[copperpen]

With the appearance of the new Mid East Plus route I decided to take another look at how the manual gearbox is performing in ORTS. I think the answer is not very well.

First of all is the actual gear display in the HUD F5 windows. In the first window gear is shown as 1, go to the locomotive information page and this is shown as 0.
My max rpm is 2000 and my max speed in gear 1 is 17.4mph according to the eng file, However, at 40% throttle I reach a speed of 20.6mph and my rpm is 2351 no matter what throttle setting is used. The same discrepancy is visible right through the gear range. My main problem is with the engine rpm being linked to the gearbox instead of the throttle where it should be after the train is set in motion.
This also affects the audio, 2000+ rpm with a closed throttle is most peculiar.

There is no such problem with an automatic gearbox. RPM is controlled by the throttle, not gear and speed.

[Matej Pacha]

Hi,
let me explain how the gearbox feature is intended to work. Maybe we found out that there is a problem with your ENG settings, or just we understand the gearbox function differently.
The gearbox feature is a very simple simulation of mechanical gearbox (not the hydraulic one). It should work very similar to the automobile gearbox. The engine RPM depends on the status of the clutch. If it is "on" (connected), the engine RPM should be proportional to the vehicle speed (according to current gear ratio). If it is "off" (disconnected), the engine RPM should vary with the throttle setting according to the DieselEngineMaxRPMChangeRate parameter in the ENG file. If the locomotive is equipped with a gearbox, this parameter should be higher than 1/3 of MaxRPM.
If you want to start moving your train, you should gear up and pull up the throttle. Engine RPM should increase and the automatic clutch should close up to 100%. If your first throttle setting was 100%, you should see the RPM falling from MaxRPM to the speed dependent RPM. When a gear is on, you can change the force on wheels by changing the throttle. Setting the throttle to zero disconnects the clutch.
Automatic gear works exactly the same way, except the changing gears is automatical, based on the ENG file settings.

About the F5 HUD view - it is just a debug info that should be changed to the value according to the normal convention (N - 1 - 2 - ...).

The situation you described seems like a classic gear overspeed situation. It's the same as with the automobile gearbox - you can cause the RPM overspeed as well. Even if gearing down from e.g. 4th gear to the 1st gear will cause a huge overspeed to the engine.

If you have a download link to the locomotive, I can reproduce the problem and find out if there is some problem or not. Please let me know.

Thanks,

Matej

[dennisat]

copperpen, on 16 February 2014 - 09:50 AM, said:

With the appearance of the new Mid East Plus route I decided to take another look at how the manual gearbox is performing in ORTS...

Did you have to edit the eng file to get a manual gearbox DMU (eg Class 104) to move at all? Most of the DMUs in MEP are set for idle speed of 1 rpm (yes, one) and the stall speed at 100 rpm.

Start of act, engine running at 1 rpm, set gear to one, open throttle, and accelerate like an arthritic slug. Close throttle, change gear to two (or something else), revs drop to 1 rpm, past the stall point, engine cuts out! Engine won't now restart because, I presume, when started OR assumes engine goes to idle which is less than stall point. MSTS is quite happy with these parameters!

OK let's change idle to 500 rpm. This still works well in MSTS with a slight drop in power. You can now get going in OR, up through the gears, at the rate of the aforementioned gastropod but you can't get to 4th because there's not enough traction force being generated! It just dies and you have to go back to 3rd and tootle along at about 30mph.

Now look at traction forces. MaxForce and MaxContinuousForce are both 70kN, MaxPower is 300hp (engine was really only 150hp but let that go). GearBoxMaxTractiveForceForGears is 7.2kN, 5.5kN, 4.1kN, 3kN.

MaxForce is 70kN and you can only get max 7.2kN through the gearbox? Don't buy that torque converter!

Multiply those gear box forces by 10, though, and it goes well in OR, more or less as it should. Try this now in MSTS and you get the performance of a dragster, you can smell the overheating metal as it takes off.

I would like to somehow adjust the eng file so that it works acceptably in both MSTS and OR. Does an eng file expert out there have any suggestions as to how this might be done? Why does MSTS produce an acceptable result from such weird parameters?

