Switching out cars

[AlanB]

While it's true that the air brakes were applied from the moment that they separated the train, the conductor set the hand brake because over time the remaining air will slowly bleed off and eventually the brakes would release. Depending on leaks and other factors, it could take many hours or just a few. So by setting the hand brakes on one or two cars, the conductors ensure the utmost safety in case the switching ops take too long.
As noted, a runaway train would not be a good thing.

Perhaps I've got it completely backwards, but don't the brakes apply as the air pressure decreases?

No, you've got it right. Confused? :unsure:

However, the way things are designed, once the air totally drains from the resevors of each car, the brakes will no longer work. It's a rather complicated system, that requires that air pressure be maintained at all times to make things work. See this article for a run down on why initially no air coming through the main hose applies the brakes, but after several hours of no return of air pressure in the hose the air holding the brakes will bleed off and the brakes will release.

 

[Ryan]

I think that I get it, thanks. As is likely the case with most things on the mechanical side, it's far more complicated once you get into the details!

Would it be correct to then say that the brakes are held on by air from one of the two reservoirs (service or emergency), and that a reduction of pressure in the air lines signals the triple valve to allow air from the reservoir to apply the brakes? Then, the hand brake is just a mechanical linkage that applies pressure to the same brake shoes without the need for air from the reservoir (unlike most cars that have a separate brake shoe for the emergency brake)?

 

[MattW]

That sounds reasonable to me. When I gave a speech to a history class on the Westinghouse brake, I called the trainline a "signal" line because while yes, it does pressurize the reservoirs, it's the change in air pressure in this line that "signals" the brakes to apply or release.

 

[wayman]

I think that I get it, thanks. As is likely the case with most things on the mechanical side, it's far more complicated once you get into the details!

I have a several-hundred-page "air brake examination study manual" from the Pennsylvania Railroad, dating from the 1950s. It has lots of folded pull-out diagrams. There is a ton of material there, and you had to learn it all by heart. On some of those safety regulation tests, I believe 100% is the only passing grade.

 

[Sam31452]

Switching is a very expensive process, because you need a switcher engine and staff, so there are only 2 places in the US where this happens Spokane and San Antonio

At both locactions switching takes place in the middle of the night, which raises costs even higher.

In Europe mostly night trains are switched, but on day trains passengers are required to change trains,

and switching is avoided whenever possible.

You forgot the Lake Shore Limited at Albany.

Of course I did, but I didn't travel on the LSL since the last millenium.

But Albany is also an excellent example that switching is avoided whenever possible,

I remember that there wasn't always a through car from BOS to CHI, but passengers were required to change trains in Albany, right?

 

[jis]

Of course I did, but I didn't travel on the LSL since the last millenium.But Albany is also an excellent example that switching is avoided whenever possible,

I remember that there wasn't always a through car from BOS to CHI, but passengers were required to change trains in Albany, right?

My understanding is that the main reason for not running through cars back then had more to do with the lack of availability of enough serviceable cars than the cost of doing the switching.

 

[wayman]

The conductor, assistant conductor, and a third person, who turned out to be a train master deadheading to Omaha, walked through the diner dressed in their parkas, mitts, and snow boots. I decided to return to my room which was on the first sleeper right after the trans-dorm. We eventually stopped, and I watched the conductor working a long ratcheted lever at the vestibule to set the brake on our car....
I thought of a number of things concerning this incident during the rest of my trip, and perhaps the most significant one to me was the realization that very possibly the safety of all the passengers rested on that one brake set at the front of the first sleeper. We were without any propulsion for I would guess 45 minutes to an hour, and if we had been on the slightest of grades, only that brake prevented us from going some place that might've been very nasty.

And indeed, this just happened in South Africa today

Runaway Luxury Train Derails in S.Africa, 2 Dead

Dlali said the train began moving after the electric locomotive was removed but before the steam engine could be attached, and gathered speed while rolling down a slope.
Seventeen coaches derailed just outside a station in Pretoria, said Johan Pieterse of the capital's community safety department. Pieterse said two people died at the scene. Power tools had to be used to cut some passengers from the wreckage.

 

[toottoot]

A lot of times are just putting on blue light for worker protection.in short: train arrives, and hep shut off, blue light need applied before workers are allowed between equipment.

next electrician drops jumpers, and split is made.

Now remove blue light protection, and let move be made to set aside the part of train or car to be removed.

If a car needs to be added, you pick up car, let conductor hook up hoses for yard move, or otherwise if Mechanics do it you need blue light protection.

after car is hooked up (with air only) the train is put together again.

Now blue light protection goes back up, next set of hoses is connected, electrician puts hep and communication jumpers in , and asks for hep to be made alive.

Now car inspector needs to do a brake test.

If the new car was pre tested its a simple test, if not, entire train needs to be walked in apply and release.

Now blue light gets called off and train released back to crew.

what exactly does blue light mean?

I have several times watched the yard engine at Albany perform adding the Boston section to train 49. LSL, destined Chicago. It always took them over one hour.

There is a cross-over strategically placed on the platform track, that would have enabled the Boston section to be placed north thereof, ready, with the Engine on; the section from New York stop and cut their power off just south of the cross-over and go to the house. Back the head onto the tail end, make an air test, and be ready to leave within fifteen minutes. Amtrak sure needs competent supervisors who understand the work.

toottoot

 

[had8ley]

A lot of times are just putting on blue light for worker protection.in short: train arrives, and hep shut off, blue light need applied before workers are allowed between equipment.

next electrician drops jumpers, and split is made.

Now remove blue light protection, and let move be made to set aside the part of train or car to be removed.

If a car needs to be added, you pick up car, let conductor hook up hoses for yard move, or otherwise if Mechanics do it you need blue light protection.

after car is hooked up (with air only) the train is put together again.

Now blue light protection goes back up, next set of hoses is connected, electrician puts hep and communication jumpers in , and asks for hep to be made alive.

Now car inspector needs to do a brake test.

If the new car was pre tested its a simple test, if not, entire train needs to be walked in apply and release.

Now blue light gets called off and train released back to crew.

what exactly does blue light mean?

I have several times watched the yard engine at Albany perform adding the Boston section to train 49. LSL, destined Chicago. It always took them over one hour.

There is a cross-over strategically placed on the platform track, that would have enabled the Boston section to be placed north thereof, ready, with the Engine on; the section from New York stop and cut their power off just south of the cross-over and go to the house. Back the head onto the tail end, make an air test, and be ready to leave within fifteen minutes. Amtrak sure needs competent supervisors who understand the work.

toottoot

BINGO !!! You get the AU Oscar for the year and it is only April. The Albany yard conductor tried to come on this list and defend his foot dragging but as time goes on it is becoming more obvious even to non-railroaders or train buffs that he lacks something in his work ethic. "How To Work Yourself OUT Of A Job" is probably the title of the book he'll write if they ever do implement your idea. Knowing Amtrak that yard conductor will probably be Superintendent next time I pass thru.