Flywheels

[Cody J]

What are flywheels?

Thanks,
cody

[the Bach-man]

Dear Cody,
A flywheel is a disc of metal on the motor shaft that helps an analog loco coast after power is decreased. This is done electronically with DCC.
Have fun!
the Bach-man

[Michigan Railfan]

So, Mr. Bachmann, or anyone else, what would happen to your loco if it didnt have a flywheel, and you immediatly stopped your loco?

[simkon]

It would stop a lot quicker and less "prototypically", as in real life most trains can't instantly come to a halt while going 50mph while carrying a 50 car consist or without. The air/dynamic brakes aren't nearly strong enough to do so...have you ever heard of something called momentum.

[rogertra]

So, Mr. Bachmann, or anyone else, what would happen to your loco if it didnt have a flywheel, and you immediatly stopped your loco?

You'd stop, quickly, that's all.  Nothing will happen to the loco.

[Chris350]

The fly wheel will also add some inertia so that the loco doesn't take off like a scared rabbit when on e applies power....

Since no one else mentioned it, the flywheel is (or in most cases flywheels are) the large cylindric mass of brass that is attached to the drive lines in line between the motor and the drive gears on the power trucks.

[RAM]

A flywheel will do very little coasting when the power is shut off.  They are just not large enough.  The reason for flywheels is when you have a short gap in power, as going through a turnout, your train will not stall.

[Chris350]

A flywheel will do very little coasting when the power is shut off.  They are just not large enough.  The reason for flywheels is when you have a short gap in power, as going through a turnout, your train will not stall.

Also in DCC operation since the motor is pulsed, and not actually constantly spinning the flywheel will smooth put the pulses so it runs smoothly.  At least that's how DCC motor control was explained to me.  True also that when you dump the power they don't coast much, they just stop.  As a matter of fact my previous thought regarding inertia is probably not all that accurate either.

[Stephen D. Richards]

The flywheels do make a difference but it is sometimes very difficult to see in Model Locomotives.  If you were to enlarge the HO locomotive to the a full size locomotive you would see the difference.  Of course that would be a really big electric motor and huge flywheels!         Stephen

[Michigan Railfan]

I just wasnt sure if it would do anything to the locomotive. So, if stopping it real quick wont damage it, what about immediatly starting it, like very quickly turn the power to full? But, I still dont do that, you know, just incase.

[rogertra]

I just wasnt sure if it would do anything to the locomotive. So, if stopping it real quick wont damage it, what about immediatly starting it, like very quickly turn the power to full? But, I still dont do that, you know, just incase.

Run loco at full speed, spin throttle to zero, loco stops.  No damage.

While stopped, spin throttle to full speed, loco appraches warp speed.  No damage.

Do the above a hundred or so times and that may cause damage.

[jward]

while stopping a locomotive without a flywheel quickly doesn't harm the locomotive, if you do it with a train behind you it might pop a few cars off the track. a flywheel provides a much gentler stop. the difference IS noticeable, just ask anybody who's ever tried switching cars with an athearn blue box locomotive..... you had to be careful with them or you'd overshoot the uncoupling magnet.

as was mentioned earlier, with dcc you can adjust the acceleration/deceleration settings to compensate for the lack of a flywheel.