Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Are flywheels worth it? Locked

11198 views
59 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    June, 2009
  • From: QLD, Australia
  • 1,043 posts
Are flywheels worth it?
Posted by tbdanny on Monday, November 15, 2010 4:02 AM

Hi all,

I'm in the process of re-motoring a West Side C-25.  I would like to fit a flywheel into this model, but doing so may interfere with the motor wires without serious re-engineering (by which I mean cutting another hole in the loco shell).  It's a NWSL 12mm flywheel with a 1.5mm shaft, and I want to know if it would be worth making additional modifications in order to fit this in?  The decoder I'm using is a TSU-750, if that's relevant.

Thanks in advance,

tbdanny

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

  • Member since
    June, 2010
  • 1,012 posts
Posted by Forty Niner on Monday, November 15, 2010 4:57 AM

I seriously doubt that a flywheel is going to improve much on a Sagami can motor, not only that 99.9% of these flywheels aren't balanced anyhow and that just causes undue stress on the motor bearings. Using DCC you'll be operating that motor under "pulse" power anyhow so for my money it would be a waste of time and effort. Also it really won't be big enough to have much of an effect..............save yourself the trouble and fine tune the mechanism, you're already 99% of the way there now with that NWSL motor.

Mark

  • Member since
    January, 2003
  • From: Dover, DE
  • 1,308 posts
Posted by hminky on Monday, November 15, 2010 5:58 AM

Having run the same mechanism with and without flywheels, DCC and good electrical pickup do more for performance. The only thing flywheels do is add more weight.

Heresy, I know, but it is true. Manufacturers add them because they are an urban myth. I am sure there will be a gazillion posts to follow with no evidence how great they are.

Harold

  • Member since
    September, 2003
  • From: Omaha, NE
  • 9,511 posts
Posted by dehusman on Monday, November 15, 2010 6:18 AM

If you are using a BEMF decoder the decoder will fight the flywheel.

Dave H. Painted side goes up. My website : wnbranch.com

  • Member since
    April, 2003
  • 302,134 posts
Posted by Anonymous on Monday, November 15, 2010 7:14 AM

Flywheels can´t achieve, what a good motor and a gearbox can do for the performance of a loco.

Btw. Stonercreek RR is offereing a re-motoring kit for your loco. You´ll find it here

  • Member since
    January, 2007
  • 226 posts
Posted by Lee 1234 on Monday, November 15, 2010 8:51 AM

A flywheel is mechanical momentum for the drive when it cannot pick up power from the track.  I'd try it without the flywheel.   If you have bad power pick up you will find out in a hurry.

L

  • Member since
    June, 2004
  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
  • 25,640 posts
Posted by jeffrey-wimberly on Monday, November 15, 2010 9:12 AM

dehusman

If you are using a BEMF decoder the decoder will fight the flywheel.

Really? Funny I haven't noticed that with my two SDP40F's. One has an Athearn drive and the other has a Proto 2000 drive. They both have Digitrax decoders with BEMF enabled. Same goes with my two Atlas GP40's and my two Athearn GP38-2's. All the locos listed above have dual flywheels.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


  • Member since
    December, 2004
  • From: Pa.
  • 3,153 posts
Posted by DigitalGriffin on Monday, November 15, 2010 9:18 AM

Lee 1234

A flywheel is mechanical momentum for the drive when it cannot pick up power from the track.  I'd try it without the flywheel.   If you have bad power pick up you will find out in a hurry.

+1.  A flywheel adds something called Initial mass to the shaft.  It will resist slowing down or speeding up.  The advantage of which is if you have inconsistant electrical pickup, or a bad mechanism the flywheel will help compensate for that as it's rotational inertia carries it foward.  (More so for the former than the later)

The other benefit is it adds weight to your loco.  And that rarely hurts things.  :-)

I didn't know the stall current on canon motors was < .75 amps.  That's pretty good.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    December, 2004
  • From: Pa.
  • 3,153 posts
Posted by DigitalGriffin on Monday, November 15, 2010 9:39 AM

jeffrey-wimberly

 dehusman:

If you are using a BEMF decoder the decoder will fight the flywheel.

