Why won’t the train move?

[lvlender]

Today I was driving a 77-car RoadRailer freight train pulled by a pair of SD40’s. I was coming off the mountain on the Scenic Starter Route. I stopped the train on a 1.1% downgrade. Upon releasing the train and engine brakes (and counting to 10), I ran up the locomotive’s engines repeatedly to 50%, even 88%, power but the train would not move. This has happened to me about 50-60% of the time when I stop a train.

I have to repeatedly run the engines up and down and after about 3~5 minutes the train will start to move. Happens a lot at train stations when I am running a passenger train. Tough to stay close to schedule with this happening so frequently. I am sanding the rails with no effect. Any thoughts?

[derekmorton]

>77-car RoadRailer >counting to 10

Newcomers do this all the time.

Count to 100 might be more realistic.

If you press F5, you will get the train driving display, 3rd box down is the "train brake" information.

Lines 2 and 3, EQ and BC show the engine brake pressures,
The second BC shows the train brake line pressure.

If the train line pressure is above zero, you are not going to move.

[TrainSimJack]

Hi Kevin -

I'm going to take a guess that you're not familiar with how Train Air Brakes work. (This is not an insult, I did not know either, and assumed they weren't much different than the brakes on my car)

It's complex enough that it's worth skimming a few youtube videos to learn about it.

Here's a few pointers:
Air brakes on a train must always be 'recharged' after use.
Air brakes on a train can be "slightly" increased but only "fully released", there is no such thing as a partial release. (this means if you apply too much brake, there's no way to "ease off")
Dynamic brakes are nearly always preferred to be used first, because of their fast recovery time.
When applying train brakes (air), you'll need roughly 6lbs to start. Many people aim for an "Initial reduction" of 6-10lbs - 20lbs would be excessive in most cases. (In other words, in most cases, you don't want to jam the brake lever to the extreme.)

I'm told in real life, the independent (Engine) brake is not used until the train is going below 10MPH.
There's far more nuance than I'm sharing here, but hopefully this gives you a few ideas.

Oh and the reason it takes forever in your current scenario: Each car has an air tank, when you apply the brakes, you lower the pressure in each tank. The compressor in the engines then needs to refill 77 air tanks, and that takes time. Real life Train folks have told me they've been stuck for 20-30 minutes doing this in real life.

[derekmorton]

there is no such thing as a partial release

Errr, passenger engines have brakes that will do a partial release. It has a distributer valve.
Freight brakes cannot. It has a triple valve.

http://www.railway-technical.com/trains/rolling-stock-index-l/train-equipment/brakes/

[oper190]

This might be called a cheat, but after releasing brakes, Initialize Brakes <SHIFT> + / You should be able to move then.

[lvlender]

Thanks for responding, guys. Trainsimjack, you posted...

When applying train brakes (air), you'll need roughly 6lbs to start. Many people aim for an "Initial reduction" of 6-10lbs - 20lbs would be excessive in most cases. (In other words, in most cases, you don't want to jam the brake lever to the extreme.)

I applied train brakes to an engine (that was sitting still) to see how much brake could be supplied and stay within an initial reduction of 6-10 pounds you recommended. Perhaps I am not reading the result correctly, but it seems that a mere 1% brake application causes a drop in pressure of 6 pounds. 18% brakes netted a loss of 10 pounds pressure. I can't see where 18% brakes is going to stop a train moving at speed.
What am I missing?

[TrainSimJack]

I'm not an expert at openrails, so I hope others more qualified will chime in here.

lvlender - my best guess is that the Service percentage refers to the travel of the brake handle itself.
I'm also going to guess that the way Openrails is wired, the first position jumps directly to that 6lb reduction.

6-10 is your initial reduction - you can go more if the train needs it, but what you can't do on freight trains, is take some away.
There's also a maximum, beyond which you don't actually get any additional breaking force.

I found this article that you might find helpful:
North American Freight Train Brakes | The Railway Technical Website | PRC Rail Consulting Ltd (railway-technical.com)

The article does a better job than I can of explaining the details.

[derekmorton]

What am I missing?

Try it on a train in OR.

