Ultra Compact 8 Speed Sequential Gearbox

[Anto]

I made it almost a year ago, but I didn't have the time to make its presentation. It's a gearbox I made at the release of the rotary changeover catches.

My purpose was to make a gearbox as compact as possible. So I decided to couple a 2 speed gearbox to a 4 speed gearbox. There are 2 advantages: firstly the gearing is more compact, and then the shift system is also pretty compact.

When the changeover catch of the 4 speed gearbox makes one turn, it activates the one of the 2 speed gearbox. So to change the speeds from the lowest ratio to the highest, the 4 speed gearbox does 1; 2; 3; 4 while the 2 speed gearbox is in first gear; then the 4 speed gearbox activates the second speed of the 2 speed gearbox, and it does 1; 2; 3; 4 again.

Little trick: when you make a double gearbox like this, it's important to be sure that the gears are in the right order. This means the 6th gear (2-2) must not to be lower than the 4th gear -1-4) or you cannot control the gearbox properly.

So in Excel, I recreated the structure of the gearbox using cases in the calculations (for example F3*G3/F4*G4). Then I put the number of teeth of the gears I may use in the cases, and I got the final ratios of the gearbox. After some tries, I got a good result, and a perfectly controllable gearbox.

To control this gearbox, I used the stepper of the Bugatti Chiron that I compacted a little bit (the piece in red).

To finish, a modelization of the mechanic to have a clearer view of the gears:

Finally, this is an extremly compact gearbox, easily controllable.

 

[1gor]

I would not be surprised if similar solution pops up in upcoming Land Rover Defender set...

[SNIPE]

Hi,

Cool gearbox, I have been trying to miniturise the bugatti chirons gearbox too but to no avail. I don't suppose wehave have the LXF file?

[Vectormatic]

1 hour ago, I_Igor said:

I would not be surprised if similar solution pops up in upcoming Land Rover Defender set... 

I thought a 4 speed was already confirmed for that set?

 

On topic, this really reminds me of the Chiron's gearbox, im not entirely sure about the way the power flows through those gears, but the trick with the thin 2L arm and a pin meshing with the yellow cross gear to reduce 4 shifts of one side to 1 shift on the other side is the same.

[1gor]

12 minutes ago, vectormatic said:

I thought a 4 speed was already confirmed for that set?

Yes it is, under similar I meant by using one section with orange selector... 

[Vectormatic]

4 minutes ago, I_Igor said:

Yes it is, under similar I meant by using one section with orange selector... 

Ah right, in that case i wholely agree, the orange selector and blue clutchgear allow for a much more compact and better driven gearbox then for instance the old style porsche gearbox

[1gor]

Just now, vectormatic said:

Ah right, in that case i wholely agree, the orange selector and blue clutchgear allow for a much more compact and better driven gearbox then for instance the old style porsche gearbox

Yes that could be perfect for more compact model as Defender, despite it is 1:10 model...

Regards

[brunojj1]

Nice work @Anto ! Average people can´t recognize the efforts put into a gearbox (which equals an amount of work other people would likely invest into 2-3 single MOCs). I need to study this,  working on the development of a 6-speed drivetrain. I already can predict half-stud offsets like this won´t work in my heavy duty specification. 

 

Edited July 24, 2019 by brunojj1
I don´t know how I came to that conclusion. A hot day ​​​​​​​....

[Gray Gear]

Very cool, I always find these sequential gearboxes intresting, even though I only build and drive with manual transmissions 

If they really end up putting a simple 4 speed in the Land rover, it means they have not bothered to even try. Well, why do I even care? I dislike SUVs anyways 

[Anto]

Thanks!

The LDD file is on Rebrickable! https://rebrickable.com/mocs/MOC-26948/Anto/compact-8-speed-sequential-gearbox

Indeed on the Chiron, there is the same system to move a knob with a towball pin. I don't know exactly how its gearbox works, but I think it's more like a classis gearbox, with 4 driving rings, whereas here there are only 3.

