专业英语16-19(8页).doc

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1、-16. CouplingsVocabulary:coupling 5kQpliN 联接器couple 5kQpl 连合, 连接adjacent E5dVeisEnt 邻近的semipermanent 9semip:mEnEnt 非永久性的restore ris5tC: 恢复emergency i5mE:dVnsi 紧急情况exceptional ik5sepFEnl 异常的plant plB:nt 工厂、车间、设备propeller prE5pelE 螺旋推进器rigid 5ridVid 刚性的flange flAndV 凸缘、法兰attach E5tAtF 缚上, 系上alignment

2、E5lainmEnt 对准、同轴misalignment 5misElainmEnt 不对准、不同轴rabbet 5rAbit 槽口,榫头projection prE5dVekFEn 凸出物snugly 5snQli 紧贴地deflect di5flekt 偏斜interfere 9intEfiE 妨碍intensity in5tensiti 强度flexibility 7fleksE5biliti 挠性shock FCk 冲击spatial 5speiFEl 空间的resilient ri5ziliEnt 有回弹力的springy 5spri:Ni 有弹性的compensate 5kCmpE

3、nseit 补偿Text:A coupling is a device for connecting the ends of adjacent shafts. In machine construction, couplings are used to effect a semipermanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the

4、machine, but it can be broken and restored in an emergency or when worn parts are replaced.There are several types of shaft couplings; their characteristics depend on the purpose for which they are used. If an exceptional long shaft is required for a line shaft in a manufacturing plant or a propelle

5、r shaft on a ship, it is made in sections that are coupled together with rigid couplings. A common type of rigid coupling consists of two mating radial flanges (disks) that are attached by key-driven hubs to the ends of adjacent shaft sections and bolted together through the flanges to form a rigid

6、connection. Alignment of the connected shafts is usually effected by means of a rabbet joint on the face of the flanges, i.e., a short cylindrical projection on the face of one flange fits snugly in a circular recess on the face of the other flange.In connecting shafts belonging to separate devices

7、(such as an electric motor and a gear-box), precise aligning of the shafts is difficult and a flexible coupling is used. This coupling connects the shafts in such a way as to minimize the harmful effects of shaft misalignment. Flexible couplings also permit the shafts to deflect under their separate

8、 systems of loads and to move freely (float) in the axial direction without interfering with one another.Flexible couplings can also serve to reduce the intensity of shock loads and vibrations transmitted from one shaft to another.The flexibility provided by a coupling may be only spatial, or it may

9、 be both spatial and resilient (springy); in other words the coupling may compensate for shaft misalignment but provide no resilience, or it may be resilient and provide also for a small amount of misalignment. 17. ClutchesVocabulary:clutch klQtF 离合器rotatable 5rEuteitEbl 可旋转的coaxial kEu5AksEl 同轴的con

10、venient kEn5vi:njEnt 方便的unload 5Qn5lEud 无负荷的rotational rEu5teiFEnEl 转动的inertia i5nE:FjE 惯性switch switF 开关capacity kE5pAsiti 能力winding 5waindiN 线圈excessive ik5sesiv 过多的, 额外current 5kQrEnt 电流intermediate 7intE5mi:djEt 中间的 rotor 5rEutE 转子, 回转轴lineshaft 5lain7FB:ft 总轴reverse ri5vE:s 倒转的Text:A clutch is

11、a device for quickly and easily connecting or disconnecting a rotatable shaft and a rotating coaxial shaft. Clutches are usually placed between the input shaft to a machine and the output shaft from the driving motor, and provide a convenient means for starting and stopping the machine and permittin

12、g the driver motor or engine to be started in an unloaded state. The rotor (rotating member) in an electric motor has rotational inertia, and a torque is required to bring it up to speed when the motor is started. If the motor shaft is rigidly connected to a load with a large rotational inertia, and

13、 the motor is started suddenly by closing a switch, the motor may not have sufficient torque capacity to bring the motor shaft up to speed before the windings in motor are burned out by the excessive current demands. A clutch between the motor and the load shafts will restrict the starting torque on

14、 the motor to that required to accelerate the rotor and parts of the clutch only.On some machine tools, it is convenient to let the driving motor run continuously and to start and stop the machine by operating a clutch. Other machine tools receive the power from belts driven by pulleys on intermedia

15、te shafts that are themselves driven by belts from long lineshafts that serve a group of machine. Two pulleys that can be connected to the intermediate shaft by clutches, and driven in opposite directions by open and crossed belts from the lineshaft, can provide forward and reverse rotation for the

16、machine.Appending:Manual transmissionA manual transmission has a gearbox from which the driver selects specific gears depending on road speed and engine load. Gears are selected with a shift lever located on the floor next to the driver or on the steering column. The driver presses on the clutch to

17、disengage the transmission from the engine to permit a change of gears. The clutch disk attaches to the transmissions input shaft. It presses against a circular plate attached to the engines flywheel. When the driver presses down on the clutch pedal to shift gears, a mechanical lever called a clutch

18、 fork and a device called a throw-out bearing separate the two disks. Releasing the clutch pedal presses the two disks together, transferring torque from the engine to the transmission.18. BrakesVocabulary:brake breik 制动器flow flEu 趋向respect ris5pekt 方面resemble ri5zembl 类似arrest E5rest 停止；阻止engagemen

