Bike Drive

  1. 5 months ago

    briancole

    Dec 7 Utah 4270C

    Ok, so you know how a bike works, right? It's able to switch it's gear ratio by moving the chain onto different gears. So I was thinking, what if you imitated this on a vex drive? This would have a number of advantages:

    It would allow you to unlock more speed as you could use torque just when you need rather than having to have the same ratio all through the match.

    You could use a torque ratio to help with controllability while still having speed available.

    You could use a torque ratio to accelerate and then slowly switch up to a higher speed as you gain momentum.

    You could build up momentum with a speed ratio and then switch to a torque ratio at the last second to get over a bump.

    Anyways, this is a very sketchy, however I think it would be cool to develop.

  2. Gear Geeks

    Dec 7 Event Partner, V5 Beta Tester Virginia, USA 8044

    There have been people that have done this. I think if you search youtube for "vex transmission" you should find them.

  3. Download Complete

    Dec 7 Greater London, UK 7975F

    @Gear Geeks There have been people that have done this. I think if you search youtube for "vex transmission" you should find them.

    I’ve seen quite a lot of pneumatic transmissions that work well before but none using a system like a bike. It’s a good idea although I think the vex sprockets have too much of a size difference to make transitions smooth and efficient. Also the sprockets would need to be modified to make sure they are close enough together on the shaft to prevent the chain from going down the middle of two.

  4. Easton

    Dec 7 GA, USA 1958A

    I think you are better off using pneumatics for a transmission. Look up the VCAT NBN worlds reveal, and you'll see a really good transmission. As well as GER's robot from Toss up

  5. Rick TYler

    Dec 7 Teachers/Coaches, Event Partner, V5 Beta Moderator Redmond, Washington Founder of Exothermic Robotics

    It works just as well to use a motor to shift the transmission if you have a motor available.

  6. Ethan W.

    Dec 7 99402D

    Our team created a 3 speed transmission that we used during NBN that used no pneumatic only motors. We had to scrap it due to the last two games requiring more weight. It would skip chain when you turned with a lot of weight.

  7. Ethan W.

    Dec 7 99402D

    we had no shifting mechinism

  8. Easton

    Dec 7 GA, USA 1958A

    @Ethan W. we had no shifting mechinism

    Wait...then how is it a transmission?

  9. Ethan W.

    Dec 7 99402D

    It went from 1st gear to 2nd to third without a traditional shifter like a pneumatic. It worked by running certain motors different ways. Its been awhile but i'll see if I can prototype one later and put a picture on here.

  10. Easton

    Dec 7 GA, USA 1958A

    @Ethan W. It went from 1st gear to 2nd to third without a traditional shifter like a pneumatic. It worked by running certain motors different ways. Its been awhile but i'll see if I can prototype one later and put a picture on here.

    That is actually pretty cool, I'd love to see pictures

  11. Jawdin_1233f

    Dec 8 Northern Indiana 1233F

    We actually have someone who has been working on a transmission just as a fun side project. If you were at Andersonville in Indiana, then you might have seen my team member, Jake, working on it. It's pretty cool to have around.

  12. tabor473

    Dec 8 V5 Beta Tester OYES, WPI

    @Ethan W. It went from 1st gear to 2nd to third without a traditional shifter like a pneumatic. It worked by running certain motors different ways. Its been awhile but i'll see if I can prototype one later and put a picture on here.

    O ya that technique is strictly inferior. It has been talked about a lot on the forum in the past.

  13. Ethan W.

    Dec 8 99402D

    @Easton Here is an animation by jpearman about this style. We actually found out after we built it that it looked almost alike. Ours had some differences but this is the basic idea.

  14. Ethan W.

    Dec 8 99402D

    sorry forgot to put it up here it is
    link text

  15. the biggest problem with a bike transmission is that it uses a derailer that also doubles as a tensioner for the chain, this means that you can only go one direction, because when you ride your bike forward it is using the tension across the top of the chain run, however, if you tried to pedal backwards, it would just pull the tensioner out and then you would have a ton of slop in the chain.

 

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