[steamer_ctn]

Hi Jorgen,

jorgen, on 12 April 2014 - 12:37 PM, said:

Here there will be an educational thing when you're done with version 1. Writing about this.
For the first time I drove with this effect , I thought it was something seriously wrong with the train.
It felt glued to the track. I got to sand and running with 80 % of the power of the engine to get the train to move at all (no slope).
I haven't set roller bearings in all wag files for I didn't know it at the time.

I agree that there will need to be a re-alignment of expectations as I suspect that MSTS allowed some behaviours that would not be possible with real trains.

jorgen, on 12 April 2014 - 12:37 PM, said:

Long trains with low hp/ton
http://youtu.be/n8uL3OkT_vM (three engine 140 loades coal wagon 21000 ton train) (0,62hp/ton)
http://youtu.be/aQimgGr4KKo (two engine 120 loaded grain wagons about 13000-14000 ton) (0,62hp/ton)

These values is very low but the trains is real and running.
in OR I'm not sure that it will work with starting trains and uphill.

Whilst I can see that these types of trains are possible, the question is what sort of route do they run on? Both trains are shown moving on "level" track.

What is the ruling gradient? How steep a hill are they required to start on?

jorgen, on 12 April 2014 - 12:37 PM, said:

Mathematics test on coal train Open rails.
Starting Resistance = 12 x wagon weight ( U.S. ton ) - roller bearings
12 * 143 ton =1716 ibs (778 kg) 7629 N
Totally 7629 N * 140=240240 Ibs 1068060 N Or (109 ton force)
es44ac Tractive Effort (starting) 183,000 lbs. (with lots of sanding)
It takes 1.5 locomotive just to overcome the start no slope.
With uphill will probably locomotives not overcome the friction and the hill.

I agree, they will probably struggle to start on a hill (depending upon the gradient). Other forms of resistance, such as curve, etc will also impact these calculations.

To confirm actual performance we need to obtain the relevant load tables for these locomotives and the route in question.

jorgen, on 12 April 2014 - 12:37 PM, said:

Have done a downhill test with roller bearing 105 wagon 50 ton each (5500ton).
It is 5,5 per thousand downhill. I release the brake and the train don't to start to roll.
Is that behaviour normal? I asking train engineer here.
I do not know right now in OR what slope it takes to train to roll. (maybe 8)

Whilst I tend to agree with you in principle, I can't comment on this aspect at the moment as the ability to roll a train down the hill is handled in a different section of OR, which I haven't explored.

jorgen, on 12 April 2014 - 12:37 PM, said:

Is this really correct after 70 years?. 12 x wagon weight (and range 0-5 mph)
Has it been no development on roller bearings in 70 years?
I'm certainly not an expert but the overall experience here on the forum
can properly speak, how easy rolls a train?.
Train drivers and conductors must surely have an opinion too.

The issue, as always, is to find information that is accurate and realistic. It also needs to align. For example, the information that you quoted from the forum does not line up with the Baldwin info. Therefore it is necessary to make a call as to which one appears to be the most accurate and provides sufficient detail to build a functional model. In this instance the Baldwin info has been used, as it seems to fit both of these criteria. Future investigation may reveal more up to date info that meets these criteria..

jorgen, on 12 April 2014 - 12:37 PM, said:

I wish that it had chosen the opposite. that you have typed
solid bearing and no text they had roller bearings .

I can understand your wish, but I expect that there will be others out there who would want it to default to friction, so sadly the default value will always be different to the way that some people would desire to have it.

jorgen, on 12 April 2014 - 12:37 PM, said:

Now I have to change 90 % of my 797 wag and 390 eng files.
It will probably take a while ....

I would not start making major changes to your wag files yet, as I suspect that there will need to be other parameters needing to be added to the WAG files as well. For example to calculate curve friction, see the documentation in SVN.

Thus it may be even more difficult to start heavy trains, especially if they are stopped on curves as well.

Cheers

Peter

[gpz]

steamer_ctn, on 13 April 2014 - 12:28 AM, said:

I can understand your wish, but I expect that there will be others out there who would want it to default to friction, so sadly the default value will always be different to the way that some people would desire to have it.

I think the vast majority of players use the program with vehicles with roller bearings. And it will be increasing even further in the future, since there are no new vehicles with solid bearings. So the program should default to that type.

Also MSTS didn't have this high resistance, so the compatibility would by maintained better with rolling bearings default.

[gpz]

Or at least must have an option for setting the default in main menü.

