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AeroShift Gearbox

November 30th, 2009 Leave a comment Go to comments

New gearbox concept – a 3-speed sequential synchronized pneumatic gearbox that can be operated entirely remotely.

The gearboxes are very useful even today, with the speed control feature available with the Power Functions system. They are even more useful when they are remote-controlled, because this way the vehicle doesn’t need to stop to shift gears – instead, the gears can be shifted while driving. This type of gearboxes can work just like the real ones: it can have some gears that are unable to start the vehicle, but can speed it up once it has some momentum already.

The easiest type of a remote-control gearbox is a 2-speed one, because it can be easily motorized like an end-to-end device; it can shift between 2 gears with a single motor easily. I always wanted to build a remote-controlled gearbox that would have more than 2 speeds and still require only a single motor to be operated. It was eventually achieved with the AeroShift gearbox (I made up that name because the ‘3-speed remote-controlled sequential synchronized pneumatic gearbox’ didn’t sound too catchy ;)).

This gearbox is, as mentioned above, sequential, which means that it can’t shift from any gear to any gear. Instead, it has to shift through gears in a sequence, e.g. from 1st to 2nd and then from 2nd to 3rd. This type of gearbox is quite popular in motorbikes. The gearbox is also synchronized, thanks to the use of the driving rings, on assumption that it would be troublesome to watch for grinding gears in a gearbox that’s supposed to be operated remotely.

If you look closely enough, you’ll notice that the gearbox consists of two identical modules set as ‘mirrors’ of each other. It is perfectly possible to build more than two modules – the first one will provide two speeds, and each next module will provide one extra speed (hence 3 speeds with two modules). The gearbox would have 5 speeds with four modules, 7 speeds with six modules, and so on. I did not attept to use more modules, because for me 3 speeds with a gearbox of this size was a good solution, while 5 speeds with a gearbox twice as large was not. Additionally, it would require more than a single pneumatic cylinder to be operated, and thus greatly complicate the pneumatic system.

It should be mentioned that this gearbox can be operated without pneumatics. It would, however, require a number of gears, including gears with clutches, as well as a mechanism that would work like a stepper motor. Since a single pneumatic cylinder can replace all these mechanic parts, I have chosen this solution as a significantly simpler one.

The picture above shows a testing setup. The pressure gauge and speedometer are obviously not needed for the gearbox to work, and the pneumatic valve is supposed to be operated by a motor. The parts that are important for the proper functioning of the gearbox and may not appear so on the photo include the rubber band which makes sure that the driving rings are switched sequentially, not simultaneously, and the grey thin plates described as ‘limiters’ above, which make sure that the movement of the pneumatic cylinder is contained within a desired range. The cylinder can be mounted with its inlets pointing downwards to take less space, but it requires placing the pneumatic hoses in such way that they don’t interfere with the moving parts of the gearbox. I believe that this photo along with the ones that follow it are sufficient to build a copy of this gearbox, so I will just list the pros and cons of this gearbox according to my observations.

Pros: relatively small size, 聽ability to handle huge torque (the critical elements are the driving rings that tend to disengage when too much torque is applied), convenient location of the input and the output, identical functionality for the driveshaft rotating clockwise as well as counterclockwise, and a minimal chance of the mechanical failure in the gearbox (e.g. because all the gears that transfer the drive are encased in solid bricks).

Cons: uses pneumatics, doesn’t work well with high air pressure (it causes strain on the driving rings and thus slows the gearbox down, so use of an airtank with this gearbox is not recommended), is sequential (impossible to omit the middle gear, though it can be switched through it really quickly) hitting the medium gear precisely can be tricky (depends mainly on the proper calibration of the rubber band and the pneumatic pressure in the cylinder), the gears are shifted relatively slowly, 聽and there is a number of dead gears that generate additional friction.

The gearbox offers the following gear ratios: 1:1, 3:1 and 9:1. If these differences are too large for your use, it is perfectly possible to replace the 8t & 24t gears pairs with 12t & 20t gears pairs. It will result in the gear ratios changed to 1:1, 1.66:1 and 2.77:1, while the functioning of the gearbox will remain the same.


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  1. EV3fan
    May 17th, 2014 at 10:30 | #1

    Oh that idea is great!

  2. Sariel
    September 1st, 2013 at 09:35 | #2

    Because it has a worm gear inside and won’t yield to a rubber band.

  3. Matthew
    August 31st, 2013 at 22:40 | #3

    Why wouldn’t the rubber band work on the linear actuator?

  4. Sariel
    August 31st, 2013 at 10:35 | #4

    You could, but it would be more difficult to control. The rubber band won’t work on a linear actuator.

