[dcarleton]

jorgen, on 27 April 2014 - 06:33 AM, said:

If you find no solution to the problem maybe you should introduce
Default (low) instead of Solid Bearings.
Now we can put in line ORTSBearingType (Low) to solve the problem.

Is "low" really the best default? Regardless, for various reasons "friction" is the worst default of the three choices. Once a solid bearing is broken loose from a standstill the oil coats the bearing surfaces and it remains lubricated until after the train is no longer in motion. If the train slows down but does not stop the solid bearing surfaces remain lubricated. The solid, oil lubricated bearing does not suddenly become a "friction" bearing just because the train is moving slowly. That is propaganda promulgated by manufacturers of roller bearings.

One question, however. Does it matter where in the wag file the line "ORTSBearingType ( Roller )" should be placed?

[cjakeman]

jorgen, on 27 April 2014 - 06:33 AM, said:

Because it is right in the first wagon but second wagon and back problems begin.

OR optimises the reading of WAG files. If it finds another wagon defined by the same file as the first, it copies the settings rather than re-reading the file. I suspect that the new code is in place along one path through the code and missing from the other.

Just a thought,

[Gehe]

Hi All,


I followed the discussion with much interest since I also experienced the fact that identical vehicles may have different starting resistances which is really strange I guess there is a bug here, which will be fixed in one of the next experimental releases.

With respect to the calculation of the starting resistance I had a look into the source code and would like to share the result: As already mentioned in the forum OR tries to recover the most approximate Davis equation from the friction values. This is done under the precondition that it looks like for OR that the friction values are calculated with fcalc (or in other words the values can be assumed to be "reasonable"). Otherwise OR creates new Davis values for the respective vehicle.

If in the first case the MSTS friction value E1 is <0 the starting resistance is calculated by OR from the C1 and E1 friction values in the following way: Starting resístance SR = C1*(0.0025*0.44704)**E1.
This algorithm gives with E1=-0.25 SR=C1*5.47 or if E1=-0.1 SR= C1*1.97 or with E1=-0.05 SR=C1*1.40.
For my personal taste the last value is good to be applied to modern rolling stock.

But of course to get the values here you want to have a modification of the .engs and .wags by doing the fcalc calculation again is necessary. Or you just change the E1 values and accept some inaccuracies with respect to friction (depending on the parameters the resulting deviations may be small).
Compared to the approach to add an ORTS statement both approaches give .eng / .wag files which remain compatible with MSTS.

But I am convinced to benefit from the advantages of OR each of us will have to make the decision to go for OR and to leave MSTS behind. A well working ORTS V1.0 will allow to do this more easily.



Cheers
Gehe

[steamer_ctn]

Hi Jorgen,

jorgen, on 27 April 2014 - 06:33 AM, said:

This problem is that some wagons may solid bearings do not seem easily solved.
In the pictures below you can see how weird it gets.

The same eng and wag file makes some wagons become normal and some wagons have solid bearings.
I think we can rule out that it is wrong to wag file.

Thanks for identifying this problem, I will have a look at.

It may take me a few days as I will be away for a while.

Cheers

[steamer_ctn]

dcarleton, on 27 April 2014 - 07:26 AM, said:

One question, however. Does it matter where in the wag file the line "ORTSBearingType ( Roller )" should be placed?

Strictly speaking, it shouldn't matter. Though it might be best to insert it around the same area as the current friction statement.

For example:

Comment ( ********* Start OR Friction Parameters ********* )	

	Comment ( Speed: 100km/h, Weight - 3.64 tons (US), Area - 2.5m2, Bearing - Friction, Axle - 2, Type - Freight Car Standard )
	ORTSDavis_A ( 281.18 )
	ORTSDavis_B ( 1.7966 )
	ORTSDavis_C ( 0.299475 )

	ORTSBearingType ( Friction ) 
	
Comment ( ********* Finish OR Friction Parameters ********* ) 	

Chers

[steamer_ctn]

I have updated the friction code in #2209, which should address the issues raised above with wagons of the same type not having consistent friction values, etc.

Cheers

[jorgen]

steamer_ctn, on 03 May 2014 - 05:36 PM, said:

I have updated the friction code in #2209, which should address the issues raised above with wagons of the same type not having consistent friction values, etc.

