# Transmission Building???

[FONT=“Arial Black”] I am starting the new game and would like to build a transmission and would like assistance. Thanks!!![/FONT]

What kind do you want to build? A pneumatic shifter?

planetary

A transmission for the lift? Goes from a 1:5 to a 1:15?

Speaking of planetary systems–I didn’t hear much mention of those this year. I thought they’d be all the rage, seeing as a simple way to make a basic one was found last year…

Can I possibly get a link to that here? We are in the process of building a Pneumatic shifter right now, but I would be interested to at least look at a Planetary.

And how exactly do they work? We tried figuring out last year, but they didn’t make a lot of sense. It seemed like driving forward was one speed, backwards was another. Which doesn’t make sense at all.

I have fairly clear idea of how the differential the Taiwanese team built with the exception of the Planetary Gears themselves. After reading 50+ posts and looking at a dozen videos, I still can’t understand how they switch from Speed to Torque, especially without a Pneumatic. And the Wikipedia article was (for once) no help at all.

Can someone explain to me like I’m an idiot who is just taking his first Physics class how the shifting happens? I can build the assembly at this point, but I don’t know why they work. And I would really like to know.

It all has to do with the directions of the drive motors.
Lets call them Motor A and Motor B.
Motor A controls the direction(clockwise counterclockwise) of the output shaft
Motor B controls the different gear ratios

So, if I power motor A I get the strength of both motors moving the gears, and if I power motor B, the gear ratio shifts?

That sounds very useful. I still don’t exactly understand how this works, but thanks.

https://vexforum.com/t/4194b-drivetrain-differential-planetary-pneumatics/21482/1&highlight=planetary

How would you fix the back drive issue with out the use of pnuematics

What back drive issue?

Never mind found the answer

were you thinking that the 60 tooth gears were not free spinning or something else?

Like when you hold the wheel and the motors continue to spin, like seen in this video:

We had built a pneumatic shifter for sack attack and had won the world championship build award for it, as well as a few others at local competitions. if you like a photo i might be able to send you a picture or video or something just let me know.

P.S. word of advice the gear ratios you choose for a pneumatic shifter are everything they cant be too tall (fast) because then you wont get the power you need and it will stall out constantly and if they’re too strong (torque-wise) then you’ll be really slow…

anyway if you want pics just let me know

What were the gear ratios you used, also how do you calculate the gear ratio on a planetary transmission

I would like some pics

There is some transmission info on this thread on pages 5 and 6.

There are also ways to set up planetary gears where running motor A forward and motor B forward will be fast and running A forward and B backwards will be slow and the same in reverse.

We originally had a 3:1 and a 1:3 for both speed and torque respectively, but at worlds we changed it to a 1:1 and a 1:9. So we had good speed and torque but there were better gear ratios that could and probably should have been used