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AEM7 Retirement

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IRM (outside Chicago) has an overhead electric system, however I don't know the capabilities of it. They normally run interurban and streetcars on it, but they do own some regular electric engines (including a GG1). I don't know if they can actually run the regular electric engines on their system. It looks fairly light, but then they don't have much distance to travel, so you aren't going to see speeds requiring a high-tension system.

 

peter

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OK, I did a little research. Perhaps the best possibility would be for a "museum" AEM-7 to be stationed in Harrisburg, next to the non-working GG1. http://en.wikipedia.org/wiki/PRR_4859 Apparently there are enough spare tracks there to just leave a museum exhibit sitting there... and the tracks are electrified. Some museum would have to sponsor this, of course.

 

(This also seems like the best place for a restoration project to get a working GG-1.)

The last I had heard Amtrak would like to get rid of the GG-1 at Harrisburg. Unfortunately if it would leave there it would most likely head to Strasburg. But they already have 2 GG-1's there, with one needing restoring.

 

Preserved locomotives that are not used in any kind of dedicated excursion service really have no need or use as a "working" model, simply due to the costs involved. It is similar to having a "working" Concorde, but no where to fly it.

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I can't see one ever being operated at a museum. I don't think there are any museums that have that capability.

 

While I would love to see one remain operation, I think the most we will see is a static display. Some of the copper and metal may be salvaged out as well and it will never operate again. I think the Railroad Museum of PA as being a perfect location for one.

 

I would think Amtrak, would try to preserve at least one example. However, with the political climate, Amtrak may want to get every penny the can from them.

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There has been occasional talk about converting some of them into Cabbages.

Edited by jis

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IRM (outside Chicago) has an overhead electric system, however I don't know the capabilities of it. They normally run interurban and streetcars on it, but they do own some regular electric engines (including a GG1). I don't know if they can actually run the regular electric engines on their system. It looks fairly light, but then they don't have much distance to travel, so you aren't going to see speeds requiring a high-tension system.

 

peter

 

I think it is 750 volts DC. They run some electric engines sometimes but there is no way that they could run an AEM7.

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Guest Nathanael

IRM (outside Chicago) has an overhead electric system, however I don't know the capabilities of it. They normally run interurban and streetcars on it, but they do own some regular electric engines (including a GG1). I don't know if they can actually run the regular electric engines on their system. It looks fairly light, but then they don't have much distance to travel, so you aren't going to see speeds requiring a high-tension system.

 

peter

IRM has DC overhead, suitable for running both trolleys, interurbans, and (for light loads) the locomotives of nearly all the former electrified railroads in the Midwest. Remember that Metra Electric and the South Shore Line *still* use DC overhead. So does the Iowa Traction Railway. (I don't think IRM has any of the pre-1926 South Shore Line AC equipment -- I'm not sure any of it survives, actually.)

 

This makes sense for an Illinois railroad museum. Most locomotives can handle some changes in voltage with relatively little work, so the ones designed for higher DC voltages (3000V or 1500V) can often be adapted to run on lower voltages (750V or 600V) for low-speed museum operations.

 

Museums are generally afraid to run third rail DC because of worries about people stepping on it. (There is one group in England which is really trying to figure out how to set up a third rail museum line, but it seems particularly difficult!) However, DC third rail vehicles can often be jerry-rigged to run off of DC overhead at low speeds without too much trouble or damage to historic fabric. Or, for short distances, they can be run off "battery cars".

 

By contrast, the difference between AC power and DC power systems is quite substantial. No museum has AC overhead, and converting an AC locomotive to run on DC would basically strip large portions of the innards (at least the main rectifiers, and quite possibly more depending on the design), which is very undesirable from a historic preservation point of view. Furthermore many of the parts of an AC locomotive may rely on the very high power supply from 12500V or 25000V, which is a big difference from the 750V usually supplied for streetcars or interurbans.

 

Probably eventually for the benefit of railroad preservation, *some* museum *somewhere* should set up an AC overhead line, just as *some* museum should have third rail. There's probably only room in the world for one of each given the difficulty involved in either. I suppose Germany, where practically every line is electrified with AC overhead, might be the best bet for a museum with overhead AC electrification. (Heck, maybe they have such a museum, and I just haven't found it due to my poor grasp of technical German.)

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So I'm not to familiar with RR electric systems. I know there are AEM-7DCs and AEM-7ACs; but I don't really know the difference between them (I know the ACs are refurbished DCs) Is there something that could be done with the DCs?

 

peter

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So I'm not to familiar with RR electric systems. I know there are AEM-7DCs and AEM-7ACs; but I don't really know the difference between them (I know the ACs are refurbished DCs) Is there something that could be done with the DCs?

 

peter

Just to confuse you a bit more, both the AEM-7DC and AEM-7AC are AC locomotives in the sense that term is used by Nathaniel above. He is referring to the type of power that is fed to the engine from the catenary, and not what kind of motors it has.

