[HELP] A, B, or AB Gear Selection

[SNIPE]

Hi, Is there some way (using a clutch ring) to have 3 speeds however 3rd is where the clutch ring is in the middle position and it is engaging 1ST and 2ND at the same time so for example EG: 1ST = 1.667:1 & 2ND = 3:1 so 3rd = 5.001:1 [1.667 x 3]). This is a single output single input gearbox. I don't know what else to say really but I cannot seem to get it to work.

I multiplied because it will assumably be a compound gear train.

Regards, S

[That_LEGO_Guy]

Does it need neutral? if not I may have an idea

Edit: didn't work, good luck though

Edited October 5, 2014 by That_LEGO_Guy

[SNIPE]

Nope no neutral needed

Sorry, forgot to mention that

[fasterthanlight]

I'm just thinking off the seat of my pants here, but you could try using two selector parts (6641) where one is used to select A or B

and the second one moves based on the position of the clutch ring and its rotation activates some gear mesh that would be AB when the ring is in neutral .. .

[anton1678]

I think I have a solution.

What if the clutch stops axle A if it is shifted to the right, stops axle B when shifted to the left, and doesn't stop anything when in neutral, activation both A and B?

This would require 2 clutch gears, since you can't just "stop" a moving axle, you could just increase the torque enough for the clutch gear to work

Edit: I don't know if this could give 3 speeds, but it would allow for 3 functions with one clutch ring. I'll post some pictures if it isn't clear how it works

Edited October 5, 2014 by anton1678

[Moz]

Add a differential to Anton's idea and it should all work. Ideally one of the old style ones with a different size gear at each end to make different ratios easier to build in.

[anton1678]

I couldn't find a way to include a differential without making the gearbox too big, so here's a first prototype.

It has functions A, B and A and B at the same time.

It works fine, though I wouldn't use the separate functions A and B for anything requiring speed, so I'd make all the speeds slow.

Only one motor to drive needed, and it it works pretty well, though is kind of crap when using only 1 function at a time because of the clutch gears.

Here's a photo, easy to build if you have the right parts and want to experiment with it

[SNIPE]

I've built it but it just spins both grey gears always, the middle position is neutral

I've tried using a different ratio instead of a second white clutch gear, so now its 16c:8:8 and the other is 16c:24 the 24 clutch gear inner part is not being used at all. but I'm getting two speeds by the middle position is again just neutral.

When I say 16c here I mean 16 clutch.

Edited October 5, 2014 by SNIPE

[SNIPE]

Ive did it!

The middle position is 1st as it's fastest.

the gear box 5x7x7 but I'm busy trying to make it smaller.

An L or XL motor is recommended for drive. The gap in the middle is so I can see what the gears are for the middle axle.

There are 3 axles in parallel and two in linear (for the clutch ring.)

I also have another version with another set of 8+24 gears rather than a 12 to 20 train but it is not as strong and a lot of torque is lost.

How I could make a 6 speed gearbox using only two red clutch rings if I wanted bur first like I mentioned ill try and make this one smaller.

Regards, Snipe.

Edited October 5, 2014 by SNIPE

[anton1678]

:thumbup:

Nice work

Edit: I built it, it really does need an XL motor, that thing is tough

Edited October 6, 2014 by anton1678

[anton1678]

I've built it but it just spins both grey gears always, the middle position is neutral

I've tried using a different ratio instead of a second white clutch gear, so now its 16c:8:8 and the other is 16c:24 the 24 clutch gear inner part is not being used at all. but I'm getting two speeds by the middle position is again just neutral.

When I say 16c here I mean 16 clutch.

I think you built it wrong in on the beam with a cross hole and a pin hole

I should've posted more pictures of it, it wasn't clear from that angle

The whole axle is stopped by it, so it can't move.

The clutch ring stops the grey gears instead of moving them

Edited October 6, 2014 by anton1678

[SNIPE]

Oh the black end is the input, green is output

I've made it way smaller now, it is now 1x5x7 excluding the length/height of the gears.

The white clutch is close and on the same axle as the motor too.

i'll buy some type 1 white clutches as those are weaker than type 2 or 3. I believe they only came in early lego education sets though so getting the right type from brick-link is going to be hard so I might just stick to the one I'm using.

it is ok and ill post a video of it working soon along with LXF files.

I tried white clutches in a similar thread to this but could not get it to work and that had a third gear train instead of combining A and B into a compound train.

As always, i'm using an L motor.

Edited October 6, 2014 by SNIPE

[anton1678]

Can you upload pictures?

I need to build this thing, I don't understand how you could get it that small

Edited October 6, 2014 by anton1678

[SNIPE]

Here is the LXF

Regards, Snipe

[cgg199]

I posted this idea a couple of weeks back, however we vetoed the idea, as the torque need for the 24 tooth gear is too high to make the gearbox useable. If you can get it to work though I'll be very impressed!

[SNIPE]

Hi

Yes, I managed to reduce the vibration caused from the white clutch, maintain enough of the torque

try building the last picture I posted if you want to see it work as that is the working model

iv'e tried using an 8+24-24-8 compound train but it loses too much torque and is very slow in one of the gears.

Edited October 6, 2014 by SNIPE

[torso]

Here you go. The differentials are input and output. I don't know if the gear ratios are correct and I'm sure it can be built smaller.

That small liftarm is a 60483 that prevents the driving ring from spinning.

[arik]

Wow! That's clever! I tried to figure this out some time ago but ended up thinking it can't be done even with a differential. Didn't see it takes two :-)

[Hrafn]

I don't have access to my bricks to test it, but I think this will work. It's not synchronized, and requires a long throw to switch gears. The two axle joiners are not connected by an axle. When the driving ring is on both of them, the input:output ratio is 1:1. When the driving ring engages one or the other of the clutch gears, the ratio is 12/20 or 20/12. When the driving ring is centered on one joiner or the other, it's in neutral. Obviously 8/24 pairs could be used as well, or 8/8/8 for reverse.

Edited October 8, 2014 by Hrafn

[SNIPE]

Hi

Being able to side the selector ring between two axle joiners sounds quite hard as the notches have to line up and one will always be spinning even in neutral.

The 16 tooth gears are not really needed if you don't want neutral, so it would be quite small then which is good.

Cool idea though.

Edited October 8, 2014 by SNIPE

[Hrafn]

Being able to side the selector ring between two axle joiners sounds quite hard as the notches have to line up and one will always be spinning even in neutral.

Quite true. Someone who was willing to mod parts could put an axle connector on a drill and sand one end down so that it tapers and could be used to self-synchronize.

The 16 tooth gears are not really needed if you don't want neutral, so it would be quite small then which is good.

Could you explain what you mean? The neutral wasn't intentional, it just emerged from having to have 2 axle connectors. I'm not sure how you could get rid of the 16t gears.

[SNIPE]

You can still select the L R or both axles using just the red clutch, the 20 tooth gears mesh to the corresponding axle joiner depending on where the input and output is, In some cases you'd need the 16 tooth gears.

Regards, S

Edited October 9, 2014 by SNIPE