An observtion on releasing brakes in OR,

**OTTODAD** · 08-11-2011, 07:10

Originally posted by lindsayts

The Brake release on a 5 car train takes under 3/4's of a second. ON release the pressure rises within 1/4 of second to around 67 PSI then takes the rest of the time (1/2 of a second) to rise to the line pressure of 70PSI , OR on the other hand takes over 5 seconds, as I said way to slow. On the 208 vehicle train this time runs out to nearly 6 minutes.

How long does it take for the brakes on all wagons of such a long train to be applied, using the Westinghouse braking system ?

If going downhill will the wagons at the rear of the train not yet having their brakes applied push into the couplers of the wagons that have ?

I thought that when brakes are being applied or released, they do so an all wagons / cars simultaneously ?

As for colors shown by your messages window have a look at this below.

O t t o

**GaryG** · 08-11-2011, 11:53

Hi Otto and Others

I used Google and found this link - loads of info...

fogchart.com/Down/BNSF/abth_updated_062405_3.pdf

Page 61 has a table listing times to allow to recharge a train with uncharged brakes when an air flow meter is not in the loco.
Under 2,500 feet, allow 8 to 25 minutes to fully charge
11,000 feet, allow 80 to 160 minutes

This doesn't answer your question but interesting numbers.

Now, more in line with your question...

https://www.train-dynamics.com/

With ideal conditions, an emergency application propogates at about 921 feet per second. A 5,526 foot long train would take 6 seconds for the last car to sense an emergency application then a maximum of up to 10 seconds to apply maximum braking pressure. With these numbers, a mile long train could take 16 seconds before all brakes are fully applied in an emergency application.

In normal braking, I think the propogation times are slower but at least these numbers start to give an idea that train braking is not fast to respond.

GaryG

**OTTODAD** · 08-11-2011, 14:53

Interesting info, Gary, thanks.

How long would it take for a real say 2+100+2 wagon train to release all brakes ?

If such a train stopped on an incline releases it's brakes from it's front wagon to the rear one, would the un-braked front locos and wagons then roll roll backwards, the extended by the locos pulling the train up the incline couplers returning to normal ?

A question about this having been asked in another thread, I usually apply some throttle to prevent this happening.

O t t o

**longiron** · 08-11-2011, 15:51

From an earler thread on OR:

Open Rails software has implemented its own braking physics in the current release. It is based on the Westinghouse 26C and 26F air brake and controller system. Open Rails braking will “read” the type of braking from the ENG file to determine if the braking physics uses passenger or freight standards, self-lapping or not. This is controlled within the Option menu.

Selecting Graduated Release Air Brakes in the Options menu allows a partial release of the brakes. Some 26C brake valves have a cut-off valve that has three positions: passenger, freight and cut-out. Checked is equivalent to passenger standard and unchecked is equivalent to freight standard.

The Graduated Release Air Brakes option controls two different features. If the train brake controller has a self-lapping notch and the Graduated Release Air Brakes box is checked, then the amount of brake pressure can be adjusted up or down by changing the control in this notch. If the Graduated Release Air Brakes option is not checked, then the brakes can only be increased in this notch and one of the release positions is required to release the brakes. Another capability controlled by the Graduated Release Air Brakes checkbox is the behavior of the brakes on each car in train. If the Graduated Release Air Brakes box is checked, then the brake cylinder pressure is regulated to keep it proportional to the difference between the emergency reservoir pressure and the brake pipe pressure. If the Graduated Release Air Brakes box is not checked and the brake pipe pressure rises above the auxiliary reservoir pressure, then the brake cylinder pressure is released completely at a rate determined by the retainer setting.

At the moment only single pipe air brakes are modeled. So the auxiliary reservoir needs to be charged by the brake pipe and depending on the WAG file parameters setting this can delay the brake release. When the Graduated Release Air Brakes box is not checked, the auxiliary reservoir is also charged by the emergency reservoir (until both are equal and then both are charged from the pipe). When the Graduated Release Air Brakes box is checked, the auxiliary reservoir is only charged from the brake pipe. The Open Rails software implements it this way because the emergency reservoir is used as the reference pressure for regulating the brake cylinder pressure. The end result is that you will get a slower release when the Graduated Release Air Brakes box is checked. This shouldn't be an issue with two pipe air brakes because the second pipe can be the source of air for charging the auxiliary reservoirs.

Open Rails software modeled most of this graduated release car brake behavior based on the 26F control valve, but this valve is designed for use on locomotives. That valve uses a control 44 reservoir to maintain the reference pressure and Open Rails software simply replaced the control reservoir with the emergency reservoir.

