DCC-Sound Equipped 2-6-6-2 Articulated Steam Locomotive

[db22]

I have a sound loco that was never as fast as other steam locos but it seems to be getting slower and slower. The chuff speed is fast so I assume that the received DCC command is OK but the loco runs about one third of the other locos. I have changed numerous CV's to no avail so I reset #8 to 8 and it's still about half the out the box speed. Anybody else seen this or have advice on CV's or could it be lubrication? I have lubed the rods but I have been reluctant to remove the boiler. It moves on startup increment 1 and has linear velocity to input but at 128 it is so slow. Any help would be appreciated. Thanks.

[Yampa Bob]

What is the locomotive?   I would run the loco on a DC powered track and check the current draw with your ammeter. Unplug the decoder and install the jumpers or dummy plug while testing. Monitor the motor for any sign of overheating.   

You probably should remove the shell and check the mechanism for any binding or lack of lubrication.  If the loco runs at good speed on DC, that will help you draw some conclusions. 

Keep us posted with your results.

[pdlethbridge]

If CV 5 and 6 are set to 0, if not them set them to 0. These control the high and midrange speed. I set my locos to about 150 and 75 for CV 5 and 6. The high range is 255 or 0.

[db22]

It is a Chesapeake & Ohio® #1521 Spectrum with Tsunami stock Bachmann. I will have to remove the boiler to see the guts but that looks a bit complicated. I have no evidence of heat build up though.

[SteamGene]

The USRA articulated as built were fairly slow locomotives.  Builders today do a better job of making the model approximate the speed of the original.  So part of your problem may simply be that it's made to go slow. 
Gene

[boomertom]

Mallets were usually used in services where slow spped power was more important than speed. The USRA 2-6-6-2 - class H-5 on the C&O was used in drag service in the coal fields of West Virginia, Kentucky and Virginia.


That said, the speed your engine operates at would be appropriate per its prototype.

Tom

[Yampa Bob]

In the case of the Big Boy, Challenger and other monsters of the rails, they are articulated to run on tighter curves used by smaller locos, and they often run at 70 mph+.  I think the smaller "Artys" were more for logging and mining, so you're probably correct about the slower speed.

DB22, have you clocked the approximate scale speed?  For HO scale, feet per minute is very close to scale mph.  So if the loco travels 60 feet in one minute, the speed = 60 mph.

[SteamGene]

Bob,
There is an enormous difference between late, massive articulated: Allegheny, N&W A, N&W Y6b, Challenger, Big Boy, and the earlier articulated.  Yes, all of them - with the possible exception of the Y6b - could run at 70+ pulling a long train, but they were the exception.  Early articulated, especially Mallets, as Boomerton says, were used in drag service, slow but powerful.  A look at driver diameter says a lot.
Gene