车辆工具，它能被用来做移植农作物，铺路和其他装备特殊工具的机械的动力装置。

也能用做牵引挂车的动力，拖拉机的发动机也能被用来做自动工具，固定式农业机械的有原动力，通过用力输出轴和皮带轮做中间媒介。

拖拉机在农业中的应用是非常的广泛的，并且不同类型的拖拉机做不同的农业作业。

农业拖拉机被分为以下几类。

就功能来说，现代的农用拖拉机可以分为三类，普通功能的拖拉机，中耕拖拉机和专用拖拉机。

普通用途的拖拉机主要的农业作业是大部分农作物的栽培，比如耕地，犁地，耕种，耙地，播种和收割。

这种拖拉机的典型特征就是有一个比较小的离地间隙，增加了发动机的扭矩和有比较好的牵引力，由于它们有较宽的轮胎或履带，使他们能够产生比较大的牵引力。

中耕拖拉机主要用来中耕作业，也可以进行许多其它的田间作业，为了达到这个目的，一些中耕拖拉机被装备了不同胎面宽度的可替换的驱动轮。

用来进行一般的田间作业和耙地，为了不损坏农作物，这种拖拉机有一个比较大的离地间隙和比较宽的轮胎，能适应特殊的农作物间距。

专用拖拉机不同于普通的拖拉机和中耕式拖拉机，它被用于特定的作业，或者在特定的条件下用于不同的作业。

因此被用来棉花中耕机械化的专用拖拉机常常有一个前轮，在沼泽地里工作的拖拉机一般装备有很宽的履带，这样能够使它们在潮湿的土壤上工作。

山地拖拉机一般被设计能在16度的斜坡上工作。

按驱动装置的设计，拖拉机有可分为轮式和履带式。

履带式拖拉机因它较大的接地面积而著称，所以它有一个很好的牵引附着性，它们能碾压土壤并能紧紧的抓住土壤。

因此这种拖
拉机有很好的越野性并且能够提供很好的牵引力。

轮式拖拉机的应用也很广泛，能被用来在田间作业并且能够用来进行交通运输，但是它们的牵引能力比履带式拖拉机要小。

拖拉机的主要组成部分
拖拉机是复杂的自走式机械，它由相互独立相互作用的机构和单元组合而成。

如果不考虑特殊的设计，所有的拖拉机都有发动机，传动系，行驶系，转向系，作业机构和辅助装置组成。

发动机把燃料的化学能转化成机械能。

传动系包括一系列的机械装置，它们能传递发动机产生的扭矩给驱动轮或履带。

并且能把驱动扭矩变成有大小和方向的力，传动系包括，离合器，连轴器，变速器和后桥。

离合器的主要用途就是当驾驶员正在挂挡时，暂时的把发动机输出轴与变速器分离一段时间。

当发动机从停机启动时，它也能使发动机传递到驱动轮上的较低的动力连接平衡。

连轴器包括很多的弹性元件，这些弹性元件能够把不在同一条直线上的离合器轴和变速器轴连接在一起。

变速器通过不同的啮合齿轮，使改变驱动扭矩和发动机转速成为可能。

在发动机曲轴旋转方向不变的情况下，变速器能够是拖拉机倒驶。

后桥机构增加了驱动扭矩，且把它传递到驱动轮上或履带上在适当的角度传给驱动轴。

在大部分的拖拉机上，后桥上也包含刹车。

在轮式拖拉机上，不同于履带式的地方。

就是传动系还包括差速器，当拖拉机在转弯时或行驶在不平整的路面上时，它能是驱动轮以不同的速度旋转，它的左右轮在相同的时间内行驶过不同的距离。

行驶系能够使拖拉机移动，驱动轮或者履带和地面接触的旋转运动被转化成拖拉机的直线运动。

转向系主要用来改变拖拉机的行驶方向，在轮式拖拉机上是靠
旋转它的前轮，在履带式拖拉机上，是靠改变一个履带的速度。

作业机构被用来耕作。

充分应用拖拉机发动机的动力去实现各种农作业。

它包括动力输出轴，悬挂机构，农具挂接机构，皮带轮。

辅助装置包括装有弹簧坐椅及加热、通风装置的驾驶室，发动机罩，照明设备，指示器，喇叭等。

离合器