Cheers

Hi
Thanks peter for the update.
Its working now. All wagon with MSTS values gets OR 0,9 settings now.
Now i can drive long trains again without stalling the train in starting moment.

Forum title is maybe it is a bug = yes it was.
We found it and peter fix it.
Now it will works for all wagons and not just for some wagons that it was before.

It was a pretty messy process to find the error on the friction on wagons and engines. (70 topics)
At first I did not know how the programmer wanted to friction would work.
It took two months before I realized that if you had just MSTS values​​, it would
act as the OR of 0.9. (no high start friction)
The only thing I felt that this can,t be right.

In the beginning I thought you wanted to have friction bearings (high start fricion) on all wagons,
Because in practice, it did so. and several said it was quite right.
So that's why I and many said we wanted Low as default for a long time.
Now, I do not think the discussion is so interesting again.

It was when I had only 10 wagons that they saw the error in F5 Hud.
When you have 100 wagons may be just information (F5 Hud) on wagon 1, 10, 20, 30 and beyond.

But we have also on the way fixed ( Low ) Thats are new wagons roller bearings values. (lower starting friction)

It would help if the programmer could talk about how he wants the change he has made to work in practice. Much easier to debug.
Possible that the information was there but I have not found it.

Will test the wagons later to compare old and new.
MSTS old friction values ​​(Fcalc) (OR 0.9 settings) Ex Friction (503N/m/s -0.10 1.5mph 4.945N/m/s 1.939)
OR New friction values ​​(Davis)
Ex.
ORTSDavis_A (500.165)
ORTSDavis_B (2.49802)
ORTSDavis_C (0.045)
ORTSBearingType ( Friction or Roller or Low )

Jorgen Naslund

[Gehe]

Hi All,

when I tested the new X.2229 with respect to starting resistance I observed the following behaviour with .eng / .wag files which do not comprise any ORTS Statements. (by F5 HUD).

When I start the act the inital resistance IR is calculated according to the OR algorithm for the recovering of fcalc based friction values into Davis values in other words:
IR=C1*(0.0025*0.44704)**E1.
After having saved the game the quitting and later restart of OR OR uses different values,i.e. the values which come from the ORTS Bearing_Type Statement. In this case: No statement means solid rollers.
This status then remains stable.

Now my simple question: Is this behaviour intended or a bug?


Regards
Gehe

[Gehe]

Hi All,

I reckognized that my wording in my posting yesterday was unprecise.
With re-start I mean to re-start OR and to continue the act not just to re-start OR and begin new.


Regards
Gehe

[steamer_ctn]

Gehe, on 12 May 2014 - 09:29 AM, said:

Now my simple question: Is this behaviour intended or a bug?

I have put a patch up. #2234.

Can you please check it and see if it resolves your problem.

Thanks

[Gehe]

steamer_ctn, on 14 May 2014 - 03:01 AM, said:

I have put a patch up. #2234.

Can you please check it and see if it resolves your problem.

Thanks

Yes this patch resolves my problem.
Thanks for the quick reaction.
Looks like that another issue is also solved.
With this patch #2234 the load meters in the cab of the loco I use work now correctly.


Regards
Gehe

[jorgen]

Hi

Tested Davis formula in Or Today.
Last week it didn't work at all.
Had 0 Newton friction in wagons although wagon rolled in 80 mph.
But this week, I get resistance in wagon in the update but I wonder if it is right.
Had these test values for easy counting.

Comment (********* Start OR Friction Parameters *********)
Comment (Speed​​: 100km / h, Weight - 50.0 tons (U.S.), Area - 2.5m2, Bearing - Low, Axle - 4, Type - Freight Car Value)
ORTSDavis_A ( 300.0 )
ORTSDavis_B ( 2.0 )
ORTSDavis_C ( 2.0 )
ORTSBearingType ( Low )

Comment (********* Finish OR Friction Parameters *********)

Formula for resistance Davis
A + BV + CV ^ 2 = Newton

Railway wagon speed 20 mph
300 + (2 * 20) + (2 * (20 * 20)) = 300 +40 +800 = 1140 N

When I check in F5 hud when the train rolled in 20 mph I had 478 Newton.
It is 662 Newton lower than 1140 N
In beginning it is right 300 Newton but then it is wrong in higher speed i think.

What is it that is wrong here, I wonder.
Counts Or the formula wrong or is it me who has something wrong here.

