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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