The perfect gearbox

[sanddrag]

If you were designing the perfect (or as close as possible) gearbox (for FRC robot drive system) what features would it have? Here's some basic points but feel free to add more

Selectable ratios Y/N and how many?
What motors input and how many?
What speed (rpm) output?
Size
Weight
Mounting
Output

And just for fun, if you had to buy all the parts and materials to build this perfect gearbox, how much would you spend on it?

[Arkorobotics]

I wouldn't emphasize on this gearbox, probably just use the one in the KOP and I would worry more about the other functions of the robot.

[sanddrag]

I'm just hypothetically speaking. Say you didn't have to build it. Say it came in the kit. Or say I walked up to your doorstep with a couple in my hands. Regardless of having to actually build it, what features/specifications would it have.

EDIT: Let's please try to make this a useful (non silly/sarcastic) thread. Perhaps we should stick to the main topic points in my first post.

[Arkorobotics]

Oh well then, I want the whole thing made of GOLD , pnuematic 4 gear transmission for no reason. Shifting is not really important, and can get to be pain. Just like driving a manual.. bah. Just make the gear box simple. And if money was no problem then just make it out of gold or silver

[Stephen Kowski]

cheap, light, reliable, shifting is always nice

[NoodleKnight]

The gearbox can be anything, just as long as it weighs less than 0 lbs, and yes, I'm talking about negative weight here.

[ForgottenSalad]

Light light light... A heavy gearbox is not your friend.. Preferrably 2 speed, anything more than that on an FRC robot right now doesn't seem to have much of a point.. Preferrably having a way making it near impossible to lose a part... That's always a problem... ("Where'd the sprocket go...?") Oh... And looking nice is always a plus.

[Conor Ryan]

Hmm, I've thought about this before and I've come down to a few conclusions. A CVT would probably be awesome beyond belief, however its quite heavy, not to mention if it really was a CVT it wouldn't be a true CVT.

So, that being said I do have another idea thats a bit more realistic:
3 speed, 1-Mini Bike, 1-Cim in combination. The smaller cim would be geared down. Next I would make it something like a 3-speed plantetary with a servo powered, ball bearing shifter. To add some kicks i'd have encoders on it so it could be programmed to drive like an automatic.

In all, the gearbox without the motors would weigh less than 5 pounds (probably 3ish), and I'd have two total. I wouldn't try anything too special like a holonomic drive system or mechanum wheels, because i watch teams use them and the driver never seems like they have full control of the robot. I want something thats easy to control and with good handling. The most unique I'd get with this design is that because its a planetary and servo shifting, it'd be small enough to use with a swerve drive, yes imagine a multi-speed swerve drive.

Hmmm, I got to get to work on this.

[Tom Bottiglieri]

I would like a 2 speed shifter, which could be directly driven to a 4" wheel.

I'm not sure on the gearing, but I would like the actual output to be 12 ft/s high and 6 ft/s low.

There should only be one reduction done after the initial motor combiner, and all shafts should be riding on ball bearings. I've definitely seen the adverse effects of loss in efficiency. This year's transmission with 2 less reduction stages (last year 4 speed, this year 2 speed) has done wonders, even at the same output spec.

But, if I had to pick something that is easily accessible off of these boards, I would 100%, without a doubt go for the team 33 style blind shifter. These things are absolutely beautiful, and NEVER have to be maintenanced.

[Veselin Kolev]

I like my drive train this year. 7 fps low, 14 fps high. Torque and speed, and a nice 6 lbs flat with the shift piston and motors included. The CIM and FP give a good bit of power. Construction out of 1/4" aluminum plate with pressed plain bearings, 1/2" OD threaded aluminum spacers, hardened allen head cap screws, and a very narrow, large OD dog shifter. Makes for a very small (1.75" wide), very light transmission.

Personally I would always stick to 2 speed dog shifter made of 1/4" plate. It is a very solid base to work off, and my teams have had lots of experience with this kind of transmission. Of course we always work for new advancements every year, but this is our sure proof drive train.

NOTE: New features of this year's transmission are: quick 4 bolt face mounting, pneumatics mounted directly on the transmission (as opposed to chassis mounted), larger diameter dog (1.375"), narrower transmission (by 1/4"), more efficient (can anyone say 'valve grinding compound'?). Not a whole lot, but sure makes maintaining it a lot better.

[nuggetsyl]

may i sugest using a gear drive train. I think it might have a chance of working well for you

shaun

[Gdeaver]

I always liked the ball shift gear box that team 222 uses. Never liked the idea of smashing gear teeth together.

[Bill_Hancoc]

Originally Posted by Conor Ryan

Hmm, I've thought about this before and I've come down to a few conclusions. A CVT would probably be awesome beyond belief, however its quite heavy, not to mention if it really was a CVT it wouldn't be a true CVT.

So, that being said I do have another idea thats a bit more realistic:
3 speed, 1-Mini Bike, 1-Cim in combination. The smaller cim would be geared down. Next I would make it something like a 3-speed plantetary with a servo powered, ball bearing shifter. To add some kicks i'd have encoders on it so it could be programmed to drive like an automatic.

In all, the gearbox without the motors would weigh less than 5 pounds (probably 3ish), and I'd have two total. I wouldn't try anything too special like a holonomic drive system or mechanum wheels, because i watch teams use them and the driver never seems like they have full control of the robot. I want something thats easy to control and with good handling. The most unique I'd get with this design is that because its a planetary and servo shifting, it'd be small enough to use with a swerve drive, yes imagine a multi-speed swerve drive.

Hmmm, I got to get to work on this.

CVT YES i was gonna put it but you beat me to it that would be the icing on the cake.

[Andrew Blair]

I have heard wonderful things about the dewalt gearboxes. Three speed, servo shifted, light, small, virtually indestructable, cheap. If FIRST wanted to include a powerhouse gearbox in the kit (Which I doubt they would, unfortunately), I would be very happy to get a couple of prepared dewalts. Wait, no, ecstatic.

[Tim Delles]

Originally Posted by sanddrag

If you were designing the perfect (or as close as possible) gearbox (for FRC robot drive system) what features would it have? Here's some basic points but feel free to add more

Selectable ratios Y/N and how many?
What motors input and how many?
What speed (rpm) output?
Size
Weight
Mounting
Output

And just for fun, if you had to buy all the parts and materials to build this perfect gearbox, how much would you spend on it?

So basically it would be a 2 speed shift on the fly transmission. The motors powering it would of course be the 2 Chips (and possibly the minibike). The arrangment would be that of a triangle, with the 2 chips at the bottom and the minibike at the top.

The gearbox would be geared for 11ft/sec (633.75 rpms using 4 inch wheels) high, and 5 ft/sec (297.99 using 4 inch wheels) low.

I would give around 8 pounds for each of the transmissions, but then again it is like the most important part of the robot, so if it needs to be a little heavier she can be.

Assuming that we are given the same chassis as we have been given for the past 2 years it would sit down within the chasis, with 2 output sprockets running to each end of the drive train.