White Paper Discuss: Dual-motor, dual-speed gearbox

Thread created automatically to discuss a document in the White Papers.

Dual-motor, dual-speed gearbox by dlavery

I’ve never responded to a white paper before but…

Ok, Wetzel gave me this link to this particular white paper and we started investigating this design as a possibility on this years robot for my team.

We ran into a bunch of design inconsistencies while planning the fabrication on this.

Some we solved by trial and error, but I just wanted to let you all know that there are problems with this design.

For one, the shaft location holes are in different places on the Y axis of the part and they don’t line up when put together.

But, we solved that problem but still want to verify the correct gear for the bosch output shaft.

Is it supposed to be a 55 or 56 tooth gear?

If wetzel or anyone from Team 116 can answer these questions, please reply here.


BTW, I am not the one who found the inconsistancies, I am just relaying the word and trying to find solutions for my team’s mechanical team.

The correct gear for the bosch output shaft is a 55 tooth gear.

I do not see the inconsistency with the shaft location holes that you mention. I do not believe that there is any inconsistency. BTW, this design has worked well for us in the past, so it should not have any major problems, there just might be some improvements to the design.

Well, like I stated before, I m only relaying info from another team member, so I can only guess what is wrong or right.

Thanks for the confirmation on the gear size though…

If I find out the details for the supposed inconsistencies, I will PM you and try to work them out if that is alright.

Thanks for the help, and I will be getting back to you as soon as I can!

The “55-tooth question” has already been answered in two other threads (here and here). Please search before you post.

Please make sure that you have the correct URL. The correct link to the white paper is http://www.team116.org/2004/TransmissionDescriptionV6a.zip. Other development versions are out there, so make sure you are linking correctly.

As noted in the original white paper description, this design is intentionally an “unfinished work.” It is intended to provide a basic shifting solution for those teams that want to take on that challenge, but may not have very sophisticated manufacturing capabilities or experienced machinists. If you have greater capabilities, there are a LOT of improvements that can be made to this basic design (ranging from significantly lightening the gears to reducing the face widths to using multiple pitch values for the cascading gears to minimizing the plate widths to …). We KNOW there is a lot of room for improvement - it is SUPPOSED to be that way. The intent is that teams will improve upon it and post their improvements and thereby increase the overall knowledge/experience of the whole FIRST community, while maintaining the design as one that can be built with minimal manufacturing capabilities. So far, we know that at least 12 other teams have built this design (and there may be several more we cannot confirm). But so far, none of them has “gone public” with any modifications/upgrades they may have made. We are waiting to see who has taken the idea to the “next step.”


You are correct … as I also noted in this post, the veritcal dimension for the hole in the “motor side” plate is .734 (which is correct) while the dimension for the “same” hole in the other plate is .810.

Also, I chose to use the 56 tooth gear and adjust the center distance to maintain proper mesh at PD. However as Dave has mentioned a couple of times, the 55 tooth gear is correct and can be ordered from PIC by substituting a ‘55’ for the ‘56’ in their part number.

See response in this thread.


Where can I find the “0.7 module, 20° pressure angle, 1/2” face width, 55 tooth steel gear.” I cannot find it on the PIC Designs site (listed supplier), MSC, or Small Parts.

Where can I find the “0.7 module, 20° pressure angle, 1/2” face width, 55 tooth steel gear.” I cannot find it on the PIC Designs site (listed supplier), MSC, or Small Parts.

Please read the thread. This gear has already been talked about many times.