The explanation of the brakes in a stable state is misleading.As you can see from the diagram there is no method for air to pass from the brake line to the brake cylinder whilst it is like this so whether the loco is running or not doesn't matter.

The first two recommendations from the TSB are for more stringent handbrake regulations and for better procedures for securing driving cabs.

Everything I've read, including some train forums, talk about air bleeding off over time. Although some people think someone might have triggered something in the engine that empties the air pressure.

Yeah the air bleeds off from the brake cylinder over time, but that has nothing to do with the loco running or not.

The other thing is that you shouldn't be depending on the air brakes to hold the train anyway so if they were they weren't operating safely who/whatever caused the air brakes to release.Our procedure for stowing a train is you put on the required number of handbrakes, then you release the train and loco brakes and apply power.If you can move the train you have to put on more handbrakes.You then apply the air brake and shut the loco down.The air brakes are a bonus not a necessity to hold the train in place.

With the TSB recommending changes to securing cabs on stowed trains , it will be interesting to see if that was because someone did something in there at the time of the fire or whether it just noted that the companies procedures didn't include this as they were looking at them.

Sure it does. If the loco is running its actively maintaining the pressure in the line. That seems to be stated in many different places do in inclined to believe it.


I was surprised when I read this in other places too. Seems a bit flawed since you really don't know your margin of safety with this method - you just know that you have enough holding power.

Seems like after you can't move the train you should apply another 10% (or whatever) hand brakes to make sure you have a margin of error in holding power.

Someone pointed out that it's possible (although unlikely) that the engineer did this procedure but ended up with just barely enough stopping power at that time. During the fire the train could have been shifted or changed in some way that now there wasnt quite enough holding power.

It'll be interesting to see if the blank box type device can or does show if the engineer performed the braking test you described.

Look at the brake diagrams you posted and see what happens when you either add or remove air from the brake pipe and you will see that potentially adding air by having the loco running isn't going to keep the brakes on.

With regard to checking if you have enough handbrakes on I believe that the force of the loco/s trying to pull it is greater than the other forces that the train will be subject to ( gravity etc.) so the margin for error is built into the test.You then add loco handbrakes and wheel chocks on top of that and then train is going to stay where you put it.

The black box should show whether a test like this was done and also if any alterations were made to the control settings afterwards.

The engine isn't adding pressure it's maintaining it (so effectively only adding air to counteract whatever leaks out) . That's why the diagram says to maintain static pressure you need the engine on.

I'm not trying to be difficult but literally everything I have read says the same thing.

The air produced maintains the brake pipe pressure at whatever it is set for, if you don't have that because the loco is turned off the pressure in the brake pipe will reduce due to leaks and if you look at the diagrams reducing the brake pipe pressure leads to the brakes applying.

Maybe I have found an answer to the confusion

An American driver was suggesting that it is possible for the loco brakes to bleed off after the engine was shut down as these unlike the wagons do use main reservoir air to directly maintain their effectiveness and for some reason tend to leak more than wagon brake cylinders,I guess that that is a possibility if the driver didn't follow or the company didn't have safe procedures in place.

So instead of having enough handbrakes applied to hold the train he had enough handbrakes whilst the loco brakes were on fully to hold the train.Turn off the train and a bit of leakage from the loco brakes releasing them slightly could have been enough to let it roll.The loco handbrakes would either have to have not been applied or the train was so finely balanced that having one bogie on each loco with brakes on rather than all of them was enough to set things in motion.

A bit like the chance that someone moved the brake handles when shutting the train down ,applying enough handbrakes and testing you have done so would have prevented this becoming a problem.

Yeah, then the human error would be in the HR department.

Or something something, CEO's fault.

Another train derailed today.

why has no one made any "oh look, lirva made another train wreck" jokes yet?

The video of the Spain crash is nuts.

Amtrak actually haz this chit?

Also... if they can make wheel chocks for big-azz C-5A's [they do... we're talkin' herniating!],
there's no reason not to chock up locomotive wheels if left idle for that long.
Or at least hella more secure spring operated emergency brakes [that can only be RELEASED with air]
like with semis.
And even those precautions in the past have caused 30,000 pounds of BANANAS...