I seem to recall that Milwaukee 261 has HEP located in the tender somewhere??
RME This is SPECIFICALLY a concern for any Roots-blown EMD engine, which is a relative 'fuel hog' in part because the blower load goes up out of proportion to the developed rpm even at relatively low developed crankshaft torque. Yes, it's still a concern on an EMD turbo engine, but I'd like to hear a dollar maintenance-cost comparison of engines that spend a large portion of their life throttling up and down through the engagement and disengagement range of their mechanical low-speed turbo drives vs. engines that can operate in reasonably full turbo boost (which is related to the 70-odd percent of actual engine power used to hold rpm, as that shows up in the exhaust heat and volume) and without repeated rotational engine-speed changes that would otherwise be characteristic of most commuter service. The issue is more than sfc at different rotational speed, it's overall capital and maintenance cost for the alternatives, and that includes concerns like the dead load and packaging of the gensets. Look back in part at the discussion about why streamliners did not retain the multiple Cummins generator setups of some early prototypes...
This is SPECIFICALLY a concern for any Roots-blown EMD engine, which is a relative 'fuel hog' in part because the blower load goes up out of proportion to the developed rpm even at relatively low developed crankshaft torque. Yes, it's still a concern on an EMD turbo engine, but I'd like to hear a dollar maintenance-cost comparison of engines that spend a large portion of their life throttling up and down through the engagement and disengagement range of their mechanical low-speed turbo drives vs. engines that can operate in reasonably full turbo boost (which is related to the 70-odd percent of actual engine power used to hold rpm, as that shows up in the exhaust heat and volume) and without repeated rotational engine-speed changes that would otherwise be characteristic of most commuter service. The issue is more than sfc at different rotational speed, it's overall capital and maintenance cost for the alternatives, and that includes concerns like the dead load and packaging of the gensets. Look back in part at the discussion about why streamliners did not retain the multiple Cummins generator setups of some early prototypes...
Nuclear News, the house organ for the American Nuclear Society, ran a bimonthly column "On Line with Verna" describing various issues with operations of nuclear genertaing stations. One of the topics was problems with the overrunning clutch on the EMD engines often used for emergency back up, specifically when running at power levels where the clutch would be frequently engaging/disengaging.
I would also think that the SFC for the inverter based HEP with a variable speed prime mover would be more efficient than a constant speed prime mover. Using the same prime mover for traction and HEP does make for a lighter and smaller package than a separate genset plus prime mover.
As for early streamliners, a few of the UP's "City" trainsets had HEP, with electric resistance heating in supplementing steam heat. Despite the losses in converting diesel fuel to electricity, the resistance heating used less fuel than steam heat.
- Erik
RME I'm quoting the original for clarity of my comments (such as it is). Paul Milenkovic So why the effort to replace gensets for HEP (such as on the Chicago and Northwestern commuter F7's and E8's and 9's) with constant-RPM prime movers running both the traction and HEP alternators? This deserves a more specific set of comments that in my opinion it has gotten so far. I was blissfully unaware that any operation with genset-equipped power had torn out the installation in favor of synchronous-prime-mover-speed AC HEP generation. I would (perhaps in ignorance) think that the situation might be different for HEP using synthesized frequency and phase, where the prime-mover load is more or less precisely governed to match aggregate HEP and traction demand with relatively low latency (essentially for maintenance and pollution reasons) -- this would allow removal of the relatively heavy and bulky gensets and associated systems, and their separate maintenance concerns. Isn't running the prime mover at full RPM all the time "heavy on fuel"? Yes, I know, the "throttle rack" setting is adjusted to match the load on the alternator, but idling a Diesel, any engine, at full RPM must use more fuel than low RPM idle on account of mechanical friction in the engine? This is SPECIFICALLY a concern for any Roots-blown EMD engine, which is a relative 'fuel hog' in part because the blower load goes up out of proportion to the developed rpm even at relatively low developed crankshaft torque. Yes, it's still a concern on an EMD turbo engine, but I'd like to hear a dollar maintenance-cost comparison of engines that spend a large portion of their life throttling up and down through the engagement and disengagement range of their mechanical low-speed turbo drives vs. engines that can operate in reasonably full turbo boost (which is related to the 70-odd percent of actual engine power used to hold rpm, as that shows up in the exhaust heat and volume) and without repeated rotational engine-speed changes that would otherwise be characteristic of most commuter service. The issue is more than sfc at different rotational speed, it's overall capital and maintenance cost for the alternatives, and that includes concerns like the dead load and packaging of the gensets. Look back in part at the discussion about why streamliners did not retain the multiple Cummins generator setups of some early prototypes... I do not think most mechanical comparisons to small air-cooled spark-ignition engines, of the kind found in lawn and garden equipment, are particularly applicable in this particular context, in part because issues of fuel economy are not, I think, the determinants either of equipment detail design or the choice of engine technology in those applications. Presumably these engines are designed to be run at constant power and rated load 'indefinitely', in part because their cooling is optimized at the higher speed, are not governed with any particular sophistication so they could make better-optimized torque at lower rotational speed, and the application calls for the cheapest, and perhaps smallest or lightest, engine that will serve in the application effectively. (I'm not implying that in a pejorative sense. The 8hp cast-iron-block Kohler in my Troy-Bilt Horse is a 'better' engine than the optional Briggs... but it is certainly not what an equivalent Hatz would be, nor is it a Kubota diesel like that in a Walker MHD. It's interesting to speculate what the advantages of pressure-charging equipment in this price, durability, and 'ease of use' range might be...)
