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Getting rid of Flywheels

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Getting rid of Flywheels
Posted by sandusky on Monday, May 11, 2015 4:49 PM

I wonder if any of you have decided that flywheels don't offer enough benefit to mess with. I have been contemplating using mashima/kato motors (in one case) and the ubiquitous athearn gold motors or atlas/roco (from 70s GP-38/40 SD-24-35) motors (in the second case), and thinking control systems are advanced enough that the problems flywheels were employed to solve are no longer an issue, or can be better solved through other means. BTW, I plan to use either straight DC or dead rail, no DCC.

Thx

 

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Posted by NP2626 on Monday, May 11, 2015 5:06 PM

I don't think that I'm ready to do without, as I like the smoothness they give my so equipped locomotives.  

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Posted by RR_Mel on Monday, May 11, 2015 5:54 PM

All motors need inertia to help smooth out their mechanical operation, inertia is very important to make a motor run smoothly.  With the new rare earth magnets the can motor manufacturers use less mass in the rotor and that makes a flywheel even more important.
 
Mel
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Posted by snjroy on Monday, May 11, 2015 6:46 PM

 

Personnaly, I find my steam engines work better with a flywheel. Seems to me they are especially important in DC operation.

For DCC, Graffen thinks that flywheels mess up the BEMF:

http://cs.trains.com/mrr/f/744/p/239937/2676708.aspx#2676708

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Posted by jjdamnit on Monday, May 11, 2015 6:52 PM

Hello All,

I posed a similar question here:

Flywheels & DCC (http://cs.trains.com/mrr/f/744/t/239937.aspx)

Hope this heps.

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Posted by Soo Line fan on Monday, May 11, 2015 6:57 PM

sandusky
BTW, I plan to use either straight DC or dead rail, no DCC.

Per DC systems, everything I have ever read or experienced, a flywheel is a worthwhile addition. Cannot image any type of DC power pack which would change that.

The Roco, Mashima and Kato motors you mentioned, while 3 of the best, still need a flywheel to help with coasting and momentum.

Jim

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Posted by Mark R. on Monday, May 11, 2015 7:30 PM

I regularly remove one flywheel when doing sound installations in smaller engines like switchers. It gives the much needed room for a speaker and I've noticed no discernable difference in performance. 

I've yet to completely remove both of them even though I've heard from a couple sources that they are no longer needed with todays decoders .... not sure about that myself.

Now - if I were to add a keep alive module, I'd have no hesitation to remove them both. Kind of a catch 22 kind of thing though .... remove the second flywheel to make room for the keep alive module so you don't need the second flywheel !

Mark.

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Posted by mlehman on Monday, May 11, 2015 7:41 PM

With DCC, you can adjust various CVs and get performance that simulates what a flywheel does -- but it would perform still better with an actual flywheel.

With DC, I know there are some high quality systems out there, but don't believe I've heard it said they replace the benefits of a flywheel. Even if there are ones able to simulate smooth action like you can often get by fiddling with CVs in DCC, I would imagine they, too, would still perform better with a flywheel than without.

It's hard to replace the obvious benefits of spinning mass no matter how "smart" your power supply may be.

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Posted by crhostler61 on Monday, May 11, 2015 8:26 PM

I was doing a bit of research on this back some time ago...the idea of an electronic flywheel. The use of a bipolar arrangement of capacitors with diodes in parallel, looked like it had some possibilties. I didn't test out what I found, though. So I can't say how well it works or not.

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Posted by BRAKIE on Monday, May 11, 2015 9:03 PM

While I agree setting  CVs would do basically same job as the flywheel I would still not remove it..

I base that on my thoughts I would hate to see my locomotive stop at a speck of dirt on the track like in the old days when my Brass diesels would stall on dirty track faster then my flywheel equip Hobbytown RS3.

Larry

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Posted by bogp40 on Monday, May 11, 2015 9:15 PM

[quote user="BRAKIE"]

While I agree setting  CVs would do basically same job as the flywheel I would still not remove it..

I base that on my thoughts I would hate to see my locomotive stop at a speck of dirt on the track like in the old days when my Brass diesels would stall on dirty track faster then my flywheel equip Hobbytown RS3.

