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6 Speed Allison Automatic Transmission / Gearbox

by InterlinkKnight Oct 27, 2015
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Hi, another couple of dumb questions;
If not using solenoids is there a different case that needs to be used?
If using this case without solenoids are the shifter forks then not needed or do the forks help to hold the clutch in place?
Thank you in advance ever so much for your speedy reply to my request.
Much appreciated!

You should be able to use the same case, if you find servos small enough. The clutch forks are needed to be able to move the clutches.

Hi, I'm presently starting to print this Alison Trans. Some dumb questions:
Can this trans function okay without the solenoids? If so is it complicated to shift manually?
Can the solenoids be added at a later date? The solenoids I'm seeing say they are only recomending power to them for a couple of seconds at a time. Is this a sufficient time? I already have the Toyota 22R engine, so no problem there.
Thank you in advance ever so much for your speedy reply to my request.
Much appreciated!

You can move/stop the clutches manually, yes. About the solenoids power time, you are right. I made a mistake choosing solenoids to apply the clutches. I plan to modify the design to apply the clutches with geared motors or servos. If you can, use servos instead of solenoids.

Publish some photos when you get it working.

Could you upload the STP models or some non-mesh model to run some simulations please?

I made this with blender. Not sure how useful would be for you to have that file, but if you still want it, send me a PM with your email address and I can send the file. I didn't upload the blender project because I don't think is relevant to have that file. My technique of creating 3d models is not the best.

YAY! Another Blender user. The new 2.8 is coming soon and I'm on the edge of my seat in anticipation for it's release.
Thank you for this great project. I'm printing it right now. I'll upload photos once it's complete.

I built the transmission scaled up 150% and printed parts for powering the transmission and shifting gears.

Great! Would be nice if you post pictures

What are the tolerances on this design? Still figuring out how precise my printer should print :)

I don't have a 3D printer so I am not sure, but I design this model to be printed on a normal 3D printer.

Hi mate, I was just checking this for a while, and as you made this I would like to ask you something. I'm about to start a project of a realistic FPV RC car with a gas engine, and the idea is to put a two speed manual transmission + reverse. I had been checking around for a while already and I cannot find something like that already made so I will get into building or modifying something. Do you think it is a good idea to use this concept to build a manual transmission (With the same functionality shown in the video but speeds manually activated with some solenoid/servo). The thing is that using a real manual transmission will require a clutch, and for RC cars I found nothing, all transmissions I saw for RC cars are automatic and based on centrifugal clutches, and building a clutch (correct me if I'm wrong) could be much harder that building just the gear box, not because of the technology, but because of materials used. I would really appreciate your feedback.

Hi, OPSO. If you want to use my transmission, or any other transmission, to use with high speeds and load, you do need a clutch. You could try changing gears at high speed and load without clutch but that could damage the transmission very quickly.

The reason why automatic transmission don't need to use a clutch between the transmission and the engine is because the transmission itself has clutches (hydraulic). In real transmission those clutches pass for a lot of stress so are build with that in mind, using a bunch of disks to increase surface and are cover with lubricant at all time. My transmission is made of plastic and is very small, so it can't take that abuse.

Maybe with a centrifugal clutch between the transmission and the engine could work, though. RC cars with gas engine usually have those clutches already, and that could disconnect the engine to the transmission while changing gears. You would have to release the throttle while shifting. If you can manage that, it should work.

One more thing: the gear ratios of my transmission are like real transmissions that are design to work at 1000 to 5000 RPM on the input, and considering a differential on the output. Not sure what gear ratios you need for your RC car.

Just starting to print one, at 2x size (cause I already have 6 mm and 4 mm rod).
so far pretty good, using bushings/spacers to use odifferent bearings (https://www.amazon.com/gp/product/B00G3DBQ3I/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AFLT987H7WA7G) , and will likely use pneumatic cylinders with solenoid valves instead of straight solenoids (couldn't find any with a long enough stroke).

for tolerances I'm leaving the gears as is (so they'll be kinda loose) but for the 6 mm rod holes (used to be 3.5 then doubled to 7) I changed to 6.5 mm holes, and the 4 mm rod holes (used to be 1 mm, doubled to 2 mm, but I had 4 mm rod anyways so I made them that big) I made exactly 4 mm on the carriers (I will press them in after heating the rod) and 4.5 mm on the gears.

also made keyed shafts to hook things up maybe (I would probably have to print new ones anyways with multiple slots for reinforcing rods that would be printed lengthwise because the layers don't bond too well as it is now)

Will let you know how things turn out and thanks for an excellent model to print!

Very cool that you want to try to build my model. Let me know if you have any question. Make sure to visit my website for more details and tools you are going to need. Link on the description. Keep in touch.

starting from the output shaft and working my way up, have everything up to the P1 sun gear printed and working on assembly! I had to make some bulges on the planetary gear carriers because 4mm holes are a bit big and give it an extremely thin wall.)

I've been using sketchup with the .stl plugin to import and export things which has worked out alright except for the importer function occasionally making errors and leaving holes/gaps that I have to fill.

for the code, I went through yours which looks quite good although I think I am going to write my own version that is based on engine rpm telling it to shift up/down (a base shift point at 1500 rpm, which increases to up to 3500 rpm shift point at full throttle because the rev limiter is at 3600) and another solenoid that activates the engine choke while it shifts to drop the rpms to match closer.
for downshifting, if the engine drops below 2800 while at full throttle, it will downshift, and when downshifting the choke will not get activated.

