Shifting Gearbox on Kitbot

[xForceDee]

Typically when I see teams with shifting gearboxes, they are a running a non kit bot. It makes some sense (teams with shifting gearboxes likely have lots of experience and therefore, are more likely to run non kit chassis). Regardless of this observation of accurate, I am curious if there is any reason that a shifting gearbox would not be beneficial on a Kitbot.

[Steven Donow]

Last year, my high school team mentored a rookie team, and we gave them a set of AndyMark SuperShifters to use with the kitbot. The speeds were a little wonky because of the gearing of the kitbot, but mounting them was easy.* I think a lot of times teams stick with the kit gearbox with the kitbot because they choose to spend more time focusing on other aspects of their robot, as opposed to DT


*I can't speak towards the actual success of the two speeds because there was something screwy with the servo shifting so they primarily stayed in the super slow low gear

[KrazyCarl92]

Originally Posted by DevenStonow

*I can't speak towards the actual success of the two speeds because there was something screwy with the servo shifting so they primarily stayed in the super slow low gear

This brings up another point. To shift with COTS shifters, either pneumatics or servos are a requirement. Servo shifting is less than ideal, and pneumatics require some extra work to add to the robot. If a rookie team is already struggling to execute a design in 6 weeks, it simply makes sense for them to forgo the extra time and complexity of adding shifting in their drive train, especially if that alone would require the headaches of servo shifting or the extra work of adding pneumatics.

[Andy Brockway]

We have used the kitbot or the 2005 Vex kitbot every year it was available. We run a version of 716's 2005 2 speed most years. The use of a 2 speed is not dependent on the chassis type. You can change the sprockets/pulleys/wheels to run the speeds you need to make your bot perform the task you design for.

[Billfred]

Originally Posted by Andy Brockway

We have used the kitbot or the 2005 Vex kitbot every year it was available. We run a version of 716's 2005 2 speed most years. The use of a 2 speed is not dependent on the chassis type. You can change the sprockets/pulleys/wheels to run the speeds you need to make your bot perform the task you design for.

This. I've had two-speeds on kitbots before. There can be benefits, depending on the game and the nature of your drivetrain (i.e. if your speeds are 7 feet/second and 2 feet/second, you're not going to gain much of anything).

That said, AndyMark is doing a new kitbot for 2014 that is supposed to direct-drive the center wheel. We don't know specifics yet (FIRST has embargoed them since it could tip things about the game), but that may impose more challenges on anyone trying to chain up a shifter. We'll see in two weeks.

[thefro526]

I think one of the biggest reasons that we don't see more shifting gearboxes on the Kit Bot, at least in years past, has been that there are A LOT of other more beneficial modifications that can be done to the Kit-bot drivetrain before a team would ever even need to think about adding a shifting gearbox. Usually, by the time a team gets to the point that a shifting gearbox is going to net them some sort of true gain, they've gotten so far from the 'as shipped' kit bot, that some may not even recognize it as a kit bot - or they decide to skip over the kit bot and build a custom chassis.

In previous years, it wasn't uncommon to see teams swapping out the standard wheels for smaller wheels, or wheels with a different design/purpose, swapping out the transmissions for a better single speed unit (cimple box to toughbox), or last year, swapping to a 3-CIM gearbox.

With all of that being said, there's usually one or two teams per event that I've been to that are running some sort of shifting box (usually the AM shifter, since it seems to package the best) on the kit bot, and it's reasonably effective.

Originally Posted by Billfred

That said, AndyMark is doing a new kitbot for 2014 that is supposed to direct-drive the center wheel. We don't know specifics yet (FIRST has embargoed them since it could tip things about the game), but that may impose more challenges on anyone trying to chain up a shifter. We'll see in two weeks.

All of this is purely speculation, but I'd imagine that any kit bot made by Andymark will be able to incorporate any of their standard transmissions without hassle.

One of the neat thing's about AndyMark's Gearboxes - specifically the Original Toughbox, Super Shifter, and Sonic Shifter, is that they they all share similar (nearly identical) mounting hole patterns. The Toughbox and Supershifter both have a 4.375" W x 4.375" H Hole pattern for their mounting holes, and the Sonic Shifter's pattern is 4.375" W x 5.25" H. Because of this shared pattern (specifically the 4.375" W measurement) any of these transmissions could be mounted to the C-Base (2009-2013 Kitbot) using this bracket

[BrendanB]

Our team has used shifting gearboxes for all three seasons with two of them being on the kitbot (2012 robot was custom tube frame). Of all three years, this past season was probably the one year we could have gotten away with a single speed as having a powerful low gear wasn't part of the requirements.

In 2011 our strategy was to be a defensive robot that could play some tube game but mainly defense and minibot. Our low gear really helped us slow down opponents trying to get to to their scoring zone in addition to 6in plaction wheels. We used the Andymark Supershifers that came with some mounting brackets so with four 1-4 20 bolts they were a breeze to install.

In 2013 our strategy called for fast movement across the field and a slow speed to line up at the feeder station & pyramid. We debated using the Vex 3 motor single speeds, but with our CIMs allocated elsewhere and the Vexpro Ballshifters being lighter compared to the AM SuperShifters we used in previous seasons we decided to go with the light two speeds. Mounting was similar to AM however the bracket for mounting to the C-Channel placed the bolts in an odd position under the gearbox and didn't leave a lot of room for access.

We have always loved the ability to push opponents around the field in low gear or push through defenders, but by the end of this season our driver adapted to sticking in high gear and maneuvering quickly around the field to avoid pushing matches that would slow us down. At the beginning of the season the low gear was helpful but I doubt we would have seen a performance drop if we moved to single speeds. We actually saw increased performance when we dropped our speed down slightly from a 16:22 to a 12:22 reduction from the gearbox to 4in wheels. Our high gear was slower from IRI on, however our driver felt like he had much more control over the robot and could then avoid periods of having to slow down or stop to regain control.

I would say analyze your strategy and see if it fits. In 2012 the low gear was beneficial when it came time to balance as you could push opponents up the bridge or gear low enough to almost create a break effect. Your driver also needs to know when to shift to reap the benefits of the system. Many drivers get into pushing matches in high gear forgetting to shift or they stick to low gear that is easier to control and lose precious time while traveling across the field.

The kitbot is changing for 2014 so swapping for different gearboxes might not be as easy or require and updated mounting bracket, but I'm sure companies like Andymark and Vexpro will adapt.