[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.

Attached File(s)

•  FCalc 2.0 COFC_jorgen.xls (98.5K)
  Number of downloads: 261

[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

Attached thumbnail(s)

• 
• 
• 
• 
• 
• 

Attached File(s)

•  FCalc 2.0 COFC_jorgen ee.xls (83.5K)
  Number of downloads: 250

[Genma Saotome]

What is the value of Mass() for these cars Walter? And what Locomotive(s) are pulling the train?

[Genma Saotome]

Walter Conklin, on 07 June 2014 - 07:58 AM, said:

Hi Dave,

The entry for each car is Mass ( 42t ). I am pulling a consist of 6 cars plus the NYC 4-6-4 and its tender.

That's half of the correct weight and so IMO the problem appears to be with your locomotive and/or what you are doing as an Engineer and Fireman.

Is this on a grade or level track?

What's going on w/ your boiler pressure?

[copperpen]

Dave,

The original problem was that the engine would not run higher that 10mph in OR. I have the same engine and I could get it running much faster, ran it up to 34mph using the same throttle/ reverser settings as Walter, even with a 15 car NYC consist.

I then asked Walter what cars he was using and then used a 5 car consist of the same set. This acted in exactly the same way as Walter described to me, 19mph was the fastest this train would go.

I then checked the resistance figures in the extended hud and found the cars were generating far more resistance than the engine/tender.

My next move was to insert my Davis figures taken from a BR Mk1 set, which are a few tons lighter than those heavyweights, and also remove the MSTS friction lines. This returned the more normal performance expected with a 5 car train, I ran it up to 70mph with more to be gained beyond that.

I have suggested to Walter that he comment the MSTS friction lines and try again. If he gets the same result as me, then either there is a bug in the resistance code which forces OR to use the MSTS friction if present, or the OR Davis statement MUST be placed after the MSTS friction lines. I will check that one out later.


EDIT;22:32Z
The retention of the MSTS friction lines makes no difference to the operation of the ORTSDavis lines, whether they come before or after the MSTS friction lines.

[copperpen]

I am at a loss as to why your consist behaves that way, but mine does not. Even with the bearing type commented out so you have friction type bearings, at 5 mph the rolling resistance is the same as the roller bearing. Can you post a zip of one of the wag files please.

Mervyn

[dcarleton]

You must be using the passenger cars from GNHVYSET.ZIP. There is also an update, gnhvyupd.zip. The contents of the readme for the update is copied below:

Some people have pointed me to a little typing mistake I did in the wag files of the Great Northern Heavyweights I recently uploaded to the F/L. This mistake has the quite dramatic effect of literally glueing the wagons to the rails, without any loco being able to speed them up to much more than 20 mph.

The zip contains the corrected wag files. Simply copy them to your GN Heavyweights directory, allowing to overwrite the old ones. (Back up first if you have done any changes to them.)

Here is what I did wrong: I left out one decimal point in the wagon's friction. Blame my old age for it...

In the *.wag files, my first friction line read like this:
1034.2N/m/s -0.25 6.01mph 3516N/m/s 1.704

However, it should be "3.516N/m/s" instead of "3516N/m/s"! Quite a difference... As far as I know, this value defines how much the wagon gets effected when on speed, thus my little mistake has this dramatic effect on train handling.

SORRY for the inconvenenience!

Mike

In other words, in this particular case it has nothing to do with OR.