英语翻译Overtheyears,apopularmethodoftransmittingpowerfromoneshafttoanotherhasbeenbypulleysandbelts.Beforetheadventofindividualelectric-motordrivesforeachmachine,centrallineshaftswithanelaboratearrayofpulleysfor

Question

英语翻译
Over the years,a popular method of transmitting power from one shaft to another has been by pulleys and belts.Before the advent of individual electric-motor drives for each machine,central lineshafts with an elaborate array of pulleys for operating each machine were used.In those days,practically all belts were made of leather.Today,belting still popular; however,various types of drives are open-belt,crossed-belt,serpentine,and quarter-turn,Fig.4-4 illustrates some of these types.When compared with geared drives and chain drives,belting has certain advantage and disadvantages.A belt drive will tend to slip when an overload is applied to the system .This slipping,while not desirable,is preferable to a complete failure,which could happen if gear teeth were stripped or a roller chain were to break .Unless the overload persisted for an extended period of time,the system would return to normal with only a small amount of wear; failure would not necessarily occur.Belts can absorb quite a large amount of sudden shock.Except for a positive-drive belt,no belt will deliver the theoretical rotational speed that can be calculated.Theoretically,the belt speed should equal the peripheral speed of the pulleys.The following equation indicates the relationship between rotational speed and pulley diameters:
This equation makes no provision for slip or creep.Slip is defined as an actual movement (or sliding) of the belt relative to the pulley.Creep,however,id a different phenomenon.When a driving pulley connected by a belt to a driven pulley,the belt tensions on the two sides of the driver differ.The tension stretches the belt; this stretching is released after leaving the driver pulley.Therefore,the pulley is delivering a different amount of belt than it is receiving.This difference is known as belt creep.A designer is concerned only with the total loss of rotational speed,which is partly creep and partly slip.An assumption in the neighborhood of 4% is often reasonable.Since all belts stretch with use,any belt drive should allow for streching.This can be done by providing an adjustment for one of the pulleys or a weighted idler pulleys resting against the belt.
Flat belts are used with pulleys that are either flanged at the edges or crowned in the middle.Flanges ensure that the belt stays on the pulley,but they also damage the edges of the belts.Crowning the pulleys is considered better practice.The amount of crowning is greater for leather belting than for.In addition,crowning must be greater for low speeds than for high speeds.The of crowning varies from 1/16 in.per foot of pulley face to 1/4 in.per foot of pulley face.


Answer 1

多年来,一个受欢迎的方法,将动力从一个到另一个轴已通过滑轮和皮带.到来之前,个别电机驱动器对每一台机器,一个中央lineshafts精心阵列,每个操作机进行滑轮.在那些日子里,几乎所有带皮革制成的.今天,带仍然流行；然而,各类传动副,crossed-belt,蛇纹石,并回转,fig.4-4说明其中的一些类型.相比齿轮传动,链传动,带具有一定的优势和劣势.皮带驱动将滑动时,过载应用系统.这种滑动,而不可取的,最好是一个彻底的失败,这可能发生如果齿轮牙齿被剥夺或一滚子链被打破.除非负荷持续一段较长的时间,系统将恢复正常只有少量磨损；失效不一定会出现.带可吸收相当数量的突然冲击.除了一个积极驱动带,不带将提供理论转速可以计算.理论上,带速度应等于圆周速度的滑轮.下列公式表明之间的关系旋转速度和皮带轮直径：
这个方程未作任何规定或蠕变.滑动的定义是一个实际的运动（或滑动）的带相对于滑轮.蠕变,然而,身份不同的现象.当驱动皮带轮皮带连接从动皮带轮,皮带张力两侧的驱动程序不同.张力拉伸带；此拉伸释放后留下的驱动轮.因此,滑轮是提供不同数额的带比接受.这种差异被称为带蠕变.设计师只关心损失总额的转速,这部分是蠕变和部分滑移.假设在4%附近的往往是合理的.由于所有带弹力与使用,任何带传动应允许拉伸.这可以通过提供调整滑轮之一或加权导轮休息对带.
平带是用滑轮,要么是法兰在边缘或在中间.法兰确保带停留在滑轮,但他们也损害边缘带.在滑轮被认为是更好的做法.数额最高是更大的比皮革皮带.此外,加冕必须是更大的低速度比高速度.为不同的1 / 16.每英尺1 / 4滑轮脸.每英尺滑轮脸.