8 Speed OR Gate Gearbox

[SNIPE]

Hi,

I have had an idea for a while to take a dual clutch ring 4 speed gearbox but use all 8 possible clutch positions along with a mechanical OR gate to get 8 speeds instead of the extra 4 "combined speeds" jamming the gears.

the OR gate would reroute the output back into the input but while actually gearing up/down to get an additional 4 unique ratios. (we don't wanna have duplicate ratios obviously)

Such a mechanism was used in set 9396 but in my case  it swings between two possible gears and when the torque gets too high (i.e when the gears would normally jam)

You could also use a differential as an OR gate but its kinda big and not as flexable.

So really this setup is equivelant to the 42083 gearbox in that it is a 4 speed gearbox with two modes (4 * 2 = 8 speeds)

The difference is, this is much more compact since it only uses 2 clutch rings not 4 and fewer gears.

Does anyone have any insight on how to actually build this as I can't seem to crack it.  Maybe @TechnicBrickPower can help since he has already made several cool and new gearbox ideas but any help is appriciated!.

Regards, Snipe

Edited June 24, 2020 by SNIPE

[TechnicBrickPower]

Hi Snipe, thanks for calling me to help. Will do my best. Can explain more what you are trying to do? Just so I understand you said there are 8 possible combinations for two clutch rings, so you mean there are 3 for each (left, neutral, right) and since there are two of them that gives 9 combinations, but you are discounting the combination (neutral, neutral) to leave 8? Is that right? And therefore you are saying it should be possible to create an 8 speed gearbox based on that idea. I am on the right track..? 

[Didumos69]

5 hours ago, SNIPE said:

I don't know, but what you're showing here, is a 4-speed gearbox with 2 driving rings and 2 rotary catches (similar to this one). If you would engage more than one clutch gear, it will jam. Also, this gearbox relies on transmitting torque via idler gears that are not placed in one line, which is a recipe for severe friction in at least one direction.

Still, and maybe that is what you're looking for, you could make two equal 4-speed gearboxes, with slightly different input ratios such that one can be used for gears 1, 3, 5, 7 and the other for 2, 4, 6, 8, and combine that with a selector (OR gate) that toggles between the 2 gearboxes. @Jeroen Ottens did something like that in his Audi R8. If you would go one step further and make a shift a 2-phase shift with phase 1 putting the not-engaged gearbox in the right gear and phase 2 selecting the not-engaged gearbox, you would have a real dual clutch gearbox.

Or you could use 2 gearboxes and combine the 2 outputs with a differential.

Edited June 24, 2020 by Didumos69

[SNIPE]

3 hours ago, TechnicBrickPower said:

Hi Snipe, thanks for calling me to help. Will do my best. Can explain more what you are trying to do? Just so I understand you said there are 8 possible combinations for two clutch rings, so you mean there are 3 for each (left, neutral, right) and since there are two of them that gives 9 combinations, but you are discounting the combination (neutral, neutral) to leave 8? Is that right? And therefore you are saying it should be possible to create an 8 speed gearbox based on that idea. I am on the right track..? 

Thats right :D, Thanks!

[TechnicBrickPower]

Hi @SNIPE, The fundamental problem with that approach is that you need to able to somehow change the gearing ratio at the output when you disengage a gear with the clutch gear, e.g. if the 2 clutch gears are in position [left, left] and then you change to [left, neutral] then somehow the shift from left -> neutral has to change gear ratio at the output - you're essentially disconnecting the gears from one another and not connecting to another. It's counter intuitive for that to work. However that said I have thought of a solution that I think would work but it's not going to be efficient or pretty.

 

[SNIPE]

1 hour ago, TechnicBrickPower said:

Hi @SNIPE, The fundamental problem with that approach is that you need to able to somehow change the gearing ratio at the output when you disengage a gear with the clutch gear, e.g. if the 2 clutch gears are in position [left, left] and then you change to [left, neutral] then somehow the shift from left -> neutral has to change gear ratio at the output - you're essentially disconnecting the gears from one another and not connecting to another. It's counter intuitive for that to work. However that said I have thought of a solution that I think would work but it's not going to be efficient or pretty.

 

if I understand correctly: if you go from L L to L N then the OR gate would switch outputs.

The or gate does not have to use all 16 tooth gears, it must step the final ratio up in order for the 4 speeds to not be repeated again.

The OR gate only is in the output B when the 4 'combined' speeds are engaged, Else the OR gate uses output A.

The or gate itself does not use a clutch ring. just a friction pin and gears on a lever with a 90 degree rotational limit

I think the best way to get the selector rings to work is by using linkages and the clutch patterns should be

 

 

 

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[TechnicBrickPower]

21 hours ago, SNIPE said:

if I understand correctly: if you go from L L to L N then the OR gate would switch outputs.

The or gate does not have to use all 16 tooth gears, it must step the final ratio up in order for the 4 speeds to not be repeated again.

The OR gate only is in the output B when the 4 'combined' speeds are engaged, Else the OR gate uses output A.

The or gate itself does not use a clutch ring. just a friction pin and gears on a lever with a 90 degree rotational limit

I think the best way to get the selector rings to work is by using linkages and the clutch patterns should be

 

 

 

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Hi @SNIPE can you point me to where I can see an example of a lego OR gate. The helicopter video looked more like a one directional gate to me.

[SNIPE]

Here you can see the OR gate in both positions: yellow is the outputs the middle two gears are the gate itself and the bent liftarm is the limiter. the dark gray pin is the input.

