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More Brake Enhancements Rate Topic: -----

#1 User is offline   steamer_ctn 

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Posted 22 July 2021 - 08:11 PM

I am proposing to add some additional brake functionality.

The first feature will be:

Wheel Slide Protection, which is described in the following extract from a XPT (High Speed Train) manual.

"During braking wheelslide control is effected throughout the train by additional equipment on each vehicle. In the piping to each pair of brake cylinders are fitted electrically operated dump valves. When axle rotations which are sensed electrically, differ by a predetermined speed the dump valves are operated releasing brake cylinder pressure to both axles of the affected bogie.

Dump valve operation will cease when differences in axle rotations arewithin specified limits or the axle accelerates faster than a specified rate. The dump valve will only operate for a maximum period of seven seconds after which time it will be de-energised and the dump valve will not re-operate until the train has stopped or the throttle operated.

Dump valve operation is prevented under the following conditions:-
(i) When the Power Controller is open.

(ii) When Brake Pipe Pressure has been reduced below 250 kPa."

#2 User is offline   Weter 

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Posted 23 July 2021 - 09:03 AM

The analog of ABS of wheeled vehicles?
Similar function can be present as a feedback of dynamic braking controller for skidding prevention as well.
Since we have anti slip subsystems for 6 decades already.

#3 User is offline   steamer_ctn 

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Posted 04 August 2021 - 09:54 PM

Wheel Slide Protection (WSP) has now been added to the latest unstable version.

To activate it, ORTSWheelBrakeSlideProtection ( 1 ) needs to be added to the wagon section of each ENG/WAG file where it is required to operate.

Under normal operation WSP is disabled if the BP pressure drops below 250kPa. This limit can be disabled by inserting the following parameter into the ENG/WAG file.

ORTSWheelBrakesSlideProtectionLimitDisable ( 1 )

In principle, some TCS functions should be able to activate WSP, however due to issues with TCS these will not activate it. For example, pressing the Emergency Stop (ES) button will only activate WSP if the throttle is closed (ie =0) after the ES is pressed.

#4 User is offline   darwins 

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Posted 12 August 2021 - 09:41 PM

More good news on train brakes. Peter has now added to OR that we can have different pressures in the Main Reservoir and the Main Reservoir Pipe.

https://i.imgur.com/J2leFqe.png

To do this you will need to includ AirBrakeMaxMainResPipePressure in the eng file like this:

AirBrakesMainMaxAirPressure( 10.00bar )
AirBrakeMaxMainResPipePressure ( 7.00bar )

and to get a correct reading for the reservoir pipe in the cab view file you will need to use:

Type ( MAIN_RES_PIPE DIAL )

========

For WSP in UK (and I beleive most of Europe) the "normal" settings would be

ORTSWheelBrakeSlideProtection ( 1 )
ORTSWheelBrakesSlideProtectionLimitDisable ( 1 )

#5 User is offline   cjakeman 

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Posted 15 August 2021 - 11:09 AM

View Poststeamer_ctn, on 22 July 2021 - 08:11 PM, said:

Wheel Slide Protection, which is described in the following extract from a XPT (High Speed Train) manual.

"During braking wheelslide control is effected throughout the train by additional equipment on each vehicle. In the piping to each pair of brake cylinders are fitted electrically operated dump valves. When axle rotations which are sensed electrically, differ by a predetermined speed the dump valves are operated releasing brake cylinder pressure to both axles of the affected bogie.

Dump valve operation will cease when differences in axle rotations are within specified limits or the axle accelerates faster than a specified rate. The dump valve will only operate for a maximum period of seven seconds after which time it will be de-energised and the dump valve will not re-operate until the train has stopped or the throttle operated.

I can see that this protects the train (by preventing damage to the wheels and track) but what does the driver experience?

Does the braking distance increase?
Does an alarm sound?
Will the driver be aware that the WSP activated?

#6 User is offline   Weter 

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Posted 15 August 2021 - 11:13 AM

Looks like ABS system of wheeled vehicles and planes.
Without skid, braking is expected to be more efficient, isn't it?

#7 User is offline   darwins 

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Posted 15 August 2021 - 12:49 PM

Quote

I can see that this protects the train (by preventing damage to the wheels and track) but what does the driver experience?

Does the braking distance increase?
Does an alarm sound?
Will the driver be aware that the WSP activated?



Excellent questions.

The braking distance should decrease. Wheels that are rotating offer a greater braking force than wheels that are sliding. The driver of course can release the brakes and apply them again if he is aware of sliding or low adhesion. The electronics can do this much more rapidly. Where the driver must apply or release the brakes for the whole train, the WSP can do this for each wheelset or bogie.

No, there is no alarm, but the driver will be aware that WSP is working, at least on the leading bogie as the brake cylinder pressure will fluctuate rather than remain steady. The speed on the speedometer will drop to zero if the wheels start to slide, but will rise again as they rotate more freely.

These two films give more information:

https://www.youtube....h?v=0DfL06f1NM8

https://www.youtube....h?v=bgXTE6jaAGI

#8 User is offline   Laci1959 

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Posted 15 August 2021 - 10:56 PM

Hello

I asked a motorcycle driver friend of mine who drives FLIRT and KISS type. He sees a decrease in traction and braking force and hears the computer working. But nothing more.
There is some increase in braking distance, but then it helps with the air brake and corrects it. The vehicle brakes with an electric brake, use the air EP brake only when stopping. The computer also uses the EP brake for correction, only in its experience a little late.

Sincerely, Laci 1959

#9 User is offline   Coolhand101 

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Posted 16 August 2021 - 04:25 AM

About increase and decrease in braking distance.

If WSP operates, the braking distance will be increased from normal braking under good adhesion conditions. This increase depends on the low adhesion for the rails.

Without WSP, the wheels will lock, leading to almost no retarding effect, which will lead to an enormous braking distance under low adhesion conditions. WSP can decrease the braking distance sufficiently in this case!

As Darwin stated, the WSP computer can shorten the braking distance compared to the driver doing this manually. However, it is very hard for drivers to do absolutely nothing when WSP operates. They are advise to fold their arms in this case, as the human nature is to release the brakes and try again, which in turn, can (will) increase the braking distance.

In the UK, if the driver does release the brakes and try again, Network rail will not take into account the increase in braking distance causing a S.P.A.D or overshooting of stations due to low adhesion and past the blame to the train operating company( T.O.C ). The driver can be discipline for this!

Thanks

#10 User is offline   cjakeman 

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Posted 16 August 2021 - 10:19 AM

View Postdarwins, on 15 August 2021 - 12:49 PM, said:

Excellent questions.

No, there is no alarm, but the driver will be aware that WSP is working, at least on the leading bogie as the brake cylinder pressure will fluctuate rather than remain steady. The speed on the speedometer will drop to zero if the wheels start to slide, but will rise again as they rotate more freely.

Thanks for this information.

These are quite subtle cues. If the driver doesn't spot them, then the work that is going into this feature will not be appreciated.

How about notifying the player that WSP has operated with a "confirmer" announcement?

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