[Fablok]

Gentlemen. I bring up this topic, because thanks to you we have beautifully recreated the Oerlikon type brakes, I would like to suggest to our specialists whether it is possible to divide the throttles so that they work in a given setting as a series of engines and then in parallel. Polish electric locomotives with resistance start have just such control. For example, the position of the controller from position 0 to position 28 is driving on resistances in a series system. Position 29 is shunting, operated by a separate lever with 6 positions. And from position 30 to 43 is driving on a series motor system and 44 is shunting. What exactly am I talking about? A 4-engine locomotive has 2 ammeters, one for serial driving and two for parallel driving. 3 axle locomotives have 3 ammeters for series, series-parallel and parallel running. So, would it be possible to divide the work of ammeters and add shunt. For example, as an additional controller, which would be operated with, for example, Shift+D and Shift+A keys. Below is a video of the locomotive driving and what it looks like in reality.

4 motors

https://www.youtube....h?v=NQL9LUK89z0

6 motors

https://www.youtube....h?v=R-97Dq4z7dk

[Csantucci]

Older Italian locomotives work this way too (in fact both Poland and Italy have 3 kV DC supply).

[Fablok]

Exactly. After the war, Poland followed the example of Italy regarding the electrification of railways ;) That's why we would need this function as an international one. Most electric locomotives on resistance start have such control.

https://baur.pl/wp-content/uploads/2013/09/mierniki_elektryczne.jpg

[Paul B]

This is something that would be a good addition to the sim. Early U.S. diesels had a manual 'transition' lever to change, for example from series-parallel to full parallel. The same lever also put the locomotive into dynamic braking if so equipped. I believe some even had the option for both automatic and manual 'transition'. A separate control for transition and field weakening is/was not uncommon, particularly for earlier diesel electric and pure electric locomotives. In more modern designs transition and field weakening are often automatic based on track speed and throttle setting.

The behavior of the ammeter(s) may be tricky to model here, I believe at the moment the ammeter reading is directly linked to the tractive force.

I think we would need soething like .eng file table(s) to allow the user to define the ammeter reading and tractive force for the various configurations:

Track speed - Traction motor connection* - throttle setting - ammeter reading - tractive force

*Traction motor connection may be any combination of field weakening (shunt) and or variations of series, series-parallel or full parallel groupings. This could be automatically controlled (like automatic gearbox transmission) or manually controlled as we are discussing. I wonder if a 'black box' approach may be easier to implement rather than a full electrical simulation of the volts amps watts etc. As long as we get the correct ammeter behavior and tractive effort at a given setting.

For the Polish electrics is the shunt lever interlocked? Can it only be used when the throttle wheel is in the correct position with all the resistances removed? I'd imagine in some designs designs it may be necessary to shut off power before selecting a new traction motor grouping. We would need some way of interlocking the various controls which may vary considerably from one locomotive to another. For example this quote from the U.S. EMD GP7 manual: "The transition lever cannot be moved from position 2 to 3 or 3 to 2 unless the throttle is in Run 6 or lower."

Just some thoughts;

-Paul

[Fablok]

First, it would be nice to separate the ammeters. So that they can be set in cvf as, for example, ammeter 1, ammeter 2. And the reference that, for example, one works throughout the entire range and 2 starts, for example, from 30 positions. This would be defined as a notch in the eng file. For example on EU07 which has 4 engines and 2 systems:

EngineControllers (
Throttle ( 0 1 0.04 0
NumNotches_serial_arr ( 29
Notch( 0 )
Notch( 0.1 ) <-closing main drive circuit
Notch( 0.2 )
I
I
I
Notch( 0.29 )
NumNotches_serial_shu ( 6
Notch( 0 )
I
I
I
Notch( 6 )
NumNotches_par_arr ( 14
Notch( 0 )
Notch( 0.1 )
Notch( 0.2 )
I
I
I
Notch( 0.14 )
NumNotches_par_shu ( 6
Notch( 0 )
I
I
I
Notch( 6 )

Something like that more or less. I don't know much about it, but maybe that's how it should be described in the eng file. The position numbers are important because in the position from 1 to 28 and further from 30 to 43, the fans of the starting resistances work and this must be assigned accordingly in the sms file. And as for the lever, yes. the left lever at the adjuster works only in position 29 and 44. This is on the example of the 4-axis EU07, as I wrote earlier.

https://www.youtube....h?v=XeagSS6Ey3E

https://kolejowyportal.pl/files/pcargo_eu07-241_pt.jpg

[ErickC]

I dunno, this could get as out of control as it did on the real locomotives. :lol:

As an example, while the GP7 had four transition stages, the GP35 had sixteen. The SD35 had seventeen. This was the source of most of the 35-series' reliability issues and is one of the major reasons why most 35-series locomotives were either retired or rebuilt a relatively young age. By 1972, EMD had enough and gave up on DC generators and transitioning altogether. The Dash-2 series use a main alternator rectified to DC and full-time parallel operation with the exception of the SD40-2 and SD45-2, which start with the motors in 3 parallel pairs (unless the units are one of the later test units with AR16 alternators, in which case they're full-time parallel) and transition around 20-ish mph.