In the helicopter set theres only one output so yes its acting like a saftey clutch/ne way clutch. here we have two outputs.

hope this helps. I think akiyukis catch 'n' spin robots use or gates. theres also this which uses a worm gear as the gate instead of a centeral16 tooth gear

 

Edited June 25, 2020 by SNIPE

[Didumos69]

So you have an OR gate, which will induce a lot of friction by itself, as the torque will translate itself to a moment of force to the pivot point, which is the drive axle. Also, it requires the drive axle to reverse to select the other gear. If this is intended as high-low selector, you need another selector to reverse the input or not.

How on earth is this going to help in making the above gearbox, which as depicted only works when a single clutch is engaged, an 8 speed gearbox?

Can you make a sketch with black boxes for the main components and short descriptions of what they should do?

Edited June 25, 2020 by Didumos69

[Rudivdk]

On 6/24/2020 at 8:50 AM, Didumos69 said:

Still, and maybe that is what you're looking for, you could make two equal 4-speed gearboxes, with slightly different input ratios such that one can be used for gears 1, 3, 5, 7 and the other for 2, 4, 6, 8, and combine that with a selector (OR gate) that toggles between the 2 gearboxes.

I am working on exactly this setup: 2x 4speed gearbox with a 0,9 difference in input ratio and an OR gate (left/right) between the two gearboxes, mechanically linked and synced with the gearshifters of the two gearboxes. I'm still in doubt whether I'll add an DNR, or omit 1 speed for reverse... It is not finished yet (gears are, shifters not), will post more on it later.

[Didumos69]

12 hours ago, Rudivdk said:

I am working on exactly this setup: 2x 4speed gearbox with a 0,9 difference in input ratio and an OR gate (left/right) between the two gearboxes, mechanically linked and synced with the gearshifters of the two gearboxes. I'm still in doubt whether I'll add an DNR, or omit 1 speed for reverse... It is not finished yet (gears are, shifters not), will post more on it later.

Funny, because I'm working on the same concept, but with a 2-phase shifter. Pulling or pushing the shift lever will first shift the unengaged gearbox to a higher or lower gear and recentering the shift lever will toggle from engaged gearbox to unengaged gearbox. I have a 0.8 ratio between the odd and even gearbox.

Edited June 26, 2020 by Didumos69

[Rudivdk]

1 minute ago, Didumos69 said:

I have a 0.8 ratio between the odd and even gearbox

Interesting, I guess we use a different setup for the 4speed boxes than... 0.9 was the only proper input difference that would work on mine to have all even speeds fall nicely between the odd speeds. It all ends up pretty close-ratio, but it is mathematically correct.

[Didumos69]

2 hours ago, Rudivdk said:

Interesting, I guess we use a different setup for the 4speed boxes than... 0.9 was the only proper input difference that would work on mine to have all even speeds fall nicely between the odd speeds. It all ends up pretty close-ratio, but it is mathematically correct.

My ratios are something like 0.16, 0.26, 0.33, 0.45, 0.6, 0.8, 1.0. Of course there is some symmetry involved. And no idler gears transmitting torque.

Edited June 26, 2020 by Didumos69

[TechnicBrickPower]

On 6/26/2020 at 5:12 AM, SNIPE said:

Here you can see the OR gate in both positions: yellow is the outputs the middle two gears are the gate itself and the bent liftarm is the limiter. the dark gray pin is the input.

In the helicopter set theres only one output so yes its acting like a saftey clutch/ne way clutch. here we have two outputs.

hope this helps. I think akiyukis catch 'n' spin robots use or gates. theres also this which uses a worm gear as the gate instead of a centeral16 tooth gear

 

Hi @SNIPE ok I see I was imaging a logical OR gate used in computers. This is pretty cool - so if the input turn clockwise it selects one output and otherwise the other. That's clever. But is has a friction problem right? Still not sure how this well help with your problem as you are in effect selecting one of two different outputs instead of combining inputs which is what your gearbox idea seems to require. Instead of the OR gate design you have shown can't you just use two of the helicopters ones, i.e. two ratchets, one for clockwise rotation and the other for anti-clockwise. That way you don't need the gray friction pin to do the selecting.

[SNIPE]

like 10 years ago I made agearbox that had 4 speeds but had a white clutch gear for when the two clutch rings were both engaged for the extra 4 gears.

The idea was to have two conditional ratios on the input shaft, before you even got to the internal gears, one was just teh clutch gears teeth + an 8 tooth gear and the other was some other pair of gears connected to the white clutch gears gray output.

The white part would jam when any of the extra 4 speeds were engaged but the axle hole still worked. However the clutch gear kinda acts like an 8 position stpepper which was no good and it puts a load of strain on the motor so the idea was scrapped but the whole thing fitted into a 3x3x11 space (excluding the two changeover catches)!.

Perhaps we could just use a 4L differential since I always like having a center differential in all of my MOCS/MODS anyhow

The 4L differential can act as an OR gate.

Regarding the high friction concern, I have rarley broken lego parts in my life so I prefer to move my ideas away from a digital model as fast as possible.

Edited June 29, 2020 by SNIPE

[SNIPE]

@TechnicBrickPower I decided to use a differential as a summer (not sure if its adding, subtracting, dividing or multiplying) where it would normally jam, this seems to work in all 8 positions:

Would someone mind giving me the ratios for each output and for all 8 positions, I am hopeless at working that out and dont have the old yellow 9v speed omiter.

The input is the petruding yellow axle.

Bricksafe keeps cropping my images unless I select 'full size' so they are very big, but I can crop and resize them if needed.

Edited November 11, 2020 by SNIPE