just wondering if team 33 was planning or has already published information about their transmission from this season. hopefully a whitepaper is coming soon, but in the meantime i’d love some decent pictures and a little description. thanks.
I’ll see Jim next tuesday and see what he’s doing with the whitepaper. It’s not out yet. I’ll try to get some closeups at IRI
This page has some info on it.
Random tidbits that I can think of:
-It’s obviously 2 two speed trannies in series
-It’s made with a lathe and a mill…or a drill press with a moving table.
-The gears are heat treated pinion rod. We turned them down on the lathe and had them heat treated.
-Yes, the gears will be fine if you heat treat them, and we filed the edges a bit just to be safe. You wouldn’t want to use this method if you were designing a transmission for a go kart or something, but for the amount of time a robot is used, it should be fine. We went to three regionals, nationals, and will attend 3 offseasons.
-The side panels are polycarbonate of some sort
-That is actually a big version of the tranny in the picture. It can be compressed down to roughly half the size by staggering the shafts rather than having them in a straight line.
-The automation code uses a shaft encoder that is actually in the transmission, but our demo used banner sensors. Same concept, it bases the shifting on the output RPM.
-There is obviously no motor matching in it, we used #35 chain to match the speeds of the drill gearboxes in low and chips, exactly like the martians (494) did in 2003, and put the output into the transmission
-The transmissions can be mounted between the wheels
-The motor pan/mounts weighed about a pound, it was a folded sheet of aluminum.
-You can also make a rock solid, feather light 2 speed transmission with this method, just build half of it.
Here’s something I threw together in Paint, it would be our robot’s drivetrain this year if it wasn’t for the climbing system.
Just looked at that picture again. Obviously, the slave chain between the wheels would have to clear above and below the transmission in the above view, I don’t know what I was thinking.
Also, the motor reduction occurs after the transmission. Rather than building it in, we just reduce it between the transmission and the wheel by putting a big sprocket on the wheel and a small one in the transmission (obviously)
thanks for the info…i talked with jim on several occassions about the tranny, but what i’d really love are some decent pictures. i may be ar iri, but if i’m not please take some basic photos of the gear switching components and post them for me. thanks again.
I’m just thinking out loud…
According to my sources, 33’s version had the tranny shift on the fly, complete with shift points and everything.
Given that our programming department is sorely lacking, wouldn’t it be possible to set up a bump-shifting setup and get World Rally on things? Just set up a switch and a small shifter a driver could nudge with a free hand.
(And count me on the list of people awaiting this white paper. This might just be the next killer app in FIRST.)
actually the demo version of the tranny was setup as a sequential style gearbox. clicking the trigger advanced one gear up, another click went another gear up and so on, then the thumb would walk you back down. obviously this can get hectic on the field so an automatic shift scheduler was used to take the burden of the drivers.
Yeah, you could do the bump shifting, but one reason that the whitepaper isn’t out yet is because Jim es working on making a totally generic code. He will distribute the code with the whitepaper, so everyone who builds the transmission can have it automated if they choose.
I’ll get pictures at IRI.
Awesome, you guys are too much.
where did you guys buy the pinion rod for the gears?
I’m guessing SDP but they may have gotten it locally.
I went to the killer bees booth at least three or four times to watch their demo box, and sent everyone from my team to see it at least once. Here are some of my impressions:
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Shifting is extremely smooth. They would rev up the gearbox, hit a button and it changed in the blink of an eye.
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Very, very, consistent! I never once saw it malfunction in the slightest. I’ve heard of issues with other trannies ripping gears apart or freezing up, but this is truly a shift on the fly design.
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Four speeds is probably overkill for most applications, and they weren’t using four in their (very successful) robot. The two speed served them very well.
See the FIRSTwiki entry! As soon as this whitepaper goes up I plan to wiki it with a vengence (Copyright permitting, naturally). 
I’ll ask about the whitepaper and where we got the pinion rod Tuesday at our IRI practice. I’m also going to try to get a video of the demo board shifting and put it online.
the pinion wire is from Mcmaster
i read in the original post (by d. lavery) about this transmission that they used 16 DP gears. in addition, i’ve read (and seen) that they use pinion rod/wire. i’ve been looking for 16 DP pinion rod/wire for almost a year, and i was persuaded that it didn’t exist, until i found out about the 33 transmission. now i’m starting to think i was mixed up. was i wrong? are ya’ll using 16 DP gears?
I don’t know what they are using since I’ve never seen it in person but McMaster does sell 16P spur gear stock. Check the bottom of this page Quite a limited tooth count selection though.
much appreciated. i’m suprised that i missed that, since mcmaster-carr is usually the first place i look.
Yes, that’s it, and it is, in fact, from McMaster. Just cut it down on a lathe and you’re golden.
Apparently Jim has it mostly drawn in Inventor, but got sidetracked with developing a new streamlined autonomous code. I told him that there’s interest here and he’s going to try to post it soon.
I have video of the transmission running/shifting. I need to get the firewire cable from my friend in order to capture and upload it.
Awesome, can’t wait.
Alright, well I can’t post the videos just yet, here’s some pictures. Nothing really new, but it shows the first through fourth gear positions.
(quick note, third gear in the picture isn’t completely in gear. That’s what happens when you shift when it’s not moving)
http://www.freewebs.com/ddj331/Transmission.htm