The best multi-speed transmission
 

AndyMark's transmission is alright, but I've seen many that are just as good and much lighter. What do you guys think is the best multi-speed transmission that are also light and durable?

Re: The best multi-speed transmission
 

you're own custom gear box. whatever your heart desires and your machining capabilities. you can build the best one ever. It doesn't matter who's is best. I see if you made one and it works on the bot and is effective you have reached your goal.

other then that general stuff, i do love the orginal 33 4 speed auto which 1126 has adapted for the last 3 years.

Re: The best multi-speed transmission
 

The 254/968 transmission was quite impressive this year, weighing in at a shocking 1.3 lb.s. It was obviously lighter than virtually any other shifting transmission (and most single speed) in FIRST, could take input from 1 or 2 small CIM motors, and worked without a hitch.
The AndyMark's are fantastic for their reliability, ease of assembly, flexibility (can take 1 or 2 small CIMs, Large CIM, or even a FP through an AM planetary), low weight and cost, and durability. They have several areas teams can lighten them even more will little trouble (namely the cluster gears and mounting plates).

Re: The best multi-speed transmission
 

Yeah. But building our own gear box won't be easy. We don't have enough machines to make a transmission. The best thing we got is a mil. I’m trying to build or own drive train and wondering which transmission is the best to use. I’m looking for a light weight, multi-speed one. 254’s transmission was impressive I wonder where they got them from.

Re: The best multi-speed transmission
 

Could you guys be so kind as to show me photos and purchase information to the transmission that you think is great?

Re: The best multi-speed transmission
 

Dewalt transmissions are an awesome choice. Under 100 dollars for a three speed shift on the fly transmission; you really can't beat that anywhere else.


Joe P.'s White paper should explain everything you need to know.

Re: The best multi-speed transmission
 

254/968's are great. Looked at them in the pit, and I could barely feel the weight of them. On superficial inspection they also seemed really efficient for a direct drive setup. AM's are good also, just make lighter side plates..

Re: The best multi-speed transmission
 

254's are custom built using some pretty exotic techniques. I could be mistaken but I heard that they are planning on using Andymark gears next year to make them easier to build which will in turn make them heavier. I did look at them in the pits and they were absolutely amazing.

Re: The best multi-speed transmission
 

I had a chance to look at the cheesy poof transmissions in Atlanta, they had a display with all the parts sitting there. The parts look familiar somehow...sort of like the parts in an AM shifter, only lighter. They are beautiful!

I still haven't figured out what the advantages are to having a lightweight drive transmission, though.

Re: The best multi-speed transmission
 

More weight to use elsewhere. This year the poofs really didn't need it (weighing in a stunning 86 lb.s before adding the ramps), but many other teams would have like the extra couple pounds to play with.

Re: The best multi-speed transmission
 

The removal of weight from any system is an advantage. It gives you the ability to use that weight elsewhere, for another system, or simply as a buffer when you add things you hadn't planned to add. The argument I have heard is, "When you remove 4lbs from the base, you are just gonna end up adding it to the arm!!" Wrong!! You cant have that mentality when you design things... any weight savings from any system is an advantage. Hell, if we wanted to, we could add a 4lb block of lead to the VERY bottom of the robot, below where the CG of all the material that we removed was. Thats a pretty obvious advantage right there, and we havent changed the weight of any other system on the robot. Also, the removal of weight from rotating parts increases efficiency and acceleration. Just like lighter weight flywheels help your engine rev faster, lighter gears enable your motors to start and stop more quickly.

Re: The best multi-speed transmission
 

I can understand making a manipulator transmission as light as possible. The problem I see with a light drive transmission, is that the saved weight might be put higher up on the robot...resulting in a tippy bot.

Wheels, frame, and drivetrain is where you want the weight to be.

Re: The best multi-speed transmission
 

Yep. Exactly.

