Elvas Tower: Idea: Diesel-Electric Manual Transistioning - Elvas Tower

Jump to content

  • 2 Pages +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

Idea: Diesel-Electric Manual Transistioning For First-Generation diesel fanatics... Rate Topic: -----

#1 User is offline   Traindude 

  • Engineer
  • Group: Status: Contributing Member
  • Posts: 639
  • Joined: 17-November 13
  • Gender:Male
  • Location:Seattle, WA
  • Simulator:Open Rails
  • Country:

Posted 01 January 2017 - 08:55 PM

Hi. Here is an idea for a feature that should please any first-generation diesel fan. Manual transitioning on diesel-electric loco's. Yes, I have already sent it to the OR Trello board, but I still want feedback from fellow Train-Simmers as to whether this feature is worth it or not.

For those who don't know what transitioning is, I'll let this quote explain it:

Quote

Transition is the process by which the transmission of a diesel-electric locomoitve is brought from series wiring to parallel wiring. When in series, all current in the locomotive pass through all motors: this produces maximum low-speed force in the motors, i.e., maximum starting torque. When in parallel, current is divided among the motors: this produces maximum high-end efficency, i.e., highest motor speed. In the Early EMD 567 prime movers this could be done manually. There was a throttle lever and a transition lever on the control stands. When the engineer made transition there was a very distinct sounds of the prime mover winding down to idle then up again quickly from Idle to the throttle notch. Not all locomotives can make transition -- yard locomotives are often wired only for series. Also many locomotives were equipped with automatic transitions that occured at a high rate of speed.


Obviously what this means is that transitioning physics and sounds, as well as the necessary controls, will need to be implemented. It should be noted that on some locos the transition lever is also tied to the dynamic brake lever or the transition/selector lever allows the throttle to double as a dynamic brake handle by disabling the notching mechanism of the main throttle when the selector handle is in the "brake" position.

#2 User is offline   Csantucci 

  • Member, Board of Directors
  • Group: Status: Elite Member
  • Posts: 6,986
  • Joined: 31-December 11
  • Gender:Male
  • Country:

Posted 01 January 2017 - 11:23 PM

The same feature could be nice also for rheostatic electric locos, where you have such transitions too.

#3 User is offline   Jovet 

  • Open Rails Developer
  • Group: Status: Elite Member
  • Posts: 2,240
  • Joined: 14-January 08
  • Gender:Male
  • Location:Omaha, Nebraska.
  • Simulator:MSTS/Open Rails
  • Country:

Posted 02 January 2017 - 02:42 AM

This seems like a pretty important thing to model, if you ask me.

#4 User is offline   Hobo 

  • Foreman Of Engines
  • Group: Status: Contributing Member
  • Posts: 968
  • Joined: 19-December 04
  • Gender:Male
  • Location:Paris,Ont- Canada
  • Simulator:OPEN RAILS & MSTS
  • Country:

Posted 02 January 2017 - 07:09 AM

Isn't that the same thing as " Blended Braking " in MSTS as in a MP40 ?

#5 User is offline   Serana 

  • Conductor
  • Group: Status: Contributing Member
  • Posts: 489
  • Joined: 21-February 13
  • Gender:Male
  • Location:St Cyr l'Ecole (France)
  • Simulator:Open Rails
  • Country:

Posted 02 January 2017 - 12:43 PM

View PostHobo, on 02 January 2017 - 07:09 AM, said:

Isn't that the same thing as " Blended Braking " in MSTS as in a MP40 ?


Not at all : blended braking is mixing dynamic brake with pneumatic brake.
Transitionning, as said above, is needed on electric and diesel-electric locomotives that have a rheostat that is used to control the current in the motors.

You start with the series-parallel wiring (2 blocks of motors in parallel, each block is composed of 2 motors in series or 2 blocks of motors in series, each block is composed of 2 motors in parallel).
Basically, you start with the maximum resistance. The motor starts with the lowest voltage.
When the motor accelerates, current decreases. So you have to decrease the resistance to increase the voltage and to further increase the speed.

