Can someone address what seems to me a bald-faced lie about the train derailment?

[Kelvin Mace]

From the story in the Toronto Star:

Burkhardt, chairman of the Montreal, Maine & Atlantic Railway, said Sunday night that the train’s sole engineer shut down four of the five locomotive units on the train, as is standard procedure, in the neighbouring community of Nantes before heading to Lac-Mégantic to sleep. Burkhardt said the next engineer was probably due to arrive at daybreak.

But someone managed to shut down the fifth locomotive unit, he said. The railroad alleges someone tampered with the controls of the fifth engine, the one maintaining brake pressure to keep the train stopped.

“If the operating locomotive is shut down, there’s nothing left to keep the brakes charged up, and the brake pressure will drop finally to the point where they can’t be held in place any longer,” Burkhardt said.

Am I missing something here? My understanding is that is NOT how "airbrakes" work. When an airbrake loses pressure, the brakes engage. Airbrakes were the first example of a "fail safe" system in every course and article I have read. Pressure in the line keeps the breaks disengaged, or open. Loss of pressure causes them to engage. I had a recent example of this when a truck driver couldn't get a trailer away from our dock after a pressure line broke. The brakes locked tight and he would have had to literally DRAG the trailer to get it out of the way. After the line was replaced, the brakes disengaged and the the trailer could move.

What am I missing here? The description above is the exact opposite of how an air brake works. If someone shut down the engine causing the pressure to fall in the lines, then EVERY locomotive and car's brakes would have locked.

Is there are new kind of air brake designed by an idiot that functions as Burkhardt describes?

[Berlum]

1. Well, if it is a blunt lie as may be the case, then

it won't hold up very long.

[NYC_SKP]

2. You are correct, I think. For safetly, if air pressure drops then brakes engage.

Air pressure is needed to keep traveling.

It's a brilliant way to prevent accidents in case of loss of air pressure.

Same is true, I believe, for tractor trailer brakes on the highway.

(not an expert)

[Wounded Bear]

3. That is how air brakes work on trucks...

I do not know if they are different on trains, but I have read commentary on another thread that says it is the opposite, and that pressure needs to be maintained, meaning that they are more like hydraulic brakes on cars.

Don't know, though. But it seems to fly in the face of 'common sense' to be that way.

[cali]

4. If it came out of Burkhardt's mouth it's probably a bold faced lie

I don't know a thing about the braking systems on the train, but the guy has already been caught in a bold faced lie.

[MineralMan]

5. This Wikipedia article supports that idea.

Railroad brakes fail safe if air pressure fails and are fully applied, according to it:

https://en.wikipedia.org/wiki/Railway_air_brake

[MicaelS]

7. Based on my 17 years working as a Trainman and Conductor..

For the MKT, then the UP RR, here's what I think happened:

There are TWO types of brakes on rail cars: Service and Emergency.

Service air is supplied by air from the locomotive air compressor. Each locomotive has an air compressor, but it works only as long as the diesel engine is running. Diesel engine shuts down, no service air. No service air, no service air braking system. Service works by reducing the air pressure via the main train brake handle off the lead engine. When you reduce the main train line pressure, usually by a minimum of 10 pounds of air, the system sets up a corresponding amount of braking force on the entire rail car consist starting with the car closet to the head end of the train. It also set the the locomotive air brakes. HOWEVER, the locomotive air brakes are called independent brakes because they can be set and released completely independently of the train line. When train line air is set, an engineer will often release the independent brake to control the slack in the train couplers. AKA "slack action". When the brakes are released on the service system, the system is re-supplied with air from the locomotives.

When the service air is dumped from the main train line the emergency air brakes on each rail car engage, because each car has its own emergency air reservoir. The emergency air is supplied by air from the locomotive air compressor, and is held on each car on its own reservoir. BUT, that emergency braking air can be totally dumped by manually bleeding EACH CAR via a particular method. It has to be done manually, one car at a time, and it has to be done on the ground. Not from the locomotive. If you bleed a car when it is in emergency there are NO AIR BRAKES on that car. If you bleed the entire train down, there are no air brakes on that train. None.

There is no reserve emergency braking system for locomotives like on train cars. There is air in each locomotive in the main supply reservoirs, but they run off the compressors, and those main reservoirs can bleed down. That is why when you shut down the engine on a locomotive, you set handbrakes on each locomotive, since the air can TOTALLY bleed off the locomotive independent brakes since there are always minor air leaks in the system, and no air is being resupplied by the compressor.

According to the Toronto Star article, there were 5 locomotives, and 72 cars. Four of the locomotives were shut down, and that left one running to keep air on the train.

