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Wheelslip on steam engines Wheelslip occurs on wet rail with cutoff at 0 %

#1 User is offline   Jean-Paul 

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Posted 26 February 2018 - 03:16 PM

Using X4079 version, but unable to say if the problem existed before for a while, I could notice, by trying starting with a 800 metric tons freight in a 1.05% step, that even with permanent sanding, and with cutoff set... at 0 %, wheelslip occurs when regulator is over 57 %. I don't understand, introduced OR parameters being without relation with steam admission at 0 % cutoff... Adhesion has been adapted "widely" to guarantee a possible start in these conditions (calculated). All train brakes are fully released, and tractive effort reached just before wheelslip is 125.6 kN. I attach .eng file, where you can see that adhesion parameters allow theoritically starting with previous sanding under rainy conditions (adhesion @ 0 is 0.3304*0.61 (rain) = 0.205, which gives 160.9 kN of theoritical max effort (no sanding !) - much more, in fact, that an American-built french 141 R could develop in these conditions... Without sanding.
Overall, how an engine having a closed cutoff (neutral position) could slip ???? :rolleyes:
I don't know... But I think it's really a bug !!!
Cheers !
Jean-PaulAttached File  OR_141R511.eng (36.84K)
Number of downloads: 21

#2 User is offline   vince 

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Posted 26 February 2018 - 03:34 PM

Jean-Paul,

Sometimes the unexplained wheel slip cause can be seen on the F5 HUD Debug Screen.

regards,
vince

#3 User is offline   Jean-Paul 

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Posted 26 February 2018 - 03:54 PM

View Postvince, on 26 February 2018 - 03:34 PM, said:

Jean-Paul,

Sometimes the unexplained wheel slip cause can be seen on the F5 HUD Debug Screen.

regards,
vince

Hi, Vince
In fact, Slip monitor indicates tang© = more than 300 kN @ 58 % regulator. That's probably the reason why, right... But why tang© is not 0, considering that cutoff is closed ??? No effort on rods, then no effort on wheels... Logical, no ?
Must also say that permanent sanding, even before trying to start, seems not to have any effect on these parameters : slip factor remains, without or with, @ 0.20...
Best regards,
Jean-Paul

#4 User is offline   vince 

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Posted 26 February 2018 - 07:04 PM

Hi Jean-Paul,

I've noticed that almost all engines indicate slip when throttle is first advanced from idle to a run position.
I have also noticed slip when coasting downhill, no brakes or throttle.

Now that is quite impossible and is the reason that I mentioned the F5 HUD DeBug Screen. When the wheel slip occurs while coasting there was a lot of activity in the Loader Process, clearly tied to the wheel slip.
Conclusion? It's not actual 'wheel slip' but the game engine getting tied up in whatever it's processing.

best regards,
vince

#5 User is offline   Jean-Paul 

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Posted 27 February 2018 - 09:52 AM

View Postvince, on 26 February 2018 - 07:04 PM, said:

Hi Jean-Paul,

I've noticed that almost all engines indicate slip when throttle is first advanced from idle to a run position.
I have also noticed slip when coasting downhill, no brakes or throttle.

Now that is quite impossible and is the reason that I mentioned the F5 HUD DeBug Screen. When the wheel slip occurs while coasting there was a lot of activity in the Loader Process, clearly tied to the wheel slip.
Conclusion? It's not actual 'wheel slip' but the game engine getting tied up in whatever it's processing.

best regards,
vince

Hi Vince,
That's certainly right... But how to do with a steam engine under rainy conditions ??? I did a run with only 350 hauled metric tons, and was also unable to start on the same 1.05 % step, whilst when same train runs on flat ground, steam engine could develop efforts widely larger than those resulting from adhesion calculations.!. It really seems to be a mess ! Of course, everything is OK when "advanced adhesion" button is desactived, but in this cas, adhesion remains the same, by dry, rainy or snowy weather... Why, also, cylinder cocks when open doesn't modify tractive effort ?
Is anybody able to explain how are estimated adhesion factors and attached parameters specifcally on steam engines ?
And are there not some bugs in the calculation process ? That's the question, I think !
Must add that I have no problem with my computer system : fps remain excellent, and load of processor widely under 100 % , even when wheelslip occurs (HUD F5 datas)...
Best regards,
Jean-Paul

