MDM problem help

[Engineer_562]

Hello,

can someone confirm if this is a correct solution. I am not sure where 3 came from for Nw. Thanks in advance.

 

[emmajuwa]

No, it's a wrong solution. The author already corrected it in the errata. it should be 2 for Nw. The answer is 33.33 rpm which is not part of the answers

 

[MA_PE]

My reference gives the same relationship:

Velocity ratio = Number of "teeth" of the worm / number of teeth on the gear.

the problem states that the worm is a double  threaded.  Therefore Nw is 2 and NOT 3.  I suspect it's a misprint and should've read triple threaded worm

 

[justin-hawaii]

I apologize for the error and for any inconvenience this may have caused.  I had to make quite a few changes, please see the link below for the errata.   If anyone purchases the exam in the future, you will get the latest version with all changes included.  

http://www.engproguides.com/machineexamerrata.pdf