Bucyrus Thomas 9011: A locomotive engine is going to get the same fuel rate regardless if it is coasting down a hill or going up it. When you put the throttle into what ever notch you want,the throttle position is going to limit how much fuel is going to the injectors and limiting your speed. Locomotive engines are not like putting your car on cruise control when you go up and down a hill. The RPM's and fuel rate does not increase or decrease when you go faster or slower according to speed. If locomotives had accelerator pedals like cars do then we would see a wide range of fluctuations. But since they have notches that tell how much fuel the injectors will get at that notch it will stay constant at that notch no matter what speed they are going. Locomotive fuel use varies in any given throttle position. The throttle notches maintain the engine RPM, but the load regulator controls the fuel. To use your brick analogy, put a brick on the accelerator of a car on a level road where it balances out at 30 mph. When it comes to an ascending grade, it will slow down because the load increases, and throttle, being the only controller of how much fuel the engine gets, keeps the fuel feed constant. Put a locomotive in some notch where it runs level at 30 mph. When it comes to an ascending grade, the load regulator senses this additional load and begins to increase the electrical output in order to maintain the engine RPM. The load regulator adds more electrical loading to the generator and makes it harder to turn. Then the governor adds more fuel to match the added generator load. All the while, the throttle stays in the same notch. I would say you could state the fuel usage in each throttle notch with no load on the engine, but the information would not have much meaning for any practical comparison of locomotive work per fuel consumption.
Thomas 9011: A locomotive engine is going to get the same fuel rate regardless if it is coasting down a hill or going up it. When you put the throttle into what ever notch you want,the throttle position is going to limit how much fuel is going to the injectors and limiting your speed. Locomotive engines are not like putting your car on cruise control when you go up and down a hill. The RPM's and fuel rate does not increase or decrease when you go faster or slower according to speed. If locomotives had accelerator pedals like cars do then we would see a wide range of fluctuations. But since they have notches that tell how much fuel the injectors will get at that notch it will stay constant at that notch no matter what speed they are going.
A locomotive engine is going to get the same fuel rate regardless if it is coasting down a hill or going up it. When you put the throttle into what ever notch you want,the throttle position is going to limit how much fuel is going to the injectors and limiting your speed.
Locomotive engines are not like putting your car on cruise control when you go up and down a hill. The RPM's and fuel rate does not increase or decrease when you go faster or slower according to speed.
If locomotives had accelerator pedals like cars do then we would see a wide range of fluctuations. But since they have notches that tell how much fuel the injectors will get at that notch it will stay constant at that notch no matter what speed they are going.
I would say you could state the fuel usage in each throttle notch with no load on the engine, but the information would not have much meaning for any practical comparison of locomotive work per fuel consumption.
That's not why the load regulator moves when the train comes to a hill. The LOAD on the engine remains the same. The HP output is the same regardless (with very minor differences) of speed.
What happens when the train starts going up grades is this. The traction motors slow down. The back EMF decreases. The current increases because the back EMF went down. The total power consumed goes up because the voltage is the same (voltage is function of excitation of MG and speed of MG) and the current went up. This increased load slows the diesel engine down because the throttle rack is already at the balance point for that notch. The governor senses the engine slowing down and does two things. One, it advances the rack to get more fuel to the engine and, two, it backs off the load regulator to reduce the excitation. As long as the fuel rack is above the set balance point for that notch, the governor will continue to back off the load regulator until a steady state is reached where the rack is again a the balance point.
