Electric Flywheel

[AndyID]

This is just about an idea had and experimented with a bit. Be warned; it was not a great success, but it was interesting. Maybe someone can make something of it. It's probably not a new idea either.

 

As we all know, poor contact between the rails and a locomotive motor "can lead to disappointment" (or much worse). It's well known that one of the ways minimize this problem is with a flywheel on the motor. Flywheels help, but they tend to help more at high speed when you are less likely to need them. Also, it can be difficult to find room for them, and if they are not well balanced, they can accelerate the wear on motor bearings.

 

A much better solution might be an electronic energy storage device that can maintain power to the motor during temporary "rail-power" interruptions. A capacitor might be just the thing, but unfortunately, there don't seem to be any that are suitable. It would almost certainly be an electrolytic capacitor, but that means it only works in one polarity, and DC motors have to operate in either polarity. The same issue applies to batteries.

 

What we need is an electronic storage device that can store a lot of energy, does not take up a lot of space and is happy to operate on either polarity.

 

Sounds a lot like a motor with a flywheel. When the power is cut to the motor, the flywheel drives the motor and the motor acts as a dynamo. So, the idea is to put a free-running motor with a flywheel in parallel with the motor that is geared to the wheels.

 

I tried it, and it does work, but not as well as I had hoped. I didn't really spend a lot of time on it, so there may be hope. I think one problem might be the voltage drop across the carbon brushes which prevents the storage motor from supplying the same voltage that "charged" it.

 

 

 

[AndyID]

If you know of any ideal (100% efficient) energy storage devices, let me know. We'll make a fortune. (101% would be even better.)

[chaz]

A simple solution is available to DCC users. A strong justification for switching?

[uax6]

Sounds very much like the Raworth Booster system that was used in the Bulleid electrics....

 

Small electric flywheels aren't new either, there was one in the RM in the 60's or 70's I think!

 

The cap way is probably the one to explore, but with some sort of electronics to get around the reversability flaw. Mind you, it might be easier to fit more pick-ups!

 

andy G

[Stubby47]

Would two capacitors, protected by diodes ( one for each direction) work ?

[pete_mcfarlane]

If you know of any ideal (100% efficient) energy storage devices, let me know.

Especially the bit where you bypass the first and second laws of thermodynamics. 

 

There was an article on electronic flywheels in the very last issue of the Model Railway Constructor back in 1987. IIRC it was quite crude and had a DPDT switch on the outside of the loco to change direction. 

[34theletterbetweenB&D]

 The 'free motor' idea was in use by one of my HO operating continental cousins in the 1960s, I have a feeling that at least one of the HO brands offered a retrofit kit. The free motor driving a flywheel is ideally a more efficient motor than the train power motor, so it is spinning at a fair lick even when the loco goes slowly. (A further advantage was a slower and smoother start from a basic resistance controller as the free motor shunts the train motor.) As for getting the loco across a dead spot, there was still a lurch, but an improvement over the 'hand of god'.

[Gordon H]

I seem to recall that Dagworth did a lot of work on this a while ago. Might be worth a search for the original topic.

[brigo]

Easy to make a bipolar capacitor, one that works for both directions. Take 2 equal value electrolytic capacitors and connect the (-) terminals together. Then wire it up like a normal capacitor but using only the (+) terminals. Note though that the resulting capacitor has only half the capacitance of the individual capacitors, ie if the capacitors are 10,000uF each then the bipolar one will be only 5,000uF.

 

Brian G.

[raymw]

You need a miniature version of an on-line ups. You don't want to switch from track power to capacitor/battery when power fails, the motor needs to be always powered from the battery which is being 'continuously' charged from the track. Is it possible - maybe? Is it worth it - possibly?

[AndyID]

Thanks for all the information everyone. Sounds like a path well trodden.

 

Brian, I was just about to post the electrolytics in series story, but you beat me to the punch!

 

I'll need to do some calculations (which means I might eventually get around to doing some calculations ) but I suspect the energy density of a motor/flywheel is a good bit greater than anything you can get with capacitors. The exception might be super-capacitors, but they only operate at low voltages, which creates another set of challenges.

[polybear]

Don't forget that if you have too much storage then:

(a) You'll need to be good at guessing when to knock the power off, or:

(b) You'll drive the Loco right thru' the buffers....

 

- and every loco will no doubt have different characteristics....

 

Have fun!

 

polybear

[Dagworth]

I seem to recall that Dagworth did a lot of work on this a while ago. Might be worth a search for the original topic.

I did, including a couple of videos to prove that it did work. I still have the end  result class 37, I ought to get it out again and shoot some more video of it.

 

This was the first topic where the idea grew http://www.rmweb.co.uk/community/index.php?/topic/41763-electronic-boosters

And this is the topic that it came to fruition http://www.rmweb.co.uk/community/index.php?/topic/63055-capacitor-assistance/

 

Andi

[Andy Reichert]

I tried it in the 60's. Didn't work then either. Except as a sort of strange diesel sound unit.

 

Plus much of the track power got diverted to the 2nd motor, and so the driving motor power dropped considerably.

 

Andy

[AndyID]

much of the track power got diverted to the 2nd motor, and so the driving motor power dropped considerably.

That's to be expected if you were using a rheostat controller, which you probably were at that time. It does not (or should not) happen with a regulated voltage controller

[melmerby]

Tri-ang got there first (sort of!)

 

http://www.tri-ang.co.uk/OONew/chassisDieselSpecial.htm

 

Keith

[Andy Reichert]

That's to be expected if you were using a rheostat controller, which you probably were at that time. It does not (or should not) happen with a regulated voltage controller

 

I never had a rheostat. I started my first proper layout with a H & M Variable T'former and then I built a RM article transistor one as a second control later. (Mullard OC 71's and OC 28 IIRC).