 

Really? Funny I haven't noticed that with my two SDP40F's. One has an Athearn drive and the other has a Proto 2000 drive. They both have Digitrax decoders with BEMF enabled. Same goes with my two Atlas GP40's and my two Athearn GP38-2's. All the locos listed above have dual flywheels.

Both true and false.  The BEMF can compensate for the additional load put on by the flywheels.  There's an adjustable "kick" amount parameter on most BEMF motors.  With flywheels it's a lil higher. 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    October, 2001
  • From: OH
  • 16,837 posts
Posted by BRAKIE on Monday, November 15, 2010 9:54 AM

Got flywheels?

Yup..I won't have a locomotive that isn't flywheel equipped.

Larry

SSRy

Conductor

“Shut one’s eyes tight or open one’s arms wide, either way, one’s a fool.” Flemeth-the witch of the Wilds.
  • Member since
    January, 2003
  • From: Dover, DE
  • 1,308 posts
Posted by hminky on Monday, November 15, 2010 10:18 AM

BRAKIE

Got flywheels?

Yup..I won't have a locomotive that isn't flywheel equipped.

That is why manufacturers keep putting them on locomotives. It is an urban myth. I have removed flywheels from locomotives out of necessity:

I had to remove the flywheel in an Athearn/Roundhouse 4-4-0 to put on an IHC 4-4-0 boiler. The locomotive ran the same without the flywheel. It ran even better when the suspect MRC dcc sound unit died and was replaced with a Soundtraxx Tsunami.

I have many locomotives without flywheels and they run as well as those with them.

All flywheels do is add weight.

Harold

  • Member since
    August, 2006
  • From: Franconia, NH
  • 2,791 posts
Posted by dstarr on Monday, November 15, 2010 10:40 AM

It's a judgment call.  Flywheels store momentum, enough to allow the locomotive to coast over a small dead spot in the trackwork.  If your trackwork is first class, and you clean your track, and you clean your locomotive wheels periodically, then a locomotive without flywheels works just fine.  A number of my locomotives lack flywheels and they run quite satisfactorily.   My trackwork and track maintainance standards are better than some, but not beyond the reach of any model railroad. 

   On the other hand, I like flywheels, and for a kit bashed locomotive I would certainly attempt to equip it with a flywheel.  You say motor wires are the difficulty?  Not sure if I understand, there is always room in the top of a diesel hood for wires.  Have you considered adding wire guides made from brass tubing and glued to the inside of the shell to keep the wires up out of the works?

 

  • Member since
    October, 2001
  • From: OH
  • 16,837 posts
Posted by BRAKIE on Monday, November 15, 2010 10:48 AM

hminky

 BRAKIE:

Got flywheels?

Yup..I won't have a locomotive that isn't flywheel equipped.

 

That is why manufacturers keep putting them on locomotives. It is an urban myth. I have removed flywheels from locomotives out of necessity:

http://www.55n3.org/locomotives/roundhouse/merge/image/initial_test.jpg

I had to remove the flywheel in an Athearn/Roundhouse 4-4-0 to put on an IHC 4-4-0 boiler. The locomotive ran the same without the flywheel. It ran even better when the suspect MRC dcc sound unit died and was replaced with a Soundtraxx Tsunami.

I have many locomotives without flywheels and they run as well as those with them.

All flywheels do is add weight.

Harold

Harold,I recall how crappy none flywheel locomotives ran before flywheels and how smooth they ran after flywheels that's why I won't have a locomotive without a flywheel and that's no myth.

Clean track,dirty track,dead spot,rubber frog it doesn't really matter since the flywheel smooths everything out with momentum.

Larry

SSRy

Conductor

“Shut one’s eyes tight or open one’s arms wide, either way, one’s a fool.” Flemeth-the witch of the Wilds.
  • Member since
    January, 2003
  • From: Dover, DE
  • 1,308 posts
Posted by hminky on Monday, November 15, 2010 11:07 AM

Locomotives just got better. It had nothing to do with flywheels. It is a myth.

Unless he adds more pickup his C-25 will run poorly. You need pickup on as many wheels as possible:

Visit:

http://www.pacificcoastairlinerr.com/1879/bachmann_4-4-0/wipers/

If adding extra pickups to a crap toyish HO Bachmann 1870's 4-4-0 makes it run like a dream, it is all about electrical pickup in the engine not flywheels.

