Do I need a flywheel??

[7j43k]

I'm doing a repower of a switcher.  There's not a ton of room in there.  I WILL be putting in an ESU Loksound decoder plus their version of keep-alive.

It's my impression that the back-emf thingy and the keep-alive thingy may well make a flywheel superfluous.

To be honest, it's getting kind of tricky to fit all the stuff inside.  And it would be swell to have the extra room that leaving out the flywheel would provide.

So.

I'm asking for people's experience and advice.  IS the flywheel superfluous?????

 

Ed

[richg1998]

Scale, model of switcher?

I have the Bachmann 44 ton, 70 ton, Stewart VO-1000, all with sound. With clean track and powered frogs, no need for keep alive or flywheels.

Rich

[7j43k]

Rich,

It's an HO NW2.  The drive is a Hobbytown low speed switcher drive.  I have removed the motor, flywheel and flywheel mounts.  The motor is where the old flywheels were.  This allows an empty cab for an interior.  I can hang a flywheel off of the leftover motor shaft.  But it takes up about 3/8" that I could use for other things.

I believe the keep-alive is necessary because the Hobbytown only has four wheel pickup.  It surely won't hurt.

 

Ed

[BigDaddy]

I agree that a major issue in DCC conversion is a lack of room.

I did a search for flywheels on the forum and their necessity; it is quite controversial.   They are there to overcome the cogginess of the engine using DC.  Engines have improved over the years but manufacturers still have flywheels.   Is that proof they are necessary?  Some people think so.

Here are 3 threads, none are conclusive:

http://cs.trains.com/mrr/f/744/p/239937/2677292.aspx

http://cs.trains.com/mrr/f/88/t/247179.aspx

http://cs.trains.com/mrr/f/88/t/182542.aspx?page=1

[7j43k]

Henry,

 

Thanks for doing the search.  I didn't have confidence in pulling them up.  It's getting late, so I'll read them tomorrow.

 

Ed

[hon30critter]

Hi Ed:

I have eliminated the flywheel in one of my 'critter' installations and it worked out fine, however the motor is not the same as what you are using. This is my critter:

https://youtu.be/DcWNBd38mhA

It uses a Hollywood Foundary BullAnt drive with a Loksound Select Micro decoder and a Loksound Power pack keep alive. I removed the flywheel from the BullAnt drive but Geoff at Hollywood Foundry originally suggested that I should not remove the flywheel. Apparently his concerns were unfounded. I haven't spoken to him since to see if he has changed his mind.

http://www.hollywoodfoundry.com/

Here is another video of a Grandt Line box cab climbing (literally) through a turnout with a Loksound Power pack installed. This one still has the flywheel installed but I believe that it is the keep alive that keeps it going. The critter in the video had .088 wheels installed at the time which is why it 'falls' into the frog gaps. The wheels have since been replaced with .110 width treads so it now stays level when going through the frogs:

https://youtu.be/KbON9UdL3lI

Dave

[rrinker]

 My feeling is that BEMF and a keep alive capacitor can easily equal or best a flywheel. But - and there's a big but - the BEMF adjustment will I think be more critical to achieve smooth operation. That will depend on the decoder - TCAS uses a slef adjusting BEMF that 'learns' the motor characteristics, ESU has an auto-setup option that runs the loco back and forth to acocmplish the same thing. Other brands have varying access to 2, 3, or more CVs to fine tune the BEMF algorithm, most provide some initial guidance but fine tuning is definitely a trial and error job.

 The reason I say this is because no matter how fast the decoder processor is, there is always a  tiny bit of lag between the 'read' of BEMF and the adjustment of the motor drive to balance this out for the desired speed. A physical flywheel on the motor can smooth out some of the potential jerkiness of BEMF. Indentical everything (motor, gearing, wheels, decoder - anything in the drive train), but one with flywheel and one without, it is my theory that the loco witht he flywheel will be smoother in slowesst speeds and when slowly switching between speed steps with less work than the one without flywheel (unless you are using TCS or ESU decoders). I haven't verified this through empirical testing - mainly I don't have 2 identical locos where I am willing to yank the flywheels off one of them. Hust an intellectual exercise at this point.

                          --Randy

 

[7j43k]

Thanks, all, for your advice.

I am THIS close to dumping the flywheel idea.