 

So no. nothing can be done with the DCs relative to the type of catenary power it uses, which is AC, without essentially gutting the innards and rebuilding it as a DC engine.

Edited by jis

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Guest Nathanael

Yeah, it's a bit confusing, isn't it?

 

The AEM-7DC picks up fixed-frequency AC power from overhead, rectifies it into DC, and then feeds it to DC-powered motors. (There's a whole bunch of different types of motors. Traditional "brush and commutator" DC motors have been used heavily since the 1890s. Brush motors actually have little moving brushes which wear out and create dust. There are also a number of types of "brushless DC" motors. I'm not sure which sort the original AEM-7DC uses, but I think they're the old-school brush motors.)

 

The AEM-7AC picks up fixed-frequency AC power from overhead, rectifies it into DC, and then uses the DC to generate *variable-frequency* AC, which is what's used for "AC induction motors", which are the favorite modern motor because they have one moving part and no wear parts.

 

(This is basically the same as how my electric automobile works -- it takes fixed-frequency AC from the wall, and converts it to DC to feed the batteries. Then it takes DC from the batteries and converts it to *variable-frequency* AC for the induction motor. All the tech was already in use in trains when the Tesla Model S was designed -- not new stuff.)

 

The "AC induction motor" is actually a very old design, invented by Nikola Tesla, but it used to be extremely difficult to generate variable-frequency AC current, which is why they weren't used much until the last few decades. (In this type of motor, the frequency variation is what determines the speed of the motor, so until variable-frequency AC could be reliably generated, the induction motor could only be used for single-speed applications.) Recent developments in electronics made it possible to generate the necessary variable-frequency AC current relatively easily. (The device most commonly used to do so in locomotives is called an "IGBT".)

 

I find all this stuff terribly interesting.

 

Anyway, to explain the point I was making. AC current can actually be distributed through a single wire, known as the "hot" wire in home electrical work. (The second wire, the "neutral", is there for safety and to reduce resistance. *You don't actually need it*, and at some location it's tied to the ground wire.) DC current, by contrast, requires a complete loop where the current comes in one wire and goes out the other.

 

An AC-powered locomotive will therefore have a big pantograph to pick up the AC from the wire, and a relatively weak system "grounding" it to the rails. Since it picks up high-voltage / low-current electricity it can be wired with relatively thin wires. Then it needs a large "rectifier" to convert the AC to DC to power the motors. (There may also be transformers involved).

 

A DC locomotive picks up the DC from a wire and returns it through the rails, and it's returning a *lot* of power through the rails, so it needs a much heftier return system. Since it's low-voltage, high-current, it has to be wired with very thick wires. Then it needs DC-to-DC transformers (not rectifiers) to transform the DC to lower-voltage DC to operate the equipment.

 

So the wiring and equipment which come between the electrical pickup and the motor controller are extremely different for an "AC overhead" locomotive and a "DC overhead" locomotive. You could actually keep the same motors, but you'd have to rewire nearly everything else in the electrical system to do a conversion. This might make sense commercially (for instance, when France converts overhead-DC railway lines to overhead-AC railway lines), but makes no sense if you're doing preservation!

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An AC-powered locomotive will therefore have a big pantograph to pick up the AC from the wire, and a relatively weak system "grounding" it to the rails. Since it picks up high-voltage / low-current electricity it can be wired with relatively thin wires. Then it needs a large "rectifier" to convert the AC to DC to power the motors. (There may also be transformers involved).

Shhhh! Don't tell that to the maintenance geniuses at NJT's MMC. They had already decided once that the return straps to the axles were not that important afterall and forgot to maintain them until they wore out and disintegrated in an EMU. Then return power started flowing through the bearings destroying one eventually causing a derailment near Secaucus Junction when a wheel with its axle literally fell off the train!

 

After that they spent weeks replacing all the worn out straps on all the Arrows. Allegedly FRA made them do it before they'd allow any Arrows back in service. Yet another curious crisis brought upon itself by its own incompetence.

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Guest Nathanael

 

An AC-powered locomotive will therefore have a big pantograph to pick up the AC from the wire, and a relatively weak system "grounding" it to the rails. Since it picks up high-voltage / low-current electricity it can be wired with relatively thin wires. Then it needs a large "rectifier" to convert the AC to DC to power the motors. (There may also be transformers involved).

Shhhh! Don't tell that to the maintenance geniuses at NJT's MMC. They had already decided once that the return straps to the axles were not that important afterall and forgot to maintain them until they wore out and disintegrated in an EMU. Then return power started flowing through the bearings destroying one eventually causing a derailment near Secaucus Junction when a wheel with its axle literally fell off the train!

 

Eek! When I said "relatively weak", I meant that they don't have to be the sort of giant, beefy cables you need to use for high-current DC. You still want to ground the system properly -- stray currents anywhere can wreak havoc!

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Guest Nathanael

The key difference between AC and DC is this.

