Emergency Brake application on a steam engine.

Gregg posted:

What happens  in the cab?   Most diesels drop their load and therefore quit pulling .

I know the  engine and tender brakes are  automatically applied,

Is there an automatic steam cut off to the throttle or does it keep pulling?

Nope. It is up to the Engineer how quickly he wants to close the throttle and bail-off the independent brake. That would depend on the conditions and the terrain.

 Are there indicator lights for a emergency application other than the air pressure gauges?

Nope, no "emergency lights" on a steam locomotive. Between the sound of the emergency air application and the air brake gauges, pretty much ANY Engineer can tell when his train is in emergency, even if he didn't initiate the emergency.

  

 

 

Gregg posted:

What happens  in the cab?   Most diesels drop their load and therefore quit pulling .

1. You hear the air "hiss" when the emergency application initiates. That gets your attention.
2. You may also feel a gentle "tug" forward as the brakes all apply.
3. The Brake Pipe gauge drops to zero.

I know the  engine and tender brakes are  automatically applied,
Yes, they do begin to apply, but if the engineer is on the ball, they won't stay applied very long. He will "bail off" the Independent (engine) brake to prevent a hard run-in of slack. The brakes on the engine and the tender will release when he bails the Independent Brake.

Is there an automatic steam cut off to the throttle or does it keep pulling?  Are there indicator lights for a emergency application other than the air pressure gauges?
There is NOTHING  "automatic" on a steam locomotive. Nothing happens with the throttle. And there are no indicator lights. A good engineer doesn't need a light to tell him when the brakes went into emergency.

When a train goes into emergency without warning, you don't know WHY it happened. It could be something as simple as a burst air hose, or a passenger may have pulled the "rip cord" in one of the cars, just to "see what it does." (It has happened.) However, it could be much more serious. The train may have derailed or come apart! Since you don't know why the air went down, there are a few things a steam engineer on a passenger train must do to minimize potential injuries to passengers and damage to equipment.

I have had a couple of unanticipated emergency brake applications when at the throttle of the 765. When it happens, I must:

• Bail the independent brake off.
• Place the Train Brake handle in the Emergency position.
• Hit the sanders.
• Open the throttle all the way to the roof.

Now that may seem counter intuitive...why would you open the throttle wide open if the brakes just set? There are three reasons:

• If the train has come apart, I want to be absolutely sure that the rear half stops BEFORE the front half does. If it's the other way round, the rear half could slam into a stopped front half with resulting damage and injuries. By pulling HARD on the front half of the train all the way down to a stop, I make sure the rear half will stop before the front half does.
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• If the train has derailed, keeping the slack tightly stretched will minimize the tendency of derailed cars to accordion. On a passenger train, that will kill people! Derailed cars will tend to stay aligned with the rails if the slack is kept tightly stretched.
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• It smooths the stop. Train brakes in emergency can exert a LOT of stopping force, especially passenger equipment. There is so much braking force that passengers who are standing up could be knocked down as the train stops, By pulling on the train all the way down to the stop, it eases the final stopping force a bit. That helps to make sure that no one falls down as the train stops.

It doesn't happen often, but when it does, an engineer has to be prepared to act quickly and precisely to get the situation under control.

Rick:

Would your MO in Emergency prevented wheel damage to a large steam locomotive in Texas about three years ago when there was issues with the MU'ed SD70AC?

As a matter of fact, yes.