Harold

  • Member since
    October, 2001
  • From: OH
  • 16,837 posts
Posted by BRAKIE on Monday, November 15, 2010 11:42 AM

Harold,Sorry but,I will stand pat on flywheels and won't own a locomotive that isn't flywheel equipped.

From my experiences it was flywheels that smooth out locomotive's performance and that's no myth.

Larry

SSRy

Conductor

“Shut one’s eyes tight or open one’s arms wide, either way, one’s a fool.” Flemeth-the witch of the Wilds.
  • Member since
    June, 2005
  • 4,014 posts
Posted by Darth Santa Fe on Monday, November 15, 2010 12:17 PM

If the mechanism of any locomotive runs perfectly smooth and free, and has good electrical pickup, flywheels aren't necessary. When needed, I think they're more beneficial to DC users than DCC users. And they have to be large enough to have any effect, because a too small flywheel won't provide any noticable momentum.

I personally like using flywheels in my stuff.Big Smile

_________________________________________________________________

  • Member since
    February, 2001
  • From: Poconos, PA
  • 3,948 posts
Posted by TomDiehl on Monday, November 15, 2010 1:39 PM

hminky

Having run the same mechanism with and without flywheels, DCC and good electrical pickup do more for performance. The only thing flywheels do is add more weight.

Heresy, I know, but it is true. Manufacturers add them because they are an urban myth. I am sure there will be a gazillion posts to follow with no evidence how great they are.

Harold

Urban myth? Hardly. A feature whose time has past, maybe. Perfect electrical pickup may remove the need for flywheels, but nothing is perfect and remains that way, according to Murphy.

Smile, it makes people wonder what you're up to. Chief of Sanitation; Clowntown
  • Member since
    February, 2005
  • From: Vancouver Island, BC
  • 21,712 posts
Posted by selector on Monday, November 15, 2010 2:04 PM

I posted in a similar discussion about a year ago now that I didn't really subscribe to the idea of flywheels, at least not in HO models.  I don't think they offer enough compensation for their engineering and installation costs. 

If they were twice as large as they usually are and spun up to 2000 rpm, sure, that would be useful to get engines over dirty bits or gaps and dead frogs in the #18 range.  But I feel they are too small, spun too slowly, and really rob the engine of what would be better weight if it its volume were filled with the equivalent volume in either tungsten or lead.

I believe that I have quite a few locos with flywheels, maybe all of them (?), and none are DC...they all have either a Tsunami, QSI variants, and LokSound.  I don't believe the tiny flywheels amount to a pinch of coon poo in the mix, and that is why my decoders either don't pay them any mind or they are as innocuous as I claim they are.

I must admit that I am not a mechanical engineer, and have undertaken no method to determine all this for myself.  All I can state is when my DCC/Sound engines encounter an electrical fault, they don't coast for four or five slowing inches as a properly weighted and spun-up flywheel would make it do.  Instead, they stop dead, quick.  So, I guess I'm saying I'm not seeing their value.

Crandell

  • Member since
    May, 2008
  • 4,612 posts
Posted by Hamltnblue on Monday, November 15, 2010 3:43 PM

The benefits of running with a flywheel are definitely not a myth. Also i'm sure if it was, virtually every designer wouldn't be adding them. On modern HO looc's the flywheel or combination of 2 is often heavier than the actual motor.  This prevents jerky movement when both accelerating and decelerating.  A quick google of electric motors and flywheel will give some insight .

Springfield PA

  • Member since
    February, 2002
  • From: Reading, PA
  • 26,104 posts
Posted by rrinker on Monday, November 15, 2010 3:53 PM

 Unless you have a motor with infinite poles, a flywheel DOES help. The better the motor, the less the help - turn a 3 pole motor by hand and you can clearly fel the cogging action, a 5 pole motor, not as much, and a 7 pole motor, barely. But it IS there. This is the same principle as the flywheel in your car motor, without the flywheel to smooth out the impulses from each piston it would be a very rough ride indeed.

