PG71 Planetary Gearbox with RS775 Motor and Encoder Question

[wilderbuchanan]

My team really likes that this motor gearbox combo has an encoder on the back. However, we don't need the gearbox on the front. We were wondering if we could take the planetary gearbox off the front and still have the encoder work for just the RS775 motor?
Thanks,
Wilder

[Mike Marandola]

I don't see why not since the encoder is on the RS775 shaft and it will only be going slightly faster without the planetary.

[wilderbuchanan]

with planetary its around 64 rpm and without its around 5000 rpm

[Mike Marandola]

Originally Posted by wilderbuchanan

with planetary its around 64 rpm and without its around 5000 rpm

The motor speed is still roughly the same with and without the reduction.

[wilderbuchanan]

i'm confused because the planetary gearbox reductions is 71:1

[cgmv123]

Originally Posted by wilderbuchanan

i'm confused because the planetary gearbox reductions is 71:1

The encoder is on the motor shaft, before the 71:1 reduction happens. The specs for the encoder account for this:

Total Counts per revolution: 497 (7 Counts per motor rotation multiplied by gearbox reduction, 71)

[Mike Marandola]

Originally Posted by wilderbuchanan

i'm confused because the planetary gearbox reductions is 71:1

Yes so the motor inputs about 5,700 revolutions per minute (due to the gearbox efficiency it is more like 5,300 RPM), and after the 3 stage planetary reduction it is about 75 RPM. You can multiply the 75 RPM output speed by the 71:1 reduction and get 5,325 RPM. This is the motor speed even with the reduction with no load.

[Al Skierkiewicz]

As the motor used on this device is a legal motor, the AM-2161, I would expect the part with gearbox and encoder attached would also be legal. It is best to ask this of the Q&A. The AM part AM-2971 simply assembles the three parts into one for a discounted price.

[kitare102]

What are you going to be using the motor for? I can't imagine any applications in which 5000rpm alone is useable.