Question about Southern GP38-2 "oil bath" air filters

[MARTIN STATION]

  I'm hoping someone can answer a question for me about why the Southern Railway ordered their GP38-2s with oil bath air filters instead of the paper filters, then coverted them all over to paper filters with the added air box a few years later? I know the earlier GP38 locomotives started with the oil bath filters but then later in production I believe, made the paper filters available as an option. I thought the paper filters with the prominet air box was standard by the time the -2s came along. Just wondering what the reason was.

Thanks, Ralph 

[Overmod]

MARTIN STATION

I'm hoping someone can answer a question for me about why the Southern Railway ordered their GP38-2s with oil bath air filters instead of the paper filters...

It would be highly logical for Southern to have arranged all the locomotives of the same general type to use a single type of filter serviced with a well-established procedure.  The inertial filters also represented a cost item (perhaps even needing to be expensively sourced from EMD when first introduced) whereas cleaning and re-oiling the media in oil bath filters was done with relatively cheap commodity chemicals (and I doubt the media ever really wore out.)

By the time you had an installed base of the filters in newer locomotives, the advantages of paper over bath (there are a number) would begin to outweigh the savings -- much as AC motor savings began to prevail over established DC-motor practice on NS in the last few years, and NS went from largely DC-chauvinistic to engaging in a number of relatively high-profile AC conversion projects.

[MARTIN STATION]

  Thank You Overmod! I know the Southern did things different from a lot of other railroads (as some others did), but usually they always had a good reason. Of course what made them different makes them interesting to me. Anyway, thanks for answering my question!

Ralph

[Paul Milenkovic]

This article about older tractors

https://www.yesterdaystractors.com/articles/artint6.htm

explains some of the things to be concerned about with an oil-bath filter.  The most serious is the oil being drawn into the engine.

[Overmod]

Paul Milenkovic

The most serious is the oil being drawn into the engine.

I think this is a relatively small issue with an EMD 2-stroke, particularly as the silver-based main bearings don't allow use of oil with 'ashing' additives.  Remember how one of these engines works.  A GP-38 is a Roots-blown engine; any additional oil will lubricate the blower a little better, then either burn in the charge air or be carried out with the scavenge air before the four exhaust valves close.  There probably isn't enough oil vapor to be carried over to keep the engine running with the fuel rack shut, although there are reports of smaller Detroit Diesels being impossible to shut off when there's excessive oil getting into the intake charge (you have to put something across the manifold intake to cut off the air!)

Incidentally I doubt there is enough oil carried over from an oil-bath filter to accumulate in the exhaust manifold and cause the blue-smoke or manifold-fire problem that EMDs sometimes display...

A much more telling concern is the material that can start making it through oil-bath filters without much warning, especially if there are excessive contaminants in the air or the filter isn't kept rigorously clean and oiled ... and cause scuffing and scoring to the liners, and other damage.  At least that's something I remember from many years ago.

[MARTIN STATION]

 Thanks paul! I read the article and found it interesting. I remember years ago when working at the airport, we had a 67 Ford refueling tanker that had an oil bath filter. I remember wondering if such a vehicle was involved in an accident and the oil leaked onto the engine if it could, would cause a fire (I'm talking about a different type of vehicle because a tanker with 2500 gallons of jet fuel involved in an accident probably would have made it a moot point). But I remember being told it worked really well. It just seemed Southern didn't have their GP38-2s very long when they started coverting them to paper air filters.

Thanks again, Ralph

[Paul Milenkovic]

"established DC-motor practice on NS in the last few years, and NS went from largely DC-chauvinistic"

To be a DC-motor holdout, did NS build special DC-locomotive inline facility for servicing those locomotives?  Something nicknamed a "Brushatorium", where a team of workers could replace brushes and damaged traction motor windings in an hour, something that took 2-3 days on other roads?  Only they quietly retired their DC locomotives when DC motor parts suppliers went out of business?  