  5. Matthew
    August 31st, 2013 at 00:44 | #5

    This is an awesome gearbox. But, instead of pneumatics, could you use a linear actuator? If not, why?

  6. Sariel
  7. lluiscab
    April 15th, 2013 at 15:57 | #7

    where you purchased the speedometer

  8. Alex
    December 21st, 2011 at 20:42 | #8

    thanks, that brilliant now back to my impala thanks again

  9. Sariel
    December 21st, 2011 at 18:39 | #9
  10. Alex
    December 21st, 2011 at 18:18 | #10

    what air pressure supply do you use because im making a chevy impala and wanted to know if it was a mains connected machine

  11. Phillip
    January 8th, 2011 at 23:56 | #11

    Okay, thank you!

  12. Sariel
    January 8th, 2011 at 21:05 | #12

    I think yes.

  13. Phillip
    January 8th, 2011 at 20:11 | #13

    Could the pneumatics be replaced with the new mini LA?

  14. Marco
    July 8th, 2010 at 13:40 | #14

    Wow…we come from different countries but we had the same idea. I developed a sistem for chancing the gear by a small cilynder.

  15. HJHlego
    June 2nd, 2010 at 16:33 | #15

    I don’t think it will make a difference. Sorry. Anyway, I have approximately worked out the price now.

  16. Sariel
    June 2nd, 2010 at 16:10 | #16

    Do you really think it makes difference given the size of this battery? Can’t you order it if you don’t know the weight down to 0.1 g or what?

  17. HJHlego
    June 2nd, 2010 at 16:08 | #17

    Please tell me if you have weighed it with the battery in or not.

  18. Sariel
    June 2nd, 2010 at 15:44 | #18

    The link I gave you shows the weight too. Bricklink includes weights of most of the Lego parts.

  19. HJHlego
    June 2nd, 2010 at 15:42 | #19

    How much does a speedometer weigh in grams? The reason I would like to know is because I would like to know how much money I would have to pay on bricklink.com for it and some other things.

  20. GuilliuG
    June 2nd, 2010 at 13:38 | #20

    Hi Sariel. I know u’re really interessted by motorized gearbox.

    So i’ve decided to show you my new invention : it’s a full motorized gearbox with 4 positions and driving ring. Here is my gearbox :



    Sorry for the explications but there are in french.

  21. HJHlego
    May 24th, 2010 at 20:36 | #21

    thanks for the link

  22. Sariel
  23. HJHlego
    May 22nd, 2010 at 21:29 | #23

    Cool gearbox. How can you find a lego speedometer on peeron or bricklink?

  24. Sariel
    April 20th, 2010 at 21:20 | #24

    I wish I knew.

  25. Jetro
    April 20th, 2010 at 16:21 | #25

    when is that going to be?

  26. Sariel
    April 20th, 2010 at 15:52 | #26

    As soon as I learn to.

  27. Jetro
    April 20th, 2010 at 14:58 | #27

    You have been saying by every gearbox that the are not good for TrTr but can you show, or make one that is good for TrTr.

    thanks 馃槈

  28. Sariel
    March 31st, 2010 at 18:20 | #28

    Linear actuator of course.

  29. matthew
    March 31st, 2010 at 17:22 | #29

    But which is stronger ?

  30. Sariel
    March 30th, 2010 at 22:04 | #30

    Strength is not needed for this gearbox to work. It works perfectly well with pneumatics at a relatively low air pressure (as seen in the video).

  31. matthew
    March 30th, 2010 at 21:42 | #31

    Do you know which would be stronger since I only have pneumatics;linear actuators powered by a medium motor,or pneumatics at 20psi

  32. Sariel
    March 25th, 2010 at 06:54 | #32

    Not a good idea. It’s too long and you would need to add clutch to prevent it from tearing the gearbox apart.

  33. Eric
    March 25th, 2010 at 05:48 | #33

    I was wondering if it would be possible to use a linear actuator instead of the pneumatic cylinder. On another note, I’ve been enjoying your website over the past few weeks!

  34. Miroslav
    March 15th, 2010 at 19:48 | #34

    I wish I have such opportunities wich constructing.

  35. Sariel
    March 1st, 2010 at 10:26 | #35

    I think it’s possible, but I never really had a need for reverse gear since since I drive all my gearboxes with electric motors that can be put on reverse easily.

  36. Wei
    March 1st, 2010 at 10:21 | #36

    Nice gear box design – love the site also, do you tink its possible to convert it into a 3-R or 2-R gear box??

  37. Sariel
    February 5th, 2010 at 10:54 | #37

    @Akshat Nigam
    I’m just a linguist, I have no engineering background whatsoever.