What this means is that the fuel curves given above are correct for nearly the entire speed range of the locomotive.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
I have an old Fuel Consumption Chart that list the following:
HP MODEL IDLE GALS./HR LOW IDLE GALS./HR FULL LOAD GALS./HR
600 SW1 1.5 - - 35
1500 SW1500 3.8 2.8 90
1500 MP15DC 3.6 2.8 92
2000 GP38 5.0 3.5 124
2000 GP38-2 4.6 3.4 124
3500 GP50 5.2 4.1 191
3000 GP59 - - 2.4 149
3800 GP60 - - 2.9 186
1750 SD9 3.5 - - 115
3000 SD40,40-2 5.5 4.1 168
3500 SD50 - - 2.9 175
3800 SD60 - - 2.9 184
4000 SD70 - - 3.0 191
2250 B23-7 3.6 3.0 120
3000 B30-7 3.0 - - 152
3200 D8-32B 3.4 2.1 158
3600 B36-7 3.7 3.0 189
3000 C30-7 4.0 3.3 164
3900 C39-8 3.4 2.8 189
4000 D8-40C 3.7 2.5 192
4000 D9-40C 3.6 2.5 190
4000 D9-40CW 3.6 2.5 210
One thing to remember a diesel-electric locomotive is nothing more than a moving power plant. The engine turns an alternator that creates electricity for the traction motors. The more notches that you give the engine the more fuel you will burn. We are instructed to center the reverser when stopped so that the engine will go to the low idle setting to reduce fuel consumption. Most of our newer locomotives will actually shut down if you are stopped and do not move within 5 minutes. To keep the lead unit running we have a reset button to override this feature. Trailing units that are shut down will automatically start once move the lead unit's reverser handle.
I hope this helps!
Tim Garland
NS Locomotive Engineer
Bucyrus Yes, I was looking at it as a form of cruise control, but to maintain engine RPM, not track speed. But I can see what you are saying and I am re-thinking this. Let me ask this: Say you have a locomotive running on level track, say in notch 2, and traveling at a balance speed of say 30 mph or whatever that speed would be. Is that locomotive producing all the horsepower that it can possibly produce in notch 2?
Yes, I was looking at it as a form of cruise control, but to maintain engine RPM, not track speed. But I can see what you are saying and I am re-thinking this. Let me ask this: Say you have a locomotive running on level track, say in notch 2, and traveling at a balance speed of say 30 mph or whatever that speed would be.
Is that locomotive producing all the horsepower that it can possibly produce in notch 2?
Yes
Now say you add cars to the locomotive running in notch 2, and the load pulls the speed down to say 5 mph. At the same time, the voltage to the traction motors falls and the amperage rises. The RPM of the engine will remain constant. Does the fuel consumption remain exactly the same? I guess it would because the empty engine running at balance speed would be the same amount of work as the engine moving the cars and extra tonnage at a slower speed.
Correct
So then is it correct to say that the only thing the load regulator does is trade amperage for voltage and vice versa? What does the governor do? My understanding was that the governor adjusts the fuel to maintain constant engine RPM under a varying load. But you are saying that there is no varying load within any given throttle notch. Why have a governor then?
So then is it correct to say that the only thing the load regulator does is trade amperage for voltage and vice versa?
What does the governor do? My understanding was that the governor adjusts the fuel to maintain constant engine RPM under a varying load.
But you are saying that there is no varying load within any given throttle notch. Why have a governor then?
In the days before Microprocessor control and EFI, the throttle controlled the Governor. Increase the throttle one notch and different solenoids are energized on the Governor, which then mechanically recognizes that the engine speed is now too low. Hydraulic fluid flows to an actuator causing the fuelrack to move which causes the mechanical injectors to have a longer stroke, injecting more fuel into the engine, as the RPMs come up the Governor will sense that and stop the engine speed at the new desired speed. Before the days of Computers you needed a means to sense the engine speed and the Governor was it. The Governor also helped protect the engine if you had a baulky load regulator (One were the load regulator would "hunt" for the right load). Now if the load regulator and the Governor were set up right the "hunting" variation as conditions change would be so slight as to be barely noticeable, but if the bridge circuit was sticky or poorly adjusted you would feel noticeable surges.
