Dynamic brake failure question...

[GSkid]

The 1989 San Bernardino train disaster on Cajon Pass was the result of a cascade of events. The clerks in Mojave had miscalculated the weight of the train. So it was heavier than they thought it was. Then one of the rear helpers had non-functioning dynamic brakes from the get-go, which the engineer at the head of the train was unaware of. Then when the train was picking up too much speed, he hit the emergency brakes which deactivated the dynamics of all the remaining locomotives and it went into a runaway train situation and ultimately a massive derailment.

My questions are....

#1: If the dynamic brakes fail all of a sudden on one of the locomotives while going down a steep grade, is the calculation built into the equation that the train will still be able to be adequately slowed down by the functioning dynamic brakes of the remaining locomotives?

#2: Does the head-end get an alarm when the dynamics go out on a trailing unit including DPUs?

#3: Is there a particular procedure that is done to deal with such an event and if so, does anybody know what that is?

#4: Do dynamic brakes fail that often? And if so... is it usually a complete loss of them or a gradual loss?

It's a scenario I never hear people talk about and was curious as to what is done to deal with it.

[BNSFdude]

My questions are....

#1: If the dynamic brakes fail all of a sudden on one of the locomotives while going down a steep grade, is the calculation built into the equation that the train will still be able to be adequately slowed down by the functioning dynamic brakes of the remaining locomotives?
No. It is calculated as Tons per Operative Dynamic Brake. It doesn't compensate for DB failure enroute.
#2: Does the head-end get an alarm when the dynamics go out on a trailing unit including DPUs?
Yes. It will give you an Alarm, but it doesn't necessarily let you know what the alarm is about, though by looking at the trailing indicator, you could tell if the failed engine was the DP itself by the lack of DB effort.
#3: Is there a particular procedure that is done to deal with such an event and if so, does anybody know what that is?
Stop your train essentially. Or handle it with air.
#4: Do dynamic brakes fail that often? And if so... is it usually a complete loss of them or a gradual loss?
Not really. The main failure was the lack of a DB holding feature which would have prevented the loss of DBE when the PCS was activated. Most enginest have this, but every modern engine does for sure.
It's a scenario I never hear people talk about and was curious as to what is done to deal with it.

[Ericmopar]

This is interesting.
The only thing I know for sure, is the train should have been able to be stopped with the air brakes, just like in the steam era.
It's all about "Braking Units" and each car and engine is capable of being stopped by it's own set of air brakes.

I wonder how often dynamics fail. The reason I say this, is because there are videos of that happening on YouTube. It's pretty spectacular to watch. Dynamic failure can be a meltdown, or downright small explosion.

[GSkid]

Well at the time of the 1989 San Bernardino train disaster, apparently the Federal Railroad Administration had a mandate that dynamic brakes be deactivated when a train was put into emergency. It was accidents like this and others that had them reverse that mandate and instead require dynamic brakes be allowed to remain in use during an emergency.

I find it odd that they don't compensate in the equation for the loss of DB from one locomotive on the train. Apparently it's not really a problem or they would have added that to the equation. I'm guessing it's because the brakes are enough to compensate for the loss of the one unit's DB effort to slow it down or stop it.

The other things I often asked myself but I've seen nobody talk about on the net is......

#1: Why are GE's far more susceptible to fires than EMD locos? If you see a locomotive with fire damage to the paint rolling down the rails, it seems like to me that 90%-95% of the time it's almost always a GE and not an EMD. And then I ask myself.... is it something inherently wrong with 4-stroke engines that make them more susceptible to these fires or is it simply a problem with GE's design and that other 4-stroke locos from other locomotive manufacturers don't suffer from the same issue. Maybe EMD is just better at designing an engine that is not susceptible to this issue and has little to do with the fact it's a 2-stroke.

#2: Why does EMD's engines seem to be far less susceptible to diesel engine runaway than GE's engines? Is it the individual manufacturer's design.... or is it a 2-stroke vs. 4-stroke issue?

#3: EMD made special tunnel motor models to deal with hot air being sucked into the engine while going through long tunnels on mountain grades and overheating it. Did GE's of that era ever have such overheating problems in tunnels? I never recall hearing they did. So why did EMD have such a problem? And then I think..... why do they BOTH not have cooling issues in tunnels today with their modern locos? Better cooling or are they designed now to suck cool air from below the frame....or both!?!??

