The perfect 2 speed Transmission..... features...
 

what are some things to make a nice 2 speed transmission into a perfect one... like u know common problems with crappily designed 2 speeders.... also some nice addons you can think of to make it better.... all i could really think of was to add wheel encoders and a ratcheting tensioner on the transmission, and to have the pneumatic screw directly into the tranny instead of like on some ghetto rigged ubolt and to use 2 PNEUMatics instead of one big one going across..

Re: The perfect 2 speed Transmission..... features...
 

Some of the below may apply to transmissions of any type

Fast shifting on the fly.
The correct amount of backlash.
Along with the above, very very little room to be between gears, never a possiblity of both gears engaged at once.
Proper alignment.
No loads in undersirable directions (ie side loads)
Gears and shafts poperly spaced and captured - This one is very important. If you don't know how to do it or what I mean by that, we'll disuss it.
Both sides shifting at the same time.
All timed motors always spinning in the advanced direction while the robot is moving forward.
High durability.
Low maintainance.

Most of all, the driver nor software should not have to take any precausions when driving or shifting whatsoever. The transmission should perform sucessfully by its own mechanical doing no matter what the driver's input is. The mechanics of the transmission need to be robust enough to downshift at full speed and shift while switching between forward and reverse and shift up and down multiple times in a row very quickly and shift while turning clibming, etc any crazy thing you can think of (ie. drive into a wall)

The forces and situations that robots encounter in finals rounds I'm sure are far beyond any testing most teams do. Good drivers know the limits of their machines, but great drivers have machines with no limits. I say as soon as your robot runs (during the build period) you should run it hard. Put it through every torture imaginable. Then by the time ship comes, you'll hpefully have it made bulletproof.

Re: The perfect 2 speed Transmission..... features...
 

low weight

Re: The perfect 2 speed Transmission..... features...
 

easy enough to build in 6 weeks

Re: The perfect 2 speed Transmission..... features...
 

One word...reliable!

-Kyle

Re: The perfect 2 speed Transmission..... features...
 

make that indestructible!

Re: The perfect 2 speed Transmission..... features...
 

Simple... true that...>! infact last year ours was pretty reliable but stuff kept breaking like chain and stuff!! arrrghhh....
here is a picture of the tranny for 2005:
it has a FP and CHip....
the only thing i'm reallly worried about is using the skinny 1/8" plate shifting fork i don't think it should be too much of a problem....
i was really hoping to put the Output sprocket inside the transmission but that wasn't possible... or at least practical compared to teh current config..

Re: The perfect 2 speed Transmission..... features...
 

by gears properly spaced do you mean simply add the pitch radii and for the shafts secured you mean like collars and whatnot.... or is it something else?

if we build this thing it will be probably the hardest one to build so far.... esp considering the 1/4 " shafts, tiny parts, and the tight squeeze, our first 2 spd tranny was like 12X4X6 inches!!!! this one is like 4X4X2! (actually smaller if you don't count the extra empty plate for mounting) i mean for this thing i will have to countersink holes etc... so that screws don't hit gears etc etc... while on the last one we'd just move the gear forward some ... they were 20 pitch gears too! and like 1/2" face width ...

Re: The perfect 2 speed Transmission..... features...
 

Never Use the drill transmitions. I know that they are more then likely not going to be included in the kit this year I think a way to make a good trasmition into a great one is to run the motors into the gearbox directly without having anything inbetween (like a preassembled drill transmition) because two years ago our gearbox (a two speed shift on the fly) was almost perfect except for the fact that we would blow a drill transmition almost everyround. I got so good at fixing the drill transmitions that I could reasemble them blindfolded!

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Jeez folks.. what is with all the drill bashing lately?

I know MANY teams (mine included) that used the drill transmissions las year with NO problems.

That's right, we ran a drill motor/tranny combo all season last year powering our arm shoulder joint (under SERIOUS shock loads) with no problems. None at all. The original tranny is still in that robot today.

Everytime someone posts on these forums "never use the drill transmission! They blow up all the time! We destroyed 80 kabillion of them!"
I wonder: "What the HECK are you guys doing to that poor gearbox?"