I can make a flywheel and try the setup with and without.  But it does look like a waste of my time.  From what I can see, the flywheel will not add anything.  Except great irritation at trying to shoehorn everything in.

The key to it all is the keep-alive.  Without it, I would certainly put in the flywheel. But it appears to me that the keep-alive is, in fact, superior to a flywheel.

Now, I ain't gonna cut that motor shaft off just yet.  'Cause "ya never know".  I'll probably by trying out the drive for the first time in a couple of days (on DC, 'cause the decoder is backordered).  If I'm lucky, it'll run soopa, and calm my fears.

 

Thanks again,

 

Ed

[richg1998]

A flywheel has never done anything for me. Even if the flywheel tries to help the loco clear a bad spot, the microprocessor on the decoder will reset and stop the motor when the DCC is interrupted. The slightest interruption will do it. That is why the decoder needs constant DC operating voltage provided by Keep alive.

Rich

 

[Geared Steam]

If I could only have two, keep the decoder with keep alive, they run so well a flywheel won't be needed. I believe the flywheel has outlived it usefullness with the advent of motor control in decoders, back emf and keep alives. 

I have had my best performance with TCS keep alives as far as length of storage. 

 

[7j43k]

I've decided, since I'm pretty much a beginner on this DCC/sound stuff, to try to stay "in brand" in installlations.

Thus, my switcher will be all Loksound: decoder, speakers, and keep-alive.  I've only got room for their little one.  I believe I read that it's good for 1 1/2 seconds.  Which should be entirely adequate.  As much as it was interesting to see the new Walthers little bitty Plymouth power itself across a paper towel, I just don't think that's necessary.  I hope.

While I'm yakkin' about flywheels and keep-alives and such, I'll mention that my other project is re-doing a brass gas-electric.  It's baggage only, so there's an enormous amoun  t of room in it (as opposed to my switcher).  The drive is a vertical mount motor on one of the trucks.  I'm going to try to keep it.  Pickup is also four wheel, like the Hobbytown.  I'm using a Tsunami, 'cause they have what sounds like the proper sound for a gas electric.  It comes with a big ole keep-alive.  And, as I said, I've got the room.  Same hold for the speaker--a big ole one.

Only gripe with the Tsunami is that they don't have the right bell.  It should be an air-ring steam bell.  Which Soundtraxx obviously thought unnecessary on a diesel sound card.  NP guys will be sad.

Anyway, I'm working on the gas-electric concurrent with the switcher.  I've not yet started.  Well, actually, I just did.  An hour ago.  Wheeeeeee!!!

 

 

Ed

[doctorwayne]

7j43k

...The drive is a vertical mount motor on one of the trucks. I'm going to try to keep it. Pickup is also four wheel, like the Hobbytown....

I'm not at all familiar with that gas-electric, Ed, but would it be possible to add pick-ups to the non-powered truck?
I did so on my diesel-electric doodlebug...

My layout is DC, but even with only those three additional wheels picking-up power, this is a nice-running locomotive, and it's a great puller, too - much better than any prototype version, I'd guess.

I've also added all-wheel pick-up to several brass locomotives, and have run them, as a test, with the locomotive's wheels and those of the front tender truck all "on the ground", with pick-up from only the four wheels of the tender's rear truck.

Wayne

[7j43k]

Wayne,

 

All of what I'm doing is for DCC and sound operation.  Over the last couple of years, I've gone over to the DCC-side.  And keep-alive is just an additional reason to keep doing it.

I could add wipers for the other wheels of the gas-electric, but I am expecting the keep-alive will mean I don't have to.

Back in the olden days, I did add wipers to a Hobbytown drive, and it helped a lot for DC operation.

I do think the keep-alive will provide better service than extra wipers.  Of course, that's only opinion at the present time.  I have yet to do the work.

I ran the gas-electric on straight DC a couple of hours ago.  It runs nicely when it makes contact.  I rather think this one will be a sweetheart when I'm done.

 

Ed

 

[7j43k]

I just had the switcher drive out for its first run.  On DC.  I used my own very special version of keep-alive:  clip leads from the track to the motor.  No bad track contact there!

As I said, I substituted a Kato motor for the Hobbytown one.  I'm not seeing a lot of difference.  But then it's been awhile since I ran it with the old motor.  And the motor doesn't live in the cab, anymore.