[jorgen]

steamer_ctn, on 13 April 2014 - 12:28 AM, said:

Hi Jorgen,

The issue, as always, is to find information that is accurate and realistic. It also needs to align. For example, the information that you quoted from the forum does not line up with the Baldwin info. Therefore it is necessary to make a call as to which one appears to be the most accurate and provides sufficient detail to build a functional model. In this instance the Baldwin info has been used, as it seems to fit both of these criteria. Future investigation may reveal more up to date info that meets these criteria..
Peter

Hi Peter
I found info about starting resistance from 1992 (Goggled Train start resistance)
Canadian National Railway Resistance Formulae
----------------------------------------------------------------------------
Text from this Pdf

2.1.4 Starting Resistance (1992)
a.
The resistance of journal bearing i much higher at starting than when the vehicle is in motion. Depending upon weight per axle and the temperature of the bearings, which is in turn of function of both ambient temperature and the length ot the time the equipment has been stopped, starting resistance may be as high as 35 lb/ton below 30 degrees F.
An average for light and heavy cars of 25 Lb/ton at starting is a conservative assumption for above-freezing temperatures

b.
The starting resistance of roller bearings is essentially the same as they are in motion.
In general a resistance of 5 lb/ton or less should be satisfactory for roller bearing equipment
at above freezing temperatures

--------------------------------------------------------------------------------
The 5AT Group

Text from The 5AT Group
Locomotive and Train Resistance

Train Starting resistance, associated with static friction which is usually higher than dynamic friction - i.e. it needs to be overcome before the train will start moving.
In the case of roller bearing stock, this value is close to zero, but can be significant where journal bearings are fitted to wagons;

Rolling resistance deriving from axle bearings and wheels on rail - it increases in proportion to the speed;
wind resistance increases in proportion to the square of the speed;
Gravitational resistance when on an incline - equals the train weight x the gradient;
Rail curvature resistance - being proportional to the curvature of the track (or inversely proportional to the radius of curvature), but applying only to the length of train on the curved track.

---------------------------------------------------------------------
Summary of the text above (my opinion)

OR use now these formula. The Starting Resistance ( Baldwin reference from 1944 steam engine )
Starting Resistance - roller bearings = 12 x wagon weight ( U.S. ton )=ibs

When reading this data above (Canadian National Railway Resistance Formulae) and The 5AT Group
on roller bearings so I understand that it is not should be any formula at all on Roller bearings.
Just C1 Value in friction value in wag/eng.file
If there is to be any, it is max 5 * wagon weight (up to 1.5 mph)
This fits much more consistent way I think trains should behave

Frictions bearings working quite right what I can understand, but the problem
are roller bearings.
There is more the question of how it should be written in wag and eng file
I with many others think that you have solid bearings in wag/eng file. Default Roller bearings


bye Jorgen

[steamer_ctn]

Hi Jorgen,

jorgen, on 13 April 2014 - 02:10 AM, said:

I found info about starting resistance from 1992 (Goggled Train start resistance)
Canadian National Railway Resistance Formulae

Thanks for all the information.

I want to reflect upon it for a little while.

It may mean that I need to add an extra bearing type.

Cheers

Peter

[steamer_ctn]

Hi,

I have made some minor code changes to the starting friction, which are included in #2191.

It now caters for three types of bearings - Friction, Roller, Low (Low Torque) - These three key words (not the words in brackets) should be used in the bearing type statement. The characteristics have been based on general info, as well as that described in the FCalc2 documentation.

It should be noted that the above only applies when the Davis coefficient values are used in the WAG and ENG file rather then the original MSTS statement. If the Davis coefficient values are not present then OR reverts to the original MSTS calculations.

If imperial Davis coefficient values are used, then they must have the relevant units against with them. The FCalc2 values appear to be in metric, and can be entered with or without the metric units against them.

For example, when using imperial units:

ORTSDavis_A ( 181lbf ) - lbf
ORTSDavis_B ( 2.25lbf/mph ) - lbf/mph
ORTSDavis_C ( 0.045lbf/mph^2 ) - lbf/mph^2

Cheers

Peter

[Genma Saotome]

Minor nit: The correct term is Solid Bearings. Friction bearings came into common use only after the Roller Bearing salesman spat it out while making their sales pitch.

[jorgen]

steamer_ctn, on 20 April 2014 - 09:44 PM, said:

Hi,

I have made some minor code changes to the starting friction, which are included in #2191.

It now caters for three types of bearings - Friction, Roller, Low (Low Torque) - These three key words

Okey Thanks
Will be fun next Friday then to test this.
The Line ORTSBearingType (Low)
will then become my most common line in Eng / wag files for me.

Bye Jorgen

[cjakeman]

Hi Peter,

gpz, on 13 April 2014 - 01:03 AM, said:

I think the vast majority of players use the program with vehicles with roller bearings. And it will be increasing even further in the future, since there are no new vehicles with solid bearings. So the program should default to that type.

Also MSTS didn't have this high resistance, so the compatibility would by maintained better with rolling bearings default.

Thanks for these improvements. However I agree with gpz, for the reasons he gave, that Roller would be a better choice as the default..

[jorgen]

cjakeman, on 21 April 2014 - 06:23 AM, said:

Thanks for these improvements. However I agree with gpz, for the reasons he gave, that Roller would be a better choice as the default..

Hi

Instead for roller bearings I think the new value Low as default for wagon and engines.
Roller bearings as it was encoded also had great friction up to 5 mph.
But it might have changed in the last the encoding.

Roller Bearings year 1944 =12 * Wagon Weight = ibs friction (42 % lower friction than solid bearings)
Solid Bearings= 20 * Wagon Weight = ibs friction
Low (modern roller bearings)= X friction

I hope the new value Low have very little friction at the start now as it should be with modern trains, but we'll see when we can test it in the next version. Link

Jorgen