#Python planetary gear calculator
###DESCRIPTION
Planetary gears must respect certain mathematical equations in order to work properly. One basic rule is that the number of teeth the ring gear must be equal to twice the number of teeth the planet gear have plus the number of teeth the sun gear has.
R = 2 * P + S
Another is that for a planetary gear ccnfiguration with an even distribution of planets (that is, planets are evenly spaced), the number of teeth of ring gear and sun gear must evenly divisible by the number of planets.
R divides #Planets AND S divides #Planets
This calculator helps generating these possible gear configurations while calculating turn ratios in different scenarios: when ring gear is fixed, when carrier (planets position) is fixed or when sun is fixed.
###EXAMPLES
- Check if the following configuration is correct (R=36, P=14, S=8):
> plgcalc.py 36:14:8
36:14:08
- Check if the following configuration is correct (R=46, P=14, S=8):
> plgcalc.py 36:14:7
No results possible: invalid gear configuration
- Print out all data regarding the first configuration:
> plgcalc.py 36:14:8 --all
Gear Tp/Ts Ratio Tp/Tr Ratio Ts/Tr Ratio Angle
Configuration Ring fixed Sun fixed Planets fixed Planet-Sun
36:14:08 0.181818 0.818182 -4.500000 8.181818
- Check the configuration that is possible for a planetary having (R=42, P=18, S=any); for this configuration print Planet-Ring turn ratio (sun is fixed):
> plgcalc.py 42:18: --tpr
42:18:06 0.875000
- Print 10 possible configurations for a planetary setup that has (R=any, P=any, S=12); for the resulting configurations print Planets-Sun turn ratio (ring is fixed):
> plgcalc.py ::12 -l 10 --tps --header
Gear Tp/Ts Ratio
Configuration Ring fixed
14:01:12 0.461538
16:02:12 0.428571
18:03:12 0.400000
20:04:12 0.375000
22:05:12 0.352941
24:06:12 0.333333
26:07:12 0.315789
28:08:12 0.300000
30:09:12 0.285714
32:10:12 0.272727
- Generate all possible configurations for a planetary gear set (R=any, P=any, S=9) with evenly distributed planet gears:
> plgcalc.py ::9 -l 10 -e -p 3
15:03:09
21:06:09
27:09:09
33:12:09
39:15:09
45:18:09
51:21:09
57:24:09
63:27:09
69:30:09
- Same as above, but also print calculated ratios:
> plgcalc.py ::9 -l 10 -e -p 3 --all
Gear Tp/Ts Ratio Tp/Tr Ratio Ts/Tr Ratio Angle
Configuration Ring fixed Sun fixed Planets fixed Planet-Sun
15:03:09 0.375000 0.625000 -1.666667 15.000000
21:06:09 0.300000 0.700000 -2.333333 12.000000
27:09:09 0.250000 0.750000 -3.000000 10.000000
33:12:09 0.214286 0.785714 -3.666667 8.571429
39:15:09 0.187500 0.812500 -4.333333 7.500000
45:18:09 0.166667 0.833333 -5.000000 6.666667
51:21:09 0.150000 0.850000 -5.666667 6.000000
57:24:09 0.136364 0.863636 -6.333333 5.454545
63:27:09 0.125000 0.875000 -7.000000 5.000000
69:30:09 0.115385 0.884615 -7.666667 4.615385
- Same as above, but use sun gear with 8 teeth, which should be found as an invalid configuration:
> plgcalc.py ::8 -l 10 -e -p 3 --all
No results possible: invalid sun configuration, planets will never be evenly spaced