  38. Akshat Nigam
    February 5th, 2010 at 05:27 | #38

    Sariel (paul), could I know your educational and other qualifications, like from which field you did complete your graduation, post-graduation and all that ?

  39. Sariel
    February 4th, 2010 at 09:46 | #39

    @Akshat Nigam
    I use MLCad. All the things I build can be obviously built with self-collected parts (in fact, they ARE built in such way). And for shopping it’s BRICKLINK!

  40. Akshat Nigam
    February 4th, 2010 at 08:43 | #40

    Hi Sariel,
    Good work, you are a awesome LEGO TECHNICian. You use Ldraw, but what are you using as second generation editor MLCAD or LeoCAD, if using neither please tell.
    And all this stuff you create with LEGO TECHNIC can also be done with individual self collected parts ?
    And how can I buy LEGO TECHNICs online, how will it cost ?

  41. Sariel
    January 8th, 2010 at 07:58 | #41

    Tak, pr贸bowa艂em. Nie, jestem tylko po filologii.

  42. Filip
    January 8th, 2010 at 00:34 | #42

    Jestem pod wra偶eniem Twych konstrukcji Sariel. Gdybym mia艂 odpowiednie fundusze te偶 bym si臋 pobawi艂 jednak na razie ma bardzo mam za co. Ale planuj臋 powr贸t do Technic po ok 6-8 latach(mam teraz 20:P), nie mniej jednak chyl臋 czo艂o, cho膰 wo艂aj膮 na mnie majster 馃槈 Ale do rzeczy. Pr贸bowa艂e艣 z艂o偶y膰 gearbox’a 4 biegowego z prze艂o偶eniem szybszym czyli np 3:1? bo wsteczny nie ma sensu z racji tego, 偶e silnik si臋 kr臋ci w dwie strony… A i jeszcze jedno pytanko – jeste艣 po/w trakcie wydzia艂u mechanicznego na jakiej艣 politechnice? 馃槈

  43. jorhoerst
    December 27th, 2009 at 21:24 | #43

    Nice work! I built it myself, and found, trying to make it more suitable for RC, that it doesn’t work to build a ‘shifter’ by hooking up a regular cylinder to the one on the gearbox. It does work, however, to hook up one of the old extra long single-acting cylinders. I put a short hose from that cylinder to the base of the cylinder on the gearbox and it works very well. I’ll try to get some pics up on my Brickshelf today or tomorrow if you don’t get what I’m saying.

  44. December 25th, 2009 at 23:49 | #44

    I built the gearbox and the only time the gears skip is when the gearbox is in 5th gear. Other than that the gears don’t get damaged at all.

  45. Sariel
    December 7th, 2009 at 08:13 | #45

    It was done in LDraw.

  46. December 7th, 2009 at 07:16 | #46

    I wonder
    What kind of use cad S/W?
    Gearboxs image is very nice and quality.

  47. Sariel
    December 6th, 2009 at 20:31 | #47

    Clever and unusual, but I fear gears may get damaged when meshing at angle.

  48. AZUWSK
    December 6th, 2009 at 20:20 | #48

    Hi Sariel,
    what do you think about this gearbox?

  49. Sariel
    December 3rd, 2009 at 08:46 | #49

    I have used the old type axle connectors.

  50. echo3367
    December 3rd, 2009 at 04:35 | #50

    hey sariel, couldn’t you use the old type of axel connectors (the ones where the clutch clicks while passing) in stead of the smooth ones? in this way, you could control the switching much easier, but if you use the new (smooth) ones, that would provide a faster switching…..
    just sugesting

  51. Sariel
    December 2nd, 2009 at 15:31 | #51

    It won’t work, because if multiple cylinders were used, they would have to be switched in order. So it’s more likely that more rubber bands would be used. And filling cyinders with water destroys them.

  52. Fabian
    December 2nd, 2009 at 15:29 | #52

    Hi Sariel
    Why do you don麓t make a “add on” with this idea (http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2599393)
    and fill it with water or something.
    The second zylinder is connected to a pf motor.
    So you can change the gears remotly.
    Hope it can help.
    I think it麓s simplyier than the auto valve.

  53. Sariel
    December 1st, 2009 at 21:51 | #53

    You don’t need dual control for that. You can use this: http://sariel.pl/2008/12/pneumatic-autovalve/

  54. djtermoz
    December 1st, 2009 at 19:48 | #54

    Very smart design. But what I really would like to see is how you plan to control it. I can tell from the video that in order to use all gears you need a dual control: (1) position of the pneumatic switch and (2) air pressure in the yellow cylinder.
    Second question – apart form its size, would linear actuator work as well?

