02-05-2004 01:28 PM

JulieB

Re: pic: 716 Dual Motor/Dual Speed

Wow NICE!

02-05-2004 01:28 PM

Joel Glidden

Re: pic: 716 Dual Motor/Dual Speed

Nice work! Compact and attractive. It looks like all of your parts are do-able on manual machines. I'd be interested in seeing some more detail in the shifting mechanism. I'd also like to know what your reduction ratios are. I'd love to get my hands on your CAD drawings / models for future competitions. Thanks for the great photo.

02-05-2004 02:42 PM

Collin Fultz

Re: pic: 716 Dual Motor/Dual Speed

looks good! it looks similar to what we are trying for this year and kind of like Kokomo's from last year, but also different and (i hope) improved upon. good work!

02-05-2004 03:57 PM

Cory

Re: pic: 716 Dual Motor/Dual Speed

Joel: I modeled 716's shifting tranny, with the exception of the drill motor and it's gears. It is in Inventor, and if you'd like a copy, I'll send you one once I get home from school.

Cory

02-05-2004 04:32 PM

Brant Bowen

Re: pic: 716 Dual Motor/Dual Speed

Oh yes, very nice indeed. I like how both the motors are on the same side of the gearbox, that should save a lot of space on the robot. If you don't mind, I was wondering about how much that assembly weighs?

02-05-2004 05:14 PM

Joe Johnson

Re: pic: 716 Dual Motor/Dual Speed

Assuming I am understanding things correctly, I like the shifting yolk and I also like the tri-lobe drive blocks.

Can I ask a question? How much "back lash" do you have in your shifter? What I mean is how much angular rotation does can your last gear make with the output shaft held fixed and the shifter engaged?

I am curious because your design seems to have only a small amount and Andy (and others) have advocated having quite a lot so that the "dogs" have more room to engage.

But, generally speaking. Well done.

Joe J.

P.S. I am guessing that it weighs just under 4 lbs each without the motors.

02-07-2004 01:36 AM

tkwetzel

Re: pic: 716 Dual Motor/Dual Speed

Very nice indeed. Looks similar to 116's gearbox, except yours is a bit more compact. How does the shifter work, it is unclear in the picture. Your mount for the drill motor is nice, looks pretty sturdy.

02-07-2004 01:43 AM

sanddrag

Re: pic: 716 Dual Motor/Dual Speed

Another great design, Andy Brockway. On that shaft that is riding in 3/8" ID flanged bearings, is there a third small gear that is hidden in that picture?

02-07-2004 01:45 AM

pras870

Re: pic: 716 Dual Motor/Dual Speed

peronsally I'm counting 10 seperate gears, but I could be wrong, I do have really bad eyesight when im not wearing my glasses!

02-07-2004 02:04 AM

Cory

Re: pic: 716 Dual Motor/Dual Speed

that silver square piece with the chamfered corners does the same thing as the Technokat's "dog", but it does it without requiring CNC machining
. Basically, the final 2 gears you see are rotating freely around the shaft, since they have bearings pressed into them. What happens is when that square piece is moved in one direction, or the other, it engages the gear by going into a square hole on them. Since the silver square is fixed onto the shaft, when it engages the gear, it causes that one to also be "fixed" and allow it to transfer power to the output shaft, rather than spinning freely on the shaft.

Cory

02-07-2004 02:27 AM

tkwetzel

Re: pic: 716 Dual Motor/Dual Speed

That's an interesting way of shifting. 116's gearbox has a gear specially made with a dog on it (use the lathe to cut down gear stock), but instead of a free spinning gear, the gear moves to engage other gears. Team 116's gearbox can be made without the use of a CNC, and this one looks the same way.

04-05-2004 04:29 PM

CJO

Re: pic: 716 Dual Motor/Dual Speed

Have you checked out 223's transmission, it is similar in the free-spinning gears on a shaft, but instead of a sliding key, they have ball bearings which pop up from inside the shaft to engage the gear.

How are you moving the shifter?

04-05-2004 07:39 PM

tkwetzel

Re: pic: 716 Dual Motor/Dual Speed

That would be team 222 that has that transmission. I agree that it is very sweet.

04-05-2004 10:51 PM

sburro

Re: pic: 716 Dual Motor/Dual Speed

I have a question. When two motors are used, are both motors powered at the same time? If not is this good for the Victors since now the second motor is acting like a generator?

04-05-2004 10:54 PM

Madison

Re: pic: 716 Dual Motor/Dual Speed

There are several methods of gearing motors together that successfully minimize the potential problems you might have if one motor were to overpower another.

There is tomes of information about this is accomplished in threads and whitepapers all over this site. You could search and read for days and days, I'm sure.

04-22-2004 09:08 PM

Andy Brockway

Re: pic: 716 Dual Motor/Dual Speed

I apologize to everyone. I do not know where I was the beginning of Feb and April. Possibly stuck in a robot somewhere

Thank you sanddrag and Cory for stepping in for me. From all our conversations this year I know you guys can explain these boxes as well as me!

This gearbox is an evolution of the single speed from last year and the dual speed, see white paper titled “Dual Speed Shifter”, that we ran last Fall in the off-season. That gearbox was 4:1 and was insanely fast especially coming down last year’s ramp.

This gearbox is 3:1 with a high speed output of 500 rpm. One box with motors weighs 7-1/2 lbs as shown. It can be built as a mirror by assembling the same pieces differently. This is our arrangement with one air-cylinder attached to both shift yoke shafts. We run line pressure (60 psi) and it shifts very quick, almost simultaneous even in autonomous.

The dogs and gears have .003”-.008” total clearance. If the dry fit indicates tightness, a light filing to the tight side of the dog is done. All edges of the dog and gear pockets are sanded with crocus cloth and stoned. Nothing is hardened. Very little backlash is used to lessen impact loads. The more they run the smoother they get.

I plan on publishing complete plans for this gearbox this summer. This includes the drill motor sub-assembly.

BTW, sanddrag, I would very much like to see your version when you get it up and running. If I could only convince the team to go to the summer California Games!

04-22-2004 10:06 PM

Ryan F.

Re: pic: 716 Dual Motor/Dual Speed

Don't trust my word...but wouldn't that be pointless building a multi motor gearbox, and not running them both at the same time. I would assume that they are both powered at the same time.

04-23-2004 01:51 AM

sanddrag

Re: pic: 716 Dual Motor/Dual Speed

Man, I just spent 30 minutes making this really long post about the history of my team's drivetrains and my plans for the 6 motor two speed transmission for next year and right before I clicked the submit button my screen went dark. I accidentally stepped on the switch on the power strip under my desk. You have no idea how angry and disappointed I am. It was a really long post.

Anyway, lets just say that if anyone wants a punched out monitor, snapped keyboard, or smashed powerstrip, send me a PM or something. j/k