pic: 1276's 2007 3-Speed AM Gearboxes


These are our gearboxes for this year. They are an AM Shifter with a few changes. In order to get to 3rd gear, the shifter between 1st and second goes to a neutral position where neither are engaged.

We machined down the small cluster gear to a hex to accomadate a second dog clutch. We replaced one of the sprockets with the second gear gears in the inverse ratio (we switched the positions of the gear). We also added another servo shifter to shift the new clutch from the opposite side. The 3rd gear is about 1.5 times faster than second gear is. Also, the AM shifter has a lot of slop in the servo shifter fork. We placed it with a yoke which lets us accurately the dog clutch, becuase if both dogs engage, it locks up.

Software synchronises the shifting process so the driver can’t accidentally lock the gearbox up.

ok, I’ll be the first to say that is awesome!!!

What kinds of speeds do you get?

Have you discussed this design with AndyMark to see if maybe they’ll market it for next year?


Here I was expecting to see what kind of beast 1276 will put out this year!
I guess I’m just going to have to wait another week… :smiley:

Those are looking pretty sweet. We were the development of a 2-speed ball-lock shifting transmission before kickoff. This is kind of convincing me to try to work on a 3-speed.

Good luck at BAE, guys.

Around 4fps in low gear, 10fps in medium gear, and 15fps in high gear.

We haven’t showed them to AM (but I expect they’ll see it here). They aren’t bullet proof like the 2 speed, without proper code and additional sensors it is possible to lock them up.

When they do get locked up, is it possible to unlock them? Then it quits being a bug and becomes a feature. :wink:

Like the mods–nice and clean!

Aaaaah! I think my head just exploded from looking at this awesomeness. You guys are great. This is super cool.

I thought Kaizen Blitz was working on something interesting, as I noticed they were buying a few extra parts… but I would not have guessed this.

For all of the people who think that selling off-the-shelf gearboxes stifles the engineering and creativity of FIRST teams … phooey on you… look at 1276 and what they have done. Excellent job!!!

Andy B.

Yeah. If it is controllable then you have a 3 spreed transmission with brake…

so… is it?

It is very possible to unlock, just shift the third gear dog back into neutral. The only real problem is if you were cooking across the field at full speed and then locked them up you might do some damage.

EDIT (In response to Sean): Yep, that’s what I figured too. It’s just that if you engaged it while you were driving, you could hurt something.

I think he was referring to intentionally locking them up to create a mechanical braking feature.

The biggest issue about using the dogs to lock up the shifters is what happens when it does fail. If you accidentally lock up the gears (which may happen if you have a lock on command feature), or you recieve a significant force to the gearbox when locked up (not sure what force this could be, most external forces this large would probably just cause the wheels to skid well before a failure in the drive) the failure would almost certainly be losing gear teeth. And that spells disaster in a transmission.

That is awesome then. Keep your code so you don’t look them at high speed, but also put some code in that let’s you lock it on command. It would be really useful for holding position on a ramp at the end of the match.

In case anyone is wondering, these gearboxes held up perfectly through our regional. There was never any “bad shifting” causing a lockup or teeth stripping or anything of that sort. We found the extra high gear most useful in this years game to race around the rack to play defense and then return.

If there is any interest, we plan on creating a white paper before next season. (There, a deadline, now I’ll have to follow it. :rolleyes: )