If however you are willing to space the planets unevenly, this constraint does not apply. ( R + S ) is evenly divides by the number of planets. If you want the planetary gears to be evenly spaced, and all be engaging the next tooth at the same time, then both your sun and your ring gear needs to be evenly divisible by the number of planets.If you want them to be evenly spaced, but don’t need them to all be in the same phase with respect to their teeth, then then the sum of the ring gear’s teeth and the sun gear’s teeth must be evenly divisible by the number of planets. Now, if we drive the sun gear, we can rearrange the formula to solve for turns of the Y carrier:Ĭonstraints on number of teeth and planets
So we can remove those terms from the above formula, and we get: ( R + S ) × T y = T s × S For example, if we hold the ring gear in a fixed position, T r will always be zero. Now, usually in a planetary gear, one of the gears is held fixed. The turns ratio is as follows : ( R + S ) ×T y = R × T r + T s × S Example: Turns of the planetary gear carrier (the Y shaped thing in the previous photo) Working out the gear ratio of a planetary gear train can be tricky. Pitch diameter can also be calculated as tooth spacing * number of teeth / (2*π), where 2*π = 6.283 The gear generator program tends to refer to tooth spacing. The pitch diameter of a gear is just the number of teeth divided by diametrical pitch (larger values of “diametrical pitch” mean smaller teeth). If you go into the gear generator and select “show pitch diameter”, you can see how the pitch diameter is just a circle that the teeth are centered over. The teeth would stick out beyond the line of the wheel as much as they indent, so that the pitch line of the gears would be the line around the gears.
GEAR TEMPLATE GENERATOR PROGRAM PLUS
From the illustration at left, you can see that the diameters of the sun gear, plus two planet gears be must equal to the ring gear size.Now imagine we take out one of the green planet wheels, and rearrange the remaining ones to be evenly spaced. This can be made more clear by imagining “gears” that just roll (no teeth), and imagine an even number of planet gears.