 But high mass flywheels, or the whole idea of adding extra flywheels, is fairly pointless with DCC, or even a DC system that is more advanced than a rheostat and a direction switch. Feedback motor control works better with less inertia, and coasting action and slow acceleration can be simulated with electronic effects over a far greater range than you coudl ever do with a flywheel.

                                 --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    June, 2004
  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
  • 25,640 posts
Posted by jeffrey-wimberly on Monday, November 15, 2010 4:01 PM

I have a Proto 2000 PA1 with flywheels that can easily COAST three feet. Now that's quite some benefit.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


  • Member since
    January, 2004
  • From: Canada, eh?
  • 9,305 posts
Posted by doctorwayne on Monday, November 15, 2010 4:19 PM

I don't see the point of flywheels in our models - their relatively tiny mass is a waste of space, even as weight. 

I bought an early Proto 0-8-0 switcher and even though it ran very smoothly with no current pick-up on the tender, I was very disappointed in its pulling power.  I was going to get rid of it, as it could handle only three cars on the in-town grade where it was expected to work.  In hope of finding some available room within the boiler in which to add some extra weight, I dis-assembled it, finding a puny flywheel and an over-sized circuit board for the headlight.  After removing both and replacing them with cast lead blocks, the loco's pulling abilities more than doubled.  I decided to keep the loco, and modified it to more closely resemble a favourite prototype.  I was able to add even more weight, too, making it an even more useful loco. 

I have no problems, even without tender pick-up, of stalling or stuttering, and I don't clean track or wheels.  I'm also running DC power.

A flywheel in a carbody-style loco may be large enough to offer some benefits - the old Model Power E-units were a good example of this, especially once the noise was removed from the drive train.  However, for folks using DCC, the useful flywheel is in the electronics - that little spinning nickel is just for show. Smile, Wink & GrinLaugh

 

Wayne

  • Member since
    January, 2003
  • From: Brisbane Australia
  • 524 posts
Posted by Alantrains on Monday, November 15, 2010 5:05 PM

If there was a model train Adam and Jamie, we could ask them to bust or verify this "Myth".

I suspect that flywheels improved older motor performance considerably. Once we got 5 & 7pole skew wound armatures, I suspect the flywheel makes only minor improvement. I prefer flywheel equipped locos as my track isn't perfect.

Hey Jeff W,

3 feet is a good coast, I remember some old Hornby engines that had a single thread worm gear and a large diameter motor that would coast a foot or two from full speed.

Remember that if your controller puts any sort of short across the track in the off position, it will act as a dynamic brake. ie the motor becomes a generator any you loose some of the bebefits of flywheels.

Cheers

Alan J

Alan Jones in Sunny Queensland (Oz)

 

  • Member since
    June, 2004
  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
  • 25,640 posts
Posted by jeffrey-wimberly on Monday, November 15, 2010 5:09 PM

Alantrains

Hey Jeff W,

3 feet is a good coast, I remember some old Hornby engines that had a single thread worm gear and a large diameter motor that would coast a foot or two from full speed.

If I run it up to full speed and cut the power it will coast almost nine feet. And it's very, very heavy.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


  • Member since
    January, 2003
  • From: Brisbane Australia
  • 524 posts
Posted by Alantrains on Monday, November 15, 2010 5:35 PM

That/s impressive!

Alan Jones in Sunny Queensland (Oz)

 

  • Member since
    January, 2003
  • From: Brisbane Australia
  • 524 posts
Posted by Alantrains on Monday, November 15, 2010 5:37 PM

You might need working brakes on it!

Alan Jones in Sunny Queensland (Oz)

 

  • Member since
    October, 2004
  • From: Colorful Colorado
  • 8,639 posts
Posted by Texas Zepher on Monday, November 15, 2010 7:42 PM

jeffrey-wimberly

 

 dehusman:

 

If you are using a BEMF decoder the decoder will fight the flywheel.

 

Really? Funny I haven't noticed that with my two SDP40F's.

Yes, an electrical reality, but  I don't know how you would "notice" it.  IT would be eddies of electrical current getting shoved into the back end of the decoder.  Remember the motor becomes a generator when "coasting" under fly wheel power.  With DC it is a non-issue because the current has no where to go.

