Quote:
Originally Posted by Pinwheel
If 360 degrees is divided by 24 hours equals 15 degrees per hour, how do you calculate gear size & ratio, number of teeth & RPM.
I feel the answer will hurt my brain... 
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Hi,
Well, if the output shaft here should go at 15/360 revs/hr (not an exact decimal answer), and the motor shaft is going at, say, 1/2 rev/min = 30 revs/hr, then you need a gear train to convert the motor shaft speed to the output speed.
The motor shaft is going faster here, so it must be geared
down, by the ratio 30/(15/360) = 180. You could also express this by saying the motor shaft speed must be geared
down to 1/180.
The number, size and type of gears you have in between the 2 shafts can be varied in design so long as they produce the right ratio. A reduction this large will usually need some sort of compound gear train, doing it in say, 2 steps, or with a gear design like a worm drive, featuring a larger ratio.
If you have 2 meshing gears, the ratio is the ratio of the numbers of gear teeth, and if the first pair of gears is followed by another pair in a compound train of gears, then Ratio = ratio1 x ratio2.
Hope this helps