Locomotive horsepower

[jchnhtfd]

QUOTE: Originally posted by HighIron2003ar

Great thread about Horsepower, what about STEAM horsepower?? So much effort on the tractive side little info on HP.

NOW you're looking at a can of worms[:D]! It's no big deal to measure the horsepower of a diesel engine, or electric motor... but steam?[:(] Not so simple. Not only can it be reasonably said that a diesel engine will maintain a given horsepower more or less indefinetly (until it runs out of fuel!), but it is pretty well independent of the speed of the engine on the track. A steam engine, on the other hand... keep in mind that horsepower is the product of torque and rpm, or tractive effort and track speed (with the odd constant thrown in for fun). The tractive effort of a steam engine is relatively easy to quantify, assuming that you don't allow wheel spin -- it's related to boiler pressure and cylinder diameter. The horsepower a given steam engine is capable of, then is related to boiler pressure, cylinder diameter -- and track speed. Simple enough? No. The real problem is that you also have to figure in what the steam engine can actually maintain -- and that is related to the grate area, quality of the fuel, and -- not just a little -- the skill of the fireman. The Erie Triplex (2-8-8-8-2!) back in 1915 was a neat example of how NOT to do it -- great tractive effort (more than a Big Boy or Allehegny), reasonably sized drivers (63 inch) -- and a tidly little grate. It was impressive for about five minutes, until the steam ran out. That being said, some of the late 4-8-4s (The Niagaras and Js come to mind) could develop and sustain over 6,000 horsepower, hour after hour.

[espeefoamer]

The Milwaukee Road rebuilt some of their GP9s and upgraded them to 2000 HP.I dont know when they did this,or how many units were upgraded.

[oltmannd]

An example:

A mid-70s vintage GP40-2 in notch 8, 904 RPM at AAR std conditions (60 deg F air and fuel, 28.86 barometer, 0.845 sp grav fuel, 19350 #/gal heat value for fuel)

Shaft HP into generator for traction: 3074 (this is the "rating" - traction HP)

Electrical HP out of the generator headed for the traction motors - 2886 HP

Diesel engine is also powering an aux gen at 4 HP, a traction motor blower at 82 HP, 2* cooling fans at 39 HP , a dust bin blower at 13 HP and an air compressor (unloaded) at 15 HP. You add these to the traction HP to get the brake HP for the diesel engine. Brake HP would be = 3266 HP

* loco has 3 fans, but only 2 are needed at std. conditions.

[jeaton]

Mark, Ed, Peter and others. Thanks for your replies. My inquiry was to get a memory refresher on something that was going on while I was at the IC. I am not that interested in engine spotting but I do like reading articles and comments about engines.

[broncoman]

Question, I work with baby GM diesels (6V-92 & 8V-92s), in the forums I notice people saying that turbos are removed and roots chargers are put on instead, my question being is do the bigger GM 2 strokes not need the roots charger when they have a turbo. I thought that they had to have the roots charger even if they have a turbo, it just blows through.

Thanks for the info.

[CSSHEGEWISCH]

MP souped up some of its GP18's in the 1960's without a turbocharger and raised the horsepower rating to 2000 HP. My reading indicates that it was done by reworking the exhaust manifold and ducts.

[SSW9389]

VMV Paducah is now owned by National Railway Equipment.(NRE). Those rebuilt Geep/Slug sets and rebuilt GP38-3s on PAL were done in Paducah.

Ed in Crestwood, KY

[M636C]

jeaton,

This is off the top of my head, but the majority of GE 44 tonners were 380 HP, 190 from each Caterpillar D17000 prime mover. I would guess that the engine might have been 250 HP gross, but that's a guess.

The GP-8 Paducah rebuilds were fitted with rebuilt 16-567B engines, and I think they were rated about 150 HP higher than the original engine, which would give about 1650 HP. I can't remember whether they were converted to 645 power assemblies. The GP-10 and GP-11 used rebuilt 16-567C engines, and I think they were rated at 1850HP.

Later rebuilds, the SD20s, were fitted with rebuilt 16-567D3 engines which had been turbocharged engines, but were converted to Roots blowers and fitted with 645 power assemblies (head, liner, piston and rod). These engines were 2000 HP.

Data on these rebuilds was given in the "Contemporary Diesel Spotters Guide", which appeared in two editions, complementing the "Second Diesel Spotters Guide".

As far as I know, no current "Guide" gives details of rebuilds, but copies might be found using the web.

