Is a shifting transmission really necessary?

[Jim Zondag]

Good thread.....I agree with many points stated above.

No, you do not need to shift.
Yes, it is a good option to have.

Team 33 has make multispeed robots for many years.
As the kit had gotten better and the motors have gotten bigger, the need to shift has diminished. If you tried to get your 1999 robot to go 12-15 ft/sec you could not do it without a shifter. Now you can simply brute force the issue by throwing tons of power at it. I still like having a shifter for a couple of reasons:
1. Power budgeting: Liberating some of the good motors for something other than driving around is a good thing. After all who want to build a high speed brick that does nothing but smash into others.
2. Control: As a programmer one thing I know very well is you must have a mechanically capable design in order to have good controlabilty. In FIRST, you often have very distinct operating modes for your machine during a match: i.e. Push like crazy to get past someone and then run full speed down the field. Having gears selected for both of these actions well enables you to do both well.

Regardless, shifters are a detail. The major items of FIRST are still what they always were.....understand the game, build a reliable quality machine to play it, train you drivers to use it to its full potential. If you do these things, you can win with or without any specific machine feature.

[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

[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.