kolechovski Is there software within the locos themselves to do all of the calculated operating to constantly monitor and manage train forces, or is the engineer on the lead somehow responsible for that as well?
Is there software within the locos themselves to do all of the calculated operating to constantly monitor and manage train forces, or is the engineer on the lead somehow responsible for that as well?
I've seen these types of questions asked on this forum before, so allow me to take a crack at answering them. Some time ago I found a video on Youtube that shows DPU operation as they were 30 years ago next summer. By seeing the whole thing spread out, it may be easier to understand how DPU works today.
CPR DPU started using only SD40-2's, so let's set out a few terms. For simplicity on a normal train we will call the lead engine with the engineer a Leader, and how ever many units follow it are Trailers. When DPU started you needed engines with extra controlling equipment, including radio transmitters, called Master units. These radio signals were received by a Robot unit, which transmitted commands to the mid-train units, in the beginning normal Trailing units.
The Robot units received the radio signals, and using electromechanical switching equipment converted these signals into something that could be transmitted from the Robot to the Trailers using the normal M.U. connectors used on every locomotive. The mid-train units responded to commands as though they were physically connected to the lead unit. This was not easily done, and the equipment was very bulky, so hollowed out "B" units with no prime movers or traction motors were used, as they had the structural integrity to handle mid-train forces, and they already had the necessary M.U. technology installed.
As time progressed the technology was able to be reduced to the point where the Robot equipment could be installed in the cabs of dedicated SD40-2 units, now called Slave units. You now had four types of SD40-2's; Masters, which could also be used as Leaders if they were not needed for DPU work; Slaves which could not be used for any other purpose, as their cabs were filled with Robot equipment; and regular Leaders and Trailers. When there were two units mid-train, one was a Slave unit, and one was a Trailer connected by normal M.U. connections.
When CP started purchasing AC units the technology had progressed to the point where every unit can lead, trail, be a Master or a Slave. In a 2+2+1 situation you have a Master, Trailer+Slave, Trailer+Slave. Let us now see the video and deal with questions later.
http://www.youtube.com/watch?v=n4klYbnEPYU
Bruce
So shovel the coal, let this rattler roll.
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gsrrman I am wondering if these 200 car trains will not be mineral trains (e.g Coal, potash, etc) which can run at slowr speeds and move when the tracks are clear of higher priority traffic.
I am wondering if these 200 car trains will not be mineral trains (e.g Coal, potash, etc) which can run at slowr speeds and move when the tracks are clear of higher priority traffic.
Most of the time you would be correct, but not always. A video shot two weeks less than exactly 29 years later than the above video.
http://www.youtube.com/watch?v=C-o4dJnQNqk
kolechovski I'm curious how DPU is controlled. Is there software within the locos themselves to do all of the calculated operating to constantly monitor and manage train forces, or is the engineer on the lead somehow responsible for that as well?
I'm curious how DPU is controlled. Is there software within the locos themselves to do all of the calculated operating to constantly monitor and manage train forces, or is the engineer on the lead somehow responsible for that as well?
The engineer is responsible for managing in-train forces. The DP equipment/software is only a tool that allows the engineer on the lead consist to control and monitor the DP consist(s). Today coming home from Fremont I had a 11500 foot, 17400 ton manifest with 3 engines up front and 1 DPU cut in mid-train about 8000 feet back. And lots of cushioned/long travel drawbars. Keeping it in one piece (and the conductor happy) was up to me.
You have to think of the track profile not only where your train is at, but what's coming up. Where the head end is, where the DPU is, and where the rear end is. Some areas it's not too hard, the track is either fairly level or a fairly constant up or down grade. Even where the grade tops or bottoms out if it's gradual it usually isn't a problem. The real problem areas are places where the track has short, abrupt rises or sags, especially if there's a series of them in a few miles. Those places are where the slack is most likely to change harshly. So you plan ahead and make throttle or dynamic adjustments gradually. It's really not different than running a "regular" train, just a bit more intense.
And I agree with what EMD#1 said, I'd rather have a long unit/intermodal train than a long manifest (or auto rack) train. A manifest can have a lot of different type of cars, some (like auto racks) with the long cushioned draw bars. That's a lot of slack, that can change harshly and get a knuckle or drawbar. Unit trains have more uniform equipment. They have slack, but not as much. They are a bit more forgiving. Just don't get too stupid.
Jeff
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