Flywheel

Hi All.  I am considering a Bachmann class 47 modern image Diesel ,but when I read the word "Flywheel" I could only think of my old Hornby , so I googled Flywheel and read "LOL" comments of alleged events from the past, which got me worried about my decision. Why is the new flywheel any different from my old Hornby? that it will allow the Loco to stop where one expects it to stop without an overrun?    All the best. Kevin

Hi Kevin.

I can't remember if you have gone DCC or not.

If you have, the flywheel is redundant.

If you are still DC, the flywheel helps, but not so much.   

Kevin, some reading info re flywheels
DC Train Motors
Flywheel or no flywheel | Model Railway Forum
Getting rid of Flywheels - Model Railroader Magazine - Model Railroading, Model Trains, Reviews, Track Plans, and Forums
Flywheels & DCC? - Model Railroader Magazine - Model Railroading, Model Trains, Reviews, Track Plans, and Forums
http://forum.atlasrr.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=55432


Predominantly used to smooth slow down  ( inertia) and also carry the loco over dead spots in the track power.

Hi Max.  Thank you. Yes I am DCC. And the new Bachmann Locos have got a flywheel Kevin

Hi Ron  Thank you. Recently there was " LOL" when a "Stay Alive Decoder was fitted".There were howls of laughter at the thought of overrunning stations . Signals, and everything else?
All the best. Kevin

Hi Kevin,

Electric motors for model trains are usually designed to work optimally at 6000-12000 rpm. DCC control simply applies short periods of full power to achieve what is very slow atypical running, something they were never intended to do. Modern pulse-width DC controllers work on the same principle. At speed 1 with my NCE system many locomotives will literally crawl along. Difficult to see with a can motor, but those armatures are spinning at just a few rpm. Now depending on the design cogging torque comes into play at low speeds, where the armatures are jerking very slightly on their way around the magnetic field. This is minimized by having 5 or even 7 armatures that are angled, not straight. Keeping the momentum going with some relatively large flywheels helps smooths out the judder. I think that's why it often requires speed 3-4 to get the motor in motion by overcoming the cogging torque and getting some flywheel inertia established. The speed setting can then be lowered to 1. My experience with modern 5-armature can motors is that flywheels are certainly useful at low speeds. Older open frame motors with 3-5 straight armatures and a lot of cogging really benefit from having flywheels. Where they are a waste of time is with straight cut gear sets that lock immediately power is shut-off.

Throw in some inertia control and it means that you really have to drive the locomotive.

Small motors, especially those in N-scale locomotives, really benefit from them. I always put one (or 2, space permitting) flywheels (as large a diameter as possible) in when upgrading a motor in an HO diesel or steam locomotive. The other thing that we tend to ignore is the intrinsic resistance/inertia in diesel locomotive gear trains (located in the bogies). Flywheel inertia keeps things moving along. Big O-scale motors have lots of mass, the impact of a flywheel with these will be a lot less than with HO/OO or N-scale motors.

Coreless motors are another story. They do not suffer from cogging. However, they also have relatively little mass for their size compared with a regular motor, and for this reason also benefit from a flywheel or 2, especially in the smaller scales.

Nigel

Hi Nigel. Thank you. I use NCE Powercab, as you undoubtedly know, but the talk of  steps 1, 2, 3, etc are confusing to say the least,  In the small loco classes I have one Bachmann 08 Diesel shunter in DCC , two ex GWR London Transport L94 is DCC , L97 is DC,  The D Jones Models 02 if DCC , The Hornby M7 is awaiting a Decoder 
(If I am able to find one small enough to fit in? ( being resplendent in LSWR livery, and awaiting the decision on whether or not I should invest in "Roxey  Mouldings Carriage kits. to work in train with it) The Hornby Schools Class Repton (Tender Drive) is DC and awaiting its own stretch of track. The remaining stock of course I are  "Southern Region  EMU's, being both Hornby and Bachmann notably only some of which have Decoders fitted, the remainder are awaiting .. But not forgetting the Power Cab speed steps 1,2, and 3, etc as I have only been able to run the two DCC shunters on my Planks , and their speed, I assume would be a lower ratio prototypical speed speed for 0-6-0's then to get any movement I have to press the " inc fast " button once, then that displays4 and the second push of the button shows 8. Then does that 8 represent two speed steps? Or could that be 8 speed steps? Surely not the latter?Please advise.  Kevin

[user=1801]Passed Driver[/user] wrote: 

I have to press the " inc fast " button once, then that displays4 and the second push of the button shows 8. Then does that 8 represent two speed steps? Or could that be 8 speed steps? Surely not the latter?Please advise.  Kevin

"inc fast"  pace at 4 = 4 speed steps  …. second push  showing 8 = 8 speed steps

Hi Ron.   Thank you for your explanation , it seems that I may have answered my own question on speed steps. bearing in mind the " low gear ratio of shunting Loco's". But now I should really  "pull my finger  out" and get on with the search for a permanent home for a decent sized layout.    All the best. Kevin

Hi Kevin,

Speed 1 (step 1) on the display. Use the knob. My older Powercab goes up or down in increments of 10 using the increase/decrease buttons. Make sure you have 128 steps selected (28/128 button at the bottom). Yes, 8 on the display means 8 speed steps are activated. That would have your locomotives moving along smartly.

With step 1-2 you should be able to start at one end of the plank, make a cup of tea, and come back and find it still going. 4 mph in 12 inches to the foot is around 4.7 feet/min in 1:76. Some of my Co-Co diesels can manage a scale 1-2 mph with flywheels on step 1 or 2. Without them you can see the effect of the motor cogging (and needing step 3/4). That flywheel mass smooths things out once the inertia is overcome.

I try and remotor older models with an Athearn "DCC Ready" motor and flywheels. Athearn claim this motor is optimized for DCC, so it's probably designed for pulse-width control/minimal clogging. Closed can, so I have no idea what's inside.  Swapping the old dinosaur open frame (no flywheel) for an Athearn on the Tenshodo SD-9 (Co-Co) transformed it. Even better when I added a flywheel.  Unfortunately with most small steam locomotives we're stuck with whatever the manufacturer put in. Bachmann making the worm a flywheel helped things a bit.

Nigel

It's analog control, but I've read that 100-ohm rheostat throttles with a wiper or knob that can turn the better part of 360 degrees do wonders for fine control and slow-speed running of geared motors

Hi Nigel.   Thank you , my NCE Powercab does have the wheel for speed, but also the buttons. Press either button once ( I will press this only once?) and the speed will will go up or down, from 4 to 8 and soon, or 12 to 8 and so on, where the wheel will increase 4,5,6,7, etc. As you say about tea( but I take tea drinking , more seriously ) at the slow speed it is like watching paint dry, but okay for shunting, but no "milelage payment".With the "Running In" ,it would take a lot of up and down trips, over a four foot plank to complete the task, and that is 
"Watching paint dry".Meanwhile I have found another project , fitting a switchable battery powered circuit for a flickering tail lamp, to a brakevan.    All the best. Kevin