在传动系中离合器位于发动机与变速器之间，作用就是使驾驶员可以把发动机与变速器结合和脱离。

现代拖拉机上广泛应用摩擦片式离合器。

这种离合器利用摩擦力来传递动力，这种离合器的摩擦面由压盘提供，它的数量取决于传递扭矩的大小。

大部分拖拉机上广泛应用的是单片和双片式离合器。

单片离合器的压盘和发动机飞轮连接在一起，但是从动盘安装在变速器离合器输入轴上。

从动盘上有花键毂与输入轴上的花键相配合。

从动盘被一组螺旋弹簧紧紧地压在压盘与飞轮之间，这一组压力弹簧被支撑在离合器和压盘之间，由于在飞轮，从动盘与压盘之间产生了摩擦力，所以扭矩能够被从发动机传递到变速器输入轴，在这个位置时离合器开始工作。

离合器通过离合器转向传动机构来操作，离合器转向传动机构包括一个操作杆和一个分离拨叉。

它能够传递离合器踏板的运动给离合器分离轴承。

当驾驶员踏离合器踏板时，离合器转向传动机构迫使分离轴承向内（向左）移动。

随着分离轴承向左移动，它就向左推三个分离杆的内端。

当三个分离杆的内端被分离轴承向左推时，分离杆的外端就使压盘向右移动，压缩螺旋弹簧。

随着弹簧压力从从动盘上消失，在从动盘，飞轮和压盘之间出现空隙，这时离合器被分离。

但飞轮继续转动，但不通过从动盘传递动力。

当离合器踏板被松开，螺旋弹簧通过使压盘向左移动，从动盘再次被紧紧的压在飞轮与压盘之间，从动盘再次随着飞轮一起旋转。

在这个位置，离合器开始工作，刚开始从动盘进行滑动，直到它被完全压紧在飞
轮与从动盘之间，使工作趋于平滑。

上边所描述的是干式摩擦弹簧离合器。

传动轴和万向节
传动轴将动力从变速器传送到后桥的驱动轴上。

传动轴将变速器的主轴或是输出轴，连接到后桥上的差速器。

变速器主轴的旋转运动通过传动轴传递到差速器上，使后车轮转动。

设计传动轴时必须考虑两个因素。

第一，发动机和变速器是刚性地安装在车架上。

第二，后桥壳（连同车轮和差速器）是通过弹性元件与车架相连。

当后车轮在高低不平的路面上滚动时，弹簧上下伸缩，使变速器和差速器之间的传动角度和距离发生变化。

传动轴要能适应这些变化，也就是说，当后桥壳随差速器车轮一起上下运动时，与变速器输出轴之间的角度变大的原因是后桥和差速器运动的弧度小于传动轴运动的弧度。

后桥壳弧线摆动的中心点是固定在车架的后弹簧或控制臂上。

为了使传动轴适应这两种变化，就笔削装有两套独立的装置。

一个或几个万向节来适应传动角度的变化，一套伸缩花键，能够改变传动轴的现有长度。

传动轴可以是实心的也可以是空心的，有套管加以保护或裸露在外。

有些传动轴在中心或在中心附近装有支撑轴承。

两段传动轴之间各有中间支撑轴承，并由万向节传动连接。

万向节基本是个双铰链节，有两个Y型万向叉，一个在主动轴上，另一个在从动轴上，还有一个叫万向节十字轴的十字形零件。

万向节十字轴的四个轴颈叫做万向节十字头，分别装在两个万向节叉顶端的轴承中。

主动轴使万向节十字轴转动，另外两个万向节十字头使从动轴转动。

当两轴相互处在同一角度上，主动轴转动时万向叉上的轴承使万向节叉绕万向节十字轴摆动。

汽车上使用的万向节有多种形式，但是使用最普遍的是双十字轴万向节、等速万向节和球叉万向节。

伸缩花键由在传动轴上的外花键和与之相连的空心轴中对应的内花键组成。

伸缩花键使两轴一起转动，也能使两轴相对移动。

当
后桥在车架上向前或向上运动时，这种结构足以调整转动轴长度的任何变化。

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