[daveklepper]

Are suppliers of DC motor parts really out of business?

There are plenty of DC motor locos still running.

There are used but servicable parts available from locos converted or retired.

[Overmod]

Paul Milenkovic

To be a DC-motor holdout, did NS build special DC-locomotive inline facility for servicing those locomotives?  Something nicknamed a "Brushatorium", where a team of workers could replace brushes and damaged traction motor windings in an hour, something that took 2-3 days on other roads?  Only they quietly retired their DC locomotives when DC motor parts suppliers went out of business?

Dave, he's being humorous by recounting the way things were 'supposed' to go in the Forties and Fifties as the last 'stalwarts of steam' made the best out of external-combustion power ... to little ultimate avail, as the specialty manufacturers who made modern sophisticated steam possible slowly went out of business or switched themselves to other product lines or specialties.

The DC motor situation is different.  There is little doubt that AC drive is technically superior; the 'catch' being that early (and even not-so-early) electronics are expensive, much of the motor technology not particularly common, and that some of the advantages of AC drive were not deemed substantial enough, for a long period of development and experimentation, to adopt for major fleet use.

Meanwhile NS in particular did, in fact, have well-honed repair facilities and supply chains centered around DC traction motors, which saved them enough "net" of AC performance advantage to keep ordering DC-motored modern power and limit the number of spare parts and suppliers needed to keep their engines running effectively.  Once there was an established AC aftermarket, and the advantages of straight AC consists began to be recognized, there began to be perceived advantages to convert to a 'modern' AC approach, first by specific groups of locomotives or rebuild projects and then more 'wholesale' (and now, presumably, with selective mothballing or retirement of DC-motored classes, since most of the rebuilding economics are no longer as enticing, net of current traffic drop.

[Paul Milenkovic]

Overmod

 

 

Paul Milenkovic

To be a DC-motor holdout, did NS build special DC-locomotive inline facility for servicing those locomotives?  Something nicknamed a "Brushatorium", where a team of workers could replace brushes and damaged traction motor windings in an hour, something that took 2-3 days on other roads?  Only they quietly retired their DC locomotives when DC motor parts suppliers went out of business?

 

 

Dave, he's being humorous by recounting the way things were 'supposed' to go in the Forties and Fifties as the last 'stalwarts of steam' made the best out of external-combustion power ... to little ultimate avail, as the specialty manufacturers who made modern sophisticated steam possible slowly went out of business or switched themselves to other product lines or specialties.

The DC motor situation is different.  There is little doubt that AC drive is technically superior; the 'catch' being that early (and even not-so-early) electronics are expensive, much of the motor technology not particularly common, and that some of the advantages of AC drive were not deemed substantial enough, for a long period of development and experimentation, to adopt for major fleet use.

Meanwhile NS in particular did, in fact, have well-honed repair facilities and supply chains centered around DC traction motors, which saved them enough "net" of AC performance advantage to keep ordering DC-motored modern power and limit the number of spare parts and suppliers needed to keep their engines running effectively.  Once there was an established AC aftermarket, and the advantages of straight AC consists began to be recognized, there began to be perceived advantages to convert to a 'modern' AC approach, first by specific groups of locomotives or rebuild projects and then more 'wholesale' (and now, presumably, with selective mothballing or retirement of DC-motored classes, since most of the rebuilding economics are no longer as enticing, net of current traffic drop.

 

Thanks, Overmod!

The saying "history doesn't repeat but it rhymes" is attributed to Mark Twain.

I had no idea the DC motor practices on Norfolk Southern were anywhere as close a parallel to the specialized maintenance facilities and practices on Norfolk and Western used to keep their steam operating into the 1950s until, it was claimed, the manufacturers of needed parts went out of business.

I simply guessed that NS had specialized and streamlined procedures to stay in the DC traction-motor lane, saving the expense of the more expensive AC units.