 

In DC, the electrons are actually flowing around in a loop. So you have to make a complete circuit. (Or... if you don't... the electrons spray out one end. This is actually used for Cathode Ray Tubes and a few other applications, but it's usually a bad idea.)

 

With AC, you're not really moving the electrons much. At the power plant, you push them down the wire... then you pull them back... then you push them... then you pull them again. Each electron remains pretty much right where it is and bounces back and forth a little. The "frequency" of the AC is how fast you bounce them back and forth.

 

As you can see, there's no actual need for a "return" route with AC. But whatever you put at the far end of the wire has to have something able to deal with all of this back-and-forth pressure. It will wear out and damage delicate parts (like bearings) if they're in the way. It's usually easiest and safest to attach it to the Earth (grounding), but there are other alternatives (they're something like capacitors conceptually) which are used in specialized applications.

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And then there were two:

 

9840.1351523578.jpg

 

 

99a74ef3-4fd0-40cd-94fc-f4b817bf956d.jpg

 

With the retirement of the 926, the last two Amtrak DC AEM-7s that remain in service are scheduled for a few non revenue test trains and then they will be retired together since they are "pair only" units.

 

The end. :(

Edited by Thirdrail7

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Wait, they phased out all the AES including the rebuilds already? Wow, the cars really came in at a fast clip if this is accurate. I thought theh weren't going to be phased out till later on as 3 a month were arriving of the Sprinters.

 

Can anyone else confirm this? Great news for Amtrak and customers since it means cheaper costs, improved efficiency and more reliable service and perhaps faster speeds somewhat and better safety standards.

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Oh wait you said DC and not rebuilds. I misread the post but is still excellent news as the rebuilds are a lot better than the non rebuilds which were causing fires, and were unreliable and had antiquated electronics. The rebuilds are a lot more capable and will be able to handle the service till the rest of the Sprinters finally come in.

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Guest Al Smith

Man, retiring these AEM-7 locomotives makes me feel old! I was working at the Transportation Test Center (what it was called at the time of testing) near Pueblo when Amtrak sent one locomotive to see how they would work at 110mph. One night, I was in the cab as we went around the RTT (Railroad Test Track) at speed. At that time, it was a beautiful, state-of-the art motor! I vividly remember when it was time to disembark. After going 110 mph for several laps, we slowed to 65mph, and it seemed like a crawl. When I thought it was time to open the cab door and swing out on the ladder to "land", I checked the speedo. I'm glad I did, because we were still going 40mph, so I delayed! I had misjudged the speed that much.

 

Riding that night in an AEM-7 at that speed was one of those lucky memories that I truly cherish!

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Yes, Al Smith, many who call them names for catching fire don't realize that they are old; at one time, they were among a class of locomotives that helped save Amtrak, along with its diesel cousin, the F40.

 

AEM7 handled Amtrak's fastest trains for almost three decades, had amazing capabilities with its acceleration and longevity. Heads turned when these machines started rolling out in 1981 or so. And they looked handsome! I absolutely hate their last design scheme, and if the Strasburg Rail Museum does get one, pray that they'll restore the original phase-3 painting. A lot of tears will spill when the last one hands the torch over completely to the ACS.

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Well the good thing is that the old cars had electronics failing and got phased out just in time and maintaining them would be cost inefficient. The rebuilds are perfect to tide over till all the new cars are in.

 

Agree on the cars back then but the newer cars are far superior.

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I'll celebrate with some toast for breakfast this morning.

Very appropriate for celebrating the Toasters! :)

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These mentions of the GG1's early on kind of surprised me. Were they around in general use after around 1970? Did they change the look of them later in their careers because they look WAY old school.

 

I thought the old Great Northern F7's looked dated with the engineer, brakeman and the fireman climbing what looked to be a 20 foot tall wall of locomotive to get into it. (I was a good deal shorter back in the late 1960's so it might not have QUITE been 20 feet to the entryway...)

 

But the GG1's look and are much older than the F7's. Hard to believe they may have still been around and in relatively common use in the late 70's.

Edited by Ziv

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These mentions of the GG1's early on kind of surprised me. Were they around in general use after around 1970? Did they change the look of them later in their careers because they look WAY old school.

 

I thought the old Great Northern F7's looked dated with the engineer, brakeman and the fireman climbing what looked to be a 20 foot tall wall of locomotive to get into it. (I was a good deal shorter back in the late 1960's so it might not have QUITE been 20 feet to the entryway...)

 

But the GG1's look and are much older than the F7's. Hard to believe they may have still been around and in relatively common use in the late 70's.

GG-1s were quite common in both Amtrak and NJTransit (various random liveries) through the 1970s. They ran early Amfleet equipped trains with special USArmy Kitchen Cars converted to HEP generators to supply power to the train.

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The GG1's were a sad loss to me. Beautiful and powerful and sexy. By comparison the AEM7's look like a powered boxcar from Soviet Russia. All function and no form. Or at least that's how they looked to me. I can't imagine missing it in the future.

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