Paul Milenkovic My understanding is that the effect of this control system is to maintain a nearly constant fuel consumption at a given throttle notch
My understanding is that the effect of this control system is to maintain a nearly constant fuel consumption at a given throttle notch
Referring to the Lemp system - The combination of battery (i.e. constant), shunt (proportional to output voltage) and differential series (field decreases with increasing current) windings created a nearly constant power output characteristic. Combining a differential series winding with a battery winding would give a nearly linear voltage current curve, adding the shunt winding makes the V-I curve distinctly non-linear, causing the voltage to rise faster at low output currents. The nearly constant power output meant that the generator was putting a nearly constant load on the prime mover and thus nearly constant fuel consumption for a given throttle notch. A very nice piece of work.
With an AC drive, the DC bus can be held constant and the inverter control set up to maintain constant power output.
- Erik
Bucyrus So then is it correct to say that the only thing the load regulator does is trade amperage for voltage and vice versa? What does the governor do? My understanding was that the governor adjusts the fuel to maintain constant engine RPM under a varying load. But you are saying that there is no varying load within any given throttle notch. Why have a governor then?
In place of the governor, you could have an "open loop" control system. The load regulator would regulate the generator load, the throttle notch would command the engine RPM for that much load, and one would employ a look-up table to program how much fuel to inject into the engine to achieve that RPM. The advantage of the "closed loop" control in having a governor regulate injection to achieve an RPM target is that the control system can compensate for the "known unknowns" of engine friction, air temperature and pressure, etc. that would make the preprogrammed fuel delivery be "off" in the engine RPMs.
I don't know what they do know in computer-controlled AC traction motor locomotives, but electrical engineering Herman Lemp invented the classical Diesel-electric drive control system, where the generator load and engine RPM's were coordinated in their settings in response to a single throttle handle, and closed-loop control was applied to both the engine fuel rack and the generator excitor.
My understanding is that the effect of this control system is to maintain a nearly constant fuel consumption at a given throttle notch, but the very fact that the fuel rack is under closed-loop control means that the precise fuel use may vary a little bit depending on operating conditions. On the other hand, Notch 8 hooked up to a heavy train means you accelerate slowly (provided you are going fast enough that you don't slip the wheels) whereas Notch 8 with a light locomotive means that you really scoot, but the fuel consumption in each case should be roughly the same.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
timz As speed decreases, the electrical output in amps increases. The electrical output in kilowatts remains about the same-- at least that's what the control system is trying to do. Constant kilowatts out of the main generator demands about constant horsepower into the main generator-- and constant fuel burn. Your logic would apply in Run 8 same as any other notch. When a passenger train is accelerating from 20 mph to 100 mph with the throttle staying in Run 8, do you think its fuel burn at 100 mph is a third to a quarter of its burn at 20-30 mph?
As speed decreases, the electrical output in amps increases. The electrical output in kilowatts remains about the same-- at least that's what the control system is trying to do. Constant kilowatts out of the main generator demands about constant horsepower into the main generator-- and constant fuel burn.
Right Tim, what Bucyrus is describing is a form of cruise control.
As long as the electrical output of the Main Generator/Alternator expressed in Watts doesn't change then the load on the diesel engine doesn't change.
Using Joule's Law P= I*V where P is the Power in Watts, I is the Amperage in Amps, and V is the Voltage in Volts. If P must stay constant then as I goes up V must fall proportionately, an v.v.
Now consider the Traction Motor circuit using Ohm's Law where the I and V of the above equation are the same values. I = V/R. Now with a series wound DC motor "R" will increase as train speed and hence motor speed increase and v.v. The load regulator will compensate for decreasing Amp flow as speed increases by increasing the Voltage. The system will remain in balance and the load on the diesel will remain the same. The amount of power flowing to the traction motors will determine the torque that they produce, and the torque through the leverage of the gearing will determine the tractive effort. Finally the tractive effort offset by the train resistance will determine the speed.
