[HELP] Meshing Gears with the New Z60 Turntable

[doug72]

The new Z60 turntable (TT) is slightly bigger in diamenter, more stable for rotating loads and has less friction than the old Z56 BUT is harder to mesh tecnic gears to it when axles are parallel.

Its OK for double bevel 12T gear as when used in the 42042 crawler crane with axles at 90 degs

BUT not when axles are parallel unless a 1/2 plate spacer is ised to mesh the gear correctly giving a 5:1 reduction.

A 20T double gear will mesh OK to give a 3:1 reduction.

A 24T gear also will not mesh.

The old Z56 turntable with a 8T gear gave a 7:1 reduction ideal for rorating heavy superstructure etc.

60 / 8 would give 7.5:1

Suggest Lego make a10T gear to mesh with this new turntable to give 6:1 ratio.

Edited September 14, 2015 by Doug72

[zux]

I don't have new turntable yet, sadly. However i would like to suggest a different approach - rather than matching in linear think of a gear intersecting in space plane, something that showed in here. Please let us know if you find a better place for 12T gear.

Edited September 13, 2015 by zux

[BachAddict]

I assume Sariel will eventually add it to his gear helper :)

[Zerobricks]

I think you could mesh a 60 tooth gear at a diagonal, like you can 28 small tunrtable with an 8 tooth one?

Edited September 14, 2015 by Zblj

[Jeroen Ottens]

You can add the number of teeth of the two gears and divide the result by 16 and then you get the required distance in studs.

So two 16 gears mesh at a distance of ( (16+16)/16 =) 2 studs (center-axle to center-axle), same for 24+8 and 12+20 gears.

So gears that mesh directly with the new turntable are:

4 (gear doesn't exist)

20 (5 stud distance)

36 (6 stud distance)

52 (gear doesn't exist)

Other gears might mesh, but then Pythagoras is needed to get a non-integer distance. The most heavily used example for that is the 20-16 mesh (ideal distance is 2.25 studs which is pretty close to sqrt(5), which can be made with a 1 stud offset in one direction and a 2 stud offset in the other).

[Josephiah]

By that logic, a 12-tooth might manage a reasonable mesh with the turntable at a spacing of 4 across and 2 up. (A spacing of 4.47 vs the ideal 4.5 - might be a bit tight - it'll depend on how much tolerance they leave between gear teeth.)

Alternatively, one might try an 8-tooth at a spacing of 4 across and 1 up, or 3 across and 3 up, though again, these might be a little tight.

Someone with a new turntable want to experiment and report back?

[doug72]

Now experimented with various gears and the new Z60 turntable.

See Photo.
Z60 Turntable-gears by Doug Ridgway, on Flickr


1:- 12T meshes OK on centre line (c/l) at 1.5 L spacing from 60T turntable gear ring- by using a thin technic plate, giving a 5:1 reduction.

2:- 20t gear meshes OK on centre line at 3L spacing giving a 3:1reduction

3:- 12T gear meshes by being offset by 3L from turn table c/l. giving a 5:1 reduction.

4:- 20T gear meshes OK by being offset by 4L from turn table c/l giving a 3:1 reduction

5:- 36T gear meshes on centre line by 4L giving a 1.66:1 reduction.

So far have not found a way to mesh 8T / 16T / 24T plain gears.

Edited September 24, 2016 by Doug72

[bananaworld]

Now experimented with various gears and the new Z60 turntable.

Very useful!

Please could you post a photo of the rear of this setup, just to help my brain visualise it?

[doug72]

Unfortunately not as the two Z60 turntables I have are now built into my TC8 luffing jib tower crane and the alternative horizontal tower crane jib I am working on now.

[doug72]

Very useful!

Please could you post a photo of the rear of this setup, just to help my brain visualise it?

I have made a mock up of the other side minus the Z60 turntable showing the rear view of the spacings required to get double bevel gears to mesh with the Z60 turntable.


The Red and Green pins would connect to the lower part of the turntable.

IMG_2604 by Doug Ridgway, on Flickr

Edited September 24, 2016 by Doug72

[Tamas Juhasz]

It's a bit off topic, but not far at all. So, I needed to drive the turntable, like in 42042, with 90 degree 12T bevel gear. The result is a bad drivetrain, it's noisy, and someteimes can "get stuck", but if you increase the torque at the driving axle, it will run again. The running is very lumpy, you really feel the polygon effect. I saw the teeth profile of the 60 teeth turntable, and it's a bit other than the 12t bevel gear's: http://img.bricklink.com/ItemImage/EXTN/2989.png

My question:

Is there any way to make much smoother, better running the new turntable with 90° 12T bevel gear drive? It seems to me, this turntable is nearly unusable at 90° drive, if not.

(of course, I placed everything very carefully, the frame is very rigid and correctly placed, and I used brand new gears and turntable)

[Alasdair Ryan]

If the gears are not meshing properly then perhaps it might be better to change how you are powering it,two ideas would be ether to have it driven by a chain or a driveshaft.