#6 User is offline   vince 

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Posted 27 February 2018 - 12:01 PM

View PostJean-Paul, on 27 February 2018 - 09:52 AM, said:

Hi Vince,
That's certainly right... But how to do with a steam engine under rainy conditions ??? I did a run with only 350 hauled metric tons, and was also unable to start on the same 1.05 % step, whilst when same train runs on flat ground, steam engine could develop efforts widely larger than those resulting from adhesion calculations.!. It really seems to be a mess ! ...........snip..............................
Best regards,Jean-Paul

Hi Jean-Paul,
Yes . . . a mess I agree.
Much of the problems are in the engine files themselves plus the fact that OR is still under development.
Have you tried any other steamers under the same conditions?

I had problems with some engines which were all caused by bad engine file paremeters.
Try changing engines and see what happens. Be sure to use same the conditions for testing or it's not a test.
regards,
vince

#7 User is offline   steamer_ctn 

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Posted 27 February 2018 - 06:25 PM

View PostSP 0-6-0, on 27 February 2018 - 12:30 PM, said:

ORTS physics are a mess and need overhauling. I will second that.

Thanks for your constructive, helpful and encouraging comment.

View PostJean-Paul, on 26 February 2018 - 03:16 PM, said:

Overall, how an engine having a closed cutoff (neutral position) could slip ???? :rolleyes:
I don't know... But I think it's really a bug !!!

The OR model probably did not contemplate that somebody would open the throttle wide up, with the reverser in the 0 position.

I will have a look, and "fix" this sometime next week.

View PostJean-Paul, on 26 February 2018 - 03:54 PM, said:

Must also say that permanent sanding, even before trying to start, seems not to have any effect on these parameters : slip factor remains, without or with, @ 0.20...

It is not realistic to apply sanding before commencing to move. If this did happen, it would create little piles of sand on the tracks, and add to the starting issues.

View PostJean-Paul, on 27 February 2018 - 09:52 AM, said:

I did a run with only 350 hauled metric tons, and was also unable to start on the same 1.05 % step, whilst when same train runs on flat ground, steam engine could develop efforts widely larger than those resulting from adhesion calculations.!.

There are a number of factors, including the starting resistance of the train, and the steepness of the slope, adhesive weight of the locomotive, driving technique, etc, that could make it difficult or impossible to start a train, especially on a wet slope.

The tractive effort, and the rotational forces are different values. For example, the tractive effort is an "average" value of the force available to move the train. The rotational force of a steam locomotive will vary as the wheel rotates, and it will reach a maximum value at certain points around the cycle. This maximum value can be in excess of the tractive effort, hence why it might seem that the locomotive is slipping before its tractive effort is reached. Diesels are different, and have constant rotational forces around the full cycle.

Do you have load tables for the locomotive in question?

After I have adjusted the code next week, I would be happy to participate in some additional testing if it is of interest. If so, it would be necessary to set an agreed scenario, and test set.

Thanks

EDIT: Just out of interest, it appears that this locomotive had a Factor of Adhesion = 3.88. Locomotives with FoAs less then 4 were more prone to wheel slip.

#8 User is offline   ErickC 

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Posted 27 February 2018 - 10:41 PM

It may not be "realistic," to sand before moving, but it happens all the time in the real world. And little piles of sand do indeed form.

At any rate, I noticed that "transient wheelslip" generally occurs during periods of high processing demands. Every locomotive I have will slip when moving from idle to 1, even light. I even tried setting the adhesion to extreme values and it still happens. I've learned to ignore it. Ain't no biggie.

#9 User is offline   vince 

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Posted 27 February 2018 - 11:08 PM

View PostErickC, on 27 February 2018 - 10:41 PM, said:

It may not be "realistic," to sand before moving, but it happens all the time in the real world. And little piles of sand do indeed form.

At any rate, I noticed that "transient wheelslip" generally occurs during periods of high processing demands. Every locomotive I have will slip when moving from idle to 1, even light. I even tried setting the adhesion to extreme values and it still happens. I've learned to ignore it. Ain't no biggie.

But the Buzzer!

regards,
vince

#10 User is offline   ErickC 

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Posted 28 February 2018 - 12:11 PM

Oh, I deleted the clip. I also deleted all of the default track sound clips because they're garbage.

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