>I can't see where 18% brakes is going to stop a train moving at speed.

What % are you using in the OP?

[lvlender]

Try it on a train in OR.

>I can't see where 18% brakes is going to stop a train moving at speed.

What % are you using in the OP?

until I started reading the responses to this post, I never considered what % I was using. I just applied more (and more) brake until the train stopped. I need to look into this more.

[PerryPlatypus]

As others have said, most of the time you should only be using 6 to 12 lbs of BP reduction, and more than that only in extreme cases or on very steep grades. Except on steep grades, "18%" (12 lbs in your example above) is plenty for freight operations. If you have dynamic brakes, use them in combination with the train brakes - keeping in mind that dynamic brakes apply braking force from just the locomotives, while train brakes spread the braking force out across the entire train - real world engineers are very mindful of which type of braking they want to use in different situations and depending on the grades, so they can properly manage the slack running in and out along the train. There is a reason heavy freight trains usually take *miles* to come to a stop from high speed. That's the challenging part of operating trains - planning waaaay ahead.

If you are applying more and more and more brake % until you stop, you are likely at or near a full service or even emergency application by the time you are stopped, which means it will take several minutes for the system to re-charge after you release.

In reality most North American equipment has a quick release valve which lets the brakes release the moment they sense a slight rise in pipe pressure, rather than the BP having to fully recharge. The advantage to that is you get a fast release even after a heavy brake application; the downside is you start rolling quicker, long before the brake system has re-charged, which is potentially very dangerous on steep downgrades and has been the cause of many catastrophic runaways (my understanding is that quick release is not properly/fully implemented in ORTS yet, but I'd love to see if someone has figured it out)

[pschlik]

In reality most North American equipment has a quick release valve which lets the brakes release the moment they sense a slight rise in pipe pressure, rather than the BP having to fully recharge. The advantage to that is you get a fast release even after a heavy brake application; the downside is you start rolling quicker, long before the brake system has re-charged, which is potentially very dangerous on steep downgrades and has been the cause of many catastrophic runaways (my understanding is that quick release is not properly/fully implemented in ORTS yet, but I'd love to see if someone has figured it out)

Direct release (release on the slightest increase in BP) has worked fine forever BUT there is the "Graduated Release Air Brakes" setting in the options that will disable direct release entirely. I wouldn't be surprised if that option was turned on, causing the extended release time in the first post. For anyone here, do not use the graduated release air brakes setting for North American freight trains. This option is only accurate for passenger trains and any train from many other countries. If the content was made for Open Rails, the settings inside the engine and rolling stock should have the correct type of brakes by default and the graduated release air brakes option can remain off.

'Quick release' strictly speaking is something different that speeds up the brake release signal, that's only available in testing versions (added since 1.5) and would require manually editing .wag files to add ORTSEmergencyResQuickRelease ( 1 ), but that's not exactly the solution to unexpected brake performance. Lots of old content just has compressors far too weak and charges the brake pipe far too slowly.

If you really want to simplify things, look in the options for the "Brake Pipe Charging Rate" setting. Entering 1000 psi/s will disable the complex brake pipe simulation and restore MSTS-like behavior that makes the brakes much faster to respond and works better with content not built for Open Rails.

[PerryPlatypus]

Direct release (release on the slightest increase in BP) has worked fine forever BUT there is the "Graduated Release Air Brakes" setting in the options that will disable direct release entirely. I wouldn't be surprised if that option was turned on, causing the extended release time in the first post. For anyone here, do not use the graduated release air brakes setting for North American freight trains. This option is only accurate for passenger trains and any train from many other countries. If the content was made for Open Rails, the settings inside the engine and rolling stock should have the correct type of brakes by default and the graduated release air brakes option can remain off.

'Quick release' strictly speaking is something different that speeds up the brake release signal, that's only available in testing versions (added since 1.5) and would require manually editing .wag files to add ORTSEmergencyResQuickRelease ( 1 ), but that's not exactly the solution to unexpected brake performance. Lots of old content just has compressors far too weak and charges the brake pipe far too slowly.

