VEX Shift able Transmissions

Well I was looking on today and saw a cool shift able transmission. Heres a link to the post HERE It occurred to me that many people here might be interested in this. Also has anyone else built a shift able transmission that they would like to share.

so far from just lookin at the CAD design the transmission on the robot looks pretty dern good and i can easily understand how it works
ty so much for link

That is pretty awesome, it it takes up a lot of room and requires a few gears that you cant buy on VEXLabs site. At least i dont think you can… Where did they find those extra thick gears?

those gears are the same ones vexlabs sells. its just the sides are sanded down to be flush with each other

Oh…Smart thinkin:)

i made a working model of that cad design and it works very well. i didnt even bevel the gears or use a triple-wide gear, just two normal ones.

team 1086 may try to devolope one over the summer.


Paco pictures?

What do you guys think about the advantages of a shiftable transmission in FVC. Considering the field is small and speed would make the robot harder to control on a small field. Power is needed though, so do you guys think it would be better to have the robot geared up no matter what but just change how much it’s geared up.

I noticed that some of the gear teeth have been grinding from the constant sliding in and out. Have you though of or implemented a clutch to prevent this?

What are you talking about Nate? In some of the pictures the corners of the gears have been beveled off to make them easier to mesh when they slide back and forth.

our team competed with one that shifted between 3:5 and 5:3. it moved the shaft with a rack and pinion type setup. it works very good however we dropped it because we needed the motor for our new design that we took to nationals. in this game a shifter doesn’t give you as much advantage as you think.

here is a picture of ours:
we didn’t bevel our gears or make wide gears but it works great without that

I was trying to find a way to shift gears in compound ratios.

like if you had a compound gear ratio of 1:5 x 1:5, and could design a way to make it 5:1 x 5:1 or 3:1 x 3:1.

if you find out how, please tell me

well, you could make it a two stage shifter with 2 sets of gears. although this would probably be very complex.:slight_smile:

A clutch would not be that difficult if a chain was used and was engaged and disengaged by pivoting a sproket that would push the chain on and off of the transmissions sproket. In Oregon there is no such thing as vex competitions so basically everything i build is for my fun. I was planning on building a auto transmission with a clutch after i finish current bot. Anyone tried getting 3 ratios in a single stage transmission? 3:5, 1:1, 5:3

There are people at Intel, working on getting a FIRST Vex Challenge going in Oregon.

Contact the sponsers of Vex Challenge, OregonFIRST at the ORTOP page.

Nate, the College Mentor for Team 957 and myself want to get a FVC Team together for the 2007-2008 year.

:smiley: i know what your talking about…
its a bicyle style shifting the only :frowning: fault to this is you’d need to buy a metal chain because the plastic one would wear dramatically and break making it more of a pain to accomplish a robot like that

Those are called Derailleur gears.

From what I understand you want to have more ratios than what other people have already done. One thing you could do is take the current shifters and put two in line. What I mean is instead of have it go,

  1. Drive Axel from motor Stationary
    2)Shifting Axel
    3)Out put Axel Stationary

Don’t stop there but then do it again and get this,

  1. Drive Axel from motor Stationary
    2)Shifting Axel Movable
    3)Intermediate Axel Stationary
    4)Axel with same con-fig as #1 no motor Stationary
    5)Shifting Axel
    6)Out put Axel Stationary

I think the plastic chain would work if you shifted the front and rear sprockets at the same time keeping the chain strait. It would need a sprocket with a spring to keep it tight (like a bike). or maybe you could use a small wheel and let it rest on the chain and let gravity keep it tight… or maybe not… or maybe… :slight_smile:

if it was a short enough chain it might shift front and back with one shifter.