问题 问答题 论述题

主轴变速箱设计中,为什么要遵循“前多后少”的原则?

答案

参考答案:

(1)主变速传动系统从电动机到主轴,通常为降速传动。接近电动机传动件转速较高,根据公式可知,传动的转矩M较小,尺寸小些;

(2)反之,靠近主轴的传动件转速较低,传递的转矩较大,尺寸较大。

(3)因此,在拟定主变速系统时,尽可能将传动副较多的变速组安排在前面,将传动副较少的变速组安排在后面,使主变速传动系统中更多的传动件在高速范围内工作,尺寸小些,以便节省变速箱的造价,减少变速箱的外形尺寸。

单项选择题 A1型题
阅读理解
It is possible that the majority of the teenagers accepted the advantages of the iPad. In most cases they were expressing strong opinions about it. But today we already know that another three high-end computer tablets(平板电脑) are going on sale, with the aim of taking a bite out of the iPad's market. For tablet computer fans, iPad may not be the only choice, as the Motorola Xoom, the HP Touchpad and the BlackBerry PlayBook will have been launched (推出)by this summer, according to foreign media reports on Tuesday. Here is Product Information Guide as follows. We would like to listen to your reviews later.   
Apple iPad2
Size: 9.7 inch screen, 8.8mm thick
Weight: 601g (Wi-Fi only version)
Battery life: 10 hours of heavy use
Price: a base price of $499(3,278yuan)
Available(可使用的): March 11, 2011 in the US
Strength: over 65,000 *apps that are fit for the iPad
Weakness: lack of USB port and flash support
 
Motorola Xoom
Size: 10.1 inch screen, 13mm thick
Weight: 730g
Battery life: 8hours of heavy use
Price: $800(5,252RMByuan)
Available: now
Strength: great multi-tasking feature, better cameras than the iPad2    
Weakness: limited options(选择权)of apps
 
HP Touchpad
Size: 9.7 inch screen, 13mm thick
Weight: 740g
Battery life: 8hours of heavy use
Price: not yet announced
Available: summer 2011
Strength: killer software features, including a virtual(虚拟的) keyboard which comes in four sizes
Weakness: lack of a rear-mounted(后置式) camera which would allow users to get images and photos
 
BlackBerry PlayBook
Size: 7- inch screen, 10mm thick
Weight: 400g
Battery life: 8hours of heavy use
Price: not yet announced
Available: Spring 2011
Strength: business-oriented, powerful multitasker, excellent data security(安全)
Weakness: Some features require users to have a Black-Berry phone
小题1: Which type is the biggest one?
A.Apple iPad 2B.Motorola XoomC.HP TouchpadD.BlackBerry PlayBook
小题2:Which is True according to the passage?
A. Apple ipad 2 has excellent data security. 
B. Four types above of Battery life are the same.
C. Most people are satisfied with HP Touchpad.        
小题3: Which one can you buy as a present with only 4000yuan RMB at hand?
A.Apple iPad 2B.Motorola XroomC.None of the fourD.Any of the four