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5 Speed Linear Gearbox

January 13th, 2009 Leave a comment Go to comments

Idea of a linear gearbox extended beyond the usual 3 speeds. Features fixed input and output shafts.

The idea of a linear gearbox is quite popular and far spread, although the usual design features 3 speeds, or 3 + R at most. I was curious if more is possible, and it resulted in that design. Basically, it uses the idea of a 3-speed linear gearbox,  but flippedand set on a sliding middle shaft. The latter solution eliminated the biggest drawback of the usual linear gearboxes, that is sliding input and/or output shafts. Here, they remain fixed, connected by the sliding middle shaft, so the gearbox can be incorporated into a construction much easier. There are, however, the problems with unsynchronized clutching/unclutching, typical for all linear gearboxes. I have not yet solved these so far, nor have I been able to think of a linear gearbox with a higher number of gears. There is one serious drawback concerning the parts needed: the middle shaft requires an axle no shorter than 16 studs. 16-studs long LEGO axles exist, but are only available in 7 LEGO sets as of the end of 2008. Their availability in the online shops is quite satisfactory though.


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  1. Sandesan
    September 18th, 2013 at 08:39 | #1

    Back to this type of gearbox after failing to build the Veyron-box… I think I just managed to build this type of gearbox in a 9-speed configuration and a stepper+Reverse seems feasable. A great inspiration this gearbox is! Fingers crossed

  2. Sariel
    October 5th, 2011 at 18:39 | #2

    No, thanks.

  3. Ruben
    October 5th, 2011 at 18:12 | #3

    but i have to do is put it on it and make a program! and you kan doe it wit other motors but that hard.

  4. Sariel
    October 5th, 2011 at 17:05 | #4

    I don’t have NXT.

  5. Ruben
    October 5th, 2011 at 16:57 | #5

    I like this gearbox!

    can you make one with 6 gears with a nxt like this: http://www.youtube.com/watch?v=4hKCEMFpV7I&feature=feedlik
    the one how build it don’t give a reactoin of how it made!

  6. Sariel
    August 24th, 2011 at 00:34 | #6

    I would love to see it, but your photos are smaller than post stamps.

  7. hacatu
    August 24th, 2011 at 00:24 | #7

    I have recently designed a stepper/selector mechanism for this purpose. It is bigger than the gearbox, but allows remote control. https://picasaweb.google.com/104815240336781491383/LegoRemoteGearboxShifter

  8. hacatu
    January 14th, 2011 at 00:27 | #8

    For the stepper mechanism, you could have a worm gear between three 8 tooth gears on the bottom and two on the top. These 8t gears would have another 8t gear on the shaft in front of them. Then, a slider with one 8t gear would run between these so it always meshes one of the five 8t gears. Another slider would be pushed and pulled by the worm gear and attached to the first slider via a rubber band. This way, when you activate the motor, it pushes the worm gear one stud, which moves the gear selector (second slider) one stud. When the motor stops, the gear is no longer turning so the first slider is pulled into place by the rubber band. This mechanism is 5 studs by seven studs by five studs.

  9. Sariel
    September 29th, 2010 at 22:30 | #9

    Well, I’m not using vacuum engines.

  10. Alan
    September 29th, 2010 at 13:54 | #10

    @Sariel Well, if you are hooking it up to a vacuum powered engine or something that can run in reverse, it would be helpful.

  11. Adam
    June 10th, 2010 at 01:37 | #11

    It would be fun to have an R gear on a gearbox actually.

  12. Sariel
    March 8th, 2010 at 07:46 | #12

    You don’t. Why would you need an R gear when you can simply switch the motor to run backwards?

  13. Wei
    March 8th, 2010 at 01:18 | #13

    How would you create an R gear with the linear gearbox??

    Cheers Wei

  14. Sariel
    December 13th, 2009 at 02:04 | #14

    Well the problem is to make it move by one stud every time. It has to be exactly one stud, and that would require a very accurate stepper mechanism, which could be larger than the gearbox itself.

  15. arnau
    December 12th, 2009 at 21:08 | #15

    I think it could actually work, if you use a clutch gear. Every time that the gear changes, it just moves one stud, so no matter what position the actuator is in it will always be meshed with another gear. When driving the car you don’t know what gear you are using at each moment, but you do know when you’re going to a higher gear and when you’re going to a lower one.

  16. Sariel
    December 12th, 2009 at 13:31 | #16

    No, it would suck. Firstly this gearbox is not synchronized, and secondly I would have to keep an eye on the actuator’s position all the time.

  17. arnau
    December 12th, 2009 at 13:20 | #17

    could you not motorize that with a linear actuator and use it on the Lamborghini you’re building?

  18. Ralf
    September 23rd, 2009 at 14:44 | #18


    I have not the time to do it myself.
    For detailed information why I want such a gearbox(es) please use my email adress.


  19. Sariel
    September 17th, 2009 at 10:16 | #19

    Why would you buy it if you can easily build it yourself? I think the construction is clearly visible on photos, the only thing you ned are parts which you can get at Bricklink.

  20. Ralf
    September 17th, 2009 at 09:50 | #20

    Hi Paul,

    might it be possible to buy one of this 5 speed liear gearboxes from you?


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