问题 问答题 简答题

简述联轴器的找正的具体方法。

答案

参考答案:

(1)找正时一般以转动机构(如风机、水泵等)为基准,待转动机械固定后,再进行联轴器的找正。

(2)调整电动机,使两联轴器端面间隙在一定范围之内。端间隙大小应符合有关技术规定。

(3)用钢板尺放在联轴器的圆周平面上进行初步找正。

(4)用一只联轴器螺丝将两联轴器的连接起来,再装上找正夹具的量具(百分表)。

(5)转动联轴器,每旋转90°用塞尺测量一次卡子与螺钉之间的径向、轴向间隙,或从百分表上直接读出,并先做好记录。一般先找正联轴器平面后找正联轴器外圆。

(6)根据上述所测数值用相似三角形法进行计算,确定电动机各底角下垫片的厚度。

单项选择题
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根据短文内容,从短文后的七个选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

                                                   Are Societies Ageing Too Fast?

     An ageing society is one in which the population of people over the age of 60 is increasing. The global

population at present is about 6 billion with l person in every 10 aged 60 or above. 1._____ This will mean

that for the first time in human history the population of older persons will be larger than the population of

children! What are the causes of this population change?

     2._____ And another is that birth rates have dropped as people, especially women, are educated. Measures

to slow population growth like China's one-child policy, have also contributed to lowered birth rates. The

increase in the aged population is not just an interesting trend, however; it also has severe implications for the

future of global economies.

     People traditionally retire at 65 and live on government pensions. 3._____ Another concern is that as medical

expenses increase with age, the demands of the growing aged population will eventually cause medical systems

to face bankruptcy (破产).

     4._____ They suggest that because people are living longer, they ought to work longer, while governments

need to establish a sound social security system. They also suggest that individuals start saving as soon as

possible to ensure a financially secure retirement. People should also develop good health habits in their youth

to ensure an active and productive old age. 5._____ By finding cures for diseases like Alzheimer's and cancer,

medical bills and the need for care would be drastically reduced.

     Finally, an important step to ensure a bright future for all is to do away with negative stereotypes that see

valuable members of society only as pensioners or patients. It's high time we stopped seeing ageing as a disease

and started playing our parts in securing the future of our ageing societies.

A. Due to ageing problem, cities are facing more challenges.

B. Experts insist that steps should be taken now to prepare for the future.

C. As people grow older, a huge financial burden will be placed on the government.

D. Biomedical research is another tool we can use to deal with the problems of ageing societies.

E. One reason is that dramatic health advances have added 20 years to the average life expectancy.

F. The United Nations projects that by 2050, it will be l in every 5.

G. As is known to all, good habits lead to good health.