I'm quoting the original for clarity of my comments (such as it is).
Paul Milenkovic So why the effort to replace gensets for HEP (such as on the Chicago and Northwestern commuter F7's and E8's and 9's) with constant-RPM prime movers running both the traction and HEP alternators?
This deserves a more specific set of comments that in my opinion it has gotten so far. I was blissfully unaware that any operation with genset-equipped power had torn out the installation in favor of synchronous-prime-mover-speed AC HEP generation. I would (perhaps in ignorance) think that the situation might be different for HEP using synthesized frequency and phase, where the prime-mover load is more or less precisely governed to match aggregate HEP and traction demand with relatively low latency (essentially for maintenance and pollution reasons) -- this would allow removal of the relatively heavy and bulky gensets and associated systems, and their separate maintenance concerns.
Isn't running the prime mover at full RPM all the time "heavy on fuel"? Yes, I know, the "throttle rack" setting is adjusted to match the load on the alternator, but idling a Diesel, any engine, at full RPM must use more fuel than low RPM idle on account of mechanical friction in the engine?
I do not think most mechanical comparisons to small air-cooled spark-ignition engines, of the kind found in lawn and garden equipment, are particularly applicable in this particular context, in part because issues of fuel economy are not, I think, the determinants either of equipment detail design or the choice of engine technology in those applications. Presumably these engines are designed to be run at constant power and rated load 'indefinitely', in part because their cooling is optimized at the higher speed, are not governed with any particular sophistication so they could make better-optimized torque at lower rotational speed, and the application calls for the cheapest, and perhaps smallest or lightest, engine that will serve in the application effectively. (I'm not implying that in a pejorative sense. The 8hp cast-iron-block Kohler in my Troy-Bilt Horse is a 'better' engine than the optional Briggs... but it is certainly not what an equivalent Hatz would be, nor is it a Kubota diesel like that in a Walker MHD. It's interesting to speculate what the advantages of pressure-charging equipment in this price, durability, and 'ease of use' range might be...)
Completely agreed, and as stated, the lawn tractor example was simply another case where constant RPM is an advantage. No doubt the railroad application it is a tradeoff - the question is how big a tradeoff?
And, as stated, since my interest in this converstation was to clarifiy steam era passenger technology, and I have no interest in how or why passenger cars are heated/cooled or illuminated today, I will leave you all to it.
And, yes, in their day, the Kohler Magnum twin, or the Onan twin, were both relatively "expensive" small engines, both being originally designed for full throttle generator applications - but yes, they are relatively simple in design........
Sheldon
Paul MilenkovicSo why the effort to replace gensets for HEP (such as on the Chicago and Northwestern commuter F7's and E8's and 9's) with constant-RPM prime movers running both the traction and HEP alternators?
Paul Milenkovic So why the effort to replace gensets for HEP (such as on the Chicago and Northwestern commuter F7's and E8's and 9's) with constant-RPM prime movers running both the traction and HEP alternators? Isn't running the prime mover at full RPM all the time "heavy on fuel"? Yes, I know, the "throttle rack" setting is adjusted to match the load on the alternator, but idling a Diesel, any engine, at full RPM must use more fuel than low RPM idle on account of mechanical friction in the engine?
So why the effort to replace gensets for HEP (such as on the Chicago and Northwestern commuter F7's and E8's and 9's) with constant-RPM prime movers running both the traction and HEP alternators?
As explained, I have no idea why this approach was taken......except, maybe the fuel penalty is small?
I do have some background in internal combustion egines, and will share a much smaller scale example.
