Shifting Device
 

Has anybody out there come up with a good idea on how to shift the drill motors from high speed to low speed?

how about a leadscrew mechanism and some kind of collar around the shifter.

Or howabout a servo?
Check the whitepapers.

shifter
 

We are using servos to shift the drill motors. We used a similar system in 2001. We have found that this works quite well and reliably

Last year we used a servo, and we are looking to using the same thing. (we have a 2 speed transmission) the only problem was the servos are not the most reliable thing....so we are trying to work the bugs out of it!

Want..to post..but..team kill... if I do....


Sucks being an animator..

use a very short pnumatic cylinder.

Last year we used servo's to shift. It worked pretty well. We got sick of having to stop when we shifted, so we have redone our transmission :) Can you say 'Variable Speed Drive'?

Programing
 

come on guys, there's a much easier way. program a max speed allowance then just add a trigger command that will allow you to switch to a higher speed. it's doable in not a lot of coding and with multi-bank programming it's like nothing to add in.

Re: Programing
 

Are you serious????

If you are... you might want to confer with the more mechanically inclined members of your team so they can edumacate you better.

2001 we used a servo to shift. We got it working well so it never failed to shift.

2002 we built a custom transmission so we could shift on the fly, but this year we decided to try the new drill motor transmission that comes with the kit. We got the shifting to work with just a servo, and it has worked 100% so far (though we've only had a running base for a day or so).

Re: Programing
 

::Must not flame..must not flame..must not flame::

Uhh....the theory you describe there won't really help you torque-wise..which is the point of having a tranny, so you can shift from High-speed to High-torque....

Last year we used servo's to shift. It worked great except you had to stop. The only other problem we had was that it would pop out of gear every once and a while. To solve that proble we used a coulple of springs.

Re: Re: Programing
 

The whole point of shifting gear ratio in a drive train is to trade off between speed and torque. You have constant power from the motor, and since Power = speed times force, or angular velocity times torque, you get a combinations of speed and force from the motors depending your wheel size and your gear ratio.

By switching to a different ratio, you slow down your robot but you get more pushing force, or you speed up your robot but you have weaker pushing force. Controlling it in software only limit how much power you have from the motor, and thus making the motor weaker when you slow it down, instead of trading off speed for torque.

Few ways I've seen for shifting gear ratio: Drill motor's transmission using a servo or pneumatic cylinder, that's the most simple way for a team to shift gear ratio.

Have two sets of wheels with different ratio, and lower one set at a time depending what ratio you want. You can shift on the fly that way.

Custom gear box like team 45 and 60 last year, or the 67 bot at 2001, where you use pneumatics to move gears outside the drill transmission to from one ratio to another ratio. This is much more complicated, and if your team doesn't already know how to do this, I wouldn't start right with only a few weeks left in the 6 weeks.

Or, you can add more motors to your drive system, and get more mechanical power out of it that way. You have more overall power, and thus more torque and speed at the same time.

team 69 did the same in 2001 and 2002
We used pneumatics to shift on the fly for 2002 using the big atwoods i believe if you need a diagram i can find one just email me xdohhhx@aol.com

also to reply to the programming reducing it would work but not give you the same aspect as shifting.

This year we are going to have an awesome drive train again! Watch out NH and TX!