Slickest drive transmission yet...

[Salik Syed]

They are all different........most of the shifting ones i've seen have 2 sets of gears and a pneumatic slides an input gear into one gear and out of the other, one that we built a while ago based on Technokats had dogs which catch on to the gears and engage them...the gears are on bearings so they don't do anything without a dog...
its kinda hard 2 explain...check out some pics and you will understand

[Paul H]

Sam, I know that some teams shift the drill transmission with servos, and to the best of my knowledge, these cannot be shifted on the fly.

[Paul H]

Originally Posted by sanddrag

Is there a picture of the real thing? That would serve us both better than me asking a bunch of questions. Thanks.

Raul posted a picture.

[Dima]

Very Nice, Very simple. The best part is definaly making it automatic. It is something new and refreshing so to speak. Very cool that you guys actually took time to calculate the power curves and shift at the right points, props to you guys!

Originally Posted by Paul H

Sam, I know that some teams shift the drill transmission with servos, and to the best of my knowledge, these cannot be shifted on the fly.

Except for Chief Delphi this year apperantly

[FotoPlasma]

I really must say that this is an awesome system. Congrats to team 33.

I've thought of automatic transmissions for a couple seasons now, and I never thought of monitoring output RPM. In my theoretical designs for an automatic transmission, I would have monitored current to the motor, and shift based on that information. At different gear ratios, the stall current of the motor is constant, and if you set upper and lower thresholds, you can shift up or down, depending completely on whether you need less or more pushing power, respectively. I'm sure it's more complicated than I'm making it sound, but as I said, I'm stuck in the realm of theory, here.

Just my take on the theory of an automatic transmission. With all of the talk of constructive vs. destructive criticism that went on recently, I want to say that I'm very impressed by this system. Again, many congratulations to 33.

[Elgin Clock]

Originally Posted by dlavery

Thank you very much for the kind words. Working with the team to design that transmission was a lot of fun, and we learned a lot!

-dave

BTW, Dave and the rest of the crew over on Team 116, here is our version of your designed gearbox and tranny!

http://www.pbase.com/image/26818929

[Mike K]

Just Remember to Use Hard Metal!!!!

[Paul H]

Hardened Steel is what he means. We ground down our high gear on one gearbox in Detroit.

[matt111]

well our team, 1024, design a CVT VST (continious velocity, torque, variable speed transmission). it uses bevel gears and three planetary gear systems. then we ran into the problem: it was gonna weigh around 30 lbs!!! so i was told to design a casing to replace the alumnium box it was going in (around half the weighht). well we ran out of time, but i did get a nifty looking case made from a FDM prototyping machine. Hopefully (crosses fingers) we will have it done at IRI. we had two allision transmission engineers helping us design, so hopefully we can have something to show for my 10+ straight weeks of doing CAD for this. and yes i did start in the offseason..and yes it is still not done

[Ryan F.]

I was wondering if I could get some peoples opinion over weather a variable speed/torque transmission is a big advantage, or a lot of work for nothing. Our team has a CIM/Drill motor combo for our drivetrain, with no special shifting gearbox, and we seem to have pleanty of speed and torque.

[tkwetzel]

I'm sure it's more complicated than I'm making it sound, but as I said, I'm stuck in the realm of theory, here.

Programming the robot to shift really shouldn't be too complicated, with encoders measuring the speed of the output shaft or the axles. Especially since they calculated the power curves and everything. With the power curves, they can determine the best shift point to gain the most power. Finding the shift points is the hard part. Then you prgram it to shift when the encoders measure a certain speed determined by you to be your shift point. You can also calculate downshift points as well the same way.

[jimfortytwo]

rforystek:
That might be a debate for a different thread. To answer your question, though this thread from last summer contained some good debate on that topic (4 motor vs. shifters). The fourth page of replies in particular is well worth a look.

http://chiefdelphi.com/forums/showth...g+motor+debate

[Greg Perkins]

team 151's drive this year was awesome as well... they designed the system with simplicity in mind, as well as sleek and compactness as well..
a far shot, but their tranny are smaller than the aluminum tubing

they made a new gearbox for the drills using the previous planetary gears, and made a new housing...it was gorgeous...they also implemented the pneumatic shifting, and ran the pneumatic shifter inside the drive shafts to save space...tthis thing was gorgeous...

[Elgin Clock]

Originally Posted by Elgin Clock

BTW, Dave and the rest of the crew over on Team 116, here is our version of your designed gearbox and tranny!

http://www.pbase.com/image/26818929

Apparently I got bad rep point for showing Gracious Professionalism and "hijacking this thread" to thank a team for their gearbox design we used this year.

If any one wants the name of this person who is against Gracious Professionalism and against thanking other teams, PM me.

[Gus]

Originally Posted by Jim Zondag

Thanks, I'm glad everyone likes our design.
We have made two speed transmissions for the past several years. Each year we try to make them simpler and smaller. I found that with the kind of high/low shift range that I like to have (3:1 or more) that the robot would tend to lurch severely if you downshifted at high speeds. I really want to make a 3 speed with an intermediate gear to help this. It turned out it was easier to build a 4 speed than a 3 speed ( its really two small two-speeds in series). We focused the design around reliablity and ease of construction, the demo unit on display was made entirely by high school students in a few evenings using no special tooling.
Once I had a design with 4 gears I was pretty much forced to automate the shifting in order to keep from overloading the driver. I talked with a few Automatic Transmission experts at DaimlerChrysler on how to do a shift scheduler and viola....a fully automatic electronic robot transmission.
It really is pretty neat, providing a nearly flat power output across a very wide RPM band with a 5:1 total shift span.
I plan on posting the design and engineering here as soon as I get a good set of drawings made up (I'm not a CAD guy, I made the ones in the robot from a napkin sketch).

Would it be possible to get a drawing or photo's of this transmission. It sounds perfect. Thanks Gus