Increasing the Brake Pipe Charging Rate (PSI/Second) value controls the charging rate.

Increasing the value will reduce the time required to recharge the train; while decreasing the value will slow the charging rate. However, this might be limited by the train brake controller parameter settings in the ENG file. The brake pipe pressure can't go up faster than the equalization reservoir.

The default value, 21, should cause the recharge time from a full set to be about 1 minute for every 12 cars. If Brake Pipe Charging Rate (PSI/Second) value is set to 1000, the pipe pressure gradient features will be disabled and will disable some of the other new brake features, but not all of them. Brake system charging time depends on the train length as it should, but at the moment there is no modeling of main reservoirs and compressors.

**OTTODAD** · 08-11-2011, 16:30

Thanks, Chris, that has lifted most of the fog on that subject !

O t t o

**lindsayts** · 08-11-2011, 17:00

Thank you "Longiron" for the explanation. The reason I started this thread I thought it would clear up a few things and it has done so.

A couple of points though.
How the brakes are applied along atrain depends on the brake system. It would be safe to say most(all) of the newer passenge vehicles have some kind of electrical communication to convey the brake signal down the train (Westinghouse had such a system at least as far back as 1941), so all brakes go on at the same time. This is NOT the case with systems that are completely air. The propargation of the signal down the train is basicly at the speed of sound in compressed air, on top of that would be the time it takes for the air to start to move. As a consequence to all this the train brakes go on progreesively down the train. For a train length and the type of service on the 5 car VLIne pass's I mentioned this is of little consequence but on a long freight it becomes critcal as it will take some seconds for the brakes along the train to be applied. This time must be taken into account, if you try and speed up the process you will likley end up locking the wheels up on the locomotive end of the train before even the brakes in the other part of th train are even applied.

There is a device availible that can be fitted to the rear of the train that will both signal the line pressure it sees at the rear of the train by radio back to the drivers cab and can release air from the line under control of the driver so in this case the brakes can be applied from both ends of the train. This being an advantage for long trains.
For the trains on the iron lines in the NW of western Australia, the brakes are both applied and releaesed from all locomotives along the train so in a sense I believe the trains simulated in the BHPB to port hedland route consisting of 2 Dash 9's 104 wagons another 2 Dash 9's and another 104 wagons behave not unlike two independant trains closely following one another.

I assume one day we will see the second line suppling air along the train be simulated correctly (on trains that have a second air line).

Many thanks for the info,
Lindsay

**OTTODAD** · 08-11-2011, 20:56

Hi Chris !

Gradually adjusted the "Brake Pipe Charging Rate" and found that up to 500 the continuous brakes release hiss I have reported before still does not stop, but at 1000 there was no hiss at all and the brakes released faster.

Found that on this DBTracks Protrain S-Bahn train below the passenger view is at tracks level.

Checking all the *.ENG files found that they had no Inside ( . . . . . . ) paragraph and giving all the train's *.ENG files a passenger view, it has no *.WAG files, making sure that they all quote the shape file they use and it has made no difference.

The MSTSBin #5 Passenger View which can be used with the F9-Train Monitor, providing the car has one, does not seem to work yet.

Any ideas what the problem is, other trains like the Wupper DBAG and ICEs showing at least one interior view with #5. The TGVs show none, the lead engine car not having one and can not click on F9 ones to view individual cars interiors.

Testing it with the Wupper-11 Wupperthal Schwebebahn, the #1 cab view dropped down to where the hidden under water tracks are it is using suspended on it's static tracks higher up, which are missing at one end of it's route.

This is an exceptional trick the Graphics-15 team have used you can put to the end of your bursting at the seams TO-DO list !

O t t o

P.S.: Gave the S-Bahn train a passenger view from the Rheingold Express until I find a more appropriate one !

Found one but is not good enough !

Got another one from Train-DE and that one has excellent passenger views. Now I am happy and can go to bed !

**OTTODAD** · 08-12-2011, 11:02

This still puzzling me I restored the P13 part of the DBTracks Protrain for MSTS and running it in MSTSBin realized that it has in fact got a passenger view in one of it's *.ENG files and when using #5 in the lead car MSTSBin apparently scans all wagons in the consist and if it finds an Inside ( ..... ) paragraph in one of then then displays it.

So I added it to all the other *.ENG files used by this consist to see whether ORTS will show it.

No joy !

But having done that all the consists cars now show that passenger view in MSTSBin when clicking on any car in the F9 Train Operations window and pressing #5.

Will have to wait for the ORTS team to find out why it does not show a passenger view in this consist, having no problems with other consists ?

**twpol** · 08-12-2011, 13:17