Clutch gears comparsion

[Didumos69]

25 minutes ago, Doug72 said:

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

Too bad. Thanks for clarifying! Sorry for the noise.

[nerdsforprez]

3 hours ago, Didumos69 said:

 

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.

I think another issue that has not been discussed is the distance from the center of the gears that are causing the friction when they do touch a liftarm, connector, etc.  The way I understand it, when friction is further from the center, the force will have greater stopping power.  That is why disk brake circumference on cars, motorcycles, etc. is so important and immensely desirable on high-performance vehicles.  Check out the diameter, thus the distance from the center, of the disk brake on this high-performance bike

Versus the distance on just a regular road bike (much less speed, weight, etc. - you get the picture.  Much less stopping power needed)

 

On the gears being discussed, the distance from the center of the gear that may potentially rub against another surface is pretty significant.    Taken from @didumos69 own photo....

 

 

When there is rub against another surface, the new gear acts like a large disk brake on a high performance bike, car, etc.  More stopping power for the same force generated on say something that has a smaller

radius.  Like the older clutch gear, that has a smaller radius. 

[Didumos69]

2 hours ago, nerdsforprez said:

...

When there is rub against another surface, the new gear acts like a large disk brake on a high performance bike, car, etc.  More stopping power for the same force generated on say something that has a smaller radius.  Like the older clutch gear, that has a smaller radius. 

This makes perfect sense to me.

All together the new red clutch gear only has disadvantages compared to the old dbg clutch gear. It comes closer to filling one stud and it misses a side with small radius to avoid the large disc brake effect. The only advantage you could see is that it can be used with two driving rings - one on each side - but I haven't seen any practical application of that property yet.

As for my ultimately playable Porsche: With this in mind I will be replacing the 4 essential red clutch gears - the ones that are actually used to engage with a driving ring - by 4 dbg clutch gears anyway, even when it won't make any other mod unnecessary. Simply a matter of good practice to avoid unnecessary friction.

What remains is the quest for a good explanation of Victor Imaginator's observation that the old clutch parts outperform any combination with newer parts.

Edited October 5, 2016 by Didumos69

[brunojj1]

2 hours ago, nerdsforprez said:

 

When there is rub against another surface, the new gear acts like a large disk brake on a high performance bike, car, etc.  More stopping power for the same force generated on say something that has a smaller radius.  Like the older clutch gear, that has a smaller radius. 

That´s what I wanted to say, thanks for the illustration  !

I think the variations in the total amount of friction consists mainly of these factors: 1. contact diameter of both sides combined; 2. thickness tolerances; 3. softness of the material; 4. not to forget: the inner radius of the whole which causes some "wobbling" effect of which impact on the total friction would have to be figured out yet.

49 minutes ago, Didumos69 said:

This makes perfect sense to me.

All together the new red clutch gear only has disadvantages compared to the old dbg clutch gear. It comes closer to filling one stud and it misses a side with small radius to avoid the large disc brake effect. The only advantage you could see is that it can be used with two driving rings - one on each side - but I haven't seen any practical application of that property yet. ...............

What remains is the quest for a good explanation of Victor Imaginator's observation that the old clutch parts outperform any combination with newer parts.

We wonder what advantage the red clutch gears were supposed to deliver, besides the possibility to engage a driving ring from both sides, which is almost useless, at least I haven´t seen any practical application for that purpose.

Victor mentionned that the old driving rings caused much less friction in his gearbox (version 3)! Why on earth? That´s for me the big question...

EDIT: maybe someone wants to try the 6542a gears as well, to make this "scientific research" complete .

Edited October 5, 2016 by brunojj1

[Blakbird]

1 hour ago, brunojj1 said:

We wonder what advantage the red clutch gears were supposed to deliver, besides the possibility to engage a driving ring from both sides, which is almost useless,

For an advanced builder it is useless, but for a beginner it eliminates the possibility of installing the gear backwards and making the model non-functional.  This is a big deal for younger builders since fixing it later can be very difficult.

[N-4K0]

The old 1-sided clutch gears could at least teach people to be patient and look more closely when assembling them, I guess.

[Meatman]

I remember Paul mentioning something about the strips inside the gear being thicker and more durable, but also had more of a chance to line up with the ones in the driving ring when engaging. I know my Porsche does this sometimes.

[nerdsforprez]

4 hours ago, Meatman said:

I remember Paul mentioning something about the strips inside the gear being thicker and more durable, but also had more of a chance to line up with the ones in the driving ring when engaging. I know my Porsche does this sometimes.

Perhaps, but honestly, I think the strips in the older versions were sufficiently strong themselves. 

In several projects already posted earlier this year, but demonstrate this point fairly well I took a pneumatic engine, revved it to around 1500 RPMs and applied that power to an inactive axle with at least some weight on it (not alot) and never had any problems with the gears stripping or breaking.  This really surprised me.  Akin to reeving a car in neutral and then throwing into gear which puts alot of strain on the gears.  In the video below, the old-style clutch gears were used, not the old ones.  So yea, I think they are strong enough. 

 

In my air-turbine version of a similar project (won't repost..... pretty much the same idea as above only faster) I did the same but the input axle was moving at several thousand RPMs before it engaged.  

 

[Victor Imaginator]

New red clutch gear have one advantage over old ones - they can be used with pins.

More observations - old 2L driving ring have sharp triangle teeth, while new 3L - rectangular teeth with smooth end. Same with new and old gears. And old driving ring can be moved freely for about 1mm, while new driving ring can be moved further (about 2mm), but not freely. Fixing clip act as spring forcing returning to center of ridge. Also - endings of driving rings, where driving ring contact with inner surface of clutch gear - they are different too.

[brunojj1]

Today I rebuilt the 42056 Porsche and replaced the red clutch gears by the old DBG. I implemented only Boratko´s gear sequence fix, Blakbird´s fix with bushes and turned the changeover catches around at the shifting column. The rest of the model stays as it is in the building instructions. I really can say, that the noise from the gearbox is the same compared to the original version and the white clutch engages at the highest gear due to friction. No difference at all.

Edited October 7, 2016 by brunojj1

[Didumos69]

33 minutes ago, brunojj1 said:

Today I rebuilt the 42056 Porsche and replaced the red clutch gears by the old DBG. I implemented only Boratko´s gear sequence fix, Blakbird´s fix with bushes and turned the changeover catches around at the shifting column. The rest of the model stays as it is in the building instructions. I really can say, that the noise from the gearbox is the same compared to the original version and the white clutch engages at the highest gear due to friction. No difference at all.

That's a very useful investigation, thanks! I assume you replaced all 6 red clutch gears, including the two next to the H-frame. I was planning to do the same, but won't bother after your attempt. This brings me back to the conclusion that the real friction problem inside the Porsche gearbox has to do with the two clutch gears transferring torque on axles rotating at different speed.

P.S. I suppose you al know about the Unofficial errata for the Porsche.

[Victor Imaginator]

I think i need to rebuild porshce box 1 using old clutch parts, just for test and entertainment)

[doug72]

Both the 6542a & b grey clutch gears have only a small contact area with adjacent framing wheras the Red 18946  has a much larger contact area due to the inner and outer raised rings.

Also the Red clutch gear has mouding marks on one side (the shallow deperessions at 180. degs) which might
possible catch on adjacent beams causing stiction.

Best to place these Red clutch gears so that the side with the depressions engages the driving ring and not facing the adjacent beams etc.

Edited October 8, 2016 by Doug72