 

The trouble was that the MR article at the time had either some sort of circuit component  in series with the main motor, or the two motors themselves in series, so the noise started before the loco moved. I wasn't sufficiently electrically educated at the time, nor were silicon diodes inexpensively available then. (see era of RM transistor controller).

 

Andy.

[pauliebanger]

No. Diodes are fine getting the juice in, but how does it get out again? Not via the diode, 'cause that blocks the current

 

The only real (viable) solution is a DCC chip with additional capacitor(s), which has all the electronics to get said capacitor(s) charged and releasing the stored energy when required. Oh, and don't expect this feature to function when running slow on DC, i.e. when you need it most 

 

I agree that a DCC decoder with a supercap would be the most straightforward as well as tried and tested formula.

 

I do not agree with the remark that it will not function when running slow on DC, what would be the point if it did not?

 

However, to be fair, the stay alive solution on Lenz and ESU decoders does specifically state that they are not operational on analogue.

 

No such restriction applies to ZIMO decoders, though, including sound decoders.

 

I've just run one of Hornby's 0-4-0 shunters which I have fitted witha ZIMO MX645 and 6 x 2.7v 1F supercaps in series. Runs fine on DC including playing most of the sounds at all speeds. Turn off the power and the loco continues running and sound playing for several seconds. (The duration can be limited with value in CV153).

 

Turn the power on again before the capacitors fully discharge, and it runs again under control with sound playing.

 

The decoder will charge the capacitors on DC or DCC. 

 

Running decoder equipped locos on analogue has a number of other merits besides 'electronic flywheel' capacitors.

 

Kind regards,

 

Paul

[pauliebanger]

A simple solution is available to DCC users. A strong justification for switching?

 

That's a thought. But no need for analogue users not to benefit from many of the great things DCC offers, including sound.

 

With the right brand of decoder, (ZIMO for instance), the capacitor based 'electronic flywheel' works on DC or DCC. Not all brands do this; Lenz and ESU specifically rule it out.

 

With a good quality decoder, say ZIMO for the sake of argument, it is possible to run on analogue using the same degree of inertia and momentum as on DCC, and to have the same BEMF motor regulation which makes smooth slow speed running a doddle.

 

Add in SuperCaps and you can throw yor track cleaner away, or switch off your Relco buzzer, and crawl along over all your InsulFrog point work.

 

There's a lot more to DCC  and decoders than running more that one loco on the same bit of track.

 

And, a lot of difference between what features individual decoders can provide for your money.

 

Kind regards,

 

Paul

[AndyID]

Thanks Paul.

 

I'll take a look at the ZIMO. I have no desire to use DCC control, but it it works on DC it is very interesting.

[chaz]

Thanks Paul.

 

I'll take a look at the ZIMO. I have no desire to use DCC control, but it it works on DC it is very interesting.

 

One of the joys of our hobby is that we have complete freedom to do whatever we like, limited only by space, money and our own abilities. However I find it puzzling that you might contemplate putting DCC decoders into models but not control them digitally.

 

Chaz

[pauliebanger]

One of the joys of our hobby is that we have complete freedom to do whatever we like, limited only by space, money and our own abilities. However I find it puzzling that you might contemplate putting DCC decoders into models but not control them digitally.

 

Chaz

 

Chaz,

 

That's because of your perspective and experience. Lol.

 

(And mine too - I haven't had a DC layout since the late 70s when ZERO One turned me to the dark side).

 

However, the ability to provide reliable, sure-footed slow speed movements is a need shared between analogue and digital users alike. If technology exists, the benefit of which can be shared, it is a perfectly legitimate, indeed very sound, decision to adopt those parts of it which fit with our own needs.

 

If one does not move in DCC circles, or otherwise keep up to speed with digital developments, these sorts of benefits can easily go unnoticed.

 

To some people, fitting a decoder and not using its features to the full is a strange idea, but from the other perspective, fitting a proven electronic solution will prove a cost effective alternative and more practical method than the alternatives open to analogue users.

 

Kind regards,

 

Paul

[chaz]

Chaz,

 

That's because of your perspective and experience. Lol.

 

(And mine too - I haven't had a DC layout since the late 70s when ZERO One turned me to the dark side).

 

However, the ability to provide reliable, sure-footed slow speed movements is a need shared between analogue and digital users alike. If technology exists, the benefit of which can be shared, it is a perfectly legitimate, indeed very sound, decision to adopt those parts of it which fit with our own needs.

 

If one does not move in DCC circles, or otherwise keep up to speed with digital developments, these sorts of benefits can easily go unnoticed.

 

To some people, fitting a decoder and not using its features to the full is a strange idea, but from the other perspective, fitting a proven electronic solution will prove a cost effective alternative and more practical method than the alternatives open to analogue users.

 

Kind regards,

 

Paul

 

What you say is fair comment and I must admit I do tend to think in terms of sound decoders. A "quiet" decoder would be very much cheaper and (some/most?) would offer the facility to add a KA.

You say "If technology exists, the benefit of which can be shared, it is a perfectly legitimate, indeed very sound, decision to adopt those parts of it which fit with our own needs." and I can only agree with that. Of course if Andy does start fitting decoders to get the KA facility the possibility is always there to replace his Analogue controllers with a DCC system in the future - he will have a head start.

 

Chaz

[AndyID]

Thank you Chaz and Paul.

It's a fair question but as there are many factors involved, my answer would be very long! If I ever get things going the way I have it mind, I'll write about it in a blog.

Best,
Andy

[Andy Reichert]

This was thread that solved the problem of DC keep alive about a year ago. IIRC, it had a relay and a battery and reference cap that locked onto to the driving voltage if the power cut out. I'll check my history.

 

Andy