[R-390] Gear train rebuild help needed......

[Norman Ryan]

Hi, Charles,

Thanks for that link to the Wiki article on Geneva drives.  Fascinating reading!

Will capitalize the G from now on.  :-)

Vy 73 de Norman, KG4SWM





On Thursday, December 26, 2013 5:31 PM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
 
Bob wrote:
>
>>Phil wrote R-390A.  IF that is the case, there is NO green, Geneva Gear.
>
>More misinformation.  The Geneva Drive used in both the R390 and the 
>R390A is not the same as the Green Gear in an R390.  The Green Gear 
>is not called a "Geneva Gear."
>
>The Geneva Drive is what has been suggested as a possible problem in 
>Phil's radio.  It is shown and discussed on pp. 1-2 of Scott 
>Seickel's R390A gear train rebuild tutorial.
>
>The Geneva Drive is a mechanical mechanism that moves a shaft (in 
>this case, the bandswitch shaft) in small steps for each rotation of 
>the driving shaft (in this case, the MC Change shaft).  The 390 
>manual calls it a Geneva mechanism, while the 390A manual calls it an 
>"intermittent gear."  Geneva mechanisms typically have a pin that 
>engages a slot in the driven wheel. As the drive wheel rotates, the 
>pin enters the slot and turns the driven wheel some fraction of its 
>rotation.  See <http://en.wikipedia.org/wiki/Geneva_drive>, 
>especially the "internal Geneva drive."
>
>The Green Gear in an R390 is a convenience tool that keeps the KC 
>Change gear train in alignment with the Veeder-Root counter while you 
>have the radio disassembled.
>
>Best regards,
>
>Charles
>
>
>
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