I popped the side cover off of my 260 RPM Q100H and counted the gear teeth. I couldn't get the planet gear carrier screws loose. I don't have an impact driver, and when I used a screwdriver bit in a socket wrench it felt like the screw head was going to strip before I could break it loose, so I couldn't count the sun gear. I was able to count the 1st and 2nd stage planet gears along with the ring gear though. Interestingly, they are the same as
Papa's 328 RPM motor.
Sun: (assumed) 15 tooth
1st stage planet: 36 tooth
2nd stage planet: 23 tooth
Ring: 78 tooth
Sun to 1st stage planet ratio: 36÷15 =
2.4 (
not needed for final ratio calculation)
1st stage planet to 2nd stage planet: 23÷36 =
0.64 (
overdrive, need to multiply sun tooth count by this)
Small planet to ring gear: 78÷23 =
3.39 (
not needed for final ratio calculation)
Since the planet carrier is fixed (it's part of the axle) the formula to calculate the ratio is simply ring÷sun, but since this is a multi-stage planetary, you need to multiply the sun gear by the overdrive ratio.
Sun times overdrive: 15x0.64 =
9.6 tooth
Overdriven sun to ring gear: 78÷9.6 =
8.125
So the final ratio of the reduction is
8.125:1.
Here's where things get really strange. What this tells me is that either:
- The wheel RPM (201 vs 260 vs 328) is determined by the motor winding and not by the gear ratio, or
- I received a 328 RPM motor, even though I ordered a 260 RPM
This is going to get even more weird. On BMSbattery's website, the Q100H is only available as 201 RPM, or 260 RPM and the Q100 is only available as 201 RPM or 328 RPM. The Q100H says it has a 12.1:1 reduction ratio, and the Q100 says it has an 8.2:1 reduction ratio. Soooo, what the heck is going on here? How is Papa's motor 328 RPM if it's a Q100H, and how is my supposed 260 RPM motor geared the same as his? And how are both of these motors only 8.2:1 when the Q100H is supposed to be 12.1:1?