BucyrusPut a locomotive in some notch where it runs level at 30 mph. When it comes to an ascending grade, the load regulator senses this additional load and begins to increase the electrical output in order to maintain the engine RPM. The load regulator adds more electrical loading to the generator and makes it harder to turn. Then the governor adds more fuel to match the added generator load. All the while, the throttle stays in the same notch.
Your logic would apply in Run 8 same as any other notch. When a passenger train is accelerating from 20 mph to 100 mph with the throttle staying in Run 8, do you think its fuel burn at 100 mph is a third to a quarter of its burn at 20-30 mph?
tdmidget Maybe we are speaking different languages here. Each notch is a governor setting. The engine will not exceed a set speed in that notch, and will always try to accelerate to that speed. Thus , going uphill it will add fuel trying to maintain that speed and downhill will drop back to idle fuel flow if there is no load on the engine. It will not consume a given fuel flow because of the throttle setting. The published numbers are probably at full load, which would not be frequently achieved because the engineer would have advanced to a higher notch.
Maybe we are speaking different languages here. Each notch is a governor setting. The engine will not exceed a set speed in that notch, and will always try to accelerate to that speed. Thus , going uphill it will add fuel trying to maintain that speed and downhill will drop back to idle fuel flow if there is no load on the engine. It will not consume a given fuel flow because of the throttle setting. The published numbers are probably at full load, which would not be frequently achieved because the engineer would have advanced to a higher notch.
Obviously we are speaking different languages, it sounds like your experience is with marine or truck diesels. In the case of a locomotive the "load" on the diesel engine is the same for a given throttle position for a locomotive no matter whether you have only a locomotive or you're coupled to a 10,000 ton train, and the load is the same going uphill or down. The load regulator ensures that the Main Generator/Alternator puts the same load on the diesel. Subject to its limitations it will try and keep the load the same.
These numbers at full load would only be of use as a reference point, to possibly compare locomotives or manufacturers. They cannot be used to predict fuel consumption to any degree beyond "more" or "less".
There are a whole slew of factors, from condition of the air filters, to fuel quality and on and on.
There is a slight difference and fluctuation in RPM's and fuel rate when putting a heavy load a locomotive because it has to work a little harder to keep the same RPM's at that notch level. But the locomotive wasn't designed to have this wide range of fluctuations going up and down in power at a set notch level. The locomotive was specifically designed to put out a certain amount of current at that notch. No more and no less. The RPM's were to remain constant so the load would remain constant and thus the engineer wouldn't be moving the throttle back and forth constantly because the engine RPM's are going up and down at that notch level.
Going downhill has no effect on the engine at all. Just like a model train if you keep it at the same power going uphill and do not change it, it will speed downhill twice as fast. It is the exact same thing with a real train.
The numbers concerning fuel consumption are going to be around the same on that chart regardless if it under a load or not. You have to remember that locomotives have more then enough power on those lower notches and the RPM's,current,and fuel rate is going to stay the same regardless if it is on flat ground or starting on a hill.
I think what you have a hard time understanding is unlike a car,if you put a locomotive in notch 1 with a heavy train the engine reeves up but nothing is moving. Does the engine keep reeving up to move the train? No the engine just keeps maintaining that RPM,fuel rate and current despite nothing moving. So the engineer has to move it to notch 2 and the RPM's reeve up along with more fuel,and more current. Maybe the train moves maybe it doesn't but the engine still maintains that RPM and fuel rate. If the train still doesn't move he has to move it to notch 3 and to higher RPM's and higher fuel rates.
So to a locomotive does it make any difference if we started a 10 car train up a steep grade with so much of a load,or if we started pulling a 40 car train on level track with the same load? Either way the locomotive has to pull this load to a certain speed and that is all the engine knows. That is why they can come up with the numbers they do. They know the tractive effort limit at every notch and using that they can tell fuel rate as it can not produce more power than it was designed for.
That chart looks a lot like one I have in an older pamphlet (1980) issued by the Railway Fuel and Operating Officers Association on the subject of fuel conservation.
