[TowerTalk] Rotor Selection

[Roger (K8RI) on TT]

On 4/5/2014 3:06 PM, Patrick Greenlee wrote:

Sounds like a reasonable approximation  to me. <:-))

73

Roger (K8RI)

>  I am definitely not a worm drive expert and was just relaying some 
> info I had read but not necessarily recalled accurately.   When I was 
> presented here with information above my level of experience but in 
> conflict, at least a little bit, with my recollections of a previous 
> source I thought it better to consult the oracle/guru friend who has 
> MS in Mech Eng from UCLA and 35+ years of hands on experience.  Here 
> are his comments.
>
> Patrick - The standard ratio for non-freewheeling is 15:1, but 
> depending on the pwr source, electric mtr, arm and crank, etc, the 
> direction of load, the direction of drive, and lubrication/friction in 
> the gears; that may need to increase.  If the load is loading the gear 
> in the same direction that the worm is driving the gear then a motor 
> shut off may not stop the gear from continuing to turn.  If the worm 
> is turning opposite the gear load direction then the worm would stop 
> the gear when the motor is shut off.  An electric brake on the motor 
> windings normally will stop the first condition and is normally not 
> necessary for the second condition. The first condition may need 20+:1 
> to stop the worm turning when the motor is shut down without the 
> electric brake.  In the static condition of worm to gear, 15:1 should 
> work.
>
> I did not go into detail with him regarding the cheap and dirty 
> approximation type gears so his comments are most likely aimed more 
> toward the "real" worm drive situation.
>
> Patrick NJ5G
>
>
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