Is a shifting transmission really necessary?

[JVN]

Originally Posted by Raul

I would just like to ask a slightly different question:
How many national champions had shifting transmissions?

I can't think of any. Apparently there is more to it than the drivetrain (beside in 2002).

Raul

173 - 2002 had a shifter.
They shifted the drill transmissions with a servo, if I'm not mistaken?

Still Raul... your point has been well made.

[Chris]

Originally Posted by JVN

173 - 2002 had a shifter.
They shifted the drill transmissions with a servo, if I'm not mistaken?

Still Raul... your point has been well made.

I may be incorrect but I’m almost positive that 469 2003 also had a shifting transmission.....

But Raul's point is well taken, I can list off a ton of bots just off the top of my head that have performed very well without shifting transmissions

2002 Divisional Champions without Shifting Transmissions
71, 144, 64, 25,
2003 Divisional Champions without Shifting Transmissions
292, 236, 175, 341, 25, 494, 111,

These are just teams off the top of my head...I can't guarantee 100% correctness...

I'm a firm believe that shifting transmissions are great to have, but they certainly aren't a guaranteed winning bot, a good driver and a good mechanism will take you far in any game.

Chris
229

[Cory]

Originally Posted by Raul

I would just like to ask a slightly different question:
How many national champions had shifting transmissions?

I can't think of any. Apparently there is more to it than the drivetrain (beside in 2002).

Raul

469 shifted in 2003

[MOEmaniac]

Having a shifting transmission has it positives and negatives, on the positive side you can slow the robot down if you need to make a slow and precise movment, negatives are that there are more moving parts which means more things that can break and go wrong

[Raul]

Originally Posted by Cory

469 shifted in 2003

Geez, how could I forget that about our 2003 partners?!

[Salik Syed]

well as for breaking apart... most of the times if the shifter is messed up or something you can just lock it in one stage... and then its basically just a heavy dual motor drive system.... i can't really think of much more going wrong with a shifting tranny ... now a planetary drive .... yes

[Sparks333]

Hi!
the only competition I have seen was the '04 competiton, where I co-piloted for our team, 1425. We did not shift. We did not have time to put together a tranny, but our team leader would have really been tickled if we could. I personally didn't see a reason for a transmission. In the '03 competiton, I could see why speed was required (a lot of space, a race to get to the top, ect.) but in the '04 competiton, I didn't see a reason, because there wasn't much room to get up to speed, and there wasn't anything that could have been taken back with some shoving. (not a FIRST-encouraged manuver, but these things happen.) I totally agree that it depends entirely on the competiton and what you are doing. Like I said, I am a rookie, so my test pool is minute, but I think generalizing about whether or not you need a transmission won't get you anywhere.

Sparks

[sanddrag]

Our teacher put it this way. Their is always an advantage to shifting. But is expending the extra resources to build it worth the advantage?

[Andrew]

Originally Posted by Sparks333

but in the '04 competiton, I didn't see a reason, because there wasn't much room to get up to speed, and there wasn't anything that could have been taken back with some shoving. (not a FIRST-encouraged manuver, but these things happen.)
Sparks

The rules specifically indicate that pushing [shoving] is OK and expected. Why would you say it's not FIRST-encouraged?

This is, in fact, the main reason for a low gear in a transmission.

[ChrisH]

Originally Posted by Andrew

The rules specifically indicate that pushing [shoving] is OK and expected. Why would you say it's not FIRST-encouraged?

This is, in fact, the main reason for a low gear in a transmission.

Actually, last year we used our low gear for climbing so that we could avoid all the pushing and shoving. But with the dynamics of last year's game we felt that anybody who got into a shoving match, was probably doing the wrong thing. The 02 and 03 games were a different story. There was a lot of space to cover and you had to be able to hold your ground when needed.

Design for how you plan to play the game. If you need two or more clearly definable speed regimes, then shift. If not, then don't.

ChrisH

[craigcd]

“Education is directly proportional to the amount of equipment you burn up”

I will now enter the discussions about shifting transmissions. For a rookie school I strongly suggest that they stay away from a shifting transmission. Like several of my learned colleagues have stated so elegantly that it is a can be a waste of time, weight, money and resources that need to be allocated elsewhere. A good single speed transmission with the ability to easily change the gear rations to determine speed is a solid selection. After the first year and the teams have started to climb the learning curve they can change to multi-speed transmissions.

[Aaron]

no its not necisary, but it helps. It also allows your team to decide if they want torque or speed during the game.

[Kelly322]

Team #322 shifted (pneumatically) in 2002 (Zone Zeal) and 2003 (Stack Attack). It gave us great speed and power, depending on what we needed at the time. It was a robust design... once the kinks were worked out. LOL. I think we had a really good design. I'm not totally convinced that this year's game needs it, and the extra weight of the trannies is better spent elsewhere. So, is it necessary? No, especially not for this game. Was it cool when we had it? YES!! I still fondly dream of the days of the little diamond-plate-covered Tweetie machine.

Kelly =)

[sanddrag]

I've seen a lot of people bring up the point of robustness in shifting transmissions. The thing is, just because it shifts doesn't necessarily mean it is less robust or less reliable. For us and many other teams, we have made a shifting transmission that has had no failures over the course of the competition and demonstration. We design things to work properly and not break, and I hope everyone else does to. And the end result is they work properly, and they don't break. As long as this step in the design process is taken, anything can be robust enough to not fail. There are plensty of single speed gearboxes out there that have had serious issues, and plenty that haven't. It all depends on the design and the quality of fabrication. Making a gearbox shift does not at all preclude that you will have problems with it's robustness or reliability.

Also, this issue of size and weight has been brought up. A shifting transmission will almost never be smaller or lighter than a comparable single speed, but the difference can be made very small. Also, say your transmissions come out to be a few pounds more. Now, would you really want those extra pounds out at the end of an arm, or don't you think they'd be better nice and low in the base. If you make one thing lighter, you are going to make another thing heavier since the total weight is almost always a constant. So, it is a matter of exactly where you want those pounds to be. And I vote for them to be nice and low in the base.

[Veselin Kolev]

Remember:

The number of moving parts squared is proportional to the probability of something going wrong.

If making a shifter adds too many more moving parts, reconsider your design. Apart from the pneumatic moving parts, there should not be that many more bearings or gears between a one speed and a two speed. However, there are two speed designs that only add 2 gears and two bearings, as in one more moving part. Keep it simple!