19、t in5eidVmEnt 啮合，接合stationary 5steiF(E)nEri 固定的serve sE:v 匹配, 适合arrest E5rest 制动capacity kE5pAsiti 能力kinetic kai5netik (运)动的, 动力(学)的hydraulically hai5drC:likli 液压的electrically ilektrikEli 电力的act on 对.起作用, 作用于translate trAns5leit 平移dissipate 5disipeit 耗尽metallic mi 5tAlik 金属(性)的pneumatic nju5mAtik 气动

20、的organic C:5Anik 有机的ceramic si5rAmik 陶质的asbestos Az5bestRs 石棉majority mE5dVCriti 多数, 大半fading 5feidiN 衰退effectiveness i5fektivnis 效率; 效能coefficient kEui5fiFEnt 系数sinter 5sintE 烧结, 熔结lining 5lainiN 衬里, 内层prefer prif: 首选drum drQm 鼓形圆桶thermal 5WE:mEl 热的conductivity 7kCndQk5tiviti 传导性, 传导率particle 5pB:t

21、ikl 微粒series 5siEri:z 系列plat plB:t 片alternate C:l5tE:nit 交替的, 轮流的pad pAd 衬垫caliper 5kAlEpE 卡钳shoe Fu: 闸瓦pinch 5pintF 收缩，夹紧Text:Basically, brakes are devices for controlling the flow of motion in machine, and in this respect they resemble clutches; clutches start the flow while brakes arrest it. Befo

22、re the engagement of a clutch or a brake, one of the two members in the device is moving while the other is stationary; after the engagement of a clutch both members are moving at the same speed, while after the application of a brake the moving member is either slowed down or stationary. In both ca

23、ses the desired effects are produced by devices that are so alike, structurally, that they can sometimes serve in either capacity.In arresting the motion of bodies, brakes must be capable of absorbing kinetic energy. Even when acting on translating bodies (like automobiles) most brakes are designed

24、to act on rotating mechanical elements and to absorb energy either mechanically, hydraulically, or electrically. Mechanical brakes are the most common: they dissipate kinetic energy in the form of heat generated by mechanical friction between a rotating metallic element and a nonrotating friction el

25、ement, when they are brought in contact by either mechanical, hydraulic, pneumatic, or electrical means. The material in the friction element may be organic, metallic, or ceramic.Organic materials with an asbestos bases are satisfactory for the majority of applications.When service requirements are

26、severe, however, the heat generated may cause fading (a drop in braking effectiveness caused by a reduction in the coefficient of friction). In such cases, sintered metallic linings are preferred because of their high thermal conductivity and freedom from fading. By adding ceramic particles to sinte

27、red metallic linings, extremely hard and fade-resistant linings can be produced.The rotating element in a mechanical brake is either a drum, a disk, or a series of disks. The nonrotating friction element in a drum brake may be either a band or a pair of shoes (blocks) that contract around the outsid

28、e of the drum or a pair of shoes that expand against the inside of the drum.A disk brake may be similar to a plat clutch, with alternate rotating metallic and nonrotating friction elements, or it may be of the caliper type, with a single rotating disk and two opposed friction pads that squeeze the d

29、isk between them in a pinching action.Appending:Disc and Drum BrakesDisc and drum brakes create friction to slow the wheels of a motor vehicle. When a driver presses on the brake pedal of a vehicle, brake lines filled with fluid transmit the force to the brakes. In a disc brake, the fluid pushes the

30、 brake pads in the caliper against the rotor, slowing the wheel. In a drum brake, the fluid pushes small pistons in the brake cylinder against the hinged brake shoes. The shoes pivot outward and press against a drum attached to the wheel to slow the wheel.19. LinkagesVocabulary:linkage 5liNkidV 联动装置

31、assemblage E5semblidV 装配pin pin 销钉、枢轴endless 5endlis 环形的，头尾相连的hinge hindV 铰链sliding 5slaidiN 滑动的joint dVCint 联接头definition 7defi5niFEn 定义vitally 5vaitEli 极其重要的suitability 9sjU:tEbilEti 恰当，适宜relative 5relEtiv 相对的specify 5spesifai 具体指定constrain kEn5strein 强迫，限制path pB:W 轨迹，路径determinate di5tE:minit 确定

32、的visualize 5vizjUElaiz 显现assume E5sju:m 假设compatible kEm5pAtEbl 协调的manner 5mAnE 方式Text:A linkage may be defined as an assemblage of solid bodies, or links, in which each link is connected to at least two others by pin connections (hinges) or sliding joints. To satisfy this definition, a linkage must

33、 form an endless, or closed, chain or a series of closed chains. It is obvious that a chain with many links will behave differently from one with few. This raises the vitally important question regarding the suitability of a given linkage for the transmission of motion in a machine. This suitability

34、 depends on the number of links and the number of joints.Degrees of freedom.A three-bar linkage (containing three bars linked together) is obviously a rigid frame; no relative motion between the links is possible. To describe the relative positions of the links in a four-bar linkage it is necessary

35、only to know the angle between any two of the links.This linkage is said to have one degree of freedom. Two angles are required to specify the relative positions of the links in a five-bar linkage: it has two degrees of freedom.Linkages with one degree of freedom have constrained motion; i.e., all points on all of the links have paths on the other links that are fixed and determinate. The paths are most easily obtained or visualized by assuming that the link on which the path are required is fixed, and then moving the other links in a manner compatible with the constraints.-第 8 页-