Once you reach the minimum resistance, the voltage of the motors is half the line voltage because of the wiring.
You have two choices : decrease the magnetic field of the inductor, or transition to the parallel wiring (all motors are in parallel).
Then you start again with the maximum resistance, and you decrease once again the resistance until you reach the minimum resistance.

Then, you can also decrease the magnetic field of the inductor.

The rule is to never stay too long on an intermediate value of resistance (due to the huge amount of heat produced by the rheostat).
If you are reaching the maximum speed authorized by the signals, you need to decrease the torque, so you have to cut the traction, transition back to series-parallel with maximum voltage, wait for the speed to decrease a bit, then transition back to parallel, reach once again maximum voltage, until you reach once again the maximum speed, etc.
If the needed torque to maintain your speed does not vary too much, you can regulate the torque with the inductor shunts (you decrease the magnetic field => less torque, but not too much because it can also increase the speed).

That type of operation was in nearly all electric and diesel-electric locomotives when the power electronics was not really developed (no thyristors, no transistors, etc.).

#6 User is offline   Hobo 

  • Foreman Of Engines
  • Group: Status: Contributing Member
  • Posts: 968
  • Joined: 19-December 04
  • Gender:Male
  • Location:Paris,Ont- Canada
  • Simulator:OPEN RAILS & MSTS
  • Country:

Posted 02 January 2017 - 02:20 PM

I'd enjoy seeing an old wiring diagram for that system . When were they used ? - Pre 70s ?

#7 User is offline   Coonskin 

  • Open Rails Developer
  • Group: Status: Elite Member
  • Posts: 3,691
  • Joined: 15-January 04
  • Gender:Male
  • Location:Eastern Oklahoma
  • Country:

Posted 02 January 2017 - 05:05 PM

I've run many engines that still had the decommissioned transition lever in place, having been converted to automatic transitioning. As I recall, at certain speeds you would cut the throttle, move the transition lever to the next transition, then reopen the throttle. Yes, most manual transition engines started being converted in the '70's I would think. Latest year of mfg engine that I recall a manual transition lever being in were GP38's (not -2's or AC's) made in the late 1960s, as I recall.

#8 User is offline   Serana 

  • Conductor
  • Group: Status: Contributing Member
  • Posts: 489
  • Joined: 21-February 13
  • Gender:Male
  • Location:St Cyr l'Ecole (France)
  • Simulator:Open Rails
  • Country:

Posted 02 January 2017 - 06:23 PM

In France, the locomotives with rheostat were not retrofitted. Complete manual operation.
Some of those locomotives are still running on regional trains, but they're disappearing progressively. They're replaced either by EMU/DMU or by more recent locomotives (with power electronics).

#9 User is offline   Hamza97 

  • Engineer
  • Group: Status: Contributing Member
  • Posts: 606
  • Joined: 01-March 15
  • Gender:Male
  • Simulator:Open Rails
  • Country:

Posted 03 January 2017 - 08:48 AM

A big YES....
Some videos too, of transition taking place on a WDM-3A, Alco 251C power pack:

https://m.youtube.co...h?v=WFt4E4ZmFik

https://m.youtube.co...mv-google&gl=IN

And a text explanation of the same:
http://www.irfca.org...ransitions.html

#10 User is offline   Csantucci 

  • Member, Board of Directors
  • Group: Status: Elite Member
  • Posts: 6,986
  • Joined: 31-December 11
  • Gender:Male
  • Country:

Posted 03 January 2017 - 11:26 AM

In Italy the latest rheostatic electric locos (E656) had automatic transitioning. We still have the 200 Kph E444 rheostatic loco operating.
So this feature would be welcome. However I wonder if all the variety of constructs requires a scripting approach to this feature.

  • 2 Pages +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

1 User(s) are reading this topic
0 members, 1 guests, 0 anonymous users