[MOC] Drum/Piano Gearbox (6 speed sequential)

[Victor Imaginator]

So, i finished my gearbox. It's too large for fitting inside some supercar, but i can imagine Hyundai Porter on Unimog wheels with this gearbox) Anyway, it's working, and i like how it looks and sound, so i decided to share this gearbox alone, without any car or something.

Gear ratios:

1st gear - 1 : 1.5

2nd gear - 1 : 1.2

3rd gear - 1 : 1

4th gear - 1.2 : 1

5th gear - 1.5 : 1

6th gear - 2 : 1

As you can see i used 4 shock absorbers for holding ratchet in postition and it's neccesary, because "hammers" resist and push "drum" back or forward by 30 degrees. I tryed to make some functional paddles, but failed - all that bionicle sharp parts and rubber bands just doesn't make sense here. So, i leave it with this yellow handle. Sorry for that)

Belly shot ;)

Assembling was a bit tricky, and fine tuning take 50% of time. After that tuning - selecting proper idler gears and adjusting hammer lengths - gearbox works fine, never stall, never slip, never grind (i tested it for 15-20 minutes in different conditions, hope it's enough). And, like a real one sequential 6-speed gearboxes, shfting time is measured in ms, disengaging-engaging almost instant, but it disengage first.

And video. i used M-Motor because used all my other motors in my previous MOC, and didn't dissamble it yet. And i gear it down only for this video, so difference in speed can be seen. I don't know how my gearbox will handle more torque, but it can handle much more speed - at each gear only 3 geear involved, so it's almost frictionless.

As usual - pictures are clickable for higher resolution, and more of it on FLICKR

Thanks for reading, i hope you like it)

[Lego2016Lego]

Looks very nice is it a new system I have never seen it before

[piterx]

it's cool!

but there's a problem: how much torque can it take?

when building a gearbox keep in mind that if you need a gearbox it's because your model is heavy, so you'll need 2 XL motors... if the gearbox can handle it without exploding than it's a good gearbox :P

Edited June 9, 2016 by piterx

[JJ2]

Sorry for my incompetence but why are there two outputs.

[Victor Imaginator]

Thanks for replies)

but there's a problem: how much torque can it take?

So, i decided to use my Spirit of Baja drivetrain for test. I connected gearbox instead of rear axle - there's 1 XL-motor geared up 1 : 1.67 connected via differential with 2 hardcoupled L-motors geared down 1.67 : 1... And it's all geared down 3 : 1 after differential. Sad, but i can't hold the phone, push IR controller lever and switch gears in same time, lack of 3rd arm) But i tryed it without filming - switching on the fly without any problems, no grinding or something.

Sorry for my incompetence but why are there two outputs.

Oh, my fault, i didn't explain))) LBG is input shaft, blue - output.

[zux]

The idea looks really interesting, great implementation!

But i tryed it without filming - switching on the fly without any problems, no grinding or something.

Now you need to attach the wheels and turn it up side down to see if it is grinding or not ;)

[piterx]

The idea looks really interesting, great implementation!

Now you need to attach the wheels and turn it up side down to see if it is grinding or not ;)

ehehe yes

[Victor Imaginator]

No, it's not grinding at all. Only trouble that I discovered - gearbox seriously slowing down on 4th and 5th gears if I connect geared up 1:9 M-motor. But further tuning of this 2 hammers and their idler gears will help - they pushed down too hard and generate unnecessary friction now.

[Technic Jim]

Have you seen ZBLJ's six speed gearbox - it is a very different take but still very cool:

[Victor Imaginator]

Yes, it's incredibly cool gearbox) But it's different approach, more typical for LEGO, using shifting clutch rings, addition gears e t.c. I just tryed to mimic real gearboxes, where's each gear using their own set of gears, and selecting gear do not involve additional idler gears, so i have only 3 gears per each gear now (sorry for that Gear-Gears =).

I have ideas about making similar gearbox, but with double clutch. There's some reasons - it will simplify hammer mechanics and allow me to use more gears, so 6+N+R will be possible. And i deleveloped nearly compact ball bearing this morning - i don't think it's really neccessary, but 100% pure LEGO ball bearing used in double clutch sequntial gearbox - it's cool as i think)

[Technic Jim]

Ok, cool!