pic: Team 955's take on 4 speeds (back)

Just another look…

Looks very nice. Great job.

one question, How are you planning on securing the Fisher price motor? is it just hanging there? or is there something I am missing?

Another thing (probably i cant see it just because of the plates), is there any shaft inside that transmission that are going through 3 bearings? If yes, then its bad.

great job on keepinging the transmission about 5 pounds.


Edit - I am not an Engineer YET. But from my understanding of making a transmission, I would say, try to make the transmission and put everything (gears, motors, shafts, bearings, bushings) between 2 plates and not 3.

I was just going to say the same thing. Plus the CIM. Two easily corrected problems that could spell huge trouble if you don’t do anything.

-That shaft must be supported on all three points, hence the three bearings…
-Our inventor guy was just too lazy to add the motor mounts. :smiley:
-Can’t reveal everything :cool:

I am not going to support you on this one, just because of the fact the shaft will bind if you are runing it between 3 plates with 3 bearings. But overall design is good. I still would like to know how are you mounting the motors.


Having a shaft supported by three bearings is like an over-constraint. The only way you should even consider doing this is if you are certain you can keep tolerances to around .0004 (yes 4 ten-thousandths) and trust me, that is not an easy thing to do, even on a CNC.

Will it work with three bearings on a shaft? Yes. Will it bind and cause a loss of efficiency? Yes.

Is there really much use for a 4-speed transmission this year? Surely there’s not going to be so much variance in field conditions that you’ll want or need to shift that much on a field as small as this one…

The field is longer than last year and there were two teams that used 4 speed transmissions. It’s up to each team’s personal preferences whether or not the added complexity and time is worth the advantages

Of course it’s up to teams to decide what to build. I’m just wondering how often multi-speed gearboxes are used in competition on the field. I’ve never driven a robot with a multi-speed gearbox, nor have I spoken at length to drivers on teams with multi-speed gearboxes. I simply want to hear honest opinions about what good a gearbox like 955’s here will do this year. I understand how plenty of experienced teams would do it for the cool factor alone, but I want to hear what real drivers - or mechanical designers, even - have to say about multi-speed drivetrains in practice.

Well, I’ve driven a couple shifting robots and 2 single speed robots.

One of the single speed robots was very slow, one was very fast.

Of them all I’d rather drive the two shifting robots. You have power when you need it, and speed when you need it. With the single speed ones there was always moments when I either wished I had more speed, or more torque, respectively.

Alright, wrong thread dude. Get a clue and look at the other posts perhaps?
By the way, I’d like to see what you have to say when our robot is on your side of the field in five seconds running defense and using our insane torque to push you back to the starting point. :yikes:

We’re working on ideas for not having three bearings if you’d like to add some helpful advice. Thanks for the input, but there are multiple threads on the subject you brought up. It seems like every tranny post degrades into a discussion of whether or not multiple speeds are a necessity. :mad:

P.S. We will also be mounting motors on a fourth plate, just in case you all are really curious.

The easiest solution is just to drop the middle bearing. And 4 plates? Seem’s kind of a lot, how thick are these plates? Because judging by the CAD rendering, they seem to be a lot thicker than necessary.

the plates on the tranny are 3/8 inch thick

why so thick? and what material are they made of?

They are aluminum. We are known for our “tanks”, it’ll be built to last.