There were two Paducah rebuilds, 2601 and 2602, converted from GP30s. Most information (including the "Guides") says these had de-turbocharged engines fitted, but photos show them to have a single stack at the front of the engine, indicating they still had a turbocharger. Thus they probably had a 16-645 D3, or something like that. I think they were 2200 HP.

Like the Editor, I've still got my original "Diesel Spotters Guide", and although I have no connection with the publisher. I recommend my friends to buy a copy if one shows up at a show or swap meet.

Peter

[Anonymous]

Great thread about Horsepower, what about STEAM horsepower?? So much effort on the tractive side little info on HP.

[Anonymous]

Info on the Paducah rebuilds and the 44-tonners I'd have to look up at work. I haven't got the reference material here at home.

Gentlemen, I am NOT trying to sell product here -- my job is to worry about magazines -- but about 98% of the locomotive questions I see on this forum can be easily looked up in Kalmbach's diesel books. I bought my first copy of the Spotter's Guide over 25 years ago, and I refer to it still almost every day. It's the Bible, and if you want to know about locomotives, it is THE place to start. It's where I started. You can't believe how much you'll learn from them.

[locomutt]

jeaton,
I live here in Louisville---The eastern terminus of the P & L.
I don't get alot of info,but I was under the impression that the VMV shops at
Paducah had closed down[?] I have not heard any thing on the GP-10,
GP-11 Programs of recent times.I don' usually get into the 15th St yard anymore
for some strange reason.I think they call it security[?]

Mark, What is the H.P. rating for the GE-44tonner[?] Is that Per Engine[?]
Or is that the unit total H.P.[?]
I am attempting to model a 44T in the 50's--60's time span. I've been looking
for info,but have seemed to have hit a brick wall[banghead]
I've been a model railroader for umpteen years,but for some reason
in all the files I do have,I don't for that particular engine!

If anyone could lend some help;it would be greatly appreciated[:D]
Thanks much guys[swg]

[jeaton]

Mark,

Nice note. It reminded me that the Illinois Central's Paducah shops rebuilt a ton of GP's back around the 70's. I can't recall the numbers on the change in HP, if there was any. Do you recall or have anything at hand on that program?

Jay

[Anonymous]

To elaborate:

U.S. standard is output at the flywheel after subtracting for auxiliaries -- water pump, fuel pump, oil pump, cooling fans, inertial air blower. European standard is gross h.p. before auxiliaries. Either measurement obscures something.

Net horsepower available at the rail subtracts for the efficiency of the electrical transmission. For D.C., the convention is to multiply by 82%. Most of the other 18% goes into heating up all the windings and wiring, the pinion and bull gear on the traction motor/axle combo, and a little bit into the bearings. Beats me what the efficiency on A.C. is -- anyone know?

If you wanted to install a higher-horsepower prime mover and increase hp by more than 100-250 hp, you would have to install all or most of the following:
thicker radiator cores, larger-diameter coolant water piping, and either two water pumps instead of one, or higher capacity pumps
add more or increase the size of radiator fans
bigger oil cooler and filters
install a new main generator
install a new auxiliary generator
install all new high-voltage wiring and power contactors
install new low-voltage control circuits, or at least some of the relays

You might not have to change D.C. traction motors, because most traction motors floating around now are of more modern types and the locomotive probably already has them underneath it. You look under your average GP9, and you'll find D77s, not D37s.

In other words, about all you've saved is the frame, trucks, and carbody, which constitute little of the value of the locomotive. So hardly anyone has done it. I have scratched my head for some time trying to think of a significant repowering program that raised horsepower a lot (not just 100-200 hp) and can't think of one, because at this point you might just as well buy a new locomotive and throw out the old one. (Someone will now remind me of one.)

A grizzled old mechanical officer told me one day. "Son, if you have an old truck, and you put a new motor in it, you still have an old truck. But now you've spent a lot of money on it. Don't try to save pennies, try to save dollars."

[kenneo]

Output shaft HP. Available for traction is a matter of deduction for inertia (of the rotating things such as gen., traction motors, locomotive intelf, friction of bearings -- all things that take power to operate.

[jchnhtfd]

Usually the horsepower available to drive the generator/alternator, subtracting all the accessories and auxiliaries. And yes, the generator/alternator may have to be changed, although not, usually, the traction motors. Depends on the unit in question, of course.

[Anonymous]

If a locomotive is advertised as producing a given horsepower, is that the horsepower of the diesel engine or horsepower measured at the drawbar? Also, if a particular locomotive is upgraded with a higher horsepower engine does the generator/alternator and the traction motors have to be changed to realize this increase in power?