A mechanism for your scratchbuilt project

Re: A mechanism for your scratchbuilt project

Postby krokodil » Tue Mar 11, 2014 4:19 am

Hi Bernd

it is an interesting clutch. Do you have some characteristic about the transition portions (when starting and stopping). I used earlier also mechanical clutches for my TT models, but finally I removed most of them, when the new type motors became available. They do not have braking effect.
Greetings from Austria
E.T.
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Re: A mechanism for your scratchbuilt project

Postby krokodil » Tue Mar 11, 2014 11:58 am

Bernd wrote:
krokodil wrote:Hi Bernd

Do you have some characteristic about the transition portions (when starting and stopping).


Hi krokodil,

The clutch lets the motor run at hi RPM's. It lets the rest of the drive catch up slowly until it reaches the same RPM as the motor. In effect it is somewhat like a "momentum" starting since there is no direct connection to the rest of the drive train.

Take a look at this website on "The Model Torque" drive system. It was made by an Australian modeler. It was on the market until he passed away two years ago. http://www.intercitymodels.com/ATC.pdf

Bernd



Hi Bernd

this was always the critical point on any clutch. It requires high RPM from the motor side to "close". It was also in my mechanical clutches.
The problem is how can you control later your model in start up phase? If the motor speed rises slowly (smooth start), the clutch does not lock, so the model does not start (just the noise). If you increase the speed of the motor the clutch suddenly locks and the model usually starts with a jump.
I was looking and experimenting several years with clutches to make this transition period smoother and controllable, finally I gave up. I talked also to several mechanical designers. They were telling me the same story, the clutch is not made for smooth transition, it just couples and uncouples the mechanizm at given point (speed) and it is very hard to design something what I was looking for. (Actually also on the real trains, only on diesel-electric mechanical design they can control in every phase the "coupling" between the power source and the drive mechanizm. Also in your car the clutch closes as fast as possible, and there is only a very short transition phase coupled with heat generation and other mechanical losses).
That is why I am asking for your experiences. :smile:
Greetings from Austria
E.T.
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Tue Mar 11, 2014 2:14 pm

Automatic Torque-control Couplings for railroad models

What you are looking at is not a Clutch.

It is a Torque Converter.

krokodil wrote:
Bernd wrote:
krokodil wrote:Hi Bernd

Do you have some characteristic about the transition portions (when starting and stopping).


Hi krokodil,

The clutch lets the motor run at hi RPM's. It lets the rest of the drive catch up slowly until it reaches the same RPM as the motor. In effect it is somewhat like a "momentum" starting since there is no direct connection to the rest of the drive train.

Take a look at this website on "The Model Torque" drive system. It was made by an Australian modeler. It was on the market until he passed away two years ago. http://www.intercitymodels.com/ATC.pdf

Bernd



Hi Bernd

this was always the critical point on any clutch. It requires high RPM from the motor side to "close". It was also in my mechanical clutches.
The problem is how can you control later your model in start up phase? If the motor speed rises slowly (smooth start), the clutch does not lock, so the model does not start (just the noise). If you increase the speed of the motor the clutch suddenly locks and the model usually starts with a jump.
I was looking and experimenting several years with clutches to make this transition period smoother and controllable, finally I gave up. I talked also to several mechanical designers. They were telling me the same story, the clutch is not made for smooth transition, it just couples and uncouples the mechanizm at given point (speed) and it is very hard to design something what I was looking for. (Actually also on the real trains, only on diesel-electric mechanical design they can control in every phase the "coupling" between the power source and the drive mechanizm. Also in your car the clutch closes as fast as possible, and there is only a very short transition phase coupled with heat generation and other mechanical losses).
That is why I am asking for your experiences. :smile:
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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Re: A mechanism for your scratchbuilt project

Postby krokodil » Wed Mar 12, 2014 2:00 am

Bernd wrote:krokodil

I believe I understand your confusion of how this works. No mechanical contact is made with the flywheel and the part that holds the magnets. There is a very small air gap between those two parts. The transfer of motion is through the "eddy current" principle. Wikipedia has a good explanation of this phenomena. https://en.wikipedia.org/wiki/Eddy_current To see more of the eddy current principle go here: https://www.kjmagnetics.com/blog.asp?p=eddy-currents

If after reading all this material you still don't understand how this works, then I guess I can't help much more.

Bernd



I understand very well the principes of this ATC, but even the invertor says the motor should start at about 2000 rpm (40% of max) to generate the required magnetic fields/forces what are used four coupling (the well known princip used in all old fashion power consumption meter in your electric distribution box, where an aluminium wheel rotates in magnetic field and drives the mechanical kWh counter).
I do not want to discuss about the more than 100 years old princip, just wanted to hear your experiences with the ATC.
Greetings from Austria
E.T.
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Wed Mar 12, 2014 10:29 am

Hi Bernd,

I am very impressed with what you are doing with the Eddy Current Clutch Drive.

I understand that Helical cut gears mesh more quietly and move more smoothly than straight cut gears.

I like the idea of using the 90° helical gearing as opposed to the usual Worm and Spur set up.

What are your thoughts on helical Beveled Gears and/or crown gears.

Is it just a difference in Price/Availability?
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Wed Mar 12, 2014 10:32 am

Hi Bernd,

One more question/comment.

Isn't the flywheel redundant with the Eddy Current Clutch Drive?

If you needed to stop quickly, you'd have to put the loco in reverse and gun the engine! Especially with the 90° helical gearing which doesn't lock up like a Worm and Spur do....
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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Re: A mechanism for your scratchbuilt project

Postby ctxmf74 » Wed Mar 12, 2014 2:57 pm

Eddy drives, helical gears, etc. are things that apply to all scales but are not the key to a TT scale drive. If the goal is a easy to get reliable tt drive I'd focus on that first and research the more exotic stuff after tt trains are running in everyone's train rooms :>) As of now Saz/MTB seems to be the best shot at getting more tt drives so maybe we should flood them with orders and requests for more loco variety :>) ......DaveB
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Wed Mar 12, 2014 3:20 pm

Hi Bernd,

After studying your website and the related links this afternoon I've got a couple of suggestions.

The magnets should be on the motor side of the assembly.

The magnets can be mounted on a thin disk without much mass instead of on the thicker piece.

I was also thinking that you could use a single Ring magnet instead of several disk magnets.

You can eliminate the flywheel.

Dang! I gotta get into a workshop and try this for myself!
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Wed Mar 12, 2014 7:39 pm

I'm just so glad that you did all the hard work on figuring out how to do this.

I look forward to your progress.
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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Re: A mechanism for your scratchbuilt project

Postby TinGoat » Thu Mar 13, 2014 9:17 am

Hi Bernd,

One more question: Are all the magnets oriented with the same polarity or are they alternating N S N S N S?
Happy Railroadin'
The Tin Goat
Ron Wm. Hurlbut
Overlooking Fairbank on the Toronto Belt Line
Ontario, Dominion of Canada
====
The Ontario Narrow Gauge Show:
http://www.narrowgaugeontario.com
====
Humber Valley & Simcoe Railway Blog:
http://humbervalleysimcoerailway.blogspot.com/
====
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