Here's the main point:

So, that ONE running locomotive was shut down by local fireman when they put out a fire on the train. If the engineer set only the locomotive independent brakes, no service air brakes, and THEN failed to set enough manual hand brakes on the train cars, then there was insufficient braking force to hold the train WHEN the locomotive independent brakes bled down to the point where they released. Because, remember no air was being supplied to them by the compressors. Because the number of handbrakes on the train cars was insufficient to hold the train, it rolled away.

[angstlessk]

8. Very informative, thanks, now I get it when they say there were not ENOUGH brakes

set, they are speaking of the hand brakes on the 72 cars...one question that BOTHERS the heck out of me, is why is the side rail at the TOP of a slope and not on level ground?

[MicaelS]

9. You mean a siding?

(1) You don't want a road crossing in a siding, as you would have to "cut the crossing" which means uncouple the train, every time you block it for more than 5 minutes. Almost impossible to do with a 1 man crew. If there were roads in the area on the level ground then that could force the siding to not be there.

(2) Could be a pipeline, or some other underground structure that would cause a conflict.

(3) Maybe the river had something to do with not locating the siding on level ground.

I'm speculating. I have looked the town on Google and can't see the tracks.

[angstlessk]

10. Thank you, I have asked this question on some venues and never gotten an answer..

since I am no expert on rail I probably meant siding , in fact I am sure I meant siding

[pinboy3niner]

11. But the grade shouldn't even be an issue if the brakes are set properly, right?

I'm curious about how the railroad specifies how many manual car brakes should be set in a consist of a given length/weight and in a given situation. They must have at least some internal operational rules that apply.

I appreciate the insight that you and other DU railroaders have to offer.

[MicaelS]

15. Well its one of those "CYA" type of things.

The RR is telling you if you don't do it right, it is YOUR ass that will blamed, not theirs (as is happening right now in this situation), as they told you to "Always do the Safe Action".

You are supposed to use your judgement based on total train weight, number of cars and grade. In a worst case scenario you are supposed to set a handbrake on EVERY single car and locomotive. But in my years no one ever did that. We did not have extremely severe grades in most places we might have to tie a train down here, in the territory where I worked, which was Galveston to Fort Worth. Not like what I have read of what is was in Canada which is a 1.2% grade.

Here in Texas, we would do a max of 25% of the cars on a fully loaded coal, rock or grain "unit" train. A unit train is a train consisting of one single commodity. Max number of cars would be 120 cars @ 130 tons per car (short tons, not long tons), since that is as long and heavy as the RRs wanted to run down here. So that would have been 30 cars, plus 4 locomotives with handbrakes set, PLUS the main train line air set down to max braking power, which would be 35 pounds of air set. The train would NOT be placed into emergency, because as I have stated earlier, you can bleed off the brakes of an entire train which is in emergency.

[Jazzgirl]

12. Okay, I work for a major railroad but don't have any

mechanical experience but what you said sounds pretty much like the explanations I've been given. I'm not a train person but have worked with many in the field.

I don't understand how a fireman could just shut down the engine. You would have to have a mechanism to do that. I know the engineer would have it but why would the fire department have a way to shut it down? Especially with the inbound engineer on site.

[pinboy3niner]

13. News reports said there was a shutdown device on the outside of the locomotive

Protocol for the FD is to shut down the engine when a fire involves a leaking fuel or oil line.

Everything that's been reported indicates that the Nantes Fire Department acted properly in shutting down the locomotive. They also notified MMA's dispatcher, and at least one MMA employee was on-scene before the FD left.

[MicaelS]

16. It is VERY simple to shut down a locomotive diesel engine.

All it takes is to push one button in a certain location. No key or special code is needed. It is designed that way in case of derailment, fire or other emergency situation. So, the fireman must have been trained in exactly what to do in an emergency situation. They had a fire, they killed the engine, and put out the fire.

[The Straight Story]

14. Nice post (nt)

[MicaelS]

17. Thank you. n/t

[Kelvin Mace]

18. OK, then what I thought was a brilliant fail safe design apparently isn't.

My understanding was that air pressure kept the brakes disengaged. No air, then the brakes engage. The other example I have read of was the moderator rods in nuke plants which are held by electro-magnets, and raised and lowered in the core by electric motors to moderate the reactor. In the vent of a power failure, the magnets stop working, and gravity drops the rods all the way in, killing the reactor.

Apparently I misunderstood the system's design, but it seems to me that the system should NOT be described as "fail safe", since it obviously isn't.