I use a 20 year old GRAVELY 18-G garden tractor to cut my lawn and clear snow from my driveway. It is a rear engine, gear drive tractor with an 8 speed gearbox and seperate forward and reverse clutches. It is powered by a horizontal opposed twin cylinder Kohler governed gas engine, 43 cid, 18 HP. For nearly every task the machine is designed to do, the manufacturer recommends running the engine at full throttle, 3600 RPM, and selecting the gear that provides the proper ground speed for that task.
Considering the limited RPM range and power curve of most diesel prime movers, there may not be much difference in the two approaches in terms of wear or fuel consumption.
In the case of the garden tractor, constant PTO speed is desired for mower deck, snow blower, rotary cultivators, etc, and maximum torque for changes in load is desirable. So changing ground speed with the throttle is not desireable.
The raiload application may not be much different? Just a thought?
But as I said, I have not paid much attention to prototype railroading of the last 30-40 years.....
HEP alternator locomotives do use more fuel than HEP generator locomotives for commuter service, but in long distance service where the prime mover is running at high throttle notches for longer periods of time, this is less of a concern.
The early gensets were used as a way to make as little modification as possible to make locomotives suitable for commuter service. Later commuter locomotives were almost entirely based off of the F40PH, which was originally designed for long distance service in the era of cheap fuel. The design philosophy changed in the late 1980s, with gensets becoming more popular than alternators, which they remain.
Paul, I don't know the history or reasons for each railroads specific decissions, experiments and choices. I answered the question in the broad historical sense.
North American railroads all acted independently back in the day, and there were hundreds of railroads, each with its own mechanical department managements.
Not like today with just a few big conglomerates. But they did have to maintain interchange standards except for captive equipment that never left their trackage or who's consists were never seperated.
Since many sleepers were part of the Pullman pool service, or traveled from railroad to railroad on transcontinental routes, steam powered heat and air remained the standard.
Railroads simply could not afford to upgrade older, but still serviceable equipment in the 50's or 60's. The loss of the post office contracts sealed the fate of privately run rail passenger service in the US.
To be clear, my knowledge is more centered in pre 1960's railroading. I am a modeler who models the the 1950's. I have very little interest in current day railroading and do not follow current stuff much.
But this original question was steam era/steam loco related, and area where I have considerable knowledge, even if not about all 400 common carrier railroads that existed in North America at that time.....
Honesly, I am amazed at how unaware many current rail fans of how trains worked back in the day.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
M636C For some reason (compatibility?) the widespread adoption of HEP was delayed forty years or so until Amtrak. M636C
For some reason (compatibility?) the widespread adoption of HEP was delayed forty years or so until Amtrak.
M636C
The reason is simple - diesel electric locomotives do not have a constant engine RPM or voltage output, so HEP requires a seperate source. So really what is the difference? steam generator or HEP unit?
When diesels began to replace steam locos nearly the entire national fleet of passenger cars was steam heated and steam A/C equiped - no incentive for a new system.
Passenger service was also in decline - no incentive to replace or upgrade passenger cars - not broken, don't fix it.
Sure, starting from scratch, HEP is easier/better, but was not pratical in 1910, or even 1940. So until the last of the steam heated passenger cars began to reach the end of their service life in the 70's/80's, there was no incentive to change.
The exception being captive service unit trains like commuter services, etc.
Santa Fe Hi-Levels did have on-board diesel AC plants. ACL also had a large group of steam ejection equipped cars. Some engines in commuter service had lighting generators, but they were generally used with "non-interchange" commuter coaches.
I read up on the Santa Fe passenger cars. They used Steam ejection for air conditioning. Even in the middle of the desert they needed to use the Steam Generator of the train to provide cooling for the cars. Must have worked pretty well as they did it for years.
Since no one has completely answered this question, I will give it a shot.
In North America, from the early 1900's until the 1970's, the interchange standard for passenger cars was steam heat, axle driven generators and batteries for electric lights.
Except for a few specific deticated consists, as mentioned by others above, North American passenger trains did not use head end power until the late 1970's.
In the 30's thru the 60's there was some use of stand alone diesel generator sets on some streamlined passenger cars.
Also, there is the issue of air conditioning - original heavyweight era cars used ice and salt brine systems. Later a number of different systems were used before head end power came along.
Steam locos generally only generated enough power for the locomotive electrical system, which was mainly just lights.
North American passenger equipment is/was equiped with a different version of the Westinghouse air brake that offered better control but did not use/require electricity. The "UC" and "HSC" brake systems provide the extra features desired for passenger service.
timz EDWARD ROSENBERG head-end power, supplied by a 220-volt, three-phase AC generator What cars did the steam turbine send HEP to?
EDWARD ROSENBERG head-end power, supplied by a 220-volt, three-phase AC generator
What cars did the steam turbine send HEP to?
