The decoder was changed to another DH165A0; the problem persisted. I installed the used decoder in another loco, which has not experienced any problems.

The motor does have RF suppression capacitors, which may explain why the various changes I tried to CV 57,56, and 55 had no apparent effect. I did disconnect them at one point when the loco had traction tires to see if they had an effect on the motor performance. As you mention, this had no effect on the pulling power.

Thanks to Jeffery, RGW, and Bturner for your questions and suggestions, all good points.

I did remove the traction tires to allow the drivers to slip and the motor to keep running. After about 30 minutes of running with 4 cars and the drivers slipping, the motor was barely warm.

If I remember correctly, the 13 plus or minus volts is what JMRI reports as track voltage at the output terminals of the DCS52, not the decoder output voltage.

The decoder is a Digtrax DH165A0 mounted in the boiler, so no wires to the tender to lift the rear of the loco. The tender attaches to the loco with a vertical pin on the drawbar that fits into a transverse slot in the rear of the loco. This pin was too long and was causing the tender to derail. The pin has been cut off and no longer interferes with either the loco or the tender.

As for mechanical binding, there are no unusual noises or "jumpy" operation and the loco runs like a rabbit on a 2% downgrade, even with 8 cars attached, so I would not expect any binding.

The loco runs forward ok, although 4 passenger cars or 5 freight cars up the 2% grade is the max it will do. Seems strange to see a 4-8-4 with an 8 axle tender barely making the grade with 4 or 5 cars. Oh well. This is with clean track, clean wheels and a lube job.

The problem now is the random stopping and related loss of control. The loco will make several circuits of a loop and then, just stop in no particular place. The fix is also random; sometimes, initiating a track fault near the loco will clear the problem, sometimes changing to a different loco on the DCS52 and then, changing back clears the problem, and sometimes waiting overnight does the trick.

After a complete rewire, most of the track faults have stopped; however, sometimes the loco just stops at random locations for no apparent reason and will not respond to commands even though the headlight indicates the loco has power.

Jeffery,

Thank you for all the help and suggestions. I removed the traction tires to let the wheels spin instead of stalling the motor. The loco sort of works, but it is odd to see a 4-8-4 with an 8 axle tender sliding up a 2% grade pulling 4 cars with clean track, clean wheels and a fresh lube job. It does not seem to matter if the cars are weighted or not and 4 or 6 axles; the 5th car stops the train, but now the drivers keep spinning.

If anyone has more ideas or suggestions, let us move this thread to another thread I started concerning "4-8-4 rebuild". I started that thread when I  was having track fault issues with this same loco. After rewiring the loco, front to rear and changing decoders, most of those problems are gone: except, every now and then, the loco just stops and will not respond to commands.

See you on the other thread.

I have a 2-6-0, a 2-6-2, and a 2-10-2 that all pull better than the 4-8-4. The F7s and a GP16 do not seem to mind the grade at all; although, they do slow down a bit.

Maybe I am calculating the grade incorrectly; 3/4" rise in 36".

I have not found other modellers nearby, so I am strictly OJT on these problems.

Cheers

Jeffery,

I understand the overload on the motor, but, 3 cars on a 2% grade to minimize wheel slip seems pretty weak for a 4-8-4. I do have some level areas where I can run the loco and pull 6 cars without the traction tires. I expected the loco to be a better puller. Oh well.

Thanks for chiming in on this one.

John

Going, back to the original question, restated, concerning multiple track faults: can an overloaded motor cause a track fault even if a volt meter shows 13.8 volts and the ammeter shows 1.4 amps on a DCS52?

Jeffery,

No wheel slip at any time after I changed one driver to traction tires.

Jeffery,
In reverse, I am still limited to 4 cars, but they go up the grade a little faster.

RGW, thanks for the suggestion, I can give that a try. All this work changing and removing decoders is great practice on soldering. But, I certainly need that anyway.

Hi Jeffery,

The motor is a brand new motor, purchased from Bachmann, that was designed for a Niagra. The new motor has what appears to be capacitors soldered between the frame and the motor brushes; the old motor did not have these capacitors. I tried disconnecting the capacitors with no change in performance.

I have loosened the bottom plate, under the drivers, as suggested in another thread. I have tried modifying some of the CVs on the decoder for more power or torque compensation. These last two changes allow the loco to just barely get 4 passenger cars with three axle trucks up the grade.

As for the tracks, I typically wipe them clean with a dry cloth and then a light pass with 400 or 600 grit sand paper. The wheels are cleaned by removing built-up crud with an Exacto knife, followed by an alcohol wipe. The rails on the 2% grade are brass.

Since this thread got derailed, I will ask about a 4-8-4 with DCC that will not pull 5 light passenger cars (two axle trucks and no body weights) up a straight 2% grade. Initially, the drivers spun and the loco stopped moving, then I added traction tires to one driver and now the motor stalls and the loco still stops moving. Track and wheels have been cleaned.

Ideas?

Hi,

I have a 4-8-4 that needed a new motor, DCC conversion, and traction tires. I have all the work complete and the loco works great in reverse. However, in forward, I get numerous track shorts on the DCS52 command station. Monitoring volts and amps in the DCS with JMRI, no low voltage or over current is indicated.

The loco also runs well on level track, but not forward, and not upgrade. I tried changing the decoder with no success.

Any ideas about what is going on would be appreciated.

John G.

Banjoman,
There is a DC Bachmann 2-8-0 with smoke and light on Ebay, as of 2/23/21. It has a Great Northern badge; possibly repaintable.