Just wondering is anyone have tried making a new planetary transmission using the 84-Tooth High-Strength Gear. From the last talk of the Plantary transmission, there was no existence of the 84-tooth HSG.
I would play with the Transmission myself, but my school currently does not have any 84-tooth HSG.
I might try playing with them to make a transmission once I get a bunch of parts available. I made this thing a while back and while it probably is not the same thing as what you’re thinking, I want to try and make it lighter and more viable for competition use. It really is a fun little mechanism.
How does a Planetary Transmission work anyways… many of the people in my school have been talking about it but I have no idea how it works
Yes, it is one of those pretty cool things in VEX community. Skyrise kinda made scissor lift and elevator lift common place things, but 2-speed transmission and the more mysterious planetary transmission remain very cool.
There are plenty of videos online about how a planetary transmission works. But little of them are VEX specific. Because there’s not really ideal planetary transmission gears in vex, usually a vex planetary transmission would use chains and sprockets. But oh well, Jason’s a genius.
Go check these out:
www.youtube.com/watch?v=pYeP_2jLfLU – Stanley’s super neat and cool “planetary transmission”. Because there’s not a pneumatic lockdown, many people doubt that it isn’t a real transmission. And it would be nice if Stanley appears in this thread and clears thing up a little, which I think might happen. It’s a planetary transmission thread.
www.youtube.com/watch?v=VG2rfkvUU0A – This might give you a little idea of how to make a vex conventional planetary gear assembly.
www.youtube.com/watch?v=cN7Aq8vNCkU – Solid, hard core planetary transmission on VEX. Too bad you can’t see the details.
www.youtube.com/watch?v=cpUkJMW173I – 2438’s video is perhaps one of the best. Study this.
And in the end, perhaps you wanna look into some of the old fashioned 2-speed shifter transmission in VEX. Perhaps these are a little less cool and a little easier to understand and design.
www.youtube.com/watch?v=pbDi2ORiDyE – Stanley’s video
www.youtube.com/watch?v=Ox8MIW7khI8 – Green Egg Toss Up
[www.youtube.com/watch?v=eC_tcbsR2HU – Green Egg Sack Attack
Both Green Egg machines are brutal savage pushers. Go take a look.](www.youtube.com/watch?v=eC_tcbsR2HU – Green Egg Sack Attack)
It’s still in stock now!! Go grab some!!!
Check out this thread by me if you’re interested: Wait for 84 HS gear or change design? ... - General Forum - VEX Forum
This January our team designed out everything, and just waiting for the 84 tooth hs gear to come back in stock. I’m really glad we decided to use regular gears to finish our design. 84 HS gear was out of stock all the way until skyrise world championship. 
I would, but budget is tight. I dislike having to spend club money, but I wouldn’t pay for it out of pocket either. If you wouldn’t mind, please tag me in your thread when you finish your transmission, I spent all day today trying to think of a way to optimize it. There are a lot of new gear combinations that I visualized and It just sucks that I can’t touch it…
That looks amazing! Is that a three-speed transmission? If not, what is the piston for?
Wouldn’t the piston transmission cause your robot to expand horizontally beyond the size constraints? (If that’s your drive system for this competition)
Whoa thanks man! That’s a lot of videos and information about planetary transmission! I do appreciate the help:D
It’s a two speed transmission between a 1:1 and a 3:1. There is a 36 tooth gear mounted to the center of the output sprocket (which has a hole drilled in the center so it is free spinning) which is driven by the 12 tooth sprockets in the transmission. This gives you a nice ratio for higher torque. When the pneumatic cylinder is not actuated the carrier assembly locks against the pins on the chassis, preventing the back drive issue planetary transmissions can have. If you actuate the pneumatic cylinder it compresses the whole carrier assembly into the output sprocket and locks it onto the nuts on the end, effectively jamming forcing it to a 1:1 with the added benefit/cost of being a flywheel from the weight of the assembly.
