英文翻譯：齒輪及軸的介紹中英都有(參考版)
2024-08-20 14:59本頁(yè)面
【正文】 it is almost always necessary to calculate them so that he knows they are within acceptable limits. Whenever possible, the powertransmission elements, such as gears or pullets, should be located close to the supporting bearings, This reduces the bending moment, and hence the deflection and bending stress.Although the von MisesHenckyGoodman method is difficult to use in design of shaft, it probably es closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaftdesign problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heattreatment, and surface finish and whether or not shot peen is necessary in order to achieve the required life and reliability.Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two inertias I1 and I2 traveling at the respective angular velocities W1 and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall be interested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for earth geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the heatdissipating surfaces. The various types of clutches and brakes may be classified as flows:1. Rim type with internally expanding shoes2. Rim type with externally contracting shoes3. Band type4. Disk or axial type5. Cone type6. Miscellaneous typeThe analysis of all type of friction clutches and brakes use the same general procedure. The following steps are necessary: 1. Assume or determine the distribution of pressure on the frictional surfaces.2. Find a relation between the maximum pressure and the pressure at any point3. Apply the condition of static equilibrium to find (a) the actuating force, (b) the torque, and (c) the support reactions. Miscellaneous clutches include several types, such as the positivecontact clutches, overloadrelease clutches, overrunning clutches, magnetic fluid clutches, and others. A positivecontact clutch consists of a shift lever and two jaws. The greatest differences between the various types of positive clutches are concerned with the design of the jaws. To provide a longer period of time for shift action during engagement, the jaws may be ratchetshaped, or geartoothshaped. Sometimes a great many teeth or jaws are used and they may be cut either c
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