A strange thing:  one axle of the secondary truck had a bind in one position.  I spent some time trying to puzzle it out and couldn't find the problem.  Finally, I switched the two axles and the problem disappeared.  I STILL want to know what's going on. 

Anyway, at the motor speeds I'm dealing with, I surely don't see that a flywheel would do much.  So I guess that leaves the sooper dooper back EMF to come to my aid.  I'll take what I can get.

 

Ed

 

PS:  I just put it up on blocks.  Pretty easy with my DC keep-alive system.  I ran it up to "high" speed.  A little noisy (less than the Pittman).  And the spur gears make some noise.  I think the diesel sound will mask it nicely.

Not having to worry about the clip leads running out, I was able to throttle it down.  It looks like my DC power pack can't get the voltage down low enough to get the Kato motor running real slow.  A neat problem to have, that will likely clear up with DCC.

Lookin' pretty good, I must say!

[jjdamnit]

Hello all,

Take a look at this previous thread...

Flywheels & DCC?

Hope this helps.

 

[7j43k]

In the above referenced thread, Chuck (tomikawaTT) says:

"With the old amp-hog motors and the capacitor technology of the day, the capacitor that could equal the energy storage of a flywheel would have been as big as the loco's boiler.  With present-day motors and capacitors, the situation has changed drastically."

 

I am reminded of a film (1955) and a book (1949) called "This Island Earth".  Early in the story, our hero has some sort of equipment meltdown and orders a new capacitor (still "condenser" in those days, I think) bank.  He's expecting a large crate delivered by truck.  Instead it's delivered by mail in an envelope.  Our hero and his buddies are dumbstruck at the miniscule size of the item.  Turns out it was manufactured by aliens.  They also send him their current catalog.  Etc.  Etc.  Etc.

 

Ed

 

 

[cmarchan]

The reason why the flywheel topic has had varied responces and opinions is mainly due to the simple reason - it depends.

Ever seen a Model Power E7 or E9? The very large (and not machined true) flywheel with some BEMF decoders will create erratic operation. Why? Because the inertia of the large flywheel "fights" the BEMF control. You can see it if you've especially upgraded the motor. the Flywheel/Motor combo's inertia tries to continually increase in speed and the BEMF circuit tries to reduce the current and over compensates.

Most factory installed flywheel/motor/BEMF decoder setups have flywheel sizes that complement the BEMF operation. The flywheels help to stabilize the motor speed, while allowing the decoder to control it properly.

So many of the thoughts and ideas expressed on this and other forums are true for THAT particular situation. After all, if it works, then it's good! I recommend you carefully evaluate the drive chain and decide if installing or replacing the flywheels makes the most sense.

 

Carl M.

Electronics Instructor and Technician 

Tarpon Springs, FL

[mbinsewi]

Maybe Ed will stop back in and tell us what he ended up doing.  We haven't seen him in a while.

I know he's still out there.

Mike.

[doctorwayne]

Unless the flywheel is in a full-bodied unit (F-, E-, FA- ,PA-, etc) it likely has too little mass to be of any real use.

cmarchan

Ever seen a Model Power E7 or E9? The very large (and not machined true) flywheel with some BEMF decoders will create erratic operation. Why? Because the inertia of the large flywheel "fights" the BEMF control. You can see it if you've especially upgraded the motor. the Flywheel/Motor combo's inertia tries to continually increase in speed and the BEMF circuit tries to reduce the current and over compensates.

Even I, a DC operator, I can understand Carl's point in the above comment.  However, with DC operation, those relatively massive flywheels would keep an E-unit rolling several inches after the power was cut.

This now heavily re-worked Proto 0-8-0 was on the verge of being re-sold due to it's anemic pulling power....

 

In frustration, I removed the circuit board for the headlight and the flywheel, then filled all available interior spacing with lead, dramatically improving the pulling power.  It's the early version, with no pick-ups on the tender, but runs reliably and its pulling power is more than doubled.

All of my flywheel-equipped diesels with narrow hoods eventually lost their flywheels, replaced with custom-cast lead weights.  All ran more reliably and all became better pullers, too.

For your DCC loco, the space would be better utilised by either the electrical stuff, or by the addition of some extra weight

Wayne

[jjdamnit]

OOPS! Duplicate response.