Personally I hope we see it back in the kit.
(I know everyone thinks FIRST has ruled them out, but I'm still waiting for the OFFICIAL confirmation, not this speculation stuff, that they're not coming back in 2005.) The drill and tranny (when not used for drive) make an EXCELLENT high powered mechanism motor. Lots of power, lots of reduction, small package.

Seriously,
3 competitions, lots of severe shock loading, no problems.
What are you guys doing wrong?
What am I doing right?

John

Re: The perfect 2 speed Transmission..... features...
 

Heck John, we have used two drills for a two drill transmission the past two years, and we won two regionals with it!

I love the drills, they are small, lock when not moving, and just great motors.

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Thoroughly agree with you... we used the drills with the transmisions in 2003, 2002, and 2001 with no problems. I remember asking the same question as you last year--what are all these people doing so wrong that they can't use the transmissions?

I'd love to see the drill and it's transmission in the kit this year as well.

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For the people with successful use of the drill motors, did you run them in high or low gear? We had them in high gear in 2003 with no problems at all but in low gear in 2004 we had to rebuild/replace each maybe twice.

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We ran them in both high and low, with no problems

Re: The perfect 2 speed Transmission..... features...
 

WE had no problems with the drill transmissions and have used them in combination with the chips in two different transmissions (a 2 speed and a single speed). They are fairly easy to mount and we ran them in high gear. Although we used the drill transmissions and the mounts provided, I do not like the mounts. They are flimsy and you have to be careful not to overtighten and warp them. Everyone should take apart the drill transmissions at least once just for fun :ahh:. The thing to be careful with when you are using the drill transmissions is to make sure that the transmission and the drill motor are securely held together and that you use enough zip-ties to lock it in gear properly.
-Aaron

Re: The perfect 2 speed Transmission..... features...
 

You were probably doing it right. I saw many newer teams last year encounter problems because they didn't know all the tricks... Tearing the transmission apart and removing the two pins (for coasting) or zip-tie / tape the spring clips in for the shifter or building you own mounts that work reliably. I remember using the plastic mounts in 2003; if you installed them just right, you're golden, but if you switched the rear and front mount or somehow didn't line them up perfectly, your transmission loosened up and the shifter disengaged. Oh yea, what about the back of the drill motor, how many students accidently dropped them from a height of 2" and had the plastic brush clip thing break. Very frustrating for some teams.

Will they be back for 2005? Not sure, but I'm with a lot of people in saying that we wouldn't be surprised if they're not back, and if they do come back I bet they're a slightly different model (maybe the back of the motor is made sturdier!)

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Well let's start with the FP mount.. You need to secure it in two places, otherwise it's pinion will not fully engage the other gear. The one mount you do have, how would it secure to the transmission plates? (if those plates are 3/16", will we be able to drill and tap them out for #6-32 screws, hmm?)

The shifter fork could be made out of 3/16 angle and if kept short enough, should work OK. I guess this means the internal shifting rod (Andy Baker style) is being abandon due to the reduced space next to the Chip motor?

The pnuematic cylinder is backwards. Easy fix.

Where's the pinion on the Chip? It's not that large blue gear is it!! Is it below it?

And finally, how did you get inventor to do the 701 on the side of the transmission?

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Yes I know that some teams had no problems with them that is because 2 years ago there was a mass defect in the coupler assembly line and I know my team and many other teams got defective couplers which where not drilled and taped straight. This caused the drill transmissions to torque up and down sheering the casing. This was the problem I know my team and many other's had. Because of this there where some people who got good couplers before the defect in the line happened. But those are few and far between. I have no problems with the actual drill motor or actually the transmission but those coupler's. And since you can't attach the drill transmission easily to a shaft without one it makes the drill transmission almost useless. :eek:

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very frustrating...VERY.
well other than that, we had zero problems with the drill motor or the transmission. we used a drill motor for each side of our drive and had zero problems. i think thats pretty good.