The wonky sound of the engine RPM spiking (loss of load but governor takes a moment to compensate) and turbocharger RPM dropping (loss of exhaust flow meaning less energy to drive the turbine) from the sudden drop in load at transition is what gives people the erroneous impression that EMD turbochargers drop speed under high load. Quite the opposite is true as the exhaust is what drives the turbine in the first place.

For the record, transition on a GP7 is fully automatic, but some locomotives had transition equipment installed so that trailing locomotives without automatic transition could still be controlled.

Quote

The basic GP7L locomotive is not equipped with a transition lever. There are, however, certain types of the GP7 that are equipped with transition levers, even though transition (forward and backward) is fully automatic on the GP7 locomotive. The inclusion of such a lever is principally for use with dynamic brakes, or for the purpose of providing a means for effecting manual transition in other type units (not equipped with automatic transition) when such a unit is being used in multiple unit operation with a GP7. Thus, the transition lever has 5 positions: OFF, 1, 2, 3 and 4; if the locomotive is equipped with dynamic brakes, an additional position "B " (braking range) is also included.

Those transition levers on dynamic brake-equipped locomotives are killers. This is why the standard AAR console has a separate lever that is also oriented differently, and why the dynamic brake levers move in the opposite direction of the throttle.

[Fablok]

https://i.ibb.co/5BQ0DHw/DSCN2737.jpg

[darwins]

OR is very limited regarding the control of electric locomotives. There are four fundamental things missing:

( 1 ) Modelling of series-parallel control of dc motors
( 2 ) Modelling of field weakening (or field tapping) for dc motors
( 3 ) Modelling of automatic acceleration throttle for dc motors on trains, metros and trams - possibly including different types of series-parallel transition
( 4 ) Tap changer controllers with automatic run up and run down for locomotives with dc traction motors operating from single phase ac supply

Work on these would also improve our model of the dc generator - dc motor diesel electric transmission. In that case we might also have to consider changes to the generator field.

The fact that a small number of US diesel types had very complicated throttle arrangements should not be an obstacle to recreating those control types that were almost universal on electric trains around the world for most of the twentieth century. There are some French OR models which I believe have scripted some of these features. It would be good for them to be further developed and included in OR for everyone to use.


Some related discussions:

http://www.elvastowe...post__p__290281
http://www.elvastowe...post__p__288715
http://www.elvastowe...post__p__213287
http://www.elvastowe...post__p__196437
http://www.elvastowe...post__p__189068
http://www.elvastowe...post__p__189043
http://www.elvastowe...post__p__289273
http://www.elvastowe...post__p__278387
http://www.elvastowe...post__p__227480

On Trello

https://trello.com/c/e1vqMwEP
https://trello.com/c/A4UP5mJQ

[Weter]

Hello, Jan.
First, thank You for raising this topic.
Long-awaited function.
First, I'd hint You, there is possibility in ORTS, to name controller's positions for they to cause appearance of text captions with specific names in game:
For example, not just "X%" for throttle notches, but "Notch X", or "Run 3", or whatever You'll define.
So, in cases when, handles are strictly interlocked, You can define appropriate tractive force percents, approplrate traction curves, then assign needed names to every of notches, (looks well, again, only, if sequence of positions is single)
The problem, that in real life, we can omit field weakening, not touching the other lever. But in game, if only one throttle control is defined, we have to go through all positions every time, forth and back.

Quote

electric locomotives with resistance start have just such control. For example, the position of the controller from position 0 to position 28 is driving on resistances in a series system. Position 29 is shunting, operated by a separate lever with 6 positions. And from position 30 to 43 is driving on a series motor system and 44 is shunting.

Do I understand You right: 0-28 rheostatic start on serial arrangement (rheostats are being excluded gradually from circuit), 29 all rheostats are off (pure serial connection, where 6 "shunts" I.e. field weakening steps are possible, but not obligate, as You may not to touch the other lever), 30-43 are again rheostatic (first two-three might be transitions from serial to parallel connection), but on parallel connection, then 44 is pure-parallel arrangement, with field weakening possibility again?

Quote

4-engine locomotive has 2 ammeters, one for serial driving and two for parallel driving. 3 axle locomotives have 3 ammeters for series, series-parallel and parallel running

Not sure, do I understand You right: AFAIK, ammeters are connected to measuring shunts, passing total current to motor group. So 4-motor locomotives have 2 groups, 6-motor ones - 3 groups.

Quote

an additional controller, which would be operated with, for example, Shift+D and Shift+A keys

This, I hope, is possible to add, as we already have three separate levers available for cruise control - so maybe, there would be possibility to assign them to field weakening/motor grouping controls.

[Weter]

Hello, Paul.

Quote

The behavior of the ammeter(s) may be tricky to model here, I believe at the moment the ammeter reading is directly linked to the tractive force.

I've no idea, why, but driving Odakyu's series 7000 Japanese electric trainset's model 20 years ago (it was among original MSTS rolling stock), I've observed the current's drop around 40kph speed, looking very much like re-grouping/field weakening effect.

We need to investigate 7000's *.eng-files to see, what was the reason.

Quote

I'd imagine in some designs designs it may be necessary to shut off power before selecting a new traction motor grouping.

Yes, for this "service" notches might be added - for performing bridge-scheme switching of motor groups arrangements.