Re: The best multi-speed transmission
 

I agree! but having that weight already committed to the drive base forces the rest of the robot to be as light as possible.

Re: The best multi-speed transmission
 

I think that the best multi-speed up to this point in terms of sheer engineering is that 254/968 gearbox they have been flaunting around at all the regionals my team has attended. The gears are astonishingly light. 1.3 lbs a gearbox made my jaw drop the first time I had the whole thing handed to me. It really is hard to argue against the sheer awesomeness that is that gearbox, really makes me want to one-up them and make something 1.299 lbs!
-Guy

Re: The best multi-speed transmission
 

Good point. But the extra weight somewhere else would still be nice.

Re: The best multi-speed transmission
 

And then when you are 4lbs overweight, you drill two thousand holes in everything to remove the weight...

I can see where your argument is valid had we sacrificed strength for weight savings, or something similar... But in our case, we sacrificed nothing, and saved nearly 10 pounds total from our previous years chassis and drivetrain with the same if not better robustness and strength.

Re: The best multi-speed transmission
 

Where did you guys get the transmission?

Re: The best multi-speed transmission
 

Agreed... however, I would much rather cut a chunk of my 10 lb lead block off than have to drill a bunch of holes in the rest of the robot because we forgot to put on the LED, the team numbers, or the PVC flagpole mount... you get my point.

Re: The best multi-speed transmission
 

In your case, you apparently did not have to sacrifice anything for the weight savings. In our case, bulding our own lightweight transmissions would mean not building the rest of the robot! due to limited resources.

I think if you set the weight budget about 10 lbs under the max weight allowed, and you keep track of it during build, you can probably get the robot done within wieght. Also if you start with a heavy drive base, it's easier to shave weight off it at the end if needed, than if you start with it as light as possible.

Re: The best multi-speed transmission
 

Can we please stop arguing about the pros and cons of light-weight gear box or how to save weight? That is not what this thread is for.

Re: The best multi-speed transmission
 

They designed it and built it!! They have been redesigning / refining their shifting transmissions each year since '02 I think.

Here's their '02 shifting transmission...

oops.. a better pic in CD-Media

Sure have come along way since then! I'm not sure how much more improvement can be done.. 6 motor CVT's?

Re: The best multi-speed transmission
 

Ohh... Did 254 build theirs too?:(

Re: The best multi-speed transmission
 

254 and 968 collaborate and work together.

Every part (except the bolts and bearings of course) of the transmissions were custom machined. You can not buy them at all.

Currently the two best (for overall FIRST use), off the shelf (which seems to be what you are looking for), shifting transmissions are the AndyMark two speeds and the Dewalt drill 3 speeds.

The dewalts take more work, but are 3 speed and cheaper.

The AndyMarks are easier to work with, are already done and can take two motors without modifications.

Personally, I would take the andymarks.

Re: The best multi-speed transmission
 

I agree, 1726 used DeWalts last year, and had some troubles with them. We used the AM air shift transmissions this year and they worked just fine, runout, weight, and all.

There is not much available to buy as far as shifting robot transmissions. You need to be able to make parts yourself, adapt parts yourself (such as the modified AM transmissions you have on this year's robot), or get help from someone who has the ability to make this stuff. It's not easy!

Re: The best multi-speed transmission
 

I'm gonna rank transmissions in a little list here. Keep in mind these are all my opinions and observances, so yeah.

1. Best! Your own custom tranny. You can build it to the weight, size, and everything that you want. It also gives you great control over your bot, as you can change everything to be what you want.

2. The upcoming (soon to be sold) transmissions from Trossen Robotics partnered with OutBack manufacturing. These are still in the design phase, but they'll be quite the system. Very robust and light, as well as decently cost effective.

3. AM shifters. I've never used these because my team keeps making me design and build my own, but I love these things! They're incredibly cost effective and robust for their weight. They're also proven, reliable, and an all around good system. They get the Craig Seal Of Approval.