I have made it way thinner and somewhat lighter in a later iteration of the design but I still believe it is too bulky for competition use. I’ll see if I can find it.
[EDIT]
Here’s some stuff I dug up.
v1 of the transmission. This was done during the sack attack season and was intended to be used on my world championship bot. We decided to not use it since it was unacceptably bulky and had some slop when shifting.
http://s23.postimg.org/nt33tozcr/2013_02_08_17_26_40.jpg
v2.
https://www.youtube.com/watch?v=2qXF5VJyyos
This one was much nicer and featured some laser cut parts, much more robust and could definitely be used with some cleaning up. We prototyped this idea for our two Skyrise bots but decided transmissions were not necessary this year.
The laser cut piece used to hold the rubber band which pushed the carrier back when the piston retracted to shift back into 3:1.
http://s13.postimg.org/qoy2ih7on/10682103_750890561633644_405589281_n.jpg
This is a poor screen capture of a proposed v3, with cut metal 12t gears and a turned down and milled 60t gear.
http://s12.postimg.org/zcbrxfv65/10668208_750451048344262_1179544584_n.jpg
The new 84t gears might give me the space needed to make it even smaller if I can figure out a way to make the mechanism not have to move in order to shift by using another piece to lock it. Will definitely do some prototyping.
[/EDIT]
Wow. That looks so awesome. Do you know of any other was to fix the back drive issue?
Can’t Vex U use pretty much unlimited 3D-printed parts in VRC this year? I would hate not being able to see cool gearing transmissions because there is just so much potential in that. 3-speed planetary transmissions? Now they can make their own ring gear. So excited.
You need to lock the carrier the sun or planets somehow in order to shift gears, so some part to do that is necessary, wether it is rotational force from a motor or an actuated part.
VexU will be interesting with the ability to fabricate more. I don’t think the game will change dramatically for many teams but some could go in a whole new direction with the ability to print so much. It’s still early to make the call.
https://www.youtube.com/watch?v=BcKMsORCl4k&feature=youtu.be
This is one of the two prototypes I have built for this season. I had a very limited supply of parts to work with so it ended up way too bulky, but the important parts are mostly there.
Few questions:
What are your speeds? From what it looks like, it’s a 1:1 and idk.
What is the purpose of the three motors on the front of the wheels?
Will this be used for competition?
Hoping to see innovative designs with the 3D printed parts in launcher systems.
It’s 1:1 and a 3:1 reduction on the actual planetary with a 3.73:1 coming off of the drive motors and going through the input so it ends up 1.24:1 in torque and 3.73:1 in speed.
The three motors are the actual drive motors. The drive motors don’t power the planetary directly, they are geared up 3.73:1 beforehand. The motor powering the planetary directly in the video is just for testing since I had to remove the external booster to test this out.
Yes I plan to have a much more compact and easier shifting version of this on my competition robot. I have it modeled already, I just need to buy the parts.
Oh. Awesome. Would you mind posting a link on here once you have your transmission video done? I would love to see such mechanism.
Have you tried changing the gear ratios for the sun and the planet gears?
Sure, I had already planned on making an early season reveal so it’ll probably be done by mid to late August. And yes, I have built a reconfigurable one that switches between 2:1 and 3:1 with modular sun and planet inserts that bolt between two laser cut pieces of polycarbonate that slides right on to the differential for quick changes. Both configurations have a 1:1 direct drive torque setting and are the opposite of the ratio I was going for in the video.
Have you tried two-speed teanmission with a >1:1 and a 1>1 ratio? Sorry if I am using baby words, I am but an amateur. :')
I use good old linear transmissions similar to the ones on the last two GER bots for those kinds of ratios and I add a boost or reduction before the input shaft if I want an odd ratio.
PS- No need to apologize. I was there once too!
Ahh. I see. Thanks for showing me this greatness. I am satisfied that these transmissions aren’t forgotten. 