Old 07-31-2010, 05:11 PM   #1
TrainWatcher
Junior Member
 
Join Date: Jul 2010
Posts: 4
Smile Tech Question re: Torque

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
TrainWatcher is offline   Reply With Quote
Old 07-31-2010, 06:30 PM   #2
troy12n
Banned
 
Join Date: Jun 2008
Location: Tampa, FL
Posts: 5,333
Default

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.
troy12n is offline   Reply With Quote
Old 07-31-2010, 11:08 PM   #3
JRMDC
Senior Member
 
JRMDC's Avatar
 
Join Date: Nov 2006
Posts: 11,202
Default

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.
__________________
My RP pix are here.
My Flickr pix are here.

My commentaries on rail pictures are in my blog.

RP Photo Albums:
Cabooses
Engine Details
Farm and Train
Plumes!
Railroad Details
Signal Details
Switchstand Shots
JRMDC is offline   Reply With Quote
Old 08-01-2010, 05:37 PM   #4
TrainWatcher
Junior Member
 
Join Date: Jul 2010
Posts: 4
Smile

Quote:
Originally Posted by JRMDC View Post
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
TrainWatcher is offline   Reply With Quote
Old 08-07-2010, 09:14 AM   #5
milwman
I shoot what I like
 
milwman's Avatar
 
Join Date: Feb 2007
Location: Cedar Fall's, Iowa
Posts: 2,474
Send a message via Yahoo to milwman
Default

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.
__________________
Richard Scott Marsh I go by Scott long story

http://www.flickr.com/photos/22299476@N05/

Last edited by milwman; 08-07-2010 at 09:56 AM. Reason: add more
milwman is offline   Reply With Quote
Old 08-08-2010, 10:29 PM   #6
GMEMD
Member
 
GMEMD's Avatar
 
Join Date: Aug 2008
Posts: 88
Default

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.
GMEMD is offline   Reply With Quote
Old 08-10-2010, 07:26 AM   #7
TrainWatcher
Junior Member
 
Join Date: Jul 2010
Posts: 4
Smile

Quote:
Originally Posted by milwman View Post
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 is offline   Reply With Quote
Old 08-10-2010, 07:28 AM   #8
TrainWatcher
Junior Member
 
Join Date: Jul 2010
Posts: 4
Smile

Quote:
Originally Posted by GMEMD View Post
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?
TrainWatcher is offline   Reply With Quote
Old 08-10-2010, 08:13 AM   #9
milwman
I shoot what I like
 
milwman's Avatar
 
Join Date: Feb 2007
Location: Cedar Fall's, Iowa
Posts: 2,474
Send a message via Yahoo to milwman
Default

Quote:
Originally Posted by TrainWatcher View Post
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
__________________
Richard Scott Marsh I go by Scott long story

http://www.flickr.com/photos/22299476@N05/
milwman is offline   Reply With Quote
Old 08-10-2010, 01:12 PM   #10
JRMDC
Senior Member
 
JRMDC's Avatar
 
Join Date: Nov 2006
Posts: 11,202
Default

The current issue of Trains has an article on distributed power including some operational detail.

The control is by telemetry.
__________________
My RP pix are here.
My Flickr pix are here.

My commentaries on rail pictures are in my blog.

RP Photo Albums:
Cabooses
Engine Details
Farm and Train
Plumes!
Railroad Details
Signal Details
Switchstand Shots
JRMDC is offline   Reply With Quote
Reply

Tags
emd, torque, train engineer

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT. The time now is 08:56 AM.


Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.