Very interesting coupler

[Black Forest]

I have been looking for a way to drive two rollers that will vary in the distance they are separated. I came across this type of coupler that I have never seen before. It is quite fascinating I think. This might be a fun little project to try to make in our home shops. You all have probably known about these forever but it is new to me.

https://www.youtube.com/watch?v=G2DU1s2ukHQ

[Black Forest]

Here is a lego version of the coupler.
https://www.youtube.com/watch?v=2M9cp_lJ4_I

[Noitoen]

Interesting but some couplings don't have a constant angular transmission speed. Don't know about this one.

[Rich Carlstedt]

Schmidt Coupling is described very well here- and appears to have perfect angular speed relationship ??

https://www.youtube.com/watch?v=zVt1tvD7rqk


Rich

[ed_h]

Interesting but some couplings don't have a constant angular transmission speed. Don't know about this one.

When a coupling doesn't preserve rotation speed, it's usually because the input and output shafts aren't parallel. That's the case with "U" joints and even pairs of U joints.

Ed

[A.K. Boomer]

BF if your mis-alignment is not that all severe just build an oldham coupling, much simpler and you can use self lubricating materials in the "sandwich disc"

They are fun and very easy to make...

[BCRider]

When a coupling that doesn't preserve rotation speed, it's usually because the input and output shafts aren't parallel. That's the case with "U" joints and even pairs of U joints.

Ed

And why constant velocity joints are used in front wheel drives where the rotational matching needs to be consistent across a wider angle.

The Lego version of the Schmidt joint makes it very easy to see how it works. Not anywhere near as durable but a lot more clear how the links and middle plate function.

[A.K. Boomer]

Cakewalk to build, and they do cover a fair deviation range and unlike the schmidt you can also be off a little parallel wise between the drive unit and the driven...

https://en.wikipedia.org/wiki/File:O...ated_small.gif

[Black Forest]

BF if your mis-alignment is not that all severe just build an oldham coupling, much simpler and you can use self lubricating materials in the "sandwich disc"

They are fun and very easy to make...

I have made a bunch of Oldham couplers. They work great where ever I used them in some misalignment situations.

[JoeLee]

Looks like a high maintenance coupler. There are a lot of pivot joints there.

I wonder how long it takes before excessive lash becomes a problem.

Also have to wonder what the RPM limitations are.

JL............

[ikdor]

If you design it around a bag of 608 bearings it should last a while. I think it's an interesting solution for low torque low speed high misalignment.

[Toolguy]

The Thompson Constant Velocity Joint looks interesting, can't really see how it works.
https://www.youtube.com/watch?v=UEvaOg7glKk

[Paul Alciatore]

That Schmidt coupling looks like it would work well. But there sure is a bunch of parts there. And all those links will need to have the same hole spacing. Not really a problem, just need a bit of care. I am not sure, but I suspect it is a constant velocity design. There is no audio on the video clip, but perhaps a translation of the text there would answer that question.

One drawback I do see is that it probably does not allow any angular misalignment or surely not much. Any such angular misalignment would only be possible by some slack in the pivot bearings of the links (aka bad fitting). And there seems to be a limit to the amount of offset possible, due to the fact that the links must rotate 360 degrees without colliding with each other. So for larger offsets you would need to use larger base circles. But even that may be extended if the links were made in a "Z" shape so one can pass over the pivot point of it's neighbors.

But it is interesting and surely within the capability of most home shops.

[A.K. Boomer]

The Thompson Constant Velocity Joint looks interesting, can't really see how it works.
https://www.youtube.com/watch?v=UEvaOg7glKk

Well at least he corrected himself shot himself in the foot at 51 seconds into it, and the CV axle assembly is a marvel and handles EXTREME torque so is ideal for cars and always will be - and the friction he was showing is due to two things - they have slight pre-load and also he was running a boot, and the ball bearings inside don't "slide" they are ball bearings fer cri-sakes and the ones under pressure roll...

some go a half million miles and if they do create slight friction while turning who gives a crap unless their complete idiots and drive around lock to lock in circles all day long,,,

fact is - is they are efficient as all hell - pea shooter uses them and iv had trips of over 75 U.S. mpg's --- they are original along with boots and have over 150 k on them...

so --- unique and has special uses ? I'll give it that but pa-lease do not compare it to the almighty CV joint --- that thompson looks weak an anemic in comparison...

[Black Forest]

Gentlemen, I just thought the mechanism was interesting. I certainly wasn't suggesting it was a replacement for anything or more efficient, better or anything else. CV joints are a wonder and won't be replaced by anything else in the near future I think. Now I do think that the joints in this picture are much superior to and Eco friendly and capable of transmitting huge torque and at many different angles.