pic: 254/968 Transmission

[Henry_Mareck]

Ok, I understand the pillow block now, but how exactly does the shifting rod work? I dont see how anything is or can be connected to the dog except for the output shaft because it spins with the shaft. You said it was inside the main shaft, only its only connected to the dog and not the other gears?

Edit:
I think i can see the shifting rod here, but im still not sure how it connects to the dog.

[Travis Covington]

We use a screw to connect the shifting shaft to the dog. There is a slot in the output shaft which gives the screw/shaft/dog clearance to slide back and forth, engaging one or the other gears.

Here is a cutaway that team 45 posted a few years back showing how it works.

[AustinSchuh]

How are the gears holding up for you guys? I saw what I consider significant wear on the Poof's practice robot, but I am no expert on gears.

[Travis Covington]

The teflon dry lube was wearing off, I assume. The comp bot has some of that, too. It really is of little concern. The teeth on all four of our bots are in better condition than the steel gears that we ran last year with the same amount of driving time. I am quite surprised with how well they are wearing. The 20 pitch gears show absolutely no wear whatsoever. The 32 pitch show some wear on the endges, but only slight anodize and drylube wear. Again, the teeth look pretty good on all of them though.

[Gabe]

After reading the poster, I was wondering what you meant by "clutchless" since you are using a positive clutch for dog shifting.

[Travis Covington]

It isn't really a clutch. This transmission design is most commonly found on motorcycles, with the addition of a clutch of some sort. An electric motor allows you to remove the clutch, simply due to the fact that the motor works from 0 rpm onward. An IC engine on the other hand, has an idle that would otherwise prohibit the vehicle from stopping completely without a nuetral position or a clutch. The starting and stoping are the primary needs for a clutch with an IC engine/motorcycle tranny. It is quite common to not use the clutch when shifting a motorcycle by simply easing off the throttle and engaging the next gear so long as you are already moving.

By clutchless, I meant lacking a means to engage or disengage the power coming from the motors feeding the output shaft.

[ajlapp]

Have you posted your actual gear ratios and final specs for this transmission yet?

If not, please do so. I was very impressed with the design! I'd specifically be intersted in the gear ratios. Thanks

[sanddrag]

deleted - nvm

[Madison]

irrelevant. -mk

[AndyB]

Got an drawing of it by any chance? Just curious.

[Travis Covington]

We still have not completed our final technical paper on the transmissions ourselves for school, so it'll be a while til we make any sort of white paper to post here on CD.

As for the ratios, the initial 32 pitch reduction has 20 tooth pinions and an 80 tooth driven gear. High gear reduction is 45:30, low gear is 60:15, driving a 4" diameter wheel.

[lukevanoort]

Originally Posted by Travis Covington

We still have not completed our final technical paper on the transmissions ourselves for school, so it'll be a while til we make any sort of white paper to post here on CD.

As for the ratios, the initial 32 pitch reduction has 20 tooth pinions and an 80 tooth driven gear. High gear reduction is 45:30, low gear is 60:15, driving a 4" diameter wheel.

Could you just post your paper for school when it is done?

[Travis Covington]

Originally Posted by lukevanoort

Could you just post your paper for school when it is done?

We haven't decided. Most likely, if anything, we will write a brief overview of the FIRST related uses of what we did. The rest of the paper really isn't useful or appropriate for the CD community.