Compact single direction output

[Tommy Styrvoky]

Does anyone know of a compact transmission where the output will only spin one direction. I have attempted to make a ratchet based transmission but it has problems with gears meshing. if possible a 1:1 ratio for it ?

Edited May 27, 2014 by Tommy Styrvoky

[Bzroom]

I think i've seen a mechanism where a worm gear travels along the axle, engaging with a second gear who's drive is reversed. So there is a delay when the worm gear is shuttling. But it gives you that switching behavior.

Worm gear:

Ratchet:

Edited May 27, 2014 by Bzroom

[BEAVeR]

I tried something similar once, and I got the idea of using 2 differentials. Sadly, I could never try it out because I only have one...

The way it works: you transmit the input motion on to the big gear connected to the differential. The two outputs of the differential then should each get a little ratchet mechanism. So if you turn the differential in one direction, e.g. only the left axle would turn (because the right axle experiences 'infinite friction' because it is stopped by the ratchet, therefor all rotation goes to the left axle). If you turn it in the other direction only the right axle would turn (in this example). Now you can reverse the rotation of one of the axles and tada: both axles turn in the same direction, no matter what direction the input has.

But then you need to add the outputs of the two axles together for practical use. You can do this with an adder mechanism using yet another differential. Just connect the two output axles in a new differential, and you won't even need a ratchet this time. The big gear connected to the differential is your output!

The green one is the input, the red one is the output.

The advantage is that you can easily reverse the selected direction by placing the ratchets on the opposite sides. It's a bit big though, but it works without much delay. Hopefully it helps you!

Edited May 27, 2014 by BEAVeR

[Captainowie]

A bit old now, but the first entry on this page http://www.andrewlipson.com/lego.htm should do what you want (links to a .dat file, so you'll need a LDraw viewer to see details). It really depends on what you mean by "compact" though.

Owen.

[Cadder]

https://www.bricklink.com/v3/studio/design.page?idModel=25325

This is one that I've used in a couple of my GBC modules.
I like it because it's compact, not *too* intensive on expensive parts, and it maintains a 1:1 ratio.

[Jonas]

Thanks, Cadder, for sharing it. I have built it and verified that it works. It is a very useful and compact mechanism.

[SNIPE]

I Belive that LegoTechnicMastery made a two way rotation to one way rotation converter on youtube. it just uses one 4L differential.

 

[Gray Gear]

21 minutes ago, SNIPE said:

LegoTechnicMastery made a two way rotation to one way rotation converter on youtube.

That's what I thought about as well! That channel is a gold mine for cool mechanisms, too bad it seems like its dead for good 

[SNIPE]

On 3/18/2021 at 6:17 PM, Gray Gear said:

That's what I thought about as well! That channel is a gold mine for cool mechanisms, too bad it seems like its dead for good 

Yeah he said he's busy at university so hopefully he comes back after he's done with that.

You could also possibly make a two converter by using the mechanism in the time stamp.

you have the lever acting as an or gate by switching between either a gear train with an odd number of gears OR a gear train with an even number of gears but both go to the same output.

in the video below theres only one gear train not two but you can add one.

 

Edited March 19, 2021 by SNIPE

[That_LEGO_Guy]

nice and simple 

 

Edited March 19, 2021 by That_LEGO_Guy