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  • Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.
Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.

Moderators: AMTK84, MEC407

  by MEC407
 
...to see if the regulars in this forum are still alive. :wink: It's been eerily quiet in here lately!
  by EDM5970
 
I think some of the discussion about brake shoes may have something to do with it-

Now, on another subject, I read where GE fitted exhaust driven eductors to engines in place of motor driven crankcase exhausters. Sounds like a neat trick. Anyone have any drawings or info., perhaps online? I may have an application, although the units are from another builder-

  by Typewriters
 
Oh, we're still here; just nothing of real note lately.

EDM-- do you mean the exhaust eductor that removes dirty air from the engine air filter assembly? I didn't know that GE ever used powered crankcase exhausters.

-Will Davis

  by Allen Hazen
 
I check this forum first every day, and have been disappointed at the last couple of weeks of inactivity. I've been meaning to post something, but too busy to write it. The Australian rail-enthusiast magazine "Motive Power"
(ISSN 1442-7079; Wwebsite http://www.motivepower.net.au -- it's maybe best described as an Australian "Extra 220 South" with more colored pictures and more background/technical articles)
in its August/September 2005 issue has a cover story on the Queensland National 5000 class, an Oz-ified AC4400 in a low-profile carbody. When I get a chance I'll post an abstract to this forum: shoehorning the works of an AC44 into a carbody that will fit the Australian loading gauge took some doing!

  by MEC407
 
Looking forward to hearing more about that, Mr. Hazen! :-D

  by EDM5970
 
GE fitted eductors to the Hornell rebuilt Alcos in the early '80s to replace the motor driven crankcase exhauster. I looked at my two "good" GE manuals, (-7 and -8 service manuals), and found the engine air cleaner eductor, but saw nothing motor or eductor on the crankcase.

  by alcoiowa
 
Alco was adamently opposed to putting anything in the exhaust stack, such as an esuctor tube. Chris MacDermot, then on the D&H, designed a stack that included an eductor tube, with piping to a Farr Separator, to replace the motor driven Crankcase Exhauster. It was first put on the RS11/36 rebuilds on the D&H in the late 1970's. It was found that the crankcase vacuum in 8th notch was greater with the eductor stack than with the motor driven exhauster.

The Alcos rebuilt by GE at Hornell for the D&H in 1980 were equipped with the the MacDermot designed exhaust stack.
  by Allen Hazen
 
Hmmm.
I think I remember a photo of a CN RS-18 rebuilt by the railroad in ?? the early 1980s ?? with (according to the caption-- this was either in "Trains" or in "Extra 2200 South") with transistor throttle, and also without the usual crankcase ventilator pipe. Would this have been another application of the MacDermot invention?
  by EDM5970
 
I'm not quite sure what one of these would look like applied to a crankcase exhauster application. After looking at the drawings showing the general arrangement for the air cleaner bleed air in the -7 and -8 service pubs, it looks like it would be all within the hood in either case.

The normal motor driven exhauster pipe does not always go up through the roof, however. I have seen them make a 180 bend and end up just above the rail on a few units; RS-3s come to mind, I just can't remember where.

The LIRR FA-2 power cars, which I am a bit familiar with, still have the "mushroom" fitting on the roof, but the pipe goes up, crosses over the walkway, and comes down along the side of the unit (inside). It then goes through the floor, follows the front of the fuel tank on the fireman's side, and ends just above the rail.

I can imagine that there would be many variations and railroad shop mods to that pipe. Having it end below the unit would help keep dirt, soot, oil, etc. off the roof and from running down the sides.

Funny that the 539s and the EMDS don't have exhausters (at least that I've seen on EMDS; I'm not as well versed on them), not have I seen exhausters on any GE or in any GE pubs. Seems to be a 244/251 thing-

  by Ol' Loco Guy
 
All IC engines have some form of crankcase ventilation.

The Farr oil separator used with the "MacDermot' stack is actually an EMD item.

The stack works on the same principle that governs the operator of the engine air filter pre-cleaners on early GE locomotives-momentum transfer.

Given the fact that the exhauster motor on Alcos can last for years (change the brushes and bearings as needed)-what would be the point of spending some big bucks to fab up a new stack ?

  by Paul
 
Most Dash 8 and 9 have eductor tubes. God knows we need to clean them every 15 days out here in SoCal due to CDF rules to prevent brush fires. Unlike the EMD counterparts, I havent seen one dirty enough to "cause" brush fires. I am interested in this eductor set up Chris came up with. I wonder if it could be adapted to a 244 engine. On the later 710 EMD engines, there is a an air line running from the air box across the top of the seperator. I assume this is used to assist in creating a negative pressure when the engine is at low speed or idle. Guess I will call Mr. MacDermot on Monday.

  by nickleinonen
 
Paul wrote:On the later 710 EMD engines, there is a an air line running from the air box across the top of the seperator. I assume this is used to assist in creating a negative pressure when the engine is at low speed or idle.
it doesn't really give any extra low pressure to the crankcase at idle. but under load, it helps a lot. at idle, there is very low pressure in the air box on all the turbocharged emd engines [less than 1psi, but lots of volume] there is an orifice that can be changed at the top end of the air box booster pipe above the separator to tune the crankcase pressure. there is a mod too with the GE D9 engines to add a similar air box pipe to the separator piping to boost crankcase low pressure under load..