 

Exactly, and to add that the mass of flywheels help to dampen, any imbalance/ vibrations within a drivetrain. Even a "perfect" driveline can generate harmonic vibration that is quelled by the mass of the flywheel. This can be from brush vibration, gears or the universals themselves.

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Posted by tomikawaTT on Monday, May 11, 2015 9:24 PM

I run flywheel free on DC, and use dead rail to stop trains in 'fire and forget' mode.  An abrupt dead rail stop from track speed is a good way to find weak couplers, especially on the first few cars of a heavy train running downgrade.  If you have truck mounted couplers it's also a good way to pop a light car over the railhead and onto the ties.

On the other hand, I want the train to stop where I want it to stop, not coast half a meter down the track to foul a switch (or worse.)

Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL system)

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Posted by doctorwayne on Tuesday, May 12, 2015 12:24 AM

The only flywheels of any consequence with which I'm familiar are those in the old Model Power E-units, and they turned those locos into great performers.My Bachmann locos all seem to have flywheels and they run fine - hard to say if the flywheels contribute much to that, though, as their diameter and mass isn't all that great.

The couple of Atlas diesels I have left also have flywheels and while they're very smooth runners, I have a couple of Blue Box geeps which I re-motored, and at the same time removed their flywheels and they run better than the Atlas.  My homemade doodlebug is also a good performer, with a can motor and no flywheels, as were my twin-motored U-boats, with the flywheels removed in favour of more weight.
I had a Proto USRA 0-8-0 which was a very smooth runner but pretty-well useless as far as pulling.  I was going to get rid of it, but took it apart to see if there was any place to add some weight.  After removing some extraneous wiring and a circuit board, I also lopped off the flywheel - I think its diameter was even smaller than that of the motor's armature - then managed to add several ounces of lead in the newly found spaces.  It runs just as well as with the flywheel, but can now pull a decent-size train, too.
In most cases, I doubt that the flywheel causes any harm, but from my experiences, I doubt that removing them does either. 

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Posted by mlehman on Tuesday, May 12, 2015 1:05 AM

Mark R.
I regularly remove one flywheel when doing sound installations in smaller engines like switchers. It gives the much needed room for a speaker and I've noticed no discernable difference in performance. I've yet to completely remove both of them even though I've heard from a couple sources that they are no longer needed with todays decoders .... not sure about that myself.

Mark,

A couple of thoughts about what you've found. Flywheels usually are balanced and it's easier to get two small flywheels running smoothly than one big one. Plus the typical diesel chassis make it's easier to apply two smaller flywheels than a single big one.

A little flywheel does a lot. Adding more flywheels or more weight to it brings diminishing returns past a certain point as far as drivetrain dynamics, but as you noted there are ways to at least partially compensate for removing it. As far as providing weight on the driver's, more is generally good, so if the weight can be made up elsewhere then removal is not so bad in that regard, either.

Steam locos typically use a single flywheel, as big as possible. The typical steam driveline doesn't offer an easy option for two flywheels, but they seem to do OK. I suspect having a flywheel on steam is a bigger benefit than on Diesel because it helps keep the valve gear and rods turning smoothly, an issue most diesels don't have.

Mike Lehman

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Posted by OT Dean on Tuesday, May 12, 2015 1:20 AM

Flywheels have the advantage of letting a locomotive roll over a bad spot in the track, either dirt or the frogs of certain turnouts, an advantage a momentum throttle can't help, since you still need good track to loco electrical flow.

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Posted by Anonymous on Tuesday, May 12, 2015 3:21 AM

OT Dean

Flywheels have the advantage of letting a locomotive roll over a bad spot in the track, either dirt or the frogs of certain turnouts, an advantage a momentum throttle can't help, since you still need good track to loco electrical flow.

Deano

 

I say Amen to that!

The effect of flywheels is largely overrated when it comes to the ability of coasting in case of a power shut-off, but they do help to overcome spots of dead rail. On my layout, a 0-4-0 loco without a flywheel would not traverse through the Insulfrog turnouts I have installed, but the flywheel equipped locos have no problem at all, even at low speeds.