[Vectormatic]

How do you mean @Anto? your design uses four driving rings as well from the pictures? Correct me if im wrong, but yours works by having a 4 speed on one side, which is then routed through a second gearbox which only has two effective ratios, making it a 4x2 effectively? The chiron does exactly the same AFAIK. To make a 4x2 with only 3 driving rings, you would need to either make gear op 1:2 between the cross/towball and the orange catch to make the quarter rotation from the towball into a half rotation, or use the traditional red catch and some lever mechanism (which would still require gearing up)

[brunojj1]

11 minutes ago, vectormatic said:

.. To make a 4x2 with only 3 driving rings, you would need to either make gear op 1:2 between the cross/towball and the orange catch to make the quarter rotation from the towball into a half rotation, or use the traditional red catch and some lever mechanism (which would still require gearing up)

If you use the traditional red catch, you´ll have a rotation angle below 90 degrees. Should work in theory without gearing up anything .

Btw 3 driving rings could result in 12-speed in theory. You would need a complex setup, e.g. with a differential bypassing the neutral position of the 3rd driving ring.

[Vectormatic]

@brunojj1 correct, and if you match it all up correctly, the red catch will act as a blocker prevent upshifting in 8th gear, as it simple wont be allowed to move further

[Anto]

1 hour ago, vectormatic said:

How do you mean @Anto? your design uses four driving rings as well from the pictures? Correct me if im wrong, but yours works by having a 4 speed on one side, which is then routed through a second gearbox which only has two effective ratios, making it a 4x2 effectively? The chiron does exactly the same AFAIK. To make a 4x2 with only 3 driving rings, you would need to either make gear op 1:2 between the cross/towball and the orange catch to make the quarter rotation from the towball into a half rotation, or use the traditional red catch and some lever mechanism (which would still require gearing up)

Oops, I meant that for the Chiron, there are 4 driving rings and 2 possible positions by driving ring, so 8 independant positions. But in my gearbox, there are 2 driving rings with 2 possible positions, and 2 driving rings with 1 position, so it's equivalent to 3 working driving rings. (I'll say I wasn't clear at all because it's a hot day. )

If I have a moment, I will try with a classic changeover catch, to see if it's possible to get something more compact.

 

[SNIPE]

@Anto The File on rebrickable is corrupt

Edited July 25, 2019 by SNIPE

[Vectormatic]

@Anto a right, got it, spotted the difference now! The Chiron indeed has the green side different, in that both catches there have the same gears on either side, rather then just one gear to select, this allows the Chiron to indefinitely keep shifting, looping around from 8>1, your gearbox would presumabling block on trying to shift up in 8th gear, correct?

I do think that solution is much nicer then lego's infinite loop, but i understand why lego wouldnt use it in a set, inexperienced users will run into the gearblock and might not understand what is going on, and either force it, and break parts, or think their model is broken.

[Anto]

28 minutes ago, SNIPE said:

@Anto The File on rebrickable is corrupt

I think it's a problem with the Rebrickable server (the file is hosted directly on Rebrickable), because yesterday someone has downloaded it and it worked. Try this link, this should work: https://www.dropbox.com/s/38oqygqibaxtlli/Sequential 8 Speed gearbox.lxf?dl=0

14 minutes ago, vectormatic said:

[...] your gearbox would presumabling block on trying to shift up in 8th gear, correct?

I do think that solution is much nicer then lego's infinite loop, but i understand why lego wouldnt use it in a set, inexperienced users will run into the gearblock and might not understand what is going on, and either force it, and break parts, or think their model is broken.

Yes that's correct! On the modelization, it's the black and orange thing that prevents the selector of the 2 speed gearbox from moving to the second gear to the first by the wrong way (and from the second to the first) so after this, you can't move the selector of the 4 speed gearbox. In the video you can see at 0.18, 0:39 and 0:47 that it works (but as the shifter and the gearbox are not fixed, the gearbox can be tilted a bit so it's possible to move a bit the lever even if it doesn't activate another speed).

I also understand LEGO's choise, because their aim is to show how a real car works. So they can't make something like me, as it's not representative of the reality. (But I hope on your car you can't shift from 8 to 1, or it will cost you a lot in replacing the engines! )

 

[SNIPE]

Thanks, That worked. Stay tuned

[Toastie]

On 7/24/2019 at 4:27 PM, brunojj1 said:

Average people can´t recognize the efforts put into a gearbox

Define average people ... "Average" people as in ... "illiterate gearbox gurus"? Or "illiterate mechanical engineers"?

To be honest, in this regard I am not even average but >way below< any measure of average.

