Shifting or Non-Shifting

Does your team have multiple speed gearboxes? If so what kind?

Andymark. 1-speed toughboxes and 2-speed AM Shifters/SuperShifters. The best thing now.

In the Pre-AM days, we used to use DeWalt gearboxes (3-speed servo shifted), and prior to that we built custom 2-speed and 4-speed mesh shifting gearboxes. However, an AM shifter or SuperShifter is better than the DeWalts because it shifts more reliably (the DeWalts won’t shift under very heavy load), and easier to manufacture (you make nothing, unless you are reducing weight).

Our custom 4-speed took quite a lot of manufacturing resources (we cut a bunch of gears from pinion stock, welded some together, made 5 shafts per transmission, and machined side plates).

We used tough box nano’s last year. They worked great, but in the off season were looking at the AM super shifters and were looking to use them in 2011.

My team doesn’t shift mainly for cost reasons. It’d be nice to have for specific games and specific situations, but it’s not that hard to make do with a single speed for most games. Last year wasn’t so bad for non shifting teams since the field was divided into small enough sections that you might not be able to really take advantage of a robot going >9FPS

I chose other.

At the moment, I don’t believe we have one. After our Quarterfinal defeat at NU CT Regional, there’s a lot of talk about adopting one (obviously taking the 2011 game into consideration).

What’s the game call for?

330’s had both: 2-speed drill trannies from 2001-2004, single-speed KOP gearboxes in 2005 and 2006, and AM shifters 2007 and 2010. (Can’t remember 2008/2009, but I’m pretty sure 2008 was an AM shifter as well.) It depends on what the game is and what we think we need.

Knowing how you guys played, was not shifting really your big downfall?

Was your robot 120 lbs max?

Did you have high traction wheels?

Both of those things will matter before shifting will. Shifting won’t help a mecanum drive in a pushing match either.

Last year we had single speed gearboxes geared for about 10.5 ft/s in our swerve drive and a selectable-output shifting gearbox for our dual kickers. Our real-world results confirmed our calculations that showed a single-speed gearbox geared for 10.5 ft/sec was a very good compromise between speed and traction with our customized Colson wheels.

http://www.team228.org/gallery/125/slideshow/build-season-week-five_c37fb-daae2.jpg](http://www.team228.org/media/pictures/view/6139)

In the future, we’ll likely use 2-speed shifting gearboxes on our drive train if we go with a normal 6WD.

Hey Art,
Did WPI manufacture that setup? Thats pretty impressive!

Also, AM Supershifters, shifted pneumatically. We attempted to do the servo shifting setup in 2009 (because there was nothing else that we needed pneumatics for) and we had a lot of problems!

AM Supershifters, shifted pneumatically.

1618 used AndyMark shifters in 2007 (with the big and small CIMs) and 2008 (four CIMS); 2815 and 1398 used the guts of one in a six-motor setup (CIMs and FPs) in 2010. Nobody used anything but Toughboxes in 2009, because the game didn’t call for them. (That year, for the record, 1618 used two CIMs for ease of assembly, while 2815 used FPs in an AM Planetary to free up the CIMs for the most the highest-powered conveyor dumper of 2009.)

In 2010, shifting was also scarce enough to justify leaving off the compressor.

We have used:

  • 1-speed drill transmissions in 2000-2003
  • A custom 1-speed worm gear transmission in 2004
  • AM Gen 1 shifter in 2005
  • AM Gen 1 shifter in 2006
  • ToughBoxes in 2007 (omni drive)
  • ToughBoxes in 2008 (omni drive)
  • ToughBoxes in 2009 (regolith)
  • AM Gen 1 shifter in 2010, but modified back into a 1-speed for weight/usefulness reasons (we split the difference between high and low and that was more than fine for the primarily short dashes around the field, and we were still traction-limited in brief pushing contests)

.Also, AM Supershifters, shifted pneumatically. We attempted to do the servo shifting setup in 2009 (because there was nothing else that we needed pneumatics for) and we had a lot of problems!

What problems did you have?

We have used AM shifters with servos for two seasons without incident. In fact I’d like to see AM change the wording on their site with respect to servo shifting…I feel it is robust, fast and reliable. :smiley:

All the sheet metal parts were fabricated by two sheet-metal machine shop sponsors, while the aluminum rings were machined at a regular machine shop sponsor. All the internal guts were machined or lightened on our team’s manual mill and lathe. I enjoy occasionally machining parts, so I’ve made a few parts for GUS at the WPI machine shops before, but lately it’s been easier to find machine shop sponsors.

We’ve also had intermittent issues with servo-shifted gearboxes; once the internal gears of the servo stripped out, and other times the servo seemed to lack the fortitude to actually shift. More grease probably could have helped both of those problems, but I have yet to confirm if this was the issue.

We Like shifters and have run AndyMark’s shifters in the past, but now run our own design heavily influenced by his.

We shift primarily to make sure our low gear is nice and slow with plenty of force, and that our high gears is as fast as necessary for the game. It’s tough to nail both of those with a single speed.

For all of the carpeted games in recent history, I can’t think of one where I would not want shifting.

Luckily it is now legal to use COTS metal gear servos, which are more or less the standard in ground RC vehicles now. Still doesn’t fix them having less force, but certainly they are more durable.

For the 2010 game we used two AM Supershifters with pneumatic actuation.

Excellent transmissions, never gave us any trouble at all.

The real question you want to ask yourself when you design is “Do i need to be able to put down power when necessary, or can I get away with one speed”, because it is not an insignificant increase in cost.

Please also notice that while AM supershifters do come with servos, our team never had any luck with them. The most powerful servos we were allowed to use in FRC didn’t shift at the same time, and had some pretty long delays in shifting if the robot was in motion at all. The pneumatic actuation “just works, right now”

Really depends on the game. For Overdrive they were critical last year not so much. Also you pay a big penalty in weight for shifting.

We have used AM transmissions exclusively since Aim High. Those include AM gen 1 and 2, Supershifters, Toughboxes and Nanos.

Our shifters are heavier than if we were to run our own single speeds, but they are still lighter than toughboxes by a good deal. I wouldn’t quite call it a penalty.

That’s apples to oranges man :slight_smile:

Your shifters > your single speeds

AM SS > Toughbox.

Wow! Are all of those parts fabricated on the manual mill and lathe? Some of the gearboxes and sprockets look pretty impossible with my current skill-sets on the machines.

We’ve also had intermittent issues with servo-shifted gearboxes; once the internal gears of the servo stripped out, and other times the servo seemed to lack the fortitude to actually shift. More grease probably could have helped both of those problems, but I have yet to confirm if this was the issue.

And the problems you are describing with the servo gears stripping out is the same exact problems we have had. We even went to the extreme and searched frivolously for the same servo with metal gears. Like we were going to find one of them! :rolleyes: