Clutch gears comparsion

[Victor Imaginator]

I found one unexpected thing, just want to share. After using old style 2L red clutch, using new 3L DBG looks cooler. No more half-stud offsets, one click selection, not two... But i continued to use old clutch without any reason. Today i finally found why i'm doing this)

Typical task for clutch gears. Old style parts doing this task slightly better. You can try it yourself. Why? Looks like new red clutch gear have smaller inner radius. Or 3L white axle connector with ridges longer than 3L. I dont have proper measurement tools, so i just can compare clutch gears with my eye. And it's really looks like red one have smaller hole - i'm affraid of being paranoic)

[Didumos69]

What exactly do the old style parts do better? Less friction or something else?

[Victor Imaginator]

Less friction, yes.

[TheMindGarage]

I haven't noticed this - usually the friction on thes is negligible.

[allanp]

You would think that the friction of these gears is negligible but I can tell you it's not always. Take this 5 speed + R gearbox design in the image below for example:

I remember coming up with that years ago and have seen other builders, without ever seeing mine, come up with the exact same solution for making a strong 5 speed + R gearbox, I've seen it used in a lot of places but there is a problem with it. When being used in a motorized vehicle (with the input and output being used as shown in the picture) it works fine. However when using it in a non motorized vehicle (where input and output is swapped round), only in first gear and only in one direction it will completely lock up most of the time, and the reason for that is purely because of the friction of the NOT engaged clutch gears on their axles, to be more precise, the not engaged clutch gear used for 5th gear is the problem. It's to do with the how the other gears it's meshed with are trying to move that gear in a particular way when turned in one direction. It's hard to explain. But in any case, this happens with the old clutch gears. Maybe it would be even worse with the new clutch gears? 

Edited October 3, 2016 by allanp

[Didumos69]

59 minutes ago, allanp said:

You would think that the friction of these gears is negligible but I can tell you it's not always. Take this 5 speed + R gearbox design in the image below for example:

I remember coming up with that years ago and have seen other builders, without ever seeing mine, come up with the exact same solution for making a strong 5 speed + R gearbox, I've seen it used in a lot of places but there is a problem with it. When being used in a motorized vehicle (with the input and output being used as shown in the picture) it works fine. However when using it in a non motorized vehicle (where input and output is swapped round), only in first gear and only in one direction it will completely lock up most of the time, and the reason for that is purely because of the friction of the NOT engaged clutch gears on their axles, to be more precise, the not engaged clutch gear used for 5th gear is the problem. It's to do with the how the other gears it's meshed with are trying to move that gear in a particular way when turned in one direction. It's hard to explain. But in any case, this happens with the old clutch gears. Maybe it would be even worse with the new clutch gears? 

This might have to do with clutch gears transferring torque on axles rotating at different speed. A not-engaged clutch gear that needs to transfer torque from one gear to another (inbetween gears) actually works as a kind of lever and will push itself up or down against its axle. When at the same time the clutch gear's axle is rotating at different RPM, it's easy to understand that this will cause friction. This is also an issue in the 42056 (Porsche) gearbox.

 

Edited October 3, 2016 by Didumos69

[Victor Imaginator]

Just now, Didumos69 said:

This might have to do with clutch gears transferring torque on axles rotating at different speed. A clutch gear that transfers torque from one gear to another actually works as a kind of lever and will push itself up or down against its axle. Now taking into account the axle rotating at different RPM, it's easy to understand that this will cause friction. This is also an issue in the 42056 (Porsche) gearbox.

I just make unusual for LEGO 5+R gearbox. More like real one - with 2 shafts. And neccesary for LEGO version small idler shafts. Here's all clutch gears meshing only with their corresponding idler gears. And it works without noticeable friction in both directions. Much better than usual compact version.

[Didumos69]

47 minutes ago, Victor Imaginator said:

I just make unusual for LEGO 5+R gearbox. More like real one - with 2 shafts. And neccesary for LEGO version small idler shafts. Here's all clutch gears meshing only with their corresponding idler gears. And it works without noticeable friction in both directions. Much better than usual compact version.

Nice! This all starts to make sense. Btw, the problematic clutch gears (the ones to the left of the first image) in the 42056 gearbox could be replaced with normal gears relatively easily. All remaining clutch gears only mesh with their corresponding idler gear, just like your gearbox above, and the modified gearbox operates without noticeable friction, just like your gearbox above.

Edited October 3, 2016 by Didumos69

[Didumos69]

To get back to the original topic, I also compared the new and old clutch gears. My perception is that the holes of the gears are equal. I tried to wobble each of them with an axle through them and couldn't really notice a difference. What I did notice was that the newer red clutch gear practically takes one stud of space, whereas the old clutch gears clearly leave some space for play. Here's a comparison of (from left to right) the new clutch gear, the old clutch gear and the normal 16t gear when given exactly one stud space. The last one takes even less space than the old clutch gear:

Here's a video showing the induced friction when all 3 gears are given exactly one stud space. I think the difference is clear:

 

Edited October 4, 2016 by Didumos69

[Charbel]

I noticed that the newer style of driving ring had more friction a few weeks ago when I started building my new car.

Here are some pictures who show the differences between the the 3L connector and the old one.

 

You can clearly see that the white connector is a bit longer that the regular 3L connector. In the last picture you can easly slide the connector on the left under the liftarm without touching it, but you can't with the one on the right. The same happened with the new Porsche connector. 

[Victor Imaginator]

Wow, great observations. More than one mind is better for solving complex problems)

So, better to avoid using new clutch parts whenever it's possible. At least when getting from LEGO as much as possible is needed.

[Jonfensu]

Interesting. You can see a similar case with the old vs new 8t gear, where the old one is narrower. What if you use the 3L driving ring ith the old clutch gears? Both are compatible

Courtesy of Paul Boratko

http://youtu.be/kznEFrMxZf8

[rener]

4 hours ago, Didumos69 said:

To get back to the original topic, I also compared the new and old clutch gears. My perception is that the holes of the gears are equal. I tried to wobble each of them with an axle through them and couldn't really notice a difference. What I did notice was that the newer red clutch gear practically takes one stud of space, whereas the old clutch gears clearly leave some space for play. Here's a comparison of (from left to right) the new clutch gear, the old clutch gear and the normal 16t gear when given exactly one stud space. The last one takes even less space than the old clutch gear:

 

Here's a video showing the induced friction when all 3 gears are given exactly one stud space. I think the difference is clear:

 

Interesting find, which I just confirmed myself. But doesn't that possibly imply that your solution of the friction of the gear box from 42056 depends on replacing the red clutch gears with normal LBG ones, rather than removing torque?

[RohanBeckett]

I know it's called a "16 tooth gear with Clutch", in Bricklink... but every time you say Clutch Gear, I can only think of this one:

 

[Didumos69]

13 hours ago, Victor Imaginator said:

So, better to avoid using new clutch parts whenever it's possible.

 

13 hours ago, Jonfensu said:

What if you use the 3L driving ring ith the old clutch gears? Both are compatible

Before concluding that it's better not to use any of the new clutch parts, I think it's certainly worth trying to combine the old clutch gears with the 3L driving rings.

10 hours ago, rener said:

Interesting find, which I just confirmed myself. But doesn't that possibly imply that your solution of the friction of the gear box from 42056 depends on replacing the red clutch gears with normal LBG ones, rather than removing torque?

This might very well be part of the friction problem in the original 42056 gearbox, but I'm quite sure it's not the only cause. If it would be, the problem would be equally severe in all 4 gears when pushing along the car. However, my observations are that 2nd and 3rd gear suffered the most from friction, which are the gears that actually have the red clutch gears rotating at different RPM compared to their axles. Gear / axle RPM ratio for each gear: 1st gear: 1:1, 2nd gear: 1:3, 3rd gear: 9:25, 4th gear: 1:1. I also recall having tried to give the 5 16t gears in a row some extra play by agitating the bracing a little bit, but without success.

One thing I couldn't understand though is why do clutch gears induce so much friction on their axles when rotating at different RPM? One would expect an axle rotating in a pin hole to have the same problem. My explanation for this is that gears and axles are made from a different plastic blend than liftarms and beams. They are slightly softer, more silicon-like. Liftarms are harder and have a much more smooth surface. My conclusion is that axles rotating in hard plastic pin holes suffer from less friction than axles rotating in softer gears with clutch.

Victor Imaginator's findings with his lengthy 5+R gearbox and the issues with allanp's 5+R gearbox, together with my observations in the 42056 gearbox all point in the same direction: When you mesh a clutch gear with more than one gear and it needs to transfer torque while its axle rotates at different RPM, the clutch gear will induce severe friction to its axle. Btw, I had similar problems with Paul Boratko's AWD transmission, which is based on the same idea as allanp's 5+R gearbox.

All together I think it would be a good practice to have clutch gears mesh with one gear only so they only transfer torque when they are engaged. I would even go as far as to no longer consider building a car when it doesn't oblige to this principle. Brings me back to Paul Boratko's 4-speed gearbox shown in the video mentioned by Jonfensu. I think that gearbox is as good as it can get with Lego.

5 hours ago, RohanBeckett said:

I know it's called a "16 tooth gear with Clutch", in Bricklink... but every time you say Clutch Gear, I can only think of this one:

Well, luckily the images in this thread show which gears we are talking about, altough your image kind of ruins that . But I understand the confusion. I think 'gear with pin hole' would be better than 'gear with clutch'.

Edited October 5, 2016 by Didumos69

[brunojj1]

It´s quite obvious that the old DBG clutch gears cause less friction than the new red ones. The "turntable" surface on the rings or their contact raduis, are very different, adding on BOTH sides (don´t know how to say it better in English)! I guess the difference in thickness is important too, regarding the tighter spacings between the surrounding parts. This makes me want to rebuild my 42056 in the next week and replace the gears, just for finger exercise, leaving out all of the other fan based improvements.

[Didumos69]

30 minutes ago, brunojj1 said:

This makes me want to rebuild my 42056 in the next week and replace the gears, just for finger exercise, leaving out all of the other fan based improvements.

I was thinking of the same thing. I may sound convinced in my previous post - and I am - but would be even more convinced when I could verify that replacing the red clutch gears with dbg ones doesn't solve the friction problem by itself. To find out I will undo the eliminate friction in the gearbox mod and replace the red clutch gears with dbg ones.

Edited October 5, 2016 by Didumos69

[doug72]

The critical distance is the overall length when all the correct componants are assembled.

i.e new type 5L:- Red clutch gears / grey driving ring / white sleeve

old type 4L:- Grey clutch gears / red driving ring / 2l sleeve

If mix and match parts from the two types then overall length changes along with friction.

Red clutch gears can only be used with the new DBG driving ring but not the old Red driving ring.

Grey can be used with both driving rings.

re 24T White clutch gear:
These can be modified to be used with driving rings by removing the centre part and pressing in a grey 16T clutch gear.

I am using this MOD to build a gearbox for my next MOC which requires a fast and slow output plus a seperate forward/ reverse output.

[rener]

1 hour ago, Didumos69 said:

 

Before concluding that it's better not to use any of the new clutch parts, I think it's certainly worth trying to combine the old clutch gears with the 3L driving rings.

This might very well be part of the friction problem in the original 42056 gearbox, but I'm quite sure it's not the only cause. If it would be, the problem would be equally severe in all 4 gears when pushing along the car. However, my observations are that 2nd and 3rd gear suffered the most from friction, which are the gears that actually have the red clutch gears rotating at different RPM compared to their axles. Gear / axle RPM ratio for each gear: 1st gear: 1:1, 2nd gear: 1:3, 3rd gear: 9:25, 4th gear: 1:1. I also recall having tried to give the 5 gears some extra play by agitating the bracing a little bit, but without success.

One thing I couldn't understand though is why do clutch gears induce so much friction on their axles when rotating at different RPM? One would expect an axle rotating in a pin hole to have the same problem. My explanation for this is that gears and axles are made from a different plastic blend than liftarms and beams. They are slightly softer, more silicon-like. Liftarms are harder and have a much more smooth surface. My conclusion is that axles rotating in hard plastic pin holes suffer from less friction than axles rotating in softer gears with clutch.

 

I don't have the Porsche (yet...), but when I do I will certainly look at your mods. But if the problem lies within the softness of the material, a simple solution would seem to be to make the red clutch gears from harder plastic. I find it hard to feel the difference, but the old DBG clutch gears seem somewhat harder and smoother. Have you tried them too in your 42056 gearbox? I'm curious if that makes a difference...

