Here's a stupid "what if"

[Scionic]

I do an awful lot of driving for my job, and yesterday while I was driving back and forth along the Kennedy by the Rosemont Yard, some idle curiosity. There's a whole yard full of trains there, is it possible to make one huge train out of those things? I mean, is it electrically possible since even the 3200s are basically running on hundred-year-old technology? It would be kinda neat to see a train of like 30 cars go by, even if it wouldn't even begin to fit on a platform, and likely draw too much power from a track circuit.

[Busjack]

The last clause pretty much answers it, maybe also if someone could figure out how long a signal block is. Given the 8/6/4 clear signs after switches and curves, one would have to calculate how far out the 30 clear sign would have to be to avoid derailing the tail end.

The 100 year old technology observation is a bit of a stretch, in that the 2000s received in 1963 were not backward compatible. If you were going to the 4000s and before, those were compressed air controlled, and thus the length would be limited by how reliably one could keep up the air pressure, even if each motor car had a compressor.

[RJL6000]

The 100 year old technology observation is a bit of a stretch, in that the 2000s received in 1963 were not backward compatible.

The "100-year-old technology" claim, indeed, is quite a stretch. The 2000s were actually delivered during the Summer and Fall of 1964 although they were ordered back in early 1963. Thus, the 3200s are basically using nearly 50-year-old technology, not "100-year-old" technology like the OP has claimed.

And speaking of AC-propulsion systems, to give a good example, New York City's subway cars use basically the same type of technology that the 5000s are using: The trains may be of newer technology, but the trackage that they ride on and much of its associated electrical underpinnings are still very much the same "100-year-old" technology that was meant for DC-propulsion equipment. (The oldest of the NYC cars currently in service are roughly as old as the CTA's 2400s; the newest were delivered to that city about five years ago.) Thus, the need for converters and/or inverters in the cars themselves.

[Busjack]

Thus, the need for converters and/or inverters in the cars themselves.

So long as there is reliance on either third rail or single overhead, there will be a need for inverters. I asked another group way back when how AC motors could work on DC and the answer was inverters. Assuming that AC worked on AC would convert the "stupid what if" to how long of a three wire extension cord would be needed to run the train, since third rail would certainly be out.

Mentioning that, I have to go back to Bullwinkle on Channel 26.2.

[Scionic]

50, 100, whatever. The point of the question was whether the length of a train is limited by the amount of power an individual track circuit can provide, or if it's limited by the design of the control hardware onboard the trains themselves.

[Guest]

Why dont we ask Mr. Peabody! "Set the wayback machine!" LOL!!

[trainman8119]

50, 100, whatever. The point of the question was whether the length of a train is limited by the amount of power an individual track circuit can provide, or if it's limited by the design of the control hardware onboard the trains themselves.

I believe the answer is that yes, it is limited by power capacity in the rail. However, if you could figure out a way to run 22 cars dead and drag them with 8 live, you may have a possibility of doing it.

[Busjack]

50, 100, whatever. The point of the question was whether the length of a train is limited by the amount of power an individual track circuit can provide, or if it's limited by the design of the control hardware onboard the trains themselves.

If you want to go back 100 years, the point of MU was that one controller could operate any number of cars, because all the master controller does is activate the controller under each motor car. That's why the Lake Street eventually got rid of locomotive cars (i.e. before MU, only the lead car had a controller and a motor). As I mentioned before, since some of the cars acquired in 1924 and before relied on air controls, that could be limited by whether one could maintain air pressure along the consist. So, the controller is not the limiting factor, the amount of electric power is.

As far as trainman saying towing dead cars, sure you could do that, and the pictures of 2600s towing 5000s through the Howard Interlocking show that you can do it today. Again, until CTA got rid of all the old cars it inherited from CRT, there always was a number of unpowered trailers. Of course, 8 cars towing 22 others would result in a very slow train.

The source of all this is CERA 115.