If the two turbines were so fitted, I'd expect the intention was to use them on the 1937 City of San Francisco and City of Los Angeles. These trains were built with a three unit E2 locomotive each and an 80 feet long HEP power car equipped with Winton diesels supplying power for lighting, air conditioning and cooking power. Later City trains reverted to axle driven power and steam heating.
The articulated Burlington Zephyrs powered by the E-5 units had Cummins generators in the front end of the leading baggage car for the same purpose.
EDWARD ROSENBERGhead-end power, supplied by a 220-volt, three-phase AC generator
I don't know if this is relevant, but the two steam turbine-electrics built by GE for Union Pacific in 1939 were probably the first locomotives in North America at least, to be equipped with head-end power, supplied by a 220-volt, three-phase AC generator which also provided power for traction motor blowers. Please correct me if I am wrong on any of this.
Deleted post. Should have read all other posts before posting mine.
ChuckAllen, TX
The Milwaukee had HEP for lighting LD trains in the years prior and after WW1, this was usually powered by a GE turbogenerator for steam locomotives and the low voltage M-G set on the electrified divisions.
GE made a turbogenerator set for train lighting, ISTR output power was about 25 kW, with steam supplied from the steam heating line. The rationale was that the generator would be less of a demand on the locomotive than all of the axle generators and also allowed for smaller batteries.
M636C said pretty much what I had to say. In even earlier eras the heater was a coal stove.
While I made a (dangerous) blanket statement, the major point was that HEP was reserved almost solely for commuter operations during most of the steam era in the US. Longer distance trains could be assumed to be in motion enough that batteries and axle generators could supply a ready amount of electricity to power any appliances.
timz NorthWest In the age of steam most cars were steam heated and had gas lighting. In, say, 1940 gas lighting was... pretty rare? When was the last car built with gas lighting in the US?
NorthWest In the age of steam most cars were steam heated and had gas lighting.
In, say, 1940 gas lighting was... pretty rare?
When was the last car built with gas lighting in the US?
Sorry, Covers information already posted.
Thank You.
Somewhat related, if you watch videos of trains in India you'll usually see one or two power cars in the consist. Evidently the locomotives are strong enough to pull really long trains and it's worth conserving the horsepower by using power cars for HEP.
Or, they might just not have the funds to upgrade (or most likely fix) the HEP in the locomotives, or they don't want to run two locomotives just to provide HEP.
rcdryeSP never did use lighting generators, relying on axle generators and batteries (and steam heat) until Caltrain took over.
C&NW had lighting generators on locomotives assigned to commuter service before the 1958 HEP conversion began (C&NW's first bilevels were steam heated, and ran behind steam until 1956 or so). Burlington used lighting generators as well, though their shops rebuilt single-level cars to house power generators for bilevels (which did run behnd steam until 1952!). SP never did use lighting generators, relying on axle generators and batteries (and steam heat) until Caltrain took over.
On the CNJ steam locomotives did provide electricity to commuter cars for lighting. They had large generators on the rear deck of the tender. Heatng cars was done by steam.
NorthWestIn the age of steam most cars were steam heated and had gas lighting.
In 1886, 2-2-2 inside cylinder passenger locomotive No 15 of the Australian New South Wales Government Railways was fitted with a steam engine and generator on the rear of the tender above the water tank. This was initially to provide power for electric lighting to the freight shed in Albury (on the border with the state of Victoria) for a banquet and formal dance to celebrate the linking of the railways between Australia's two biggest cities.
Subsequently, this locomotive was used with a new business train which was equipped with electric light powered from the generator. The train was found to be unsatisfactory due to a new suspension design. When it appeared later rebuilt with conventional trucks, it had gas lighting fitted in new clerestories on the roof.
This is thought to be the first application of HEP from the locomotive.
The Southern Pacific GS-4 and GS-5 locomotives each had three turbo generators, two to power the headlight and locomotive lighting and the third to power the electro-pneumatic braking on the train. So a small amount of power went from the loco to the "Daylight" trains, although most train power for lighting and air conditioning was from axle driven generators and batteries.
CandOforprogress2 Or is power generated from the car wheels?
Or is power generated from the car wheels?
It's common nowadays for excursion trains pulled by steam locomotives (i.e Union Pacific's Steam Program) to have a generator car (generally a converted baggage car with a diesel genset) in the consist to supply HEP.
The turbogenerator of a steam locomotive does not generate enough power to provide HEP...
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Commuter cars often did have axle generators. In the age of steam most cars were steam heated and had gas lighting. Some locomotives, particularly in commuter service, had second dynamos to supply some power to cars.
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