[Didumos69]

30 minutes ago, rener said:

I don't have the Porsche (yet...), but when I do I will certainly look at your mods. But if the problem lies within the softness of the material, a simple solution would seem to be to make the red clutch gears from harder plastic. I find it hard to feel the difference, but the old DBG clutch gears seem somewhat harder and smoother. Have you tried them too in your 42056 gearbox? I'm curious if that makes a difference...

No I didn't, but given this discussion I think it would be worth a try. Therefore I plan to undo the eliminate friction in the gearbox mod and replace the two red clutch gears just in front of the gearbox with dbg ones and see what happens... I'm also thinking about undoing the change-over catches extension mod and see whether replacing all other red clutch gears with dbg ones would solve the red gear getting clamped issue.

Edited October 5, 2016 by Didumos69

[Victor Imaginator]

I've done some tests with simple 6-speed gearbox. Tested it with hands at each gear in both directions. All 3 variants generate a lot of resistance when lower (higher) gear selected. Both variants with new 3L driving ring works smooth enough, but in comparsion with old parts - there's not only resistance caused by gear ratios, but also some uneven friction. At least i feel like that. And feels like 3rd variant works without any friction at all, after trying 1st and 2nd. And i didn't notice significant difference between 1st and 2nd variants.

Also - 3rd variant works ok just being assembled anyhow. 1st and 2nd variant can completely stall if gears pushed too close to each other.

 

[Didumos69]

17 hours ago, Charbel said:

I noticed that the newer style of driving ring had more friction a few weeks ago when I started building my new car.

Here are some pictures who show the differences between the the 3L connector and the old one.

You can clearly see that the white connector is a bit longer that the regular 3L connector. In the last picture you can easly slide the connector on the left under the liftarm without touching it, but you can't with the one on the right. The same happened with the new Porsche connector. 

 

2 hours ago, Victor Imaginator said:

I've done some tests with simple 6-speed gearbox. Tested it with hands at each gear in both directions. All 3 variants generate a lot of resistance when lower (higher) gear selected. Both variants with new 3L driving ring works smooth enough, but in comparsion with old parts - there's not only resistance caused by gear ratios, but also some uneven friction. At least i feel like that. And feels like 3rd variant works without any friction at all, after trying 1st and 2nd. And i didn't notice significant difference between 1st and 2nd variants.

Also - 3rd variant works ok just being assembled anyhow. 1st and 2nd variant can completely stall if gears pushed too close to each other.

Your case - stating that the new parts, including the 3L driving rings and 3L connectors, are causing more friction all together than the old parts - is getting stronger and stronger. I still would like to know why. Could the length of the 3L connector as described by Charbel be the actual problem?

Maybe the 3L connectors with ridges can each be replaced by the old 2L ones each combined with 2 half bushes. And maybe in the Porsche the new connectors without ridges can each be replaced by a 2L smooth connector combined with two half bushes.

Edited October 5, 2016 by Didumos69

[Didumos69]

2 hours ago, Didumos69 said:

Maybe the 3L connectors with ridges can each be replaced by the old 2L ones each combined with 2 half bushes. And maybe in the Porsche the new connectors without ridges can each be replaced by a 2L smooth connector combined with two half bushes.

I mean something like this:

[doug72]

33 minutes ago, Didumos69 said:

I mean something like this:

32 minutes ago, Didumos69 said:

I mean something like this:

 

Neither will work as the 1/2 bushes cannot enter either type of driving ring.

The top one using a plain 2L sleeve will not stop at positive positions - I tried that when building a c/o unit for a GBC.

 

[doug72]

4 hours ago, Doug72 said:

I am using this 24T clutch MOD to build a gearbox for my next MOC which requires a fast and slow output plus a seperate forward/ reverse output.

This is the prototype gearbox for my next MOC:-

M motor input with rotation one way only.
Yellow output either 1:1 (fast) or 3:1 (slow) ratio.
Red output either forward or reverse to a worm drive unit.
Still needs more work to be make it more compact but works OK.

IMG_4119 by Doug Ridgway, on Flickr

Edited October 5, 2016 by Doug72