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Trying to write a script for the British AWS

#11 User is offline   darwins 

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Posted 25 January 2020 - 08:00 AM

Yes, indeed on the old emu stock letting go of the deadman's was the fastest way to stop. (Same as on the London Underground.)

Since it seems a bit pointless having in OR a deadman's handle that has to be continuously held down, then I prefer not to put an alerter on those emus when writing OR files.
(Possibly emergency stop monitor could be used as an alternative - but there is no emergency stop button - maybe a second animation for the throttle - rotation is throttle and if emergency stop key is pressed the throttle springs up as if released - would have to be keyboard only not mouse control I think - could it work in 3D cabs? Is Mr Momsky reading this?)
Do you know which locos use emergency rate for AWS? I am guessing that would all be post 1980 designs? I may try to get some answers from a BR forum.
In the MSTS eng files there is:
DoesBrakeCutPower( 1 )BrakeCutsPowerAtBrakeCylinderPressure( x )
Either for a loco with TrainBrakesControllerMaxSystemPressure( 70psi ) BrakeCylinderPressureForMaxBrakeBrakeForce ( 70psi ) then BrakeCutsPowerAtBrakeCylinderPressure( 45psi ) seems about right or

Or for a loco with TrainBrakesControllerMaxSystemPressure( 70psi ) BrakeCylinderPressureForMaxBrakeBrakeForce ( 70psi ) then BrakeCutsPowerAtBrakeCylinderPressure( 38psi ) .
Firstly I am not sure how well either of the above currently functions in OR.
Secondly as things stand they do not allow for power being restored at a different pressure to that at which power is cut.
Thirdly I am not sure if they work at all with vacuum brakes.
Finally as you rightly say it would be good to have this based on brake pipe pressure (or vacuum) rather than brake cylinder pressure.








#12 User is offline   Coolhand101 

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Posted 25 January 2020 - 11:11 AM

For a loco with a 70 PSI brake pipe, a triple valve would of been used. This was set at 2.5 ratio. So a 20 psi reduction in the brake pipe allowed a maximum of 50 PSI in the brake cylinders or a 22 psi reduction would be 55 psi in the brake cylinders. These locos had no partial release from the train brake. However, the straight air brake took the air directly from the Main Reservoir. This could allow 100 PSI in the brake cylinders, but a limiting valve was in place to limit the BC pressure between 50 to 75 psi.

For a loco with a 72.5 psi brake pipe, a distributor was used. This allowed a Brake pipe reduction up to 26 psi for a full service brake( 65psi in the BC from the train brake ). As a result, a partial release could be made.

You will get some variations for the above figures, as I cannot remember the exact ratio of the distributor setting ( 2.5 to 2.7 ).

As for the AWS causing an emergency rate instead of a full service rate, some of the early A.C locos achieved this. I have to re-visit the loco docs site for more information on other locos.

It looks like Carlo script is coming along nicely :) :)

Thanks

#13 User is offline   Csantucci 

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Posted 25 January 2020 - 11:29 AM

Hi Coolhand and darwins,
again, thank you for the info. I don't think braking will be exactly as in reality, because of the difference of braking parameters in the various trainsets, and also because I believe that OR foresees now only an automatic emergency braking.
At the moment I won't cope with beacons: I'd like to publish a simple working solution in reasonable time.
I have two further questions:
1) In which state is the sunflower when the train starts the run, i.e. it hasn't yet passed over a beacon?
2) Is there a picture of the (real) cab of the NWT Class 150 where the acknowledge pushbutton can be seen? Or is this pushbutton quite a standard as shape and colour?

#14 User is offline   darwins 

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Posted 25 January 2020 - 11:39 AM

View PostCsantucci, on 25 January 2020 - 11:29 AM, said:

Hi Coolhand and darwins,
again, thank you for the info. I don't think braking will be exactly as in reality, because of the difference of braking parameters in the various trainsets, and also because I believe that OR foresees now only an automatic emergency braking.
At the moment I won't cope with beacons: I'd like to publish a simple working solution in reasonable time.
I have two further questions:
1) In which state is the sunflower when the train starts the run, i.e. it hasn't yet passed over a beacon?
2) Is there a picture of the (real) cab of the NWT Class 150 where the acknowledge pushbutton can be seen? Or is this pushbutton quite a standard as shape and colour?


There is a class 150 cab view here.
The button is centre stage.
I do not know the answer for the sunflower question though.