I think one of the type A machines marketing guys asked you if we could use the model etc, and yes I am the one doing that project with them (I'm a high school student who is interning with them for the summer).

Sounds good. Yes a guy of type A machines contact me and I said was ok to use my model to put it on your go kart and post the blog.

Good luck, and keep me inform.

have all of the gears/inputs etc printed and installed in the case. It works pretty smoothly, and I'm sure adding lubrication later will help (testing some pieces in a variety of motor and gear oils to see the effects on the plastic).

have the shift forks printed for the front 2 clutches, although for the other pieces I'll be using a different style to help engagement at higher speeds. (having a single rod down the length and using it as a pivot for L shaped pieces the stop the wheel. (angle of L is on the bar, and the either the long or short arm of the L (in reality they'll both be same size) will catch the ridges on the ring gear (which one depends on which direction that wheel turns).

since electronics seem to work just fine when bathed in oil, I'll still use electric solenoids rather than do the hydraulic cylinders (a lot easier and I don't need a bigger battery to run a hydraulic pump).

oh yeah the main reason for the shifter change is that I couldn't find a solenoid with a long enough stroke (also modifying the front forks for that reason)

I don't think I understand how you plan to make the clutches. Pictures would be nice, if you can.

just finished making them and sent photos to your gmail.
(sorry for taking so long, I've also been working on my own version of the code)

Thank you for the photos. Looks great. I now understand all your changes and make sense for your project. Can't wait to see everything working.

Great work! This looks awesome.

I have one printed and everything together, but I would like to address some flaws in the design. First, when you try to place the Sun gear inside the ring you can't without great struggle, because there isn't enough room after the ring is pushing the planet gears in making the hole smaller. Next, the C2 clutch fits way to tight on the end of the P2 Carrier. Finally you can't even put the shift forks into place with the way the inside of the case is designed and how the forks themselves are designed.

Hi. Thanks for the feedback. I need to ask: when (date) you download the 3d model? I ask because I've made many changes over the past weeks, and want to know if maybe I already address the issue.

The first issue should be easy to fix by printing the planet gears a bit smaller (like 0.96 scale).

The 2nd issue I already fix on 02/15/2016, making me think you might have an older version. Right? If you download it after that date, I maybe should increase the space between the C2 clutch and the P2 carrier even more.

The last thing is tricky. Any suggestions on how to deal with it? I never printed my transmission so is hard to know what to do. I know what you mean, and I thought it could be a problem, but not sure what to do. The first thing I thought was put the rods of each fork last. I mean, maybe put everything inside the case (including the forks) without the rods of the forks, and after that put the rods in the forks. They don't need to be glue it to the rods. They can stay in place by pressure. Well, at least that's what I thought could be solve. Or have an idea how could be easier to assemble?

I've printed it over the last week and on the planetary gears that is what I have done and that helped greatly.

On the C2 clutch I'll look into that thanks.

On the shift forks I really am not sure, but I have been thinking about and will get back to you on that.

Even though great design in general it takes time to build models like these.

So you downloaded the last version where the gears have less angle? If you want we could talk by skype or something like that (with or without video) and maybe that would be easier for both to fix this issues. I did this with another user and we solve several issues in the past months. But his 3d printer broke so we didn't finish. Maybe with you I can keep improving the model. Or maybe you could record a video showing the problems. Or pictures. Whatever you want. I am just saying I am willing to work with you to get this transmission working, and with just text is a harder and slower process.

I just reprinted the piece I was having trouble with by the C2 clutch and it worked perfectly this time so I think maybe it was my printer but everything is working now and I'm still working on the shift forks.

I just realized that my transmission case is sagging a little on the inside as well so I might reprint that and then try and put the shift forks in. The sagging filament is stopping the forks from reaching around the sliders.

Ok, good. Keep me inform

I thought about it and I think the best option is to split each fork in 2 pieces. The problem appear when I put some extensions on each fork so it could reach the solenoids, and that lower part is what prevent it from getting into the case. So I think the best would be make the extension as a separate part that screws into the fork. The screw would be on the front of each fork so you could remove it without needing to remove the solenoids. As is right now, I don't think you could remove all the main parts of the transmission without needing to remove the C2 solenoid. So my plan of splitting each fork in 2 pieces would not only make possible to assemble the forks, but also would allow to remove all the main parts of the transmission (gears, sliders, forks, input, output, etc) without needing to remove any solenoid on the lower part.

Sorry for the mistake. I will work on it when I can, hopefully soon. You would only need to reprint the forks.

If you have a different idea to solve the problem, let me know.

can you show how you use solenid to control. I am very interesting in that. thanks

What you mean? I show 2 images with solenoids ON and OFF. Or you mean how to controlled with arduino?

Bravo. This is the best and clearest Thingiverse posting I've ever had the pleasure to view. Well thought out and benefits from all the effort that went into it. Thank you and thank you.for sharing. This should be used as a model of how to post items on Thingiverse. What CAD tool(s) did you use? Best wishes for success of your toy business.

Thank you for your words. To make the model I use blender. I know is not the ideal tool, but is the only one I know (barely) how to use.