Jeff
tdmidget Those numbers are meaningless. Let's just compare 2 of them, the SW1000 and the GP38. Do you really believe that the GP38 , with twice the engine, could produce 2,000 HP while burning less fuel than the SW1,000 requires to produce 1,000? Why would anyone buy the SW1000 when he could have twice the horsepower with less fuel consumption.
Those numbers are meaningless. Let's just compare 2 of them, the SW1000 and the GP38. Do you really believe that the GP38 , with twice the engine, could produce 2,000 HP while burning less fuel than the SW1,000 requires to produce 1,000? Why would anyone buy the SW1000 when he could have twice the horsepower with less fuel consumption.
Look at the chart again, in throttle position #8 the SW1000 is burning 60 gph, the GP38 is burning 122.4 gph. Also remember that at low speeds, if they weigh the same the SW1000, can move any train that the GP38 can move.
Don't know where you got those numbers but I think someone is pulling your leg. Picture this: A locomotive ascends a 1% grade in run 2. It crests the hill and descends an equal grade, again in run 2. Does it require the same fuel consumption ascending and descending? Is the load the same?
Don't know where you got those numbers but I think someone is pulling your leg. Picture this: A locomotive ascends a 1% grade in run 2. It crests the hill and descends an equal grade, again in run 2. Does it require the same fuel consumption ascending and descending?
Is the load the same?
When you advance the throttle on a locomotive you increase the fuel injected into the diesel increasing the rpms, the load regulator senses that and increases the field strength on the Main Generator (Alternator), not the other way around, the train will accelerate until the resistance (rolling, grade, and aero) offsets the increased power coming from the engine. When the train crests a hill if the engineer makes no changes in the throttle setting with the grade resistance going from positive to negative, and most likely being a larger quantity that rolling resistance, the train will accelerate very fast. The load regulator will try and compensate by going to maximum field strength (maximum voltage).
When a locomotive comes out of overhaul it normally gets put on a load bank. In the case of a GP38 which is rated for 2000hp. (1492kW) once the initial run-in is completed and the engine is fully up to temperature. The throttle is advanced to position #8, once everything restabilizes, the Mechanic will adjust the fuel injector rack settings via the layshaft until the output meter on the load bank reads 1492kW plus or minus a small amount.
Remember on a locomotive engine speed and wheel speed are not linked, unlike a truck with its mechanical transmission, or most ships with a fixed reduction gear transmission.
If you increase the electrical loading on the generator, the engine has to work harder to maintain the same RPM. The load varies on the generator, and the engine feels that variation in load.
Wrong a Diesle Motor that has a Genarator on it the Governor is used to load and Unload the Genarator ONLY the Motor runs at the Same load all the Time. Which means the same fuel usage all the time.
Thomas 9011 A locomotive engine is going to get the same fuel rate regardless if it is coasting down a hill or going up it. When you put the throttle into what ever notch you want,the throttle position is going to limit how much fuel is going to the injectors and limiting your speed. Locomotive engines are not like putting your car on cruise control when you go up and down a hill. The RPM's and fuel rate does not increase or decrease when you go faster or slower according to speed. If locomotives had accelerator pedals like cars do then we would see a wide range of fluctuations. But since they have notches that tell how much fuel the injectors will get at that notch it will stay constant at that notch no matter what speed they are going.
Locomotive fuel use varies in any given throttle position.
The throttle notches maintain the engine RPM, but the load regulator controls the fuel. To use your brick analogy, put a brick on the accelerator of a car on a level road where it balances out at 30 mph. When it comes to an ascending grade, it will slow down because the load increases, and throttle, being the only controller of how much fuel the engine gets, keeps the fuel feed constant.
Put a locomotive in some notch where it runs level at 30 mph. When it comes to an ascending grade, the load regulator senses this additional load and begins to increase the electrical output in order to maintain the engine RPM. The load regulator adds more electrical loading to the generator and makes it harder to turn. Then the governor adds more fuel to match the added generator load. All the while, the throttle stays in the same notch.
