Regional & Division winners, did you shift gears or not?

[CyberWolf_22]

Team 647 did not shift this year but we are working on it for next year. We won lone star and were quarter finalist in the Archimedes Division.

[Daniel Brim]

294 was a regional finalist but we did not shift gears. There are several reasons for this. One: We used our servos as shelves in our stackers. Two: If we were in high gear, if we could get enough torque to move, we would still go FAR to fast (I'm talking about 30fps).

[Adi]

IRON LYONS Team 912 - Canadian Regional Champions (this was the 2nd-annual Canadian Regional) along with rookie Canadian team 1088 S. W. A. T. T. and Delphi-sponsored 378 The Circuit Stompers.

Our robot, S. D. L., does not support any gear-shifting; we had our motors set to low gear all throughout.

I think it was more the strategy of our alliance's robot combination that took us to the top. 378's was one of those that could be classified as fast and compact; it went up the ramp in autonomous real fast and real smooth, spanning the entire width. 1088's was a slow-moving ultra-torque-&-traction-loaded brick that could bully any bot it wanted to. 912's (ours) was a mediocre bot that had pretty decent torque and speed that could stack, re-orient, and bulldoze with a front-arm that goes down.

378 was reliable for autonomous, 1088 was reliable for king-of-the-hill, and 912's bot partnered up with our skilled driver, made it strategic in both offensive and defensive play.

The rule of thumb, therefore, I suppose, is to have a combination alliance consisting of slow, mediocre (but ability to multi-task), and fast robots. (one of each type).

Verdict: No need for gear-shifting! Although I think 378 had support for it, they were always menacing around in top-speed, so I don't believe they ever used it much.

[Solace]

may I ask a slightly different question?

how many teams out there (besides 45, everybody knows about them) shift gears while using a 4-motor drive? (and did it work reliably?)

[roboTICKS-236]

We, the Techno Ticks, did not shift either.

[Clanat]

Team 753 did not use a shifting mechanism. We found 6-7 feet per second and a drill/atwood drive to have more than enough power (we were able to spin our tank treads when pushing against a wall!) and enough speed to be effective.

We won the Pacific Northwest Regional, along with 368 and 233.

[Beast314]

We had great success at St. Louis with out a transmission, but it could have been useful. In the end having a lot of traction with our 13" wheels and an even mix of torque and speed worked out. I'm a believer that if you have the means and a good design a transmission is the way to go.

[Matt Reiland]

Originally posted by Solace
may I ask a slightly different question?

how many teams out there (besides 45, everybody knows about them) shift gears while using a 4-motor drive? (and did it work reliably?)

We used a version of Team 45's shifter with the CIM's and BOSCH on each side using a pneumatic shifter. We won in Great Lakes and we were Semi-Finalists at Buckeye. To date there have been no failures on the transmissions and almost no signs of wear on the gears either. We modified the design a bit to use off the shelf gears and will definately use it again. Our failures this year were all tied to the brecoflex belts, we tore 8 this year in half including 4 of the solid center rib belts.

Next year we think we can make it much smaller, half as heavy and we are looking into other methods to shift other than the air cylinder.

[DougHogg]

Originally posted by Matt Reiland
We used a version of Team 45's shifter with the CIM's and BOSCH on each side using a pneumatic shifter. We won in Great Lakes and we were Semi-Finalists at Buckeye. To date there have been no failures on the transmissions and almost no signs of wear on the gears either. We modified the design a bit to use off the shelf gears and will definately use it again. Our failures this year were all tied to the brecoflex belts, we tore 8 this year in half including 4 of the solid center rib belts.

Next year we think we can make it much smaller, half as heavy and we are looking into other methods to shift other than the air cylinder.

Thanks for the info. If you don't mind my asking,
a) Did you ever have a problem with drawing so much juice from the battery that you lost power temporarily?

b) Why do you want to use something other than the air cylinders for shifting?

c) Since weight is always an issue with us, how do you plan to make your gear box smaller?

[Matt Reiland]

Originally posted by DougHogg
Thanks for the info. If you don't mind my asking,
a) Did you ever have a problem with drawing so much juice from the battery that you lost power temporarily?

b) Why do you want to use something other than the air cylinders for shifting?

c) Since weight is always an issue with us, how do you plan to make your gear box smaller?

