Running a Helper

ANWER

DCC Decoder with incremental speed control: ProtoSound 3.

NCBG

Have you tried using the NCE 408sr's DCC speed tables to speed match your two locomotives? 

My helper district operation is slightly different than yours as I try to follow PRR prototype practice.  The Pennsy had a rule that all helpers on passenger trains had to be at the head end (probably for passenger comfort).  I don't encounter "downgrade" problems on heavy freights as on my east slope (Horseshoe Curve) grade I cut off the rear end helper at the top of the hill. To enable that operation the front coupler on locomotives in the helper pool are locked in an open position with a removable pin.  With the pin in place the locomotive can push but not pull and enables cutting off the helper on the fly.  A secondary benefit is that if the rear end helper unintentionally   stops running while the train is on a curve there is no risk of the cars being pulled off the track.  The preferred approach is to use two cabs to run the helper operation but I could consist the locomotives and break the consist with the train stopped at the top of the hill.  Using the consist (one cab) approach I'd speed match the helper slightly faster than the main line locomotives so they would always stay in contact with the rear end of the train.

Ted - I'd like to try a MTH ProtoSound 3 DCC capable decoder in a non MTH  locomotive.  Are they available now, and if so how much do they cost? 

Ed Rappe

Maybe for the derailment, you have a different problem than locomotives.    Cars 8 and 9 I assume are at the back of the train with only car 10 behind them.    If the weight of the train was causing the derailment, would not that occur to the cars up near the locos also?   

I have about 8-10 GGD cars on my layout now.    2 Pullmans, 4 coaches and various headend cars.     I have a few of the coaches and at least 1 of the pullmans that required some adjustment to the trucks.   I had a few wheelsets out of gauge.   Also more common, I found that the screws and springs holding the trucks on were too tight.    The trucks on some cars did not swivel freely.   It is easy to fix.  One turn or 2 on the screw and if it remains tight enough to not vibrate loose, you are done.   On a couple I removed the spring, and I think I cut a coil or two off some springs that caused problems.

It does sound like your grades are very steep!   it must be interesting and challenging.

I have NCE 408 decoders in all 3 locomotives, can I do it with them?

No.

Most DCC decoder makers use BEMF to infer motor speed.  The only DCC decoders that take an actual measurement of motor speed are MTH Proto 3 in all scales and Lionel Legacy in S scale.

BEMF measurement is not that accurate.  It drifts as motor temperature changes.  For running distributed power MTH and Lionel have a better approach.  MTH and Lionel also come out of the box speed mapped.

Ted - I'd like to try a MTH ProtoSound 3 DCC capable decoder in a non MTH  locomotive.  Are they available now, and if so how much do they cost? 

Ed

Unfortunately there are no separate sale Proto 3 decoders yet.  We should get a better idea of how far out they are at the DCS users dinner at York.

I was told very emphatically by an NCE technician that they DO NOT use BEMF.   It is not mentioned in the instruction sheets and when I asked their help line, they told me they do no program it into their decoders.

Jim

Thanks!  I just looked at the D408SR instructions.  Yikes!  Looks like no motor feedback at all for speed control.  No wonder Mark is having problems running down a 4% grade.

I'm running 12 passenger cars up and down 3 percent grades. Recently I bought some Golden Gate cars, and I've found on some the diaphragms would get caught on each other and derail the cars going downhill. I've installed some longer couplers as a temporary fix. It may be worth looking into that as a potential cause for derailments. Like someone else mentioned, there likely isn't enough weight at the end of the train to cause the problem.

Also, I've done speed mapping for NCE decoders on engines that did not run at the same speeds and they run great together now. It's worthwhile.