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Old diesel-electric yard locomotive

Old diesel-electric yard locomotive

Old diesel-electric yard locomotive

(OP)
An iron producing plant has four locomotives that celebrate their fiftieth anniversary this year. They have been 'maintained' by a person that, I think, didn't know about the operation and obviously built his career on trial and error adjustment of resistors and an occasional replacement of a blown fuse. Now, he has retired and has left no knowledge, no notes, no nothing behind.

My task was to try and get a grip on the situation and also make at least one more of the defunct locomotives operational again.

My findings were very simple. Open wire-wound on ceramic core power resistors in the 500 - 1000 W range showed very differing resistance values. The worst was down from nominal 250 ohms to 35 ohms. There was also a hefty leakage to ground from those resistors. After cleaning it thoroughly we got the 250 ohms back and could readjust the electronic excitation device (added some 20 years ago) back to normal operation point.

This is the first time I have met a resistor that is so dirty that its resistance dropped almost an order of magnitude. The environment is inside a diesel-electric locomotive. Close to the diesel engine and with smoke from the engine, oil leaks, dust from blast furnaces and LD converters. There had not been any cleaning of that part of the locomotive for as long as anyone could remember. Probably never.

Question: Is this a unique experience or have anyone else had the same? And, would you say that it is possible at all? I know it is, but it took a long time to realize that it could be the problem.  

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Old diesel-electric yard locomotive

I would have probably never thought of it, but the dust from such an operation could no doubt be conductive. Carbon is a decent conductor, and there are no doubt some amount of heavier C bearing byproducts (as compared to CO and CO2) from the LD convertors.

RE: Old diesel-electric yard locomotive

We used to work on WWII vintage locomotives that had been repowered with CAT engines in the 1950's at a gypsum mine in the California desert.

The gypsum dust bound everything, and by the time the locomotive was due for an engine overhaul, about 6000 hours (it was a REALLY tough environment) the operators reported all kinds of operational problems.  They'd bring it into the shop, give it a good cleaning, peel the engine out of it and send it to us.  We'd go back out for test runs after overhaul and everything would seem fine, but in a few months the "weird" problems starting happening again.

One of the old timers there convinced his boss to let them do the kind of cleaning they usually only did when they took it out of service for repair on a more regular basis. Seemd they had less problems, and a couple years later he left, then they couldn't keep the old locomotives running and finally replaced them, since the new units didn't have our engines we stopped going out there.

Also ran into a similar issue with braking resistors on engines that ran up North and had some long tunnels.  We had severe engine problems due to really high inlet air temps and the engines smoked so bad in the tunnels that the braking resistors would actually cake up.

An iron plant is probably one of the worst enviroments there is, any place that will eat up a D7 in a year has to be bad, to make matters worse the locomotives probably have a tough duty cycle, and spend lots of time idleing (and slobbering and leaking) compunding what you're seeing.

Good Luck!

RE: Old diesel-electric yard locomotive

Skogsurra, justan off-topic suggestion.  Even if there are no records or drawings for that locomotive, you might want to check with the railfan or trainwatcher hobby community.  Come to them with locomotive model and serial number and they may very well have good info for you.

These groups tend to LOVE old records about their favorite engines!

RE: Old diesel-electric yard locomotive

Let's see, iron ore powder, carbon soot dust, leaked lube oil as a carrier and binder, what better conductor can you find?

rmw

RE: Old diesel-electric yard locomotive

Does your new PMS schedule include re-cleaning (6 months?  3 months?  12 months?) to remove the carbon dust before it gets sticky and rusted into the iron dust?  

Concur with the RR society/fan groups.  A local club/group might even be interested in a "show and tell" session to see the old engine.

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