英语翻译Gears are direct contact bodies,operating in pairs,that transmit motion and force form one rotating shaft to another,or from shaft to a slide (rack),by means of successively engaging projections called teeth.Tooth profiles.The contacting

英语翻译Gears are direct contact bodies,operating in pairs,that transmit motion and force form one rotating shaft to another,or from shaft to a slide (rack),by means of successively engaging projections called teeth.Tooth profiles.The contacting
英语翻译
Gears are direct contact bodies,operating in pairs,that transmit motion and force form one rotating shaft to another,or from shaft to a slide (rack),by means of successively engaging projections called teeth.
Tooth profiles.The contacting surfaces of gear teeth must be aligned in such a way that the drive is positive; i.e.,the load transmitted must not depend on frictional contact.As shown in the treatment of direct contact bodies,this requires that the common normal to the surfaces not to pass through the pivotal axis of either the driver or the follower.As it is known as direct contact bodies,cycloidal and involute profiles provide both a positive drive and a uniform velocity ratio; i.e.,conjugate action.
Basic relations.The smaller of a gear pair is called the pinion and the larger is the gear.When the pinion is on the driving shaft the pair acts as a speed reducer; when the gear drives,the pair is a speed increaser.Gears are more frequently used to reduce speed than to increase it.If a gear have N teeth rotates at n revolutions per minute,the product N*n hat the dimension “teeth per minute”.This product must be the same for both members of a mating pair if each tooth acquires a partner form the mating gear as it passed through the region of tooth engagement.For conjugate gears of all types,the gear ration and the speed ratio are both given by the ratio of the number of teeth on the gear to the number of teeth on the pinion.If a gear has 100 teeth and a mating pinion has 20,the ratio is 100/20=5.Thus the pinion rotates five times as fast as the gear,regardless of the speed of the gear.Their point of tangency is called the pitch point,and since it lies on the line of centers,it is the only point at which the tooth profiles have pure rolling contact.Gears on nonparallel,non-intersecting shafts also have pitch circles,but the rolling-pitch0fircle concept is mot valid.Gear type are determined largely by the disposition of the shafts; in addition,certain types are better suited than others for large speed changes.This means that if a specific disposition of the shafts is required,the type of gear will more or less be fixed.On the other hand,if a required speed change demands a certain type,the shaft positions will also be fixed.Spur gears and helical gears.A gear have tooth elements that are straight and parallel to its axis is known as a spur gear.A spur pair can be used to connect parallel shafts only.
If an involute spur pinion were made of rubber and twisted uniformly so that the ends rotated about the axis relative to one another,the elements of the teeth,initially straight and parallel to the axis,would become helices.The pinion the in effect would become a helical gear.Worm and bevel gears.In order to achieve line contact and improve the load carrying capacity of the crossed axis helical gears,the gear can be made to curve partially around the pinion,

英语翻译Gears are direct contact bodies,operating in pairs,that transmit motion and force form one rotating shaft to another,or from shaft to a slide (rack),by means of successively engaging projections called teeth.Tooth profiles.The contacting
齿轮是直接接触式（挤压式）的传动装置,是成对运行的,把机械运动和力矩从一个旋转轴传到另一个旋转轴,或从旋转轴传到齿条,是它们保持啮合的突出物叫齿,
齿形；齿轮的接触面必须配合适度,使得传动精准（不丢转）,动力传递不是靠摩擦力,如直接接触式传动装置的描述中所说的,这种传动装置要求无论主动轮还是被动轮,作用力要垂直于接触面,而不是垂直通过轴线,已知的齿轮传动装置的齿形都是渐开线的,它能使得传动不丢转,速比准确,
基本关系；两个啮合的齿轮中小的叫pinion,大的叫gear,当驱动轴是小齿轮pinion时,是减速传动,反之是加速传动,齿轮更多的用于减速传动,如果一个齿轮有n个齿,每分钟n转,n,n的乘积就是每分钟齿（牙）数,如果两个齿轮啮合的好,它们的乘积应该是相等的,即,主动轮齿数X主动轮转速=被动轮齿数X被动轮转速,在齿轮传动中,齿轮的齿数比和速比是由大齿轮的齿数和小齿轮的齿数之比决定的,如果大齿轮齿数100,小齿轮齿数20,速比就是100/20=5,因此小齿轮的转速相当于大齿轮的5倍,因为切点与轴线平高,所以切点叫pitch point（节圆点）,它是齿面进行纯滚动接触唯一的点,不平行齿轮和不平行轴 上的齿轮移动式有节圆的,只是节圆的概念有区别,