pic: Planetary Transmition

[Alex.Norton]

[cdm-description=photo]29224[/cdm-description]

[Aren_Hill]

are you custom making the planetary reduction or is it a COTS item. and i assume this is for a drivetrain handling 2 small cims by the looks of it?
is there anyway to reduce the gearing between the cims and the planetary to lighten it up?

[M. Mellott]

1) Is this set up to work with an AM Planetary Gearbox or some other product?

2) Is that a pneumatic cylinder on the bottom for a 2-speed shifter?

3) What is the total gear reduction (or should I say reductions)?

4) Can your planetary gearbox handle the torque of 2 CIMs with the additional reduction?

A very nice, simple design...if it is a 2-speed transmission, it would be very economical as well.

[Alex.Norton]

1) The planetary shown is the banebots 56mm. However it does not use the week link of the carrier plates, those would need to be replaced and seriously beefed up to make this work.

2) Yes it is a two speed.

3) The reductions are:
High: 3.57:1
Low: 117.86:1

4) I don't know for sure. However planetary gearboxes in general can handle more torque than a spur gear since they have a larger number of teeth contacting. In addition given those reductions two CIM's is a little overkill on the output torque.

Basically i think it could be made to work but I would want to do A LOT of testing on a transmition before actually using one. Mostly its just a concept to be expanded upon.

[RogerR]

1) The planetary shown is the banebots 56mm. However it does not use the week link of the carrier plates, those would need to be replaced and seriously beefed up to make this work.

2) Yes it is a two speed.

3) The reductions are:
High: 3.57:1
Low: 117.86:1

4) I don't know for sure. However planetary gearboxes in general can handle more torque than a spur gear since they have a larger number of teeth contacting. In addition given those reductions two CIM's is a little overkill on the output torque.

Basically i think it could be made to work but I would want to do A LOT of testing on a transmition before actually using one. Mostly its just a concept to be expanded upon.

is that right? thats one heckuva reduction, if so...

[s_forbes]

I seriously doubt that a banebots transmission could survive very long with that large of a reduction in front of it and two small CIMs. Maybe you should look into using one of these (http://www.harmonicdrive.net/).

[Richard Wallace]

I seriously doubt that a banebots transmission could survive very long with that large of a reduction in front of it and two small CIMs. Maybe you should look into using one of these (http://www.harmonicdrive.net/).In my day job, I've used Harmonic Drive components (linked above) to construct durable test equipment, intended for many years of service. Their products are very good, and not cheap. Comparing them with competitive robotics parts from suppliers like BaneBots is not simply mixing apples & oranges, it's mixing cannonballs & oranges.

I do agree that the BaneBots gearbox will not survive long in this configuration, at the loads that a CIM motor can drive.

[Madison]

Alex,

Can you post a section view of the inside of the planetary so we can have a better look at how you're planning to modify those transmissions to achieve what seems to be coaxial shifting? Most planetary gearboxes used in shifting transmissions on FIRST robots work my sliding the ring gear between stages, but that'd be difficult to accomplish using a coaxial shifting mechanism.

Also, if you're actually getting a ~117:1 reduction in low gear and ~3.5:1 in high-- It's too early for me to do that math -- consider how useful such a large change really will be. What sort of mechanism might require a ~33.5:1 change in ratio in normal operation?

[Alex.Norton]

Thank you very much for all the comments. The reason that I'm using the banebots is because it comes with many of the necessary gears. I'm developing the concept because it is very easy to change the change in reduction by changing the size of the second planetary sun gear. At the moment with a 22 tooth second gear the ratio changes from 1:30 to 1.1:1. If instead I used the gears from the second stage of the banebots (sun being 30 teeth), the reductions would be 2.25:1 and 1:9 which is a much smaller difference in reduction.

Basically this can have a large number on different combinations of reductions without a change in the form factor. Also if anybody wants to check me on those reductions (would definitely be wise) I think that it would actually work better to have the larger gear on the first stage of the planetary. At the moment I believe the directions of the output would depend on the gear your in. So when you changed gears the robot would change direction...

Thanks again for all the coments