If three modern diesel locomotives dead head, are all three engines working or is only one working?
John
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It depends...
If the train needs the power of all three of the diesels, then they will all be on line and working. If the train does not need the power of all three units, then one or even two of them may be "isolated."
In the cab of each diesel engine is a rotary switch used to either place the engine "On Line" or "Isolated." With the simple turn of that switch, the engineer can place the engine on line or take it off line, where it will just idle along.
Sorry to butt in here, but it's great to hear from you Wyhog...or have I been on the wrong threads for a long while?
In the same vein, I was told that two Amtrak engines, when used at either end of the train (as on the VERMONTER), can each operate at half power in order to conserve fuel. Is this correct?
How about when one engine is an electric, as on the ACES?
If they were just light engines moving with no train, only one locomotive would be on line and working. The others might be idling, or could be shut down depending on the temperature. If it was below freezing they would all be running, but only one would be working.
I have seen the UP start trains with as many as 8 units on the front. Only a few units will work hard while the rest are idling (Along for the ride) one or two more will join in the chant and pull when the entire train seems to be moving as one.
There is consideration for how much pull the diesels can place on the train because the Couplers themselves can only withstand so much.
4 axles can get into places 6 cannot, however sometimes 6 can pull more but are hard on track. Railroads like to count how many total powered axles when figuring what to pull a train with.
Aren't most newer diesels equipped with a small "pony motor" to keep the fluids warm, when the engine is at rest and even shut off? It saves fuel & pollution caused by prolonged idling.
Originally Posted by Dick Kuehnemund:
Aren't most newer diesels equipped with a small "pony motor" to keep the fluids warm, when the engine is at rest and even shut off? It saves fuel & pollution caused by prolonged idling.
No. The CSX railroad tried this concept in order to obtain "credits" for EPA emissions, but the whole concept didn't really work out.
Generally speaking, no main line, class one diesel units have ANY sort of "auxiliary" on-board engine. With modern computer controlled units, the on board computer can shut down the prime mover, if the reverser is centered, and restart the prime mover if the cooling water gets too cold, air pressure gets too low, battery voltage gets too low, or the Engineer puts the reverser in forward/reverse. There is no need for any onboard "pony motor".
Does the working engine supply electricity to the traction motors of the non-working engines?? Thank-you!!
Pete
Originally Posted by Little Giant:
Does the working engine supply electricity to the traction motors of the non-working engines?? Thank-you!!
Pete
No. Only low voltage (74volts) is transmitted throughout the 27 pin jumper cable between units.
Originally Posted by Hot Water:
Originally Posted by Dick Kuehnemund:
Aren't most newer diesels equipped with a small "pony motor" to keep the fluids warm, when the engine is at rest and even shut off? It saves fuel & pollution caused by prolonged idling.
No. The CSX railroad tried this concept in order to obtain "credits" for EPA emissions, but the whole concept didn't really work out.
Generally speaking, no main line, class one diesel units have ANY sort of "auxiliary" on-board engine. With modern computer controlled units, the on board computer can shut down the prime mover, if the reverser is centered, and restart the prime mover if the cooling water gets too cold, air pressure gets too low, battery voltage gets too low, or the Engineer puts the reverser in forward/reverse. There is no need for any onboard "pony motor".
Actually, NS has equipped a lot of older units with "Auto-Shutdown" and the "auxiliary" motors to keep fluids warm. These units will not restart on their own.
As for the "computer controlled units" (Auto-Shutdown), if they have been manually shut down, they will not restart and they will drop their water if the tempurature gets too cold.
If the units have shut down from the "Auto-Shutdown" mode, they will more often than not start back up when the air pressure drops below appox. 108 psi. If they stay sitting still with the brake on, GE's will then stay running and not shut back down. I've never had a chance to ask anyone, but, it seems that even with the "Auto-Shutdown" feature these units will not shutdown if the air temperature is too low.
Originally Posted by Lee 145:
I have seen the UP start trains with as many as 8 units on the front. Only a few units will work hard while the rest are idling (Along for the ride) one or two more will join in the chant and pull when the entire train seems to be moving as one.
I can't remember the name of the device, but you were probably witnessing locomotives equipped to automatically put trailing engines on and off line instead of modulating the throttle, in order to keep the diesel engines in Run-8 as much as possible for fuel management.
Is it correct that if the front prime mover failed, you can keep moving with the trailing unit pushing you and pulling the train, assuming the trailing can pull the load and the front unit 74 volt batteries are charged enough to make the trailing unit controls work. Same idea as push pull service.
That's correct.
If you have the leading unit on the line, it pulls against the train and tracks straight. If you isolate it, it is being shoved by trailing units, and tends to hunt a bit from side to side and lurch somewhat on curves. Nothing serious, mind you, but just a characteristic change that occurs in ride quality. The ammeter on DC locomotives or the tractive effort meter on AC units, reads zero on any isolated unit(s) no matter the position in the locomotive consist.
Tom