  55. przemektechnic
    December 1st, 2009 at 13:51 | #55

    dzi臋kuj臋 za podpowied藕. chcia艂em tylko powiedzie膰 偶e adres e-mail nie jest m贸j:) gg: 4320693(je艣li gg jest potrzebne)

  56. Sariel
    December 1st, 2009 at 13:25 | #56

    Witam. Pomys艂 zrodzi艂 si臋 g艂贸wnie z potrzeby, przewiduj臋 偶e nied艂ugo taka skrzynia mo偶e by膰 mi potrzebna do nap臋dzania wi臋kszych modeli 馃檪
    Co do Bricklinka, mo偶na dokonywa膰 zakup贸w p艂ac膮c przez system Paypal – ten system mo偶na powi膮za膰 ze swoim kontem bankowym, wi臋c zwyk艂e konto np. w mBanku (w moim przypadku) ca艂kowicie do takich zakup贸w wystarcza. Przeliczanie ze z艂ot贸wek na dolary i inne waluty zapewnia Paypal, bank nie jest w to zaanga偶owany.

  57. przemektechnic
    December 1st, 2009 at 13:13 | #57

    dzie艅 dobry! Widz臋 panie sariel kolejn膮 interesuj膮c膮 konstrukcj臋. Podpisuj臋 si臋 pod pozytywnymi komentarzami koleg贸w(pan贸w). Nie umiem si臋 za dobrze wypowiada膰 na temat konstrukcji innych. sk膮t pan wpad艂 na taki pomys艂? Mam dopiero 12 lat i od niedawna (ok. roku) zajmuje si臋 lego technic.Chcia艂em si臋 zapyta膰 czy 偶eby kupowa膰 na bricklink trzeba mie膰 konto dolarowe? (bo wujek mi m贸wi艂 偶e chyba tak)

  58. icanhaslego
    December 1st, 2009 at 04:40 | #58

    yeah, zblj’s cvt improves vastly in terms of design than that of misha van beek’s. i also love how the maximimum and minimum ratios can be adjusted. however, on the subject on stalling- does it simply stall as the motor runs out of torque in the lowest ratio?

  59. Sariel
    December 1st, 2009 at 03:09 | #59

    I actually have a working, somewhat modified copy (I’ve changed it to fit in narrower space) and it works wonderfully. My only concern is that it is possible for the resistance to stop this gearbox. Not easy, but possible.

  60. icanhaslego
    December 1st, 2009 at 03:06 | #60

    ooh, yes. i want to try it as soon as i find my other differential

  61. Sariel
    December 1st, 2009 at 02:03 | #61

    No, I could, but I want to test the CVT gearbox invented by Zblj.

  62. m艂ody97
    December 1st, 2009 at 00:57 | #62

    Jak b臋d臋 robi膰 jaki艣 samoch贸d taki porz膮dny, to na pewno wykorzystam t膮 skrzynie. Jest the best

  63. Alex
    December 1st, 2009 at 00:39 | #63

    Very interesting! Will you use this one as the “automatic CVT gearbox” in the Reventon?

  64. Sariel
    November 30th, 2009 at 10:16 | #64

    OMG! Corrected 馃檪

  65. RjbsNXT
    November 30th, 2009 at 09:48 | #65

    I love the way that the elastic band makes sure that the gears change in a certain order! I also like fact that there are no sliding axles and the setup of gears is a very nice idea.
    My only concern is if a vehicle needed such power as is transmitted from the bottom gear – would it be able to cope with that from the highest gear? I suppose it would work in supercars and some trucks – look forward to seeing it in the future 馃榾

    p.s. You tagged the main photo as Aeroshoft gearbox 馃槈

  66. icanhaslego
    November 30th, 2009 at 05:54 | #66

    while the gearbox design is very clever, my personal favorite part is the use of the pneumatic cylinder to actuate two levers. simple, and yet effective.

  67. thirdwigg
    November 30th, 2009 at 05:52 | #67

    Good Design, this has more application than a standard four speed, and can be controlled easier for more application.
    Though the gearbox has to pass through neutral when shifting between gears. Like other gearboxes this limits it application to something that needs continuous power, but cannot afford to lower the speed (and therefore power) of a PF motor by use of the PF speed control IR transmitter. In a Truck Trial application, where the need for a gearbox like this can be really useful, it would be helpful to have a gearbox that can change gears without loosing power for the short time between gear changes. Automatic gearboxes, like the 2 speed you designed, are also helpful but lack the strength and syncronation of gears that some models need.

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