No Problem Doug,

a.)First, the gear ratio worked pretty well such that in high we had plenty of speed and power and we never drew so much that we had a power problem at all this year. Along the same line, next year we will make a specific left and right gearbox to keep the drills rotating the same direction to keep left right performance identical. Ratios:

From Drill to CIM Drill (Think it was 16 tooth to 48 tooth) welded to a 16 tooth and pressed onto the CIM motor. CIM mated to a 50 tooth gear which also drives a 20 tooth gear, output gears were a 50 tooth for high and a 80 tooth for low.

b.)Why would you want to use something other than air? Well our robot wasn't using the pneumatic system for anything else except for shifting this year, and if it was we ate at least one cylinder of the four for shifting some teams used two. Shifting with the 45 transmission can be done with a very light push or pull so I am looking into using a spring loaded linkage similar to a gas RC car throttle so that the servo will go to it's preset position and apply spring force until the shift is engaged. By using only 1 cylinder we also used up valuable space in the chassis for the linkage of the two transmissions. All in all it works fantastic as it is but I think we can get the same performance in a smaller lighter package (Team 45 also shrunk theirs this year)

c.)Weight & Size - The first thing to do is to look at the gear ratios. The final output stage was 1:1 in high and 4:1 in low with the High output gear an 80 tooth 20 pitch fairly heavy gear. Rather switch to 2:1 in high and 1:2 in low. We will get rid of the three finger dog mates and mill the mate into the output gears like 45 did this year. All of the heavy steel gears will not only be drilled but also the web between the hub and the teeth will be reduced considerably. The gears all start as solid steel with a large steel hub. To remove weight always look to the steel first for the biggest bang for the buck. Also for construction of the gearbox we will use some of the info gained from Team 111. Notice in many of their designs the nice 90 degree break on all of the flat plates, our gearbox plates were all 1/8" and all of them are wavy from the forces applied to them this year

Truly a wonderful design Team 45!

[Lloyd Burns]

188 didn't shift (a shiftless lot we are), but we did have more than enough torque, with 6 motor drive. we were chosen in two regionals (finalist alliance CR, champ alliance WMR) and the Finals (qf only, Curie)

We were planning to shift, but didn't need it, and so rebuilt the gear box in a few days.

[JAlpert]

If you look at all 3 national winners, none of them shifted. Obviously an optimized non-shifting robot is far superior to a shifting robot. Less that can go wrong.

I'm actually somewhat surprised nobody noticed that our robot (469) had a transmission. It ran a drill and a CIM on each side (4 motors total). This is our third year with a transmission, and our second with a custom box.

The reason I'm so surprised is that our transmission had a 7:1 split. We avoided using our high gear much in the finals becuase we bent a driveshaft in our division semis, and at high RPM it threw the chains off the sprockets. We used high gear mainly for the autonomous portion in the finals, and low gear for the rest of the match. The unusually huge split in the transmission was nice, becuase we were pretty fast in high, and powerful in low.

The problem we encountered was that at our first regional, we were snapping shafts (1/4" hardened steel I believe). Once the problem was fixed, the actual transmission gave us no more trouble. However, the cantelievered output shaft was another story . . .

I think our transmissions have been a key part of our robot design for the past few years. Every game has an aspect where speed is necessary, and another where power is needed. Once the kinks are worked out, transmissions can be a very powerful feature.

Jeff Alpert
Team 469

[ryanspensley]

No shifting for #171. The main reason that we won the St. Louis Regional was our working autonomous mode which many teams did not have.

[Travis Covington]

We won the Arizona regional with just the drill motors.

In LA we added 2 more motors and a technokat inspired shift-on-the-fly transmission.

In LA we ended up seeded 1st without any practice matches (all Thursday we were adding the gearboxes and never got to go out on the field.)

We ended up in second place overall after losing to team 60's alliance in the final match.

I felt that the transmissions were extremely valuable. We would not have done as well as we did if we still had just the drill motors.

I also felt like our transmission was more reliable than the drill motors and the drill motor gearbox. We had some problems with the plastic drill motor gearbox and housing, and with our transmission, that problem was eliminated by not using it and gearing down the drill motor to match the rpm of the CIM motor.

If done properly I think a 2 speed (or more) transmission is very helpful.

For example, we rarely used high gear aside from the 15 sec autonomous period and the rare occasions where we needed to get across the field quickly.

BUT, that 15sec mad-dash to the top was essential this year! We were able to go 14fps and make it up to the top of the ramp (when our auto mode worked right) before most other teams, while still having alot of torque once we shifted into low.

[Gene F]

We, 343, designed two systems. The first was a shifting drill motor system, the second a CIM/Drill combo that didn't shift. The combo didn't make the weight limit with our stacker so for our first regional we went with the shifting drills. Lost the quarterfinal because one of the transmissions slipped. We dropped the shifting and the stacker and went with the single speed CIM/Drill combo for Peach Tree and Nationals. At Peach Tree we tried a different track material and it changed traction all through the first day of competition, really messed up our autonomous. We made it to the finals. At nationals we went back to the original tracks, stayed with the dual drive no shift and finished top seed in Curie, won the division with 25 and 494 and went on to play in the finals.