Do DC locos and tenders, on DC powered tracks, have operating whistles?

If you're using DC on the tracks, you won't be getting whistle/bell work with conventional track voltage offset techniques.  It'll have to be some wireless rig or something more complex than a simple whistle/bell button.  I can think of ways to do the task, but none are simple or "on the shelf" solutions.

Thanks for that clear answer John.

Mannyrock

The two rail guys have been doing that with DCC.  MTH systems apparently work with AC or DC.  But you can't just slam a rectifier on an old Lionel transformer and expect the older bell or whistle to function normally.  My little prewar B6 (now converted to 2-rail) has a bell that just rings continuously on DC.

Obviously if you go with command control, you can run with DCS and have full control of the sound system.  Pretty sure that's not the situation here.

Lionel-MPC began selling DC-only sets in 1979.  The locos in these sets didn't have any kind of E-unit.  Reversing was accomplished by changing polarity at the "power pack."  To allow use with people's existing AC transformers, they also sold a "Layout AC-DC converter," which was basically a rectifier that went between the transformer and the track.

According to the catalog copy, almost all Lionel equpment made up to that point would function normally and safely on DC.  (There was no mention of "magnetized" E-units, etc.)  However, they suggested that whistles in the tenders should be disconnected, or they might blow continuously.  It's interesting to note that at that time, they had not offered a loco with whistle for several years!

I'm trying to get the horse before the cart.

Why do you want to run DC power to the track in the first place?  How do you reverse direction (maybe not required)?

Never seen it in O-gauge, but in addition to methods mentioned above, in DC HO there is a proprietary protocol used in the Broadway Sidekick Sound Controller that messes with the DC power voltage to activate the whistle/bell.  The engine must be so-equipped to recognize this messing.  And in DC G-gauge it is common to place magnets on the track bed to activate whistle/bell albeit at fixed locations so there's no user-control per se.  Again, the engine must be so-equipped to recognize the magnets (using reed switches).

I have an  old, low grade Lionel AC o27 engine, being the  the Scout.

Running that engine on AC to the track, with tight o27turns, sounds like an old coffee grinder, with lots of sparks. And of course, trying to run it at low speed creates a choppy run, with lots of buzzing sounds.

Today, I hooked up a Bridge converter between the AC output of the transformer, and the track, creating a DC powered track.

That Scout runs as smooth as silk, on ALL speeds, even the lowest.  No buzzing, no fits, no sparks, no grating noises.  Based on this, I have decided to run primarily DC to the track, with a dual post switch to switch the power to AC if I want.  This is great for a small layout with tight turns.

No, the train doesn't back up, but I never back up trains anyway.  I create side tracks for them to pull into, and then cut the power to the sidetrack.

No, the train tender does not whistle, but that's the price to pay for such a smooth ride.  I will wire a free standing loud whistle under the table, using a DC train whistle, and an a momentary on-off switch.  

I do still have a question though that I hope someone can answer.

If an AC engine has a front headlight (or you are hauling an AC caboose with a light inside the cab), will these lights come on when you run the AC engine on the DC track?

Thanks for all advice.

Mannyrock