As my subject told you, does the engineer in the cab have any control over the diesel engine, or does the engine just react according to the demand of electricity from the traction motor? When the engineer set the trottle to notch 4, is this action control only the output of the generator or the output of the diesel engine or both YM
The short answer is 'both' but it depends on the locomotive. There's a great thread from April that goes into some detail on how this works. why 8 notches on the throttle
Yankinoz gave my answer too. It's not too terribly complicated, the control settings allow X voltage to apply to the traction motors while in series by passing it through a series of resistance, or allow full voltages to apply while in parallel. The Diesel engine is responding to the need to produce more electricity to meet the pre-determined settings of the control notches. The engine also produces electricity to supply HEP to passenger trains(and usually requires throttle 3 for that demand) and to operate ancillary equipment(headlights, whistles, alerters, heaters, air compressors, fuel pumps, fans etc.
So I understand that is't impossible for the engineer to make the diesel motor turn faster while the loco is still idling on the track... Right YM
I believe that in a standard modern diesel locomotive, the Engineer does not have direct control over the RPMs of the diesel motor. But I could be wrong - I have not looked at this in a long time but the EMD SD40-2 Operator Manual is ON-Line http://gelwood.railfan.net/manual/sd40-2i.html
Actually, the throttle does control the RPMs of the prime mover. Each notch is specifically calibrated to make the PM turn at a certain RPM. These were determined to be "stable" RPMs, meaning that at some RPMs the vibrations produced are not good for the life of the locomotive (it would vibrate apart, basically). As the PM increases RPMs, the main generator is turning faster, and therefore producing more electricity for the traction motors. The engineer must monitor the amperes that are being passed to the traction motors to ensure that they don't get fried. This is especially important when starting a train moving. Unlike a car, where you can floor the accelerator and spin the tires, doing the same to a locomotive will result in too much electricity flowing to the traction motors, and you will either get wheel slip (and burn a rut into the rail), or you will melt the guts of the traction motor. How fast a train moves depends on how much weight you are pulling, how much power you have to pull it with, what the grade is, and available braking power, to name the major factors. While notch 1 may get you up to 20MPH with a single locomotive on level ground, notch 1 with several cars behind it may not move at all. It's a definite challenge (one that I hope to master in the future)!
The Engineer *can* cause the RPM's to go higher by moving the throttle to a notch above "idle" while the train's direction lever is in the neutral position (neither forward or reverse
On locomotives with a mechanical link to the air compressor, this is done quite often to speed up the pumping of air to affect a brake release. The highest throttle position which may be used will be defined by the individual railroads own rules. On the BNSF it is throttle 4.
Engine rpm can be increased in either forward neutral or reverse by increasing the throttle a notch or more. Engine rpm has to be increased to turn the Generator,Alternator to produce amperage to drive the traction motors in forward or reverse. Rpm is also increased to pump up air in a hurry to get under way. Art
Gee, steam was so simple! Full horsepower at all times, pull the throttle and GO! Just crack the throttle and you had 5,000 horsepower and she would lean into it like a snorting beast, and out on the line she still had 5,000 horses running at 70 per! What a gal! She would talk to you in the moon light, and you soon fell in love with her. In my opinion, the deezul painted kiddy cars are like a nagging wife, they just drone on..and...on....and.....on......and.......on........while you are jumping up and down trying to keep her from overheating! Bite me B****!!
What are us 'deezul' burners gonna do with you Watash? LOL. Your descriptions of my home-away-from-home always keep me smiling.
This must be why I feel at home sitting next to the yard listening to them engines hum!LOL! Russ Hoffman Valley RR
