coupling Bosch & Atwood motors

[DougHogg]

I have been trying to learn about multiple-motor drive trains (and single motor drive trains actually), so the above has been very helpful. Thank you to everyone who has been posting in this thread.

Originally posted by Jnadke
I'd error on the side of making the drill motor being the faster of the two for three reasons:
1. It is more powerful, and therefore it will pick up more slack.

If the drill motor is faster and more powerful, then the CIM motor will be dragging it back a bit, but I don't understand the reference to "slack".

Also, does the drill motor lose some power when it is geared down to the CIM's speed?

Originally posted by Jnadke

2. Since it has timing, you'll incur less negative effect when operating both motors together in reverse. (Internal friction due to the timing will cause the drill motor to be slower, we want to minimize the difference)

Could you divine "timing" in this context. (Does it relate to why the drill motor goes faster in forward than in reverse?)

Originally posted by Jnadke

3. The CIM motor has a higher internal wire resistance, so the generator effect will be less severe if you spin it faster than its free speed.

Makes sense.

Originally posted by Jnadke
Overall, I'd aim for a gear ratio in the area of 3.4 or 3.5 to 1 when gearing the drill (raw) to the CIM. I wouldn't use the drill gearbox when gearing motors together because internal gearbox friction can be unpredictable. The less gears between them, the better.

Okay, so here is the homework assignment I gave myself. Given the above information, to synchronize a Fisher-Price motor instead of the drill motor (in this year's game, we rotate our telescoping arm with a drill motor), you would want the CIM's to be a little faster, since they are more powerful. On the other hand, the Fisher-Price would have a higher resistance. Therefore I am surmising that it would be good to just get them as close as possible. How about a ratio of 2.75 to 1 for Fisher-Price to CIM? Does that sound like a good target?