 

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Posted by Metro Red Line on Tuesday, May 12, 2015 3:55 AM

Don't forget that flywheels add a considerable amount of weight to your loco; removing them will make your loco lighter and also reduce its tractive effort.

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Posted by NP2626 on Tuesday, May 12, 2015 6:34 AM
In my old and feeble brain a flywheel is far more advantageous than simply the momentum they provide.  They smooth out the power delivered to the wheels and keep slow speeds much more realistic.  Once they became somewhat standard on diesels I think everyone saw the potential advantage of flywheels for every locomotive.  They also add weight to the loco, increasing the locos footing and pulling power.  Keep Alives, Power extenders and Power Pack type electronic energy storage devices are great additional devices to improve performance.  But, I hope that flywheels will solder on! 

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Posted by sandusky on Tuesday, May 12, 2015 7:49 AM

Yeah, those Model Power/Con Cor/Roco E units are what keep me thinking that flywheels are useful.

Mike

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Posted by riogrande5761 on Tuesday, May 12, 2015 8:21 AM

The traditional advantages that flywheels offer still exist, plus a few of the advantages some mentioned like extra weight.  Sure seems the common sense approach would be to keep flywheels.

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Posted by selector on Tuesday, May 12, 2015 12:56 PM

My BLI steamers all have brass flywheels.  They all come to abrupt and sudden stops if there is a short and power is cut to the rails, or if they encounter dirty or dead track.  There isn't the slightest hint of a coast, not even with a descent down 2.2% grades and a heavy consist with momentum wanting to keep going when the engine losses power.

My suspicion for some time has been that flywheels are a nice thought, and they might actually offer some intented efficacy in some toy locomotives, but not in many of them.  Not in my experience across various manufacturers and types of locomotive, whether diesel/electric or steam.

I would rather have the space they take, with mounts, axles, and bearings, assigned to a heavier monolithic frame.

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Posted by BMMECNYC on Tuesday, May 12, 2015 1:40 PM

selector
My BLI steamers all have brass flywheels. They all come to abrupt and sudden stops if there is a short and power is cut to the rails, or if they encounter dirty or dead track. There isn't the slightest hint of a coast, not even with a descent down 2.2% grades and a heavy consist with momentum wanting to keep going when the engine losses power.

This is because the gear ratio of the locomotive does not allow it.  You can't turn the wheels on most locomtives by hand, but you can turn the flywheel.  The purpose of the flywheel is to minimize repetative starting current of the motor, or at slow speeds minimize the amount of kick you have to give the locomotive.  Its not really big enough in most cases to have a large effect the locomotive rolling. 

Also, dont your BLI steamers have traction tires?

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Posted by dinwitty on Tuesday, May 12, 2015 9:00 PM
well, whatever does the job of smoothing out running and get over bad spots helps, I see how a flywheel might play around with BEMF, but its a matter of programming, BEMF is a reactive response back to the decoder to tell it whats happening. A flywheel will simulate train load and throttling must respond to inertias. Its all a matter how the decoder is programmed to use the BEMF data. I think the flywheel will help stabilize the motor system.
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Posted by doctorwayne on Tuesday, May 12, 2015 11:35 PM

While BEMF will be present in my DC-powered locomotives, my PWM throttle simply deals with it, with no need for programming.  And there's no need to simulate train load:  train length and weight, and heavy grades do that quite adequately.  I'm not saying that flywheels are a bad thing, only that, in my experience, their benefits often appear to be over-rated or un-needed.

Wayne

 

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Posted by Bernd on Wednesday, May 13, 2015 7:31 AM

Hi Guys,

Interesting read through this thread. I was waiting to see if anybody would hit on the reason flywheels are used. I see some came close, but no cigar.

The first models that came out had 3 pole motors in them. Remember the Rivarossi steamers and their 3 pole motor drive in the tender? At a slow speed they cogged so bad the tender almost jumped off the track. Then along came the 5 pole motors, much smoother running. Add a flywheel and hardly any cogging at low RPM. Next on the list was the 5 pole skewed pole motor. Even better performance with a flywheel. The ideal motor would either be a 7 or 9 pole skewed or the coreless motors with ball bearings. But that gets into cost.

