Does anyone know what kind of air compressor does the ET44s have? Is it the standard “Whoop” compressor that GE uses on their locos, or a different type?
I’ve been told that the whoop is actually the radiator fan kicking in, rather than the air compressor.
The only Australian locomotives which gave the “whoop” sound were the 120 Cv40-9i units. None of the subsequent C44ACi units (more than 200 units) had this sound. All of the Cv40-9i units have been rebuilt with new electronics. Although they kept the original compressor, the distinctive sound disappeared. I was told that the sound was due to the particular starting arrangements, not a feature of the compressor itself.
So it seems unlikely that new GE locomotives would have the sound, since they would use the new starting arrangements.
Peter
Thanks for the insight. Would like to hear confirmation about this on the North American GE ET44 locos though. I have a model ET44 with DCC sound and on the MR forums, a few of us were wondering about the “Whoop” since the sound decoder doesn’t make that sound. If indeed the prototype lacks it, then we can rest easy knowing that it wasn’t a feature of the prototype in the first place.
That sound is indeed the air compressor. not sure what the tier 4s have but Im pretty sure its electric drive.
The GE compressor is indeed electrically driven. When much air is demanded (such as when charging a train) the engine May rev up a couple notches, I suspect to ensure that the auxiliary generator is able to supply the power demanded of it.
The GE control stand bears a notice stating “this locomotive is fitted with a motor-driven air compressor. Optimum train charging is achieved in notch 1”.
Don’t you mean EMD? And isn’t it usually notch 2?
Nope, GE. I’ve seen it on Dash-8’s, Dash-9’s and GEVO’s.
EMD compressors (except perhaps on the SD70ACe-T4) are directly driven by the crankshaft, so the faster the engine revs, the more air you pump. Our operating manual says to keep it to notch 4 or lower when in neutral, but on a lot of the SD60’s and older units you need more, especially with only one unit pumping up long cuts.
Starting with the SD70’s the computer automatically revs it up to what sounds like notch 6 to pump air. SD60’s do that too but only up to notch 3 or 4, and anything older just idles away while your MR pressure drops, waiting for you to rev it up.
I’ll take your word for it. Been a while since I ran newer crap.
Our rebuilt SD60s automatically notch up to about 3 or so when charging, so there really isn’t much to do.
I also wouldn’t be surprised if the different railroads have programmed their locomotives to operate differently, just like having different operating instructions.
The older stuff is way better to switch with anyway!