As a former locomotive mechanic those number seem dead on accurate to me. I know the SD70's had computers that told you exactly how much fuel per hour they were using in real time and in stored memory from the last couple of trips.
You need to read the chart again. A GP38 is burning twice as much fuel as a SW1000 except at notch 8 and idle. A SW1000 also does not have a turbocharger which is probably why it at notch 8 it has the same fuel consumption as a GP38.
Locomotive engines are not like putting your car on cruise control when you go up and down a hill. The RPM's and fuel rate does not increase or decrease when you go faster or slower according to speed. If you were to have your throttle position in notch 2 going down a hill your locomotive would keep going faster and faster until you moved it back to idle. Imagine putting a brick on your throttle and running at 30mph with no brakes. Going up or down a hill would either slow it down or speed it up. It is no different with a locomotive.
A better example would be to have a locomotive at notch 8 stalled on a hill not moving but at full throttle. A locomotive is not like a car where the steeper a grade is the more it bogs the engine down and the more the RPMS drop. At notch 8 the locomotive will be at full throttle and full RPM'S but if the load is too heavy the locomotive will just go slower and slower until it stops but the engine will still be running at full RPM's roaring like crazy regardless of how or slow the train is moving.
Here is what I have in the way of information now. I would like to get the same for as many locomotives as possible.
Run 5 sets the governor for the engine to turn over at X RPM....if the locomotive load meter is indicating that the load on the Main Generator is 300 AMPS it will take X amount of fuel to turn the engine at that RPM, if the Main Generator is loaded to 1000 AMPS it will take X+ amount of fuel to turn the engine at that designated RPM account of the additional load placed on the generator. This applies at any notch setting. It takes more fuel to turn the engine at the governor set RPM as the generator load increases.
timz tdmidget: So a given [throttle] position will have varying fuel consumption depending on speed, weight, hills, curves, etc. No idea whether that's true, but presumably it's not supposed to be true. In Run 5 the locomotive is probably supposed to be producing a constant horsepower (about half of its rating)-- and consuming a constant gals/hour of fuel. Maybe in the old days the control systems didn't work well enough to achieve that, but I'm guessing that's what Baldwin and FM and Alco were all aiming at, along with EMD and GE. (And of course no locomotive can produce constant horsepower at 1 mph-- so fuel consumption in Run 5 at 1 mph will be much less than the usual. But from 10-15? mph on up, gallons/hour will hopefully be near constant in a given throttle notch.)
tdmidget: So a given [throttle] position will have varying fuel consumption depending on speed, weight, hills, curves, etc.
(And of course no locomotive can produce constant horsepower at 1 mph-- so fuel consumption in Run 5 at 1 mph will be much less than the usual. But from 10-15? mph on up, gallons/hour will hopefully be near constant in a given throttle notch.)
Never too old to have a happy childhood!
tdmidgetSo a given [throttle] position will have varying fuel consumption depending on speed, weight, hills, curves, etc.
I am looking for prototype information. I was explining how I will use this information. Be polite please.
Your "layout"? DCC? As I previously noted , there is no correlation to speed. Speed is not the same as load.
This is not the toy train forum.
My layout is DCC. Each engines decoder is set to actual MPH, so the computer progrm will be able to recieve this information and compute fuel usage.
How about 0.05 gal. per horsepower - hour for computational purposes. Now all you have to do is figure out what the horsepower is or 0.067 gal. per KW - HR if its connected to a meter.
Not possible unless you specify a load on the engine. A Diesel engine's governor supplies fuel in response to the load, attempting to maintain speed. So a given position will have varying fuel consumption depending on speed, weight, hills, curves, etc.
Does anyone know where I can get the diesel locomotove fuel usage in gallons per hour for idel and all 8 run positions? I have some of the EMD and a few of the GE's, but none of the Alco, BLW o FM's.
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