In the early days of command control our club was having a very high failure rate of decoders.   We traced it to the power getting generated by flywheel generators.  Removed the fly wheels and the decoders started lasting a lot longer (longer as in instead of a few months some are still working over a decade later).

For DC a good set of flywheels on a locomotive is a nearly essential thing.
For command control locomotive a really good "life saver" capacitor is the essential thing (like the Lenz gold decoders) fly wheels not necessary and technically not desirable.

I have bunches of DCC locomotives with flywheels, but that is only because I hate rebuilding the motor to gear linkage and just I don't have the time to do it.   For a DC only locomotive I can't imagine running without flywheels.   I don't see any myths or mysteries to solve.

  • Member since
    January, 2004
  • From: Canada, eh?
  • 9,305 posts
Posted by doctorwayne on Monday, November 15, 2010 8:02 PM

Texas Zepher

 

.....For DC a good set of flywheels on a locomotive is a nearly essential thing.
For command control locomotive a really good "life saver" capacitor is the essential thing (like the Lenz gold decoders) fly wheels not necessary and technically not desirable.

I have bunches of DCC locomotives with flywheels, but that is only because I hate rebuilding the motor to gear linkage and just I don't have the time to do it.   For a DC only locomotive I can't imagine running without flywheels.   I don't see any myths or mysteries to solve.

 

Care to elaborate on the DC aspect of this?   I run DC and, while I've had lots of flywheel equipped locos, the only one that seemed to benefit was the Model Power loco with the large diameter flywheels. Even then, the only time it was noticeable was when the power was cut.  Hood-type locos or steamers don't have room for much of a flywheel, at least diameter-wise, and I remove them in favour of adding additional weight.  Any decent DC throttle can simulate flywheel-like performance and I've never seen any need to coast over dirt or dead spots on the track - that's a pick-up issue that's readily addressed if it crops up.

 

Wayne

  • Member since
    June, 2010
  • 1,012 posts
Posted by Forty Niner on Monday, November 15, 2010 9:03 PM

I think the point is being missed here with all of the "posturing" about whether flywheels are useful or not. The original poster explained he has an HOn3 C-25 loco he's working with. Now this thing isn't much larger than an N Scale boiler so the flywheel will have to be very small to fit in the loco, we aren't talking about a Hobbytown E unit here. So how much of an affect would it really have, about as much as the size of the flywheel or almost none.

Secondly, and everyone seems to want to choose to ignore the obvious here, these things aren't balanced, again, very hard on motor bushings.

Third, flywheels were introduced back before todays high torque "can" motors such as the Sagami's, they worked great on the cheap motors they were designed for, open frame 3 or 5 pole motors. They worked well removing the "cogging" action of these motors, although again they still are not balanced.

With todays super smooth new motors and good gearboxes flywheels become a mute point except to make a crappy running engine "appear" to run smoothly. It still come down to having a good motor, a good gear box, and the entire mechanism being tuned for smooth operation.

All he really needs in that C-25 now is as much "weight" in that thing as he can get into it possibly including the tender to insure good power and good contact. He has the biggest part of the equation soved with the NWSL motor.

Again, if you have a crappy running engine a flywheel will help considerably, but that's more of a cover up than a solution. Sort of like the old joke of putting lipstick on a pig, but you still have a pig, that doesn't change.

Mark

  • Member since
    February, 2005
  • From: Vancouver Island, BC
  • 21,712 posts
Posted by selector on Monday, November 15, 2010 9:30 PM

I don't understand your use of the word 'posturing', Mark.

In any event, you and others who talk about the problems with balancing and such reinforces my conviction that they don't add much to a locomotive's smoothness. If, as you say, they are badly balanced (and I wouldn't know), then spinning them up to a truly contributory rate would tear the drive-trains apart. That doesn't seem to be a big problem in the industry, certainly not in any locomotive that I run, some now onto 6 years. If they don't tear themselves apart, it means they turn relatively slowly. If they turn relatively slowly, they provide minimal assistance to a stalling engine. As Doc Wayne has agreed, the volume is better utilized with added weight. That added weight would contribute as much momentum to a stalling locomotive as a considerably lighter weight rotating four hundred times a minute.

Crandell

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!