#15 User is offline   Csantucci 

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Posted 25 January 2020 - 01:29 PM

Thanks Darwins,
that was again very useful.
Today I dedicated few time to the feature, but I could add the automatic braking (at the moment emergency braking) if the button is not activated. Next step is to add the button handling, which I think will require an addition to the main OR code. Such code already has very useful generic sound events dedicated to the train control system scripts, but no dedicated, generic (in the sense that the TCS can assign them to any function it needs) cab controls. I think I will try to add such feature to the OR TCS code.

#16 User is offline   Coolhand101 

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Posted 25 January 2020 - 01:55 PM

View PostCsantucci, on 25 January 2020 - 11:29 AM, said:

1) In which state is the sunflower when the train starts the run, i.e. it hasn't yet passed over a beacon?


Before the driver sets the cab up( Master switch/Reverser at off), the sunflower is black( Clear ).

When the cab is setup( Master switch/Reverser to On/Neutral/E.O, the AWS is activated and once the driver resets the AWS, the sunflower goes to the caution display.

As the Master Switch/Reverser has no 'off' setting in OR, the sunflower should then be at caution on simulator start.

Thanks

#17 User is offline   Stijn D.C. 

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Posted 26 January 2020 - 10:56 AM

Hello,

I remember that BVE4 and Open BVE have AWS futures on it. Maybe this is usefull for prospection ?

#18 User is offline   Csantucci 

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Posted 01 February 2020 - 12:19 PM

I'm not far from conclusion of a first test release, but I have further questions:
1) How can I identify semaphores (which are not connected to the AWS) in the sigcfg.dat file? Are they all signals that have this line
SignalFlags ( SEMAPHORE )

?
I see that there are also distance semaphores that can switch between yellow and green. Are they connected to the AWS?

2) It is not easy at all to identify where the speed warning posts are located in a route, because OR considers them as standard scenery items. So to locate the point where the AWS warning is triggered due to a major speed reduction I can rely only to the position of the speed reduction post. Is there more or less a standard distance between speed warning post and speed reduction post?

3) Is the alerter alert sound different from the AWS warning sound? Can I find or derive somewhere the alerter alert sound?

4) What is the behaviour of the sunflower when the AWS warning is triggered as advance speed restriction warning? Is the sunflower activated also in such case? And if yes, when does it return to black? Before next signal set to clear?

#19 User is offline   Coolhand101 

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Posted 02 February 2020 - 03:43 AM

Hi Carlo.

Member roeter should be able to answer your first question 100%. I'm unable to view signal scripts today.

The majority of Distant semaphore signals had AWS when the system was introduced.

The distance between the advanced warning boards and actual speed board, is the service braking distance of the train. For the UK this did vary, but for a average distance, I would say between a mile and a mile and quarter.

The alerter sound was a "beeping" sound. I will check UKTS for the sound.

The "sunflower" at an advance warning speed board shows the same caution display and also the same warning sound. It will show black again only on a green signal.

Thanks

#20 User is offline   darwins 

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Posted 02 February 2020 - 06:23 AM

Hi Carlo

In semaphore terms AWS was only placed at distant signals. (That includes of course those which combined both a stop signal and a distant signal.)


That should I think translate as for any semaphore signal which I would presume to have SignalFlags ( SEMAPHORE ) AWS is only present if the signal definition includes SignalFnType ( DISTANCE ) it is not present for any other type of semaphore signal.


The problem is looking at some MSTS signal files for colour light signals, there seems to be at least one that includes SignalFlags ( SEMAPHORE ) in the definition, which rather confuses things.I can find no easy pattern for colour light signals where the general rule would be that all colour light signals have AWS except 2-aspect colour light home signals, information signals (feathers and repeaters) and shunting signals.

There might be another way to look at things though, which should exclude the majority of signal types that need to be excluded.

If a signal definition includes SignalAspect ( APPROACH then it should have AWS. That includes all variations such as SignalAspect ( APPROACH_1 and SignalAspect ( APPROACH_2 and so on.
For any signals that do not have an APPROACH aspect then there is no AWS.


For modern traction I believe the AWS is at the speed reduction post or slightly before it - although this is a relatively recent thing - that is both speed reduction posts and AWS for speed restrictions.
It would seem reasonable to assume that in the days before speed reduction warnings were posted then there would be no AWS for the speed reduction -- except by means of a fixed signal.












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