A Quick Question about locomotives speed and power

Hey all, I have a quick question. For US lines, what is the fastest freight diesel A: Ever, B, Currently made/running. Same question about passenger lines (Turbines and other strange/weird system count as well) Then, what is the most powerful (in terms of either motive power or sheer cargo pulling ability) locomotive of all time, and currently being produced. Thank you all for your help!

For the electric side, I think the fastest is that fancy Acela, but horsepower is something that I'm not sure on as well!

The nominal top speed for a diesel-electric locomotive is determined by the gear ratio of the gears connecting the traction motors to the wheels. (Along, of course, with the wheel diameter.) The locomotive is capable of running at over the top speed, but excessive speed --> excessive traction motor r.p.m. --> danger of damage to motors ("birdsnesting"). Most freight diesels in the U.S. have been geared for a nominal top speed in the 65mph-70mph range, though high power units with four traction motors (e.g. EMD GP40, GE U36B) were usually geared for higher speeds: top speed in the 80s in many cases. Passenger diesels (EMD E-units, Alco PA...) were built with gearing for top speeds up to 120m.p.h., though most were geared for lower speeds (no point in having a locomotive that can go faster than track conditions allow!)

At a guess, given its long history of running high-speed intermodal trains on the Chicago-Los Angeles line, I would think the Santa Fe probably at least tied for having freight diesels with the highest-speed gear ratio. (Not their entire fleet, but units assigned to the fastest freights. I believe that their GE B40-8W locomotives were equipped with 42" wheels -- standard was 40" -- and special gearing to allow them higher speeds than other units.)
For passenger... I think the MLW LRC locomotives (power for trains with tilting cars) built in the early 1980s may have been the most recent North American locomotives geared for 120m.p.h.

I think the highest speed achieved intentionally (i.e. not on a runaway train!) with an American diesel locomotive was in the 1970s at the Pueblo Test Track, with a GE U30C locomotive): something well over 120m.p.h. (I would assume that it got special gearing for this test, but don't know details.)

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"Most powerful" is subject to interpretation. Very high power is usable only at very high speeds: try to put the power of an Acela onto a freight locomotive and you will just spin the wheels and not use the power to do useful train-pulling work. Often when a freight locomotive is boasted about for its "power," it is the tractive effort (train-pulling force) rather than power per se which is in question. (The power a locomotive puts out is proportional to the tractive force TIMES the speed.)

In terms of tractive force, the best pullers in history are probably the current generation of AC diesels: EMD SD70ACE and GE ES44 are only 4300hp and 4400 hp (respectively) in power, but at the speeds relevant to unit coal trains going over hills it would be difficult to use much more power without excessive wheel-slip. (When the SD70MAC was introduced, an EMD person with a knowledge of railroad history was quoted as saying it was the first time they had built a unit that could outpull a Y6b: the Norfolk & Western 2-8-8-2 steam locomotive of the late 1940s!) ... To the best of my knowledge, the EMD twin-engined DD40X of 1969, at 6600 h.p., was the most powerful diesel locomotive in history. EMD and GE have more recently built 6000 hp single-engine units and are, I think, continuing to build them for Chinese railroads: North American railroad management doesn't seem to be as daring.

If you're actually asking about power (as distinct from tractive effort) then UP's 1958 turbines are going to be hard to beat. (If you are asking about TE they're still going to be hard to beat. Nobody knows whether the N&W or C&O turbines could outpull them.)

As for speed, you maybe mean what speed the engines were officially allowed, as distinct from what they were capable of? UP and SFe both had 59:18-geared freight diesels in the 1970s; SFe allowed their FP45s and 59:18 SD45-2s 90 mph on passenger trains, and they allowed the Super C freight to run 79.

Of course!
Thanks, Timz, I should have remembered the U.P. (etc) turbines: I was narrowmindely only thinking of diesels.
The U.P.'s 1958 GTEL (gas turbine electric) locomotives from GE, and the C&O and Norfolk & Western steam turbine electrics from Baldwin-Westinghouse all had 12 powered axles, each powered by a traction motor similar to those used on diesels, so when it comes to pulling (tractive effort) they were roughly the equivalent of pairs of six-axle diesels. In terms of power, the U.P. engines were built as 8500 hp, higher than any diesels I know of. (There have, however, been straight electric locomotives of up to 12,000 hp, I think: not in North America, though.) The C&O and N&W turbines were of lower power: I vaguely remember 6000hp and 4500hp, respectively, but I'm not sure of the actual figures.

The UP turbines were supposed to be 7000 rail horsepower as built; the 8500 hp turbine rating was at 6000 ft altitude 90 F as I recall, and it (i.e. the turbine itself) was supposed to be good for 10000+ hp in denser air. Supposedly a few turbines got upgraded somehow to bring some of that higher power down to the rail-- if true that would move any disputes about steam locomotives that maybe produced 7000 rail horsepower.

I think the fastest ever produced/run in the USA was the New York Centrals jet powered RDC but it was never used in revenue service. Maglev systems are also very fast but, again, none in service yet.

Paging Otto Vondrak, Otto ....

You're the historian about the NYC jet RDC... how fast did she go?

The RDC with the J47s supposedly peaked at 180+ mph-- 183-point-something I think it was. Less than 190, anyway.

