[R H Steele]

 ErickC, on 03 June 2020 - 01:34 AM, said:

I haven't read this whole paper, as I primarily used it for the engine data, so the answer may very well be contained here.

This video also offers interesting insight into the development of GM's 2-stroke diesels.

Informative paper, thanks for attaching, Erick. Regards, Gerry

[Weter]

By the way, I looked for a transparent dieselsmoke texture, to make smoke nearly transparent at diesel set's stable states without load, and even more transparent, when decreasing throttle setting.
The best, that I found at this moment, is "Light" variant of texture by 3D trains, but the smoke becomes white, when throttle is decreasing.
Does anybody know, are there other variants of nice transparent dieselsmoke.ace?

[ErickC]

 Weter, on 08 June 2020 - 12:46 PM, said:

As I understand, the position of throttle handle more likely gives POWER reference for Diesel set, not rpm, when reverser isn't at 0 position.
Because there's complex Power-regulating system between Engineer`s controller and high pressure fuel-injecting pump in powerful locos.
So, when load rapidly rises, the RPM drops, but at the same time the exaltation of Main Generator is increased by the systrm, so DG-set gives more current (mean-more power) to traction motors. And opposite, when load drops, exaltation lowers automaticaly, but rpm rises a little, and then fuel quantity is reduced by regulator, trying to maintain defined rotation speed.

Making black clouds, when rising up calls "Loko Gived a bear" among staff in some countries.

It probably depends on the manufacturer. On EMD units the throttle commands four relays which create a binary signal for the governor to interpret. The governor solely controls engine RPM, but, as it is mechanical, it will always lag to some degree. Its operation is discussed in detail here. This lag is the reason why the engine on an EMD locomotive will tend to briefly overspeed a little bit when the load is dumped by the wheelslip control, and this lag is also why it will tend to overspeed when changing throttle positions, especially when large changes are commanded. This is something that I wish OR would model - with greater RPM acceleration values and larger commands in engine speed, the sim should have the engine speed exceed the commanded RPM briefly.

This often gives people the false impression that, under normal operating conditions, varying load changes the fuel consumption or that the governor operates on a fuel flow schedule rather than an RPM schedule. Neither is true. The governor commands engine RPM, and the power is a constant in any given throttle setting unless the wheelslip system is dumping the load (giggle). How that juice makes it to the motors without frying the whole works is, of course, why locomotives transition. There's a good explanation of that here. There's also a detailed explanation of how the governor and load regulator work together to keep both engine RPM and the generator's power output constant between pages 7-30 and 7-32 of the GP38-2 service manual.

So the main takeaways are this:

1. The governor sets engine RPM
2. Being a mechanical device, the governor lags somewhat
3. The power sent to the traction motors, and thus load on the engine, in any given throttle setting is a constant, maintained by a feedback loop between the governor and load regulator
4. During either wheelslip or transition, the load will be removed from the engine. Because the governor lags slightly during large power changes, the engine will momentarily overspeed under these conditions.

[Weter]

ErickC, I agree with You.
I didn't know, yet, that our "Регулятор"(regulator) is named GOVERNOR in English, but the scheme it works is exactly the same (same 4 relays, but 15 positions for mainline locos/8 for shunters), as we took ALCO RSD5 as a template in late 1940s. The difference, that here "UNITED REGULATOR FOR rpm/Power" is used, so mechanical governor and electric Load regulator are combined in single case and have mechanic and electro-magnetic links.
The governor, this way, maintains engine's rpm, AS YOU SAID, by controlling the amount of fuel, that High-Pressure Pump(s) are injecting to cylinders during each stroke(by monitoring the krankshaft's speed and taking in account the main Spring's tension, wich is altered by sayed four relays using hydraulic, pneumatic, or electric transition - Result is setting of all pumps to corresponding setting), But it has possibility to alter exaltation of Main generator, and in reverce way, if load of Generator changes suddenly, the change of current in traction motors cirquit, can directly change(add correction to) the governor's main Spring tension(fuel flow), not due to lagged rpm change.

Nevertheless, the instructions are ordering to engine's drivers not to make fast changes throw 2-3-4 notches of throttle at one time, but wait 2-3 seconds on each of notches to let diesel-generator unit to go to stable state before raise-up throttle setting.