I would expect a 12 tooth gear at a 90 degree to power a turntable without trouble,they are designed to work together just like that.

[Tamas Juhasz]

It works, yes, but very badly, at least for my taste. You can feel the polygon effect, it stucks, just like when you drive two gears with different teeth profile, or when you drive the old, Samsonite gears (but even those are better in this case, imho).

Chain is no option. I want to use the new turntable with the 12t bevel gear, and it's annoying, because, as you said too, they are designed to work together. Should I post a photo or a render?

[arshiaIQ]

8 tooth gear can also mesh in a diagonal way (diagonal, not perpendicular)

[doug72]

A 12T double bevel geat is designed by Lego to mesh with the new Z60 turntable BUT can only mesh with the bevelled part of the turntable gear ring.

If you look at the gear ring you will see that one edge is 90 deges and the other bevelled at 45 degs. ie. the edge closest to the gray turntable part.

If you try to mesh with the 90 deg edge you will get jerky motion as you describe.

Works fine if braced correctly.

[Tamas Juhasz]

A 12T double bevel geat is designed by Lego to mesh with the new Z60 turntable BUT can only mesh with the bevelled part of the turntable gear ring.

If you look at the gear ring you will see that one edge is 90 deges and the other bevelled at 45 degs. ie. the edge closest to the gray turntable part.

If you try to mesh with the 90 deg edge you will get jerky motion as you describe.

Works fine if braced correctly.

Ok, again: as I wrote, I placed everything as it should be, correctly. The 45 degree turntable side with 12t bevel gears, perpendicular. I make technic MOCs nearly 10 years ago, I see, how it should be placed. And, with 100% correct placing, as you can see in the pictures, it's motion is jerky, with ploygon effect and noise (yellow is the input):

Everyone, who owns the new turntable: if you drive it, like in these pictures, runs smooth and without much noise? If so, maybe my turntable is wrong, but it seems fine, no deformation can be seen anywhere. One more thing can I imagine: it's only noisy and bad running for me. (maybe my expectations were too much about smooth running)

Edited August 11, 2016 by Mbmc

[deehtha]

Is the jerkiness coming from further up the driveline for the 12t bevel gear? Gearboxes and misaligned u-joints are good sources of jerkiness. Also try to reduce the number of gears in the driveline. Many pairs of gears lead to increased friction, which causes an elastic effect as the friction is overcome

[Alasdair Ryan]

How about another 14 tooth gear on the other side and drive that as well (both 14 teeth).

[Tamas Juhasz]

Is the jerkiness coming from further up the driveline for the 12t bevel gear? Gearboxes and misaligned u-joints are good sources of jerkiness. Also try to reduce the number of gears in the driveline. Many pairs of gears lead to increased friction, which causes an elastic effect as the friction is overcome

Everything is the same, as you see in the pictures. There is no driveline, only the yellow driving axle. And even in this setup it's jerky.

No, there is no dirt anywhere, every part is brand new. That's why I don't understand, why it doesn't runs smooth.

[Lipko]

I think you can't expect smooth running in this situation, and the reason is this:

EDIT: to make it more clear: Lego bevel gears have 45° cone pitch surfaces (the cones that roll on each other) while real bevel gears should have pitch surfaces like on the image above to ensure smooth rolling.

See Wiki.

To quote from the article some disadvantages of bevel gears that highlight this geometry restriction:

"One wheel of such gear is designed to work with its complementary wheel and no other.

Must be precisely mounted"

This is actually only a theory, since I don't really understand the tooth surface of the Lego Bevel gears. Maybe they use some different-than-usual teeth surface, but even in that case the principle on the image above should be the same.

Hope that makes sense, I'm sleepy and my English is failing.

Edited August 11, 2016 by Lipko

[Tamas Juhasz]

Yes, everything is clear, I agree, this could be the reason. I remember, I learned these too in University, that's why I mentioned the teeth profile above. These bevel gears are too universal. Now I saw closely the connection, and for proper working, beside you mentioned about angles, the turntable should have contain 1 - 2 more teeth, so smaller pitch. But, then, the spur gear mode would fail. TLG wanted to give too much with this part.

Edited August 11, 2016 by Mbmc

[Bricktrain]

How about another 14 tooth gear on the other side and drive that as well (both 14 teeth).

http://www.bricklink.com/v2/catalog/catalogitem.page?P=4143#T=C

[Alasdair Ryan]

http://www.bricklink...page?P=4143#T=C

Yes I meant to say 12 tooth,it not the first time I got them mixed up which you picked up on.

You must be bored or something.

[Bricktrain]

Yes I meant to say 12 tooth,it not the first time I got them mixed up which you picked up on.

You must be bored or something.

I got rid of all my 14 t gears years ago when I changed to all LBG instead of light grey. I guess many here wont even know what a 14t gear is and have never seen one.

I thought you would know the difference by now, with all those technic titles on your posts we expect you to be on the ball ;-)

[bonox]

what's two teeth between friends