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Posted by Daywhitemtns on Wednesday, May 13, 2015 12:47 PM

I run DCC (Lenz) and all my locos, with one exception, both steam and diesel have can motors and are flywheel equipped. The one exception is my brass United Sierra 2-6-6-2. I equpped that with a Lenz Gold decoder but left the original open frame motor in place. Operationally, the Sierra responds pretty much as do my other locos with acceleration and deceleration delays and coasting set with the appropriate CV adjustments. Apart from the Sierra's noisy drive due mostly to the imposition of two spur gears in the drive train, it's performance is generally indistinguishable from that of the rest of the fleet.

Just my experience and I take no position as to the function and desirability of flywheels, per se.

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Posted by selector on Wednesday, May 13, 2015 4:36 PM

BMMECNYC
 

 

This is because the gear ratio of the locomotive does not allow it...   

... Its not really big enough in most cases to have a large effect the locomotive rolling. 

I concur, and it is why I stated that they don't/can't really help much, if at all.  If the gearing works against the motor, it must also work against that tiny rotating mass.  If that mass were spun up to the same rpm, but with it all in the shape of a bicycle wheel of a diameter of about 6", I think we both agree the loco would probably coast more than it obviously does when the power is cut to it.  More angular momentum.

BMMECNYC

Also, dont your BLI steamers have traction tires?

 

They do, and if their tractive contribution works, it should keep the loco moving as the rotating flywheel acts in stead of the motor.  Same gearing between the rotating mass and the drivers, so same impulse if it were just a spinning motor.

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Posted by Texas Zepher on Wednesday, May 13, 2015 9:57 PM

sandusky
I wonder if any of you have decided that flywheels don't offer enough benefit to mess with.

I originally started removing flywheels from locomotives when I first went to command control and realized the flywheels were turning the motors into generators and pumping electricity backwards into the decoders.  Sort of like hooking the power to the motor output by mistake.   I can attribute 1 decoder failure to flywheel generated power.  Having said that, I also have to add that story is from way back in the early days before there were fabricated chips for the decoders and before they became sophisticated. All I had to do to repair the decoder was replace two of the power output transistors.

Nowadays, considering the state of electronics and how the locos are manufactured, I would think that removing the flywheels would be the thing that does not offer enough benefit to mess with.

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Posted by mlehman on Thursday, May 14, 2015 2:12 AM

Bernd
Hi Guys, Interesting read through this thread. I was waiting to see if anybody would hit on the reason flywheels are used. I see some came close, but no cigar. The first models that came out had 3 pole motors in them. Remember the Rivarossi steamers and their 3 pole motor drive in the tender?

Bernd,

Flywheels were around before Rivarossi started using them. Certainly, most models early on had rather questionable motors by modern standards, though, so maybe you're making a general reference to this being a reason why they proved useful?

More generally, several comments refer to an expectation that flywheels should allow a model to coast. Possibly, in scales larger than HO, that might be practical, but in HO there's really not enough mass to do that. Which is not to say there are not examples that are able to coast some, just that it's not really the goal when flywheels are applied. It's more about smoothing out power output with the power applied, rather than performance with the power dialed off.

Mike Lehman

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Posted by BRAKIE on Thursday, May 14, 2015 6:35 AM

mlehman
Flywheels were around before Rivarossi started using them. Certainly, most models early on had rather questionable motors by modern standards, though, so maybe you're making a general reference to this being a reason why they proved useful?

Mike,The Pittman DC60/70,80 and 90 was the best motor money could buy back in the day and many locomotives had their motors replaced with Pittman motors.

Some brass steamers  ran slow and smooth from the box and I would pit those against today's locomotives.

The best diesels of that era was the Hobbytown RS3s or Athearn GP7s shells on a Hobbytown drive.Of course there was a large flywheel in the cab of either locomotive-we accepted that because of the smoother and slower operation.One did not rush through the building of these drives if one wanted premium performance.

Some days I miss those simple days and other times I'm glad they're long gone.

Larry

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