[Csantucci]

James,
sorry for the methodological error.
I have opened a new thread in this forum section.

[copperpen]

An interesting development in the manual gearbox saga. The models I am using as a test set have been built as a set with the trailing car made to face the correct way without flipping the car. When running, OR gives the rear car much less motive force than the lead car.

I made up a new test consist with just the lead car shape, one normal, the other flipped as the rear car. This consist gives motive power readings almost identical for front and rear. With this set I can clearly see that OR in the manual gearbox mode is ignoring the throttle setting when in gear. The max RPM for this set is 2000, yet at 50% throttle in gear as the train gathers speed the rpm figure exceeds this limit even after the throttle is closed. While accepting that train speed will increase on a down grade, the engine RPMs should in fact follow the throttle, not train speed.

Going back to the difference in power shown in the two different consist, and the rpm being linked to speed it seems that OR in not yet fully capable of running a manual gearbox model. The handling of the automatic box while better is not perfect, again the engine rpm should not be linked to train speed unless it is a mechanical single speed direct drive with no clutch.

[disc]

When the diesel load value reaches the 100% then the engine can't give more force, even if this happens at below 100% throttle, so on higher speeds i getting identical tractive force with 25% and 100% throttle, which is not too realistic. Railworks have tha same problem.

Why is that?

[Csantucci]

Here https://www.youtube....h?v=z4YkAJGMpHE I have published a short demo clip showing a gear-based DMU consist running under ORTS, and showing some new sound trigger too.

[sim-al2]

Csantucci,

Does the rpm following the throttle setting apply for diesel-hydraulic types only? I have always wondered how rpm is related to speed for vehicles with a torque converter (hydraulic), as it seems that rpm is proportional to throttle for some types but not all. My observations of vehicles with automatic transmissions show that it depends on the transmission. How do vehicles with diesel-mechanical transmissions behave currently in OR?

It seems like many vehicles that have gearboxes and that exist in MSTS/OR are diesel-hydraulic or have a diesel-mechanical transmission that incorporates a fluid coupling, but I'd imagine that vehicles that have a regular clutch (small ones, mainly) should behave differently, perhaps more like a car (rpm vs speed and gear, varies directly with speed). I apologize if I don't make sense but it seems that behavior is not clear-cut when it comes to gearbox vehicles.

[Lindsayts]

For what its worth..........

The main transmission used in a lot of dmus's since the middle 1950's would be the Voith, either 2 or 3 speed. These have a torque convertor on the first speed and straight couplings on the rest. On the first speed (torque convertor) the engine revs does not vary much with the vehicles speed but does vary greatly with the throttle position. On the gears with a straight hydralic coupling the engine revs effectively vary with engine speed.

Note: The 2 speed Voiths (T211) only have a single mechanical gear ratio, the 1st speed torque convertor and the 2nd speed coupling being in parrellel on the same shafts, the apparent gear change is caused by the control system changing to the second speed when the torque convertor ratio drops down to around 1.5:1, Voith data claiming the stall torque ratio is 6:1.
The 3 speed (T312) effectively operates the same as the above on gears 1 and 2, 3rd speed is in fact another gear ratio with its own hydralic coupling. Another major difference between the 2 and the 3 speed is power handling ability. The T211 limited to a max of around 400bhp the T312's limit being around 700bhp.

Lindsay

[Csantucci]

What I have pointed out in my video is that for gear based engines ORTS (like MSTS) makes Variable2 proportional to RPM, while I haven't mentioned the throttle. There is only a strange behaviour in the first gear, which lets infer that maybe the ORTS developer has considered a torque converter in the first gauge.
Relationship between throttle and RPM is neither linear nor the same in different circumstances.
The DMU of the video has a 5 gear manual mechanical transmission (engine is derived from an IVECO truck engine), and so within the range of a gear the speed is proportional to RPM (except when the clutch is operating during gear change).

[Matej Pacha]

First of all - the gearbox feature in ORTS introduces a mechanical transmission only. That is why after the clutch is fully "on" the diesel RPM follows the speed.

Now, there are many types of gearboxed power transmissions:

• classic automotive-like gearbox with manual control
  
• semi-automatic mechanical gearbox with auto-clutch
  
• automatic gearbox (same as above, but the gears are shifted based on the diesel RPM or the train speed)
  
• combined mechanical gearbox with hydrodynamic convertor/clutch - h-dyn convertor is used for low speeds and the mechanical gearbox for higher speeds
  
• hydrodynamic convertors - e.g. Voith
  
• even diesel-electric combined with the mechanical gearbox (e.g. http://en.wikipedia....sk%C3%A1_strela)

1) needs a clutch controller to be implemented. No big deal, but it is not compatibile with MSTS, thus I save this for the new ORTS physics
2) and 3) are implemented in ORTS as a manual and automatic gearbox
4) this should be the same as 2 or 3, because the h-dyn. convertor is used as a more efficient clutch
5) it is well known that the mechanical gearbox transmission is not efficient at all. The hydrodynamic convertor is used to get the maximal power from the diesel, thus the traction characteristics is nearly the same as the diesel-electric. The only difference is in the sound of gearbox.
6) I don't know how to cover such cases. I have some plans for the new physics but it will have some limitations

And finally, how are these types handled by MSTS? ENG Manual by Rudolf Richter:

Quote

DieselEngineType - The type of drive system the locomotive has (shortened):

„electric“ direct power transmission, no gear
„hydraulic“ an automatic gear is needed. This is realistic, most hydraulic engines I know have two gears, one for switching and one for the route. They are only changeable while stopping.
„mechanical“ a hand driven gear like in a car – only in little switchers and railcars.

So the "hydraulic" doesn't mean the Voith-like type. I've seen only 5 engines with gearbox in MSTS, but each of them has this property set to "hydraulic", even if the original car has pure mechanical power transmission. How to deal with this? We are approaching the MSTS compatibility combined with more realism, thus we should keep the MSTS structure and get the maximum from it. If somebody could explain what the DieselEngineType really means, I would love to implement it into ORTS.

Matej

[Csantucci]

Matej,
thank you for the good summary.
So the behaviour in the first gear at train start is probably due to the fact that the clutch becomes fully "on" only after a minimum speed is reached.

Matej Pacha, on 16 August 2013 - 12:46 AM, said:

I've seen only 5 engines with gearbox in MSTS, but each of them has this property set to "hydraulic", even if the original car has pure mechanical power transmission. How to deal with this? We are approaching the MSTS compatibility combined with more realism, thus we should keep the MSTS structure and get the maximum from it. If somebody could explain what the DieselEngineType really means, I would love to implement it into ORTS.

Matej

Gear-based DMUs developed for MSTS in my country all have DieselEngineType set to mechanical, accordingly to their real-life prototypes.

[Matej Pacha]

Csantucci, on 16 August 2013 - 01:02 AM, said:

Matej,
thank you for the good summary.
So the behaviour in the first gear at train start is probably due to the fact that the clutch becomes fully "on" only after a minimum speed is reached.

Yes - since a diesel engine cannot run at lower RPM than the idle is and still produce some power (but yes, there is some range the engine will make it)

Csantucci, on 16 August 2013 - 01:02 AM, said:

Gear-based DMUs developed for MSTS in my country all have DieselEngineType set to mechanical, accordingly to their real-life prototypes.

Actually, I didn't make any difference between mechanic and hydraulic setting, because I don't know how to handle the hydraulic one correctly. Let's say that this is a part of my main tasks for v1.0.