If you really want to simplify things, look in the options for the "Brake Pipe Charging Rate" setting. Entering 1000 psi/s will disable the complex brake pipe simulation and restore MSTS-like behavior that makes the brakes much faster to respond and works better with content not built for Open Rails.

Thanks for the reminder Phillip! Now I recall what we were observing is that when you have an *Emergency* application and then release, the direct release behavior does not seem to occur until the BP climbs all the way back up to around 50-60 PSI or higher. Or to be more specific, until the BP equalizes with the aux reservoir. Our understanding has been that the release should begin as soon as the control valves sense a 1 to 1.5 psi rise in BP. Have you confirmed whether that is prototypical behavior?

[pschlik]

Thanks for the reminder pschlik! Now I recall what we were observing is that when you have an *Emergency* application and then release, the direct release behavior does not seem to occur until the BP climbs all the way back up to 65 PSI or higher. Have you confirmed whether that is prototypical behavior?

The utter slowness of emergency release was just a matter of a missing feature added at the same time as quick release. The real thing uses the remaining air in the aux res to pump the brake pipe back up after an emergency application which makes it so much faster to release an emergency application, it was a no-brainer feature to add. That's actually enabled by default, but again limited to the testing versions at the moment.

[Erick_Cantu]

Thanks for responding, guys. Trainsimjack, you posted...


I applied train brakes to an engine (that was sitting still) to see how much brake could be supplied and stay within an initial reduction of 6-10 pounds you recommended. Perhaps I am not reading the result correctly, but it seems that a mere 1% brake application causes a drop in pressure of 6 pounds. 18% brakes netted a loss of 10 pounds pressure. I can't see where 18% brakes is going to stop a train moving at speed.
What am I missing?

A 6lb reduction in brake pipe pressure is a 15psi application at the cylinder. This is because the reservoir has 2.5 times the volume as the brake cylinder, so lowering the pressure in the reservoir causes enough air to flow into the cylinder to raise its volume by a factor of 2.5, and 6 x 2.5 = 15. A 10-inch brake cylinder has an area of about 78.5 square inches. This 15psi reduction means the total force is 1,180 lb at the cylinder, and typical brake rigging might multiply this force by a factor of 10, for 11,800lb at the shoes.* Multiply this by the coefficient of friction at the shoes (around 27% for high friction composition shoes at 35mph) and you get a total retarding force of 3,000lb.

This is not an insignificant amount of force. The maximum tractive effort of a GP-type locomotive is around 60,000lb (while they all have different power ratings, almost all of them weigh about the same and put out the same 60,000-ish lb of tractive effort). This equates to roughly 20 cars' worth of braking force at 35mph.

Percent is a meaningless value with air brakes and I don't even know why the OR team bothered with it. What matters is the reduction in the brake pipe relative to the reduction that results in the maximum application of force in the cylinder. This is called a full service reduction. Typically, a full service reduction is between 20 and 30 psi. Any application beyond that is a waste of air. The reason that you have more pressure to work with isn't to increase braking force, it's to increase the number of applications you can make (10psi reduction is typical) before you are out of air and have a runaway on your hands. Every time you release the brakes, the system needs to recharge, and this takes a very long time. Making a subsequent application before the system is recharged will mean you have less and less air in the pipe to work with every time you apply the brakes. Assuming you make a series of 10psi applications and release them, without the pipe being able to recharge, then that initial 90psi becomes 80 psi on the next application, then 70psi on the next, then 60psi on the next... and you will find yourself with no air to operate the brakes very quickly.

Please study this article extensively: http://www.railway-technical.com/tra...n-freight.html

*This example uses a leverage ratio of 10 to 1 for simplicity. In real life, car brakes are rigged so that the maximum braking force does not exceed a certain percentage of car weight to prevent wheel slippage. This percentage is called the braking ratio, and is typically around 13% of the car's loaded weight. Modern cars have load sensing switches which reduce this ratio to around 40% of the empty weight whenever it senses the car is not loaded. But, as you can see, the force at the wheel might be considerable with even a 6psi reduction in brake pipe pressure.

[TrainSimJack]

Erick_Cantu, that was an awesome reply!