Dennis

PS:

Why does MSTS produce an acceptable result from such weird parameters? I know the answer - because that's the way it works.

[Matej Pacha]

I'm not the right person to write about ENG file parameters for MSTS. I'm just really surprised to hear about these parameters. Well what should be the way of ORTS? Should we keep this heck of MSTS compatibility or just switch to some reasonable values? If you were a modeller, what would you prefer?

[dennisat]

Matej Pacha, on 17 February 2014 - 08:13 AM, said:

... I'm just really surprised to hear about these parameters...

I don't often do acts with manual gearbox DMUs but a lot seem to behave very oddly in MSTS. As I mentioned above, I can get good performance in OR but only by radically altering the eng file parameters. The parameters that work well in OR, though, do seem a bit more logical than those you have to use for MSTS. I just wonder if anyone out there has done any extensive research in this area of MSTS which is rather niche and probably only of interest to heritage enthusiasts.

Dennis

[Csantucci]

Italian gear-based DMUs behave quite similarly in MSTS and ORTS.

[dennisat]

Csantucci, on 17 February 2014 - 08:47 AM, said:

Italian gear-based DMUs behave quite similarly in MSTS and ORTS.

Hi,

Are there any examples of these DMUs easily available to download? I'd like to compare them with the one's I've got.

Dennis

[dennisat]

I've just found that some of the odd looking parameters come from an old topic on UKTrainsim First Generation DMUs. The idea was to improve the realism of mechanical gearbox DMU handling in MSTS given the limitations of the MSTS simulation.

Edit: I actually saw these topics - my name is on one of the posts. Amazing how your memory fails you.

Dennis

[copperpen]

Matej Pacha, on 17 February 2014 - 07:34 AM, said:

Hi,
let me explain how the gearbox feature is intended to work. Maybe we found out that there is a problem with your ENG settings, or just we understand the gearbox function differently.
The gearbox feature is a very simple simulation of mechanical gearbox (not the hydraulic one). It should work very similar to the automobile gearbox. The engine RPM depends on the status of the clutch. If it is "on" (connected), the engine RPM should be proportional to the vehicle speed (according to current gear ratio). If it is "off" (disconnected), the engine RPM should vary with the throttle setting according to the DieselEngineMaxRPMChangeRate parameter in the ENG file. If the locomotive is equipped with a gearbox, this parameter should be higher than 1/3 of MaxRPM.
If you want to start moving your train, you should gear up and pull up the throttle. Engine RPM should increase and the automatic clutch should close up to 100%. If your first throttle setting was 100%, you should see the RPM falling from MaxRPM to the speed dependent RPM. When a gear is on, you can change the force on wheels by changing the throttle. Setting the throttle to zero disconnects the clutch.
Automatic gear works exactly the same way, except the changing gears is automatical, based on the ENG file settings.

About the F5 HUD view - it is just a debug info that should be changed to the value according to the normal convention (N - 1 - 2 - ...).

The situation you described seems like a classic gear overspeed situation. It's the same as with the automobile gearbox - you can cause the RPM overspeed as well. Even if gearing down from e.g. 4th gear to the 1st gear will cause a huge overspeed to the engine.

If you have a download link to the locomotive, I can reproduce the problem and find out if there is some problem or not. Please let me know.

Thanks,

Matej

The automatic box in OR allows the engine rpm to die if the throttle is closed. The manual box does not, which is wrong. These do not have a mechanical clutch like a road vehicle, they have a torque converter style of clutch which allows the engine rpm to drop when the throttle is reduced or closed. the routine is to select gear 1 and accelerate to a given speed, close the throttle, let the revs die, then select the next gear, rinse and repeat until required speed or gear is reached. These units were able to coast in gear with closed throttle. I am aware of the gear overspeed situation, but it does not apply in the case of these units because the hydraulic converter only worked in one direction.

Setting the throttle to zero does not disconnect the clutch or allow the RPM to die which is where the error lies.

[Csantucci]

dennisat, on 17 February 2014 - 08:56 AM, said:

Hi,

Are there any examples of these DMUs easily available to download? I'd like to compare them with the one's I've got.

Dennis

You can download a set here
http://www.trainsimh...oad.php?did=354

Carlo