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TrainWatcher
07-31-2010, 05:11 PM
My first post and new interest in Locomotives!

From my home in Las Vegas, I am able to watch trains all day long as they transit Las Vegas. I see a lot of BNSF and UP north/south traffic.

Anyway, on to my question.

When you have a train of some 75 cars, the head end has 3 EMD's and the trailing end is composed of 2 EMD's. (configuration for transit over El Cajon)

Question: How do the Engineers match the torque loads of the tail end EMD's to the head end so that that trailing end isn't dragging or over pushing the system?

Is it as simple as matching amps from the front and rear EMD's?

Thanks

TrainWatcher :smile:

troy12n
07-31-2010, 06:30 PM
They dont measure it in torque figures. Locomotives have tonnage ratings and the power desk matches up a train with appropriate locomotives based on what subdivisions (lines) the train will be traveling from source to destination. Each railroad has track charts and timetables that list how much trailing tonnage a locomotive is rated for on that subdivision.

JRMDC
07-31-2010, 11:08 PM
I think the question is how are the efforts of the head-end and distributed power coordinated so the rear doesn't push "too hard" or not enough, relative to the efforts of the front.

So not how engines are assigned to a train, but how are those engines controlled once they are in operation on the train.

TrainWatcher
08-01-2010, 05:37 PM
I think the question is how are the efforts of the head-end and distributed power coordinated so the rear doesn't push "too hard" or not enough, relative to the efforts of the front.

So not how engines are assigned to a train, but how are those engines controlled once they are in operation on the train.

That is exactly the question I am asking..thanks!

Anybody with experience on this?

TrainWatcher

milwman
08-07-2010, 09:14 AM
Well, there is not much matching, They don't ask for 3 SD70's for a train( Matching not a good word for it ) just HP need to do the job on the line. The trainmasters (Boss) or power desk will just ask for what the need and if they have to much power will tell them to shut down some of them. Fast ones need more power to hold speed and slow trains just have to make the next hill.
With Electric transmissions they will add there HP and match speed of the others, Be it 4000 or 4400 HP. With DPU they will run the same throttle setting 1 thru 8 or they can set them as they need like after the front cresting a hill and the rear end still going up hill, Front in Dynamics and back ones in power and throttled down as speed comes up till there in dynamics too. But some don't like splitting the power and will just run them. Get 10 engineers together and they will all say about the same thing? But running a train is an art form.

GMEMD
08-08-2010, 10:29 PM
With older distributed power systems, the remote units do whatever the head end is doing.

With newer systems, the remotes can be controlled independently from the head end. Newer models of locomotives like the SD70ACe/M-2, and the EVO's, have computer screens in front of the engineer (usually 2, but sometimes only 1). One of these screens is used to control the power/braking of the remote units.

TrainWatcher
08-10-2010, 07:26 AM
Well, there is not much matching, They don't ask for 3 SD70's for a train( Matching not a good word for it ) just HP need to do the job on the line. The trainmasters (Boss) or power desk will just ask for what the need and if they have to much power will tell them to shut down some of them. Fast ones need more power to hold speed and slow trains just have to make the next hill.
With Electric transmissions they will add there HP and match speed of the others, Be it 4000 or 4400 HP. With DPU they will run the same throttle setting 1 thru 8 or they can set them as they need like after the front cresting a hill and the rear end still going up hill, Front in Dynamics and back ones in power and throttled down as speed comes up till there in dynamics too. But some don't like splitting the power and will just run them. Get 10 engineers together and they will all say about the same thing? But running a train is an art form.

Thanks very much for the reply...makes sense and I can see where it would indeed be an art form.

to further clarify, if the head end is throttled at say 5, the helper end is throttled at 5, how do you know that the speeds are matched? Is it just an assumption?

Thanks in advance..

TrainWatcher
08-10-2010, 07:28 AM
With older distributed power systems, the remote units do whatever the head end is doing.

With newer systems, the remotes can be controlled independently from the head end. Newer models of locomotives like the SD70ACe/M-2, and the EVO's, have computer screens in front of the engineer (usually 2, but sometimes only 1). One of these screens is used to control the power/braking of the remote units.

Thanks for the reply...are the remote units controlled by a cable link from the head end or do they use UHF/C band telemetry?

milwman
08-10-2010, 08:13 AM
to further clarify, if the head end is throttled at say 5, the helper end is throttled at 5, how do you know that the speeds are matched? Is it just an assumption?

Thanks in advance..

Would have to be at some point there cupeled to the same train ;)

JRMDC
08-10-2010, 01:12 PM
The current issue of Trains has an article on distributed power including some operational detail.

The control is by telemetry.