4. Dewalts. These are a great budget tranny, but I'm not a fan of their robustness. People may brag about them being sturdy, but I've seen too many of them shatter. There's just a certain amount of structure you gain out of going with larger and non planetary systems. I'm not dissing these, I still think they're great. Personally, I would limit them to budget bots and Crab systems looking for multi speeds.

Re: The best multi-speed transmission
 

Don't forget this one: http://www.chiefdelphi.com/forums/sh...ad.php?t=26490

Re: The best multi-speed transmission
 

That's a custom tranny. It falls under the first one, because you can change it to fit your own bot. However, it is really nice... except for the cluster shifting. Make it dog and I'd love it.

Re: The best multi-speed transmission
 

I believe it was a collaboration between 254 and 968.

Acually in '03 they didn't have a shifting transmission design until the Cal Games comp seen here...

That design went into their '04 bot seen here.

'05 was further refined when they added FP's with AndyMark Planetaries...

'06 seemed similar to '05... pic here

There are some transmission designs in the white papers section - check them out. I remember looking at Andy Baker's design back in '03 and inspired us to make our own and it looked like this... It was so heavy and bulky we never actually used it in a competition bot. With the motors on it, it weighed in at 22 lbs.

Then we got inspired by Paul Copioli, Thunderchickens, and tried to make our own version of CVT (kinda) that looked like this.... That never worked as well as we hoped, but nonetheless the students learned A LOT by trying.

So do some research and start designing a transmission of your own. Even if you don't use it, you'll be ready to adapt to any new changes FIRST makes for the upcoming seasons.

Re: The best multi-speed transmission
 

One advantage that nobody has mentioned for a lightweight transmission is rotational inertia. Force must be applied over a longer period of time when the wheel (in this case the gear) has greater mass. On startup this means that batteries will experience a current surge for a shorter period of time. Less weight also means faster acceleration.

This year was the first year we built a custom two-speed transmission. It is a ball-shift with a 1:9 and 1:3 ratio gearing with a single Minibike motor. See here: http://www.chiefdelphi.com/forums/sh...ad.php?t=55786
We learned from our stupid mistakes, like you never calculate from unloaded speed (oops), and look at power ratings before choosing motor (oops again). Although an impressive achievement, it has weight issues that could have been addressed by using smaller diametral pitch gears (I'm thinking 32 DP). We learned alot from our experience, and expect to see big improvements next year.

Re: The best multi-speed transmission
 

I think the main advantage to reducing weight on the robot is so that if you go over (as we along with many other teams did) then its just another piece that can be lightened.
I understand the worry that you would add the weight higher on the robot but I believe that the trade off of guaranteeing lighter weight over messing up where you put weight is worth it.

Also I find it easier to simply not put weight high rather than trying to monitor your weight all along with a heavy gearbox.

Re: The best multi-speed transmission
 

For the past two years Team #39 has tried to use the transmissions that come with the KOP. We felt it would be easier to help rookie teams if we had to overcome the same problems they had. After the Banebot problems this year we do not want to use them next year. My question is, do you think the KOP will have the Banebot transmissions next year? If they do, I think we will return to the AM trany.

Ken

Re: The best multi-speed transmission
 

Will the KOP have banebots next year?? My guess is probably...

After experiencing the problems they had with them this year, will they be the same exact banebots 56mm trannys?? my guess is no...


FIRST learns from their mistakes, and I think after seeing the huge struggle teams had with these this year, they WILL correct it.





As far as trannys go....254/968...the thing is just unbelievable. If you haven't seen it yet, hop around delphi and check it out:
http://www.chiefdelphi.com/media/photos/28070
http://www.chiefdelphi.com/media/photos/27018

Serious props to the guys over on the left coast for designing this thing. My entire team was drooling over it (and the rest of your guys robot ;) ). Travis, thanks for explaining the hard anodize process to me, its definitely something we'll be looking in to.