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[steamer_ctn]

jorgen, on 17 May 2014 - 12:35 PM, said:

Comment (********* Start OR Friction Parameters *********)
Comment (Speed​​: 100km / h, Weight - 50.0 tons (U.S.), Area - 2.5m2, Bearing - Low, Axle - 4, Type - Freight Car Value)
ORTSDavis_A ( 300.0 )
ORTSDavis_B ( 2.0 )
ORTSDavis_C ( 2.0 )
ORTSBearingType ( Low )

Comment (********* Finish OR Friction Parameters *********)

Formula for resistance Davis
A + BV + CV ^ 2 = Newton

Railway wagon speed 20 mph
300 + (2 * 20) + (2 * (20 * 20)) = 300 +40 +800 = 1140 N

When I check in F5 hud when the train rolled in 20 mph I had 478 Newton.
It is 662 Newton lower than 1140

I think that there is a unit of measure error in your calculations.

I assume that the Davis values that you have used in your formula are metric values (from FCalc)?

The formula should then use a metric speed value (metres/sec).

20 mph = 8.9 m/s

Try substituting 8.9 in the formula above instead of the 20 value, and hopefully this should give the HUD value of 478.

Cheers

[jorgen]

steamer_ctn, on 17 May 2014 - 05:31 PM, said:

I think that there is a unit of measure error in your calculations.

I assume that the Davis values that you have used in your formula are metric values (from FCalc)?

The formula should then use a metric speed value (metres/sec).

20 mph = 8.9 m/s

Try substituting 8.9 in the formula above instead of the 20 value, and hopefully this should give the HUD value of 478.

Cheers

Hi
Yes i have wrong values in formel.
20 mph =8,9 m/s
300 + (2 * 8,9) + (2 * (8,9 * 8,9)) = 300 +17,8 +158,4 = 476 N
same in F5 Hud in train speed 20 mph.
Thanks
Have been used the excel sheet and there you use Pound and pound / mph in davis formula
have tried to make it to the Newton and Newton / m / s not so easy.
But then I saw that Fcalc program could show Davis coefficient, much easier.

Jorgen

[jorgen]

Hi
Comparison of Friction Bearing and standard roller and Low torque on rail wagons at various speeds 0-60 mph.
Although comparison between MSTS values ​​and Davis Values.

The first picture is the values ​​I entered in Davis and MSTS values in wag file​.
Second image is the result of the test, and so on.

In picture 2 so not lean curve as in Figure 4 and 6, and it depends on
to the standard carriage compared with double stack wagons not have much air drag i think.

Facts to be drawn from the data.
From 5 mph to 70 mph , it is basically the same results, Davis and MSTS values​​.
it differs only a few percent.

But from 0-5 mph ,it is big differences.

Friction Bearings
On friction bearing MSTS values ​​are the high resistance in start but in 0.1 mph so is the normal.
This is probably not okay

Davis values ​​are high in start and at 5 mph as it becomes normal.
Are that normal?. link Got this from someone.
(Solid bearings float on a very thin film of oil. Friction at starting speeds would vary by how long the cars have sat idle -- long enough and most of the oil film drips away into the journal box. And so the slope you see in zero to 5mph is actually worse case at regular temperatures and not what would happen in all situations. The extra friction attributed to cold weather again is only applicable to when the cars have sat long enough for the oil film to drip away and the rate in which the slightly congealed oil wicks back up to the axles is slower that would be the case at warmer temperatures.

IOW the whole concept of extra friction at starting speed is really about the passage of time and not speed. Apparently by the time you get your freight train up to 5 mph enough time has passed to wick the oil into place.)

Roller Bearings
Why is 5 mph in the roller bearing it should be like in MSTS that it instantly becomes normal during movement i think.

Info Start friction Davis in Or Now
1. Solid Bearings ..... ORTSBearingType ( Friction )
22 * wagon Weight ton =lbs * 4.4482= Newton start friction (0-5 mph)

2. Roller bearings .... ORTSBearingType ( Roller )
9 * wagon Weight ton =lbs * 4.4482= Newton start friction (0-5 mph)

3. Low (Low Torque) ORTSBearingType ( Low )
4.4 * wagon Weight ton = lbs * 4.4482= Newton start friction (0-5 mph)

Bye

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