Nobody has to necessarily answer those questions.... but surely they are ones that provoke thought and at least make you think "yeah....why is that?".

On a side note..... there are pics and videos on the net of EMD SD70ACe-T4s with railroads being field tested but nobody seems to be catching them turned on or under load. The couple videos I've seen of them very recently has them completely turned off in the consist. I'm surprised with all the railfans out there, that we haven't seen videos of these running and under load. It's either nobody is really trying or maybe a running one is just really that elusive.

Thanks for answering those questions Anthony. And as a big thank you to you, I bought your new GEVO sound pack....... and....okay,.... I'm lying....I bought it a few hours before I made this thread and planned on buying it anyways. But thank you just the same!

Now I'm off to finally actually try those sounds out as I haven't had a chance to yet!

To EricMopar....

I've seen that video before.... but it just made me think..... I've seen videos of EMD's with melting or blowing up dynamic brake grids on the net.... but I've never seen videos of GE's doing the same. Weird!

[JerryC]

Just FYI, Seaboard System.

https://youtu.be/5OwMzI9P79c

[BKRR605]

It isn't dynamic but,... GE Problem https://youtu.be/GPgaS0UHsrk

[Ericmopar]

The GE fire problem has to do with GE's having an external fuel system to feed the injectors, while most EMD units have had an internal fuel feed system. IE the EMDs have their fuel injector feed lines, machined into the heads and maybe block.
I'm not sure if these newer "Cat" powered EMDs still have the internally machined fuel feed system.

I've noticed for years however, you are also more likely to see a GE engine just plain belching flames out the exhaust. That could be a blown turbo causing that. If the turbo charger blows a seal, then raw oil gets spewn into the hot exhaust, causing a big flame and smoke show.

As far as Dynamic meltdowns. I'm guessing that GE being primarily an electrical company, is why their electrical is better than their mechanical stuff. Dynamic brakes are just turning the motors into generators, then the current being fed to giant resistor packs. Well... that's over simplified, but it's the gist of it and it's far more complicated in an AC unit.

A little known fact is: "AC" units should really be called "AC/DC/AC" units.

As far as Tunnel motors, that has always confused me. S.P. and Rio Grand have said they needed them, but both railroads mixed in units with regular radiators on mountain routes...
GEs are inherently built like a Tunnel Motors anyways, with cool air intake at the bottom of the hood.

[JerryC]

Hmm, AC-DC-AC - great name for a band! I imagine their hits would include "Highway to Hell and Back", "You Shook Me All Night and All Day Long", "Thunderstruck and Rescessutated", and "Dirty Deeds Done Dirt Cheap For A Few Dollars More".

Somewhere I have an old Southern Railway manual that states that if there is fire and smoke blowing from the exhaust of a locomotive, then something in the mechanics, maybe an injector, is out of adjustment. This was confirmed to me recently by a shortline operator - mechanic. This would be more likely on a big railroad, whose inspection schedule on a large fleet of locomotives would not allow for fine tweaking of the locomotives's fueling system.

[BNSFdude]

GEs toast out because of the external fuel lines, as suggested.
EMD failures tend to be more catastrophic than any other, like turbo clutches blowing up or compressor failures.

[Ericmopar]

Hmm, AC-DC-AC - great name for a band! I imagine their hits would include "Highway to Hell and Back", "You Shook Me All Night and All Day Long", "Thunderstruck and Rescessutated", and "Dirty Deeds Done Dirt Cheap For A Few Dollars More".

Somewhere I have an old Southern Railway manual that states that if there is fire and smoke blowing from the exhaust of a locomotive, then something in the mechanics, maybe an injector, is out of adjustment. This was confirmed to me recently by a shortline operator - mechanic. This would be more likely on a big railroad, whose inspection schedule on a large fleet of locomotives would not allow for fine tweaking of the locomotives's fueling system.

I was talking to a shop mechanic one day and he confirmed the injector part of it, but told me that it's usually as simple as deferred maintenance causing dirty air filters.