Hi, thinking of upgrading one of my trains to DCC, should I keep the flywheels in place?
A great many of the better modern HO non-brass engines from several manufacturers have flywheels, and many of their models are offered with DCC or DCC/Sound. So, I don't think you should get worked up over the flywheels unless you could use some of the space they take up. Of course, that lightens the engines, which is rarely a good thing.
I think flywheels are a good thing DCC or not. I can only offer advice from a Bachmann perpective. I have 2 GP's with DCC. One has FW and the other doesn't. The one with FW runs much smoother.
brassnutHi, thinking of upgrading one of my trains to DCC, should I keep the flywheels in place?
Yes.
The mind is like a parachute. It works better when it's open. www.stremy.net
I agree, a big YES.
The purpose of a flywheel is to create momentum and smooth out glitches. In every automobile there is a flywheel for the same reason.Introducing DCC doesn't change things there. If anything it makes it morenecessary since glitches are more present.
Springfield PA
Absolutely! Flywheels are good to have regardless of the method of control.
Dave
Lackawanna Route of the Phoebe Snow
And now for a different perspective: I install sound decoders and speakers in all my locos, even the little Diesel switch engines. Finding a location for a speaker can be a challenge. In two of my locos, I have removed the flywheel to make room for a speaker and its baffle enclosure.
I'm not saying the doing so is necessarily a good idea. Just that my locos run just fine without the flywheel. I set up my decoders with a lot of momentum, but acceleration and deceleration.
For steamers in particular, I will set the acceleration momentum at 150 (out of 255) and deceleration at 100. Doing so allows the steamer to only slowly build momentum while the steam exhaust sound is really "barking." Most of the better sound decoders have another CV that allows button-control to give you faster braking at slow speeds.
The same logic applies to Diesels, although I set the accel/decel CVs to lower levels as the sound dynamic is not a great as for steamers.
brassnut thinking of upgrading one of my trains to DCC, should I keep the flywheels in place?
But I disagree with the simplistic "yes" given by many of the previous posters. And I really disagree with the analogy of an automobile fly wheel and carb vs fuel injection as it is totally wrong. Car fly wheels don't generate gasoline and pump it backward into the engine. And that is the bad part of a fly wheel in a train locomotive. When that motor is spinning due to the fly wheel it is generating electricity. That electricity is getting pumped backward into the decoder. Everyone knows that power going into electronic circuits "in reverse" is a bad thing. So my answer is that there is a trade off. Smoother operation (esp on dirty track) vs shorter lived electronics.
I generally don't remove the fly wheels just because it is easier not to, and DCC decoders are cheap. Back when decoders cost $50 each (more like $75 adjusted for inflation), I did remove fly wheels. I also had to re-fabricate the drive line each time - groan.
On yet another hand some newer decoders that have "life saver" capacitors that serve the same purpose and work as electrical "fly wheels". Naturally this type of decoder costs more, but on DCC one gets the smooth operation of fly wheels without them.
One more thing totally unrelated to the flywheel vs electronics. Removing fly wheels will lower the weight of a loco. Generally not a desired thing.
Texas ZepherBut I disagree with the simplistic "yes" given by many of the previous posters. And I really disagree with the analogy of an automobile fly wheel and carb vs fuel injection as it is totally wrong. Car fly wheels don't generate gasoline and pump it backward into the engine. And that is the bad part of a fly wheel in a train locomotive. When that motor is spinning due to the fly wheel it is generating electricity. That electricity is getting pumped backward into the decoder. Everyone knows that power going into electronic circuits "in reverse" is a bad thing. So my answer is that there is a trade off. Smoother operation (esp on dirty track) vs shorter lived electronics.
Well, mine is a simplistic answer, short and to the point. I would not have any diesels without flywheels. I say that from having been in HO since the late 1950's and having owned some really bow wow equipment over those years. And I have never found any reason to remove them to install decoders.
End of story.
Bob
What a flywheel adds is inertia which makes the motor run more smoothly, particularly at slower speeds.
The amount of electricity generated during a momentary loss of electrical power from the track is not going to hurt your decoder.
when the motor looses power (temporarily) the brass flywheels keep it going, so you don't stall on the tracks. They also prevent jerking motion.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
The electricty going back into the decoder isn't going to hurt anything - in fact better decoders actually MEASURE this, this is Back EMF. Eliminating flywheels won't elministe this - it's not like the motor armature itself doesn't have some flywheel effect. Even a loco without flywheels will coast a little, just not as much. Now you might be thinking that the decoder then has to work against the flywheels with the BEMF - yes and no. Since the flywheels add inertia, the motor doesn't slow down as quickly as one without, so the decoder doesn't have to compensate for a drop in speed nearly as much as without flywheels.
And motor efficiency works two ways. A highly efficient motor is usually a better 'generator' too. Like my Stewart Baldwin switchers with Canon motors - run those at full throttle on 12V DC and cut the power, they coast a long way with the headlight LEDs still lit!. And the concept of loading a generator can be easily shown by shorting the tracks while the loco is coasting - it stops nearly instantly. Different resistors will result in different braking rates - simple dynamic brakes.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I recall when I first got my Proto E8 maybe 15 years ago at how far it would coast after turning the (DC) power off. I assume this was largely due to the flywheels. No doubt that ability to coast helped make it such a smooth running engine overall. Most DC engines then would stop dead if you shut off the power.
BTW all electric motors generate Back EMF. A friend of mine who designs electronic gizmos was amazed that I knew what BEMF was. He said that in his business it was a bad thing that they tried to limit as much as possible. But as noted, BEMF is usefull too. BEMF has been used to keep electric motors spinning at a constant rate, such as the large turbines in a power plant, for maybe a century.
I tend to run my trains slowly in an attempt to be what I think must be realistic speeds in scale. For that reason, possibly, I find that if I get a short and the power is cut by the control unit, my trains all stop on about two dimes. It's almost like they have no flywheels in them, but I know many of them do. Maybe if I ran them faster I'd get a much stronger flywheel effect.
-Crandell
selectorI find that if I get a short and the power is cut by the control unit, my trains all stop on about two dimes.
If you get a short from the power unit, and not at the engine pickup, then the power back feeds into the rails from the motor. Essentially the motor becomes a generator. If you have power sucking devices (ie: Passenger car lights) on the same section of track, this produces resistance to the motor moving. Hence why it might be stopping so quick.
I also find higher gear ratio engines (14:1+) also have a tendecy to stop faster
Thanks, Don. Very interesting!!
Fits in exactly with what I said, Crandell. If there's a short on the rails, the power that the motor generates is also feeding into that short, which put the maximum load on the motor so - instant braking. If you cut power rather than short the track, you should see your flywheel units coast further. Not as easy to do with DCC - since if you crank the throttle knob to 0 that only sends a speed step 0 command to that particular loco - you have to yank the track power. But then the decoder will also potentially have a short or low resistence across the motor, again making it stop faster than if it was on DC.
Many thanks for all the replies. Reckon I'll keep the flywheels on.
Back when I was using regular DC I had locos that had flywheels and some that didn't. Those that did would coast a bit if the power was suddenly cut, say a power for example, while those that didn't have flywheels would just suddenly stop, sometimes even skid a bit. One would slam to a stop so fast that cars would sometimes derail behind it as they slammed together. So, yes, flywheels are a good thing to have. Today I don't run anything that doesn't have them.
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