英语翻译Spur GearsGears,defined as toothed members transmitting

英语翻译
Spur Gears
Gears,defined as toothed members transmitting rotary motion from one shaft to another,are among the oldest devices and inventions of man,In about 2600 B,C.the Chinese are known to have used a chariot incorporating a complex series of gears.Aristotle,in the fourth century B ,C,wrote of gears as if they were commonplace.In the fifteenth century A ,D,Leonardo da Vinci designed a multitude of devices incorporating many kinds of gears.
Among the various means of mechanical power transmission (including primarily gears,belts,and chains),gears are generally the most rugged and durable.Their power transmission efficiency is as high as 98 percent.On the other hand,gears are usually more costly than chains and belts.As would be expected,gear manufacturing costs increase sharply with increased precision---as required for the combination of high speeds and heavy loads,and for low noise levels.(Standard tolerances for various degrees of manufacturing precision have been established by the AGMA ,American Gear Manufacturers Association)
Of the non-ferrous metals,bronzes are most often used for making gears.Nonmetallic gears(nylon and other plastics ) are generally quiet,durable,reasonably priced,and often can operate under light loads without lubrication.Their teeth deflect more easily than those of corresponding metal gears.This promotes effective load sharing among teeth in simultaneous contact.Since nonmetallic materials have low thermal conductivity,special cooling provisions may be required.Furthermore,these materials have relatively high coefficients of thermal expansion,and this may requie installation with greater backlash than metal gears.

小KASS：
齿轮
齿轮的齿形的成员,定义为从一个轴旋转传送到另一个设备时,最古老的发明,男,大约2600乙、丙.中国是一个已知的战车组成的复合系列齿轮.亚里士多德,在公元四世纪乙、丙、写的齿轮好像他们是司空见惯的事.在十五世纪,D、达芬奇设计的多种设备合并多种齿轮.
在各种不同的方法,主要包括机械传动齿轮,带(链),齿轮,通常是最坚固耐用.他们的电力传输效率高达98%.另一方面,齿轮通常更昂贵的比链和皮带.可以想象,齿轮的制造成本和提高精度的急剧增长的组合———所需的高速度,他们把难担的重担、噪音低的水平.(标准偏差为不同程度的制造精度AGMA业已确立的,美国的齿轮制造协会).