There are two devices on modern US Diesels that limit top speed, in addition to gear ratios. As far as I know (and I have operated locos from all generations), all have overspeed devices on their governors. These are hydraulically driven devices that work like rev limiters on modern high-performance autos. When engine rpm reach a certain level (higher than normal maximum, but below that which would cause damage), these cause the prime mover to shut down. The engine has to be manually reset with a lever near the governor before it can be restarted.

The second device is found on second generation units and newer. It is an overspeed device that is driven by axle rpm rather than crankshaft speed. A typical setting for this speed limiter for units in freight service is 72mph. These will take the main generator off-line and drop the engine speed to idle if the selected speed is exceeded.

Les

Desertdweller wrote:There are two devices on modern US Diesels that limit top speed, in addition to gear ratios. As far as I know (and I have operated locos from all generations), all have overspeed devices on their governors. These are hydraulically driven devices that work like rev limiters on modern high-performance autos. When engine rpm reach a certain level (higher than normal maximum, but below that which would cause damage), these cause the prime mover to shut down. The engine has to be manually reset with a lever near the governor before it can be restarted."

Desertdweller: This is the Engine overspeed trip lever- it doesn't have anything to do with ground speed.

Yes. It is a rev limiter. It would shut down the engine if it ran too fast, even if the locomotive was standing still at the time.

Les

Yes, the engine overspeed lever will shut down the motor if it starts running too fast. That can happen a few different ways, but really has nothing to do with how fast the actual locomotive is traveling - although getting wheelslip in Notch 8 at a high speed can cause the engine to overrev, how or why I dunno, but thats what I was told.

There are overspeeds that are built into the cab signal system which will put the train into a penalty brake application if the speed gets too much. For example, on the Geeps that NJT runs, their overspeed is set at 103mph (give or take a few mph) which is the limit of the traction motors and whatever gearing that is, i dont remember off hand. If you hit that, the cab signals will start beeping and you have to get brakes on, and get your speed down, otherwise it will put you into a penalty brake.

Let me just say that you haven't lived til traveling down the NEC long hood forward in a Geep at 100mph..........Not quite what the designers at EMD had in mind 50 years ago when they were designing the '40 series, im sure.....hahahah

But like a quite heated discussion that was going on in the loconotes group on yahoo a few weeks back, a locos power does not necessarly equal how fast it can go. Like I mentioned, a 3000HP GP40 can go 100mph. A 4300HP SD70 might only be able to go 70mph. A 1500HP switcher might be able to go 70mph. It all depends on the gearing of the traction motors. Power does help, with how fast it can get to a certain speed, but by no means is it the only factor.

Now, take for example a 103mph geared GP40-2 and a 70mph geared GP40-2. Couple up say 10 100ton loaded stone hoppers to both of them. Put them next to each other on two tracks, and let them drag race. The 70mph Geep will take off like a bat out of hell (relatively speaking) and have no problem pulling the cars and getting up to 70mph. The 103mph Geep will take off slower and will struggle more with the cars to get them up to speed, but it can move them no problem. It will take a while, but it will be able to get them to 103 mph.

At NJT there is an unoffical limit with how many loaded stone hoppers a Geep is good for, which is about 10. A freight guy will be like "10 cars with a GP40? Thats nuts! These engines suck!" They don't suck, they have the same power as a freight GP40, but just gets it delievered differently because of the very high speed gearing

I suppose that an engine overspeed caused by wheel slip in Run 8 would be the result of a sudden unloading of the generator. The wheel slip indicator works off number two axle, like the ammeter does. It would take a real severe wheel slip to cause that!

I've never run a Geep a hundred miles an hour, but there may be a safety factor in running long hood forward. I did run an ES-44 long hood forward all night at 25mph. Fortunately for me, it was a CSX unit with an auxiliary speedometer on the back cab wall. I was glad I had the road crossing locations memorized by then. It was a curvy line and I couldn't see the whistle boards.

Les

Desertdweller wrote:I suppose that an engine overspeed caused by wheel slip in Run 8 would be the result of a sudden unloading of the generator. The wheel slip indicator works off number two axle, like the ammeter does. It would take a real severe wheel slip to cause that!

I've never run a Geep a hundred miles an hour, but there may be a safety factor in running long hood forward. I did run an ES-44 long hood forward all night at 25mph. Fortunately for me, it was a CSX unit with an auxiliary speedometer on the back cab wall. I was glad I had the road crossing locations memorized by then. It was a curvy line and I couldn't see the whistle boards.

Les

Oh thats true, I didn't think of the unloading of the Main Generator....yea that could do it very easily!

No problem (with the rules) with running LHF, just the conductor must be in the cab to call out signals and anything else that might not be visible to the engineer sitting "on the wrong side" - our Geeps only have one control stand.

Here's a move through Edison, NJ Station on the NEC LHF at about 90mph (MAS through that area on that track)

http://www.youtube.com/watch?v=9vuQ8Yp_LLM

Getting kinda back on topic - NJT uses diesels that are good for 100mph for shop moves because Amtrak prefers the trains to get out of the way ASAP, and one of the largest yards on NJT is in Morrisville PA (west of Trenton, NJ), so there are often equipment moves for 50 miles from Morrisville to the main NJT shops in Kearny, NJ (east of Newark Penn station). So because they need them to go fast, thats why they can't pull more than 10 loaded hoppers hahah

JT,

That video was pretty awesome!

I used to work with a fellow who had run on the Long Island. He said even the switchers were geared for 100mph. Now I know why!

Les