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i haven't drawn it yet but there willbe LONG screws going from the housing plate (with the chip mounted to it) to the FP mounting screw holes... it will look kinda wierd but should work...
there is no pinion for the CHIP :D .... it matches perfectly with the FP (once its geared down) .... so i just stuck that big gear straight on the shaft....

as for the fork ... yeah i figure we could make it from angle .... but it has to be 1/8" thick as there isn't room on the DOG for 3/16" probly we could use the 2X4 aluminum they give in the kit...
just noticed the cylinder... yeah thats easy to fix tho..

Re: The perfect 2 speed Transmission..... features...
 

Maybe I am biased, but I like this one:



Andy B.

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i think its more of a combination between bias AND a REALLY spiffy tranny... ;)

its been reworked... well actually i did it today at school.... but the dog is now longer... those gears will need bearings so i guess the dog will have to be bigger diameter with more room inside... (i'd rather do that then mill out seperate dog mates ) and the gear dogmate holes will need to be farther out to give room for the bearing...

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We all like it, A LOT !! I also like students designing and hopefully building their own transmissions too. It's interesting how close their design is resembling the AM Shifter. BTW, where does the shaft encoder hookup? With all this work, we shouldn't forget it! Unfortunately the DigiKey (http://dkc3.digikey.com/PDF/T041/0996.pdf) one we're looking at isn't rated for more than 300 RPM. Hmmm?

Re: The perfect 2 speed Transmission..... features...
 

.... lol..... 300 RPM... i guess thats even slower than the wheels are turning!!!! we probably need a better encoder than that one..
i don't know why our design resembles that one.... its the first time i've seen it! they've got the sprockets on the inside... but i think thats only useful to save on 2 pieces of extra box... thats a lot of weight actually... we could make the tranny wider so we could have the sprocket on the in side but w/ the FP sticking out the back it wouldn't really be practical ( a side hit if the chassis is open like 254 ... would be quite catastrophic) now we could move the FP to the side of the CHIP but the gearbox size would increase by like 2"! because u'd need another gear to mesh w/ the CIM pinion that is also 64th (to keep FP far away from CHIP )... then the 20th FP pinion hooks up to that...

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can u post a picture with the motors hooked up.... of that tranny? ... i;d like to see how their hooked up... or maybe a link w/ more pics...

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Simply meant about the shifting action with dogs.

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ic ic.... oh yeah... that one super complex technokat tranny was also by this same team....

lol... ur online rite now too... :ahh:

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Okay i've got it.... forget the dogs... lets just slide the gears back and forth like cheesy poofs do..! instead of 32 pitch we'll use 24pitch steel gears this larger gears will offset it so there is room for the pneumatic ... think of all the things we DON'T have to machine : The dog, the dogmates inside the gears, the hex shaft (with a nice hole running through the whole shaft!) that is quite a bit... and i'm pretty sure lack of durability is of minimal concern... cheesy poofs never had stripped gears and they slid 32 pitch steel gears! 24 pitch is stronger.... i think GUn also did this .. it'll be more compact, easier to shift, easier to build...! yay!

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okay.... i know this topic is shifting (due to me) from general to focused on our private transmission issues.... so let me bring another two things up:
* chain... how should it optimally be distributed for a 6 wheel system... (center and front an back wheels) we think it should go down from 1 sprocket to the center wheel (with sprocket reduction, then 1:1 to both front and back via sprockets... so basically 3 loops of chain...

* Encoders : what to use for appx 1200 RPM and a 6" wheel.... optical or mechanical.... i think i am leaning towards optical as it is easier to integrate into the tranny... unless it has horrible resolution... i don't really care about readings per revolution as long as its more than like 4-5 (w/ a 6" wheel it barely matters so much)

* Bearings.... do you really even need any ball bearings... esp if your trying to save SPACE...(i.e milling dog mates into gears theres no room for a 7/8" bearing!) i think brass ones are okay... they're rated for 2000 rpm... anyone else used these how do they do at high rpm... do they make bushing type bearings (not ball) for high speeds like 3000 rpm etc....