Considering the the very small amount of fuel they burn at idle about 0.5 gallons per hour and the probable damage if turned off and allowed to cool the amount of fuel wasted? is not an issue - I can only imagine how much they can burn at full throttle making them idle all night to keep them warmed up is really a moot point in the over all cost of operation. How many locomotives are we talking about here. Who would like to jump into an air temperature steel locomotive on a sub zero day and wait for it to warm up?

That one loco is running at "Notch-8" or full-throttle when in energy production mode. My Dad's old railroad had huge EBHs that they would plug their locomotives into instead, which is probably better for NOx to draw off of the grid... I guess if you string them together, the lead unit could provide power, which is what their doing. MA-EPA is pretty strict on diesel idling, that's for sure.

They also do this when on their routes. Amtrak in particular does this: if two locomotives are connected, the lead engine moves the train, while the second one is left in full-throttle to power the electrical demands of passenger train cars. It's odd to hear it stopped at a station running in "neutral" at full throttle.

Starting cold decreases the live of the ICE in a locomotive tremendously, and warm-up time is quite long. Some freights are left running for a month or more before service while they run routes, wait for another trainset to be completed and back out again, etc.

GE and GM (EMD) are producing low-emission units for 2007 with AC traction motors. These should set the standard for low-emission operation.

Still, shipping tons of freight by train is FAR more efficient than truck. It's a hybrid!

RH77

Tell that to my MB 220D! It's an old-tech diesel. The injector pump has a pnuematic governor and it has a throttle plate to generate manifold vacuum. One of the methods MB used to govern the engine speed on this one was to use a throttle limiter screw, so the throttle never even sees wide open.

two down, one to go...
 

I'm still looking for something regarding a 'throttle plate to generate manifold vacuum'. I'll post what I find.
However, I did find this:
https://www.mercedesforum.com/m_18690..._1/key_/tm.htm
The diaphragm control is used for control of fuel delivery.
The stop screw is used for limiting maximum fuel delivery.
Neither of these is an air restricting throttle. That doesn't mean that there isn't an air flow restricting throttle, just that these two items aren't.

That diphragm they are talking about is a vacuum diaphragm. There is a vacuum line going from the intake manifold to the injector pump to controll it.

Diesel Tractors with Throttles
 

I have no idea if this is thru, it's something I heard many years ago but:

I have heard old diesel powered tractors have a throttle for controlling engine speed and that if the intake (and throttle) comes loose for some reason the engine will be put into full throttle possibly damaging it.

A detroit dielsel 2-stroke engine used a fuel rack controlling individual injectors inside the valve cover that could stick. Also if well worn they could run on crankcase oil and run away ungoverned. There was a large butterfly that could be tripped to cut the air to the engine to shut it off in emergencies. It was useful.

Also the 50 year old Massey Ferguson tractors I saw as a kid had an air throttle linked to the fuel control. I thought it was used to smooth the torsional shudder at low speeds but that is just a guess. They ran fine with the air throttle open but I never worked on them.

Ernie