But as part of "people" being average is not that bad at all. Who knows ... maybe being "average" with respect to people, allows to be above average when it comes to uncountable ways of being skilled ...

All I am saying is: I am totally blasted away with what you guys are discussing here, but not on an "average people" level.

All the best and rock on with your discussion!!!

Thorsten

   

[bonox]

Put in a splitter as well as a range select and you'll get a 16 speed gearbox just perfect for any large truck like Jaap's or 2legoornot2lego's.

Effectively a pair of two speed gearboxes paired with a 4 speed is how a standard (eg 18 speed eaton fuller) is made. Do it with a 3 speed main gearbox and you lead to a 13/15 speed depending on how you arrange a crawler gear. With this compact a size, it should even be implementatable and be a huge step up in realism.

[brunojj1]

23 hours ago, vectormatic said:

@brunojj1 correct, and if you match it all up correctly, the red catch will act as a blocker prevent upshifting in 8th gear, as it simple wont be allowed to move further

The nice thing about blockers - you can put them anywhere along the shifting axle and desired ratio. Did you ever consider the following shifting scheme: first gearbox 1-2-5-6  / 3-4-7-8 second gearbox?

 

22 hours ago, Anto said:

I also understand LEGO's choise, because their aim is to show how a real car works. So they can't make something like me, as it's not representative of the reality. ..

Neither the gearbox in the Porsche nor the Bugatti gearbox can be called representative. But it resembles some mathematical & physical principles which the interest and attention (of e.g. kids) should be driven to. Sadly, they have been paved by panels so nobody ever "average people" will have a second try to understand and play with the gearbox, moreover do the unthinkable - build your custom MK1, MK2.. So You are doing the very right thing, keep us updated .

16 hours ago, Toastie said:

Define average people ... "Average" people as in ... "illiterate gearbox gurus"? Or "illiterate mechanical engineers"?

To be honest, in this regard I am not even average but >way below< any measure of average.

But as part of "people" being average is not that bad at all. Who knows ... maybe being "average" with respect to people, allows to be above average when it comes to uncountable ways of being skilled ...

All I am saying is: I am totally blasted away with what you guys are discussing here, but not on an "average people" level.

All the best and rock on with your discussion!!!

Thorsten

   

I´m sorry, as "average people" were meant NOT the EB guys, please  ! Seriously - there is no big magic behind gearboxes, even me dumbhead get behind it after tinkering a few days. Probably I will post some of my gearboxes in a week or two in a separate topic. If somebody would need a compact PF servo stepper module:

LXF here

 

Edited July 26, 2019 by brunojj1

[Anto]

On 7/26/2019 at 5:07 PM, brunojj1 said:

Neither the gearbox in the Porsche nor the Bugatti gearbox can be called representative. But it resembles some mathematical & physical principles which the interest and attention (of e.g. kids) should be driven to. Sadly, they have been paved by panels so nobody ever "average people" will have a second try to understand and play with the gearbox, moreover do the unthinkable - build your custom MK1, MK2.. So You are doing the very right thing, keep us updated .

I meant the gearbox of the Porsche or of the Bugatti are closer (or less further) from real gearboxes in their conception. But I agree that anyway it's "not possible to understand correctly how they work" for average people (as you said) since the gearboxes are hidden under panels (unlike the #8860 chassis), so in this way, my gearbox could also work, if the only objective is to show the engine turning at different speeds.

What a compact stepper!

[SNIPE]

This also works as an "idler" knob wheel: Either inline or at 90 degrees to a knob wheel

And you can also put these parts in the barholes of knob wheels:

This saves space.

[Anto]

I haven't modified this gearbox but @Leviathan has made it for me!

He has made it more compact, mainly by changing the lock system of the 2 speed gearbox using a rubber connector. This has saved space: now it is 11 studs long instead of 13.

He has modified the stop system (which makes impossible shifting from 8th to 1st).

And he has also made a new structure, using technic frames (more stiff).

Below you can see a version even a bit more compact, but it's near to the illegal build.

 

Link to his own presentation on TechLUG: http://www.techlug.fr/Forum/viewtopic.php?p=192949#p192949

[SNIPE]

Wow even more compact!, Is there a way to hook up a dedicated axle just to get a single reverse speed though? Like in the 42083 Bugatti Chiron.

Also Instructions for the two new versions pls pretty pls :)

Edited August 28, 2019 by SNIPE