机械毕业设计外文翻译.doc

Gears are vital factors in machinery. One of the first mechanism invented using gears was the clocks. In fact, a clock is little more than a train of gears.Considerable study and research have been made on gears in recent years because of their wide use under exacting conditions. They have to transmit heavier loads and run at higher speeds than ever before. The engineers and the machinists all consider gearing the prime element in nearly all classes of machinery. 齿轮在机械中占有极其重要的作用。第一个利用齿轮做成的机械装置就是钟表，事实上，它只不过是用了一系列的齿轮。对于它可以在严格的条件下的广泛使用，在齿轮上做了大量的学习和研究。相比过去，它们现在必须在更高的速度下传递更重的负荷。工程师和机器操纵工人都认为齿轮在几乎所有的机器的零件中占有首要的因素。 1. Spur gears Spur gears are used to transmit power and rotary motion between parallel shafts. The teeth are cut parallel to the axis of the shaft on which the gears are mounted. The smaller of two gears in mesh is called the pinion and the larger is customarily Designated as the gear. In most applications, the pinion is the driving element whereas the gear is the driven element. 1.直齿圆柱齿轮 直齿圆柱齿轮用于平行轴之间传递力和回转运动，轮齿被切制成与安装齿轮的轴之轴线相平行。两啮合齿轮中较小的叫小齿轮，大的习惯上叫齿轮，在大多数情况下，小齿轮是主动轮，大齿轮叫从动轮。 2. Helical gears Helical gears have certain advantages, for example, when connecting parallel shafts they have a higher load-carrying capacity than spur gear with the same tooth numbers and cut with the same cutter. 2．斜齿圆柱齿轮 斜齿圆柱齿轮具有特定的优点，比如，当连接平行轴的用相同刀具切削出来的并齿数相同的斜齿轮比直齿轮具有较高的承载能力。斜齿轮也能用于连接相互成任意角度的非平行轴。 Helical gears can also be used to connect nonparallel , non-intersecting shafts at any angle to one another. 斜齿轮也能用于连接相互成任意角度的非平行轴。 The maximum gear ratio obtainable with a single pair of gears varies with the type of gear and the application. The following are approximate maxim a for the various type for average load conditions: spur, 8; parallel-shaft helical, 10; straight bevel , 6; spiral bevel, 8;hypoid , 12; and worm , 80. For lightly loaded, instrument, and positioning gears, these rations can be exceeded. Rations as high as 400 or higher can be obtained with gears that resemble tap