An additional reason to bail off the engine brakes is to prevent heating the tires (the flanged steel circles that are fitted onto the wheels).  On diesels, when wheels are worn out or damaged, the entire wheel set is replaced.  On steam engines. the wheels are much more expensive and are counterbalanced for that particular engine.  Therefore the rim (tire) is the sacrificial part of the wheel.  It is applied to the wheel by systematically heating it with a ring of gas jets, and fitting it onto the wheel while hot and slightly expanded from the heat.  As it cools, it shrinks, and fits tightly onto the wheel.  If heated by the brakes, it can slip off of the wheel and really mess up everyone's day.  Therefore, engine brakes on steam locomotives are only used for short periods and as lightly as possible.  Some steam locomotives were equipped with valves which could be set to allow the tender brakes to apply without also applying the driving wheel brakes, but this was not the case on most steam engines.  Other steam engines in mountainous territory had a retainer valve on the tender, to allow the brakes on the tender to remain applied when running light (without cars) on descending grades without applying of the driving wheel brakes.  Helper engines used this feature to return to the bottom of grades after helping another engine and train to the summit.

All good points, Tom. Your comments about driver tire heating bring to mind something else about train braking that the layman usually doesn't understand. On a steam locomotive pulling a passenger train, the Engine Brakes are NEVER used to slow or stop a train.

One of the primary responsibilities of a passenger engineer is to give the folks a smooth ride. In order to do that, he has to be in control of the slack at all times. "Slack" is the slight amount of play found in each coupler knuckle. That play has to be there in order for the couplers to function properly when switching, coupling and uncoupling cars. Each coupler has several inches of slack. That may not seem like much, but since this slack is found in every coupler, a 20-car train has several feet of slack.

This slack in the couplers has to be controlled. That control is achieved by using a technique called "Stretch Braking." In simple terms, Stretch Braking is the technique of using the train brakes to slow the train while the engine is still working,  pulling against the brakes. Using this technique keeps all the coupler slack stretched and allows the engineer to bring the train to a very precise, smooth stop. At some of our passenger stops on the CVSR, our spot has to be accurate to within 2 to 3 feet! Using stretch braking and throttle modulation, those accurate stops can be smoothly achieved.

The Engine Brake does not get applied until after the train has stopped.

Number 90 posted:

As a matter of fact, yes.

An additional reason to bail off the engine brakes is to prevent heating the tires (the flanged steel circles that are fitted onto the wheels).  On diesels, when wheels are worn out or damaged, the entire wheel set is replaced.  On steam engines. the wheels are much more expensive and are counterbalanced for that particular engine.  Therefore the rim (tire) is the sacrificial part of the wheel.  It is applied to the wheel by systematically heating it with a ring of gas jets, and fitting it onto the wheel while hot and slightly expanded from the heat.  As it cools, it shrinks, and fits tightly onto the wheel.  If heated by the brakes, it can slip off of the wheel and really mess up everyone's day.  Therefore, engine brakes on steam locomotives are only used for short periods and as lightly as possible.  Some steam locomotives were equipped with valves which could be set to allow the tender brakes to apply without also applying the driving wheel brakes, but this was not the case on most steam engines.

Both the SP and UP had their larger, main line steam locomotives equipped with "mountain cocks", so that the Engineer could cut-out JUST the brakes on the drivers. Thus, on long mountain downgrades, the independent brakes could also be applied in order to assist braking effort. In fact, the SP even had a water spray system for cooling the wheels on the engine truck, trailing truck, and the tender trucks, i.e. "wheel coolers".

Other steam engines in mountainous territory had a retainer valve on the tender, to allow the brakes on the tender to remain applied when running light (without cars) on descending grades without applying of the driving wheel brakes.  Helper engines used this feature to return to the bottom of grades after helping another engine and train to the summit.

Does SP 4449 still has her wheel coolers?

Dominic Mazoch posted:

Does SP 4449 still has her wheel coolers?

No. All that was apparently removed by the SP when some of the 4400s went into commute service, out of San Francisco. #4449 being one of those locomotives for a short time.

Rich, 

Every time I had the privilege of riding behind 765 with you at the throttle, it was always a smooth ride.  I never saw any beverages spilled in the coaches!  

How were you able to provide that smooth ride during the 2013 trips around horseshoe curve, especially in such an environment with grades?  Does having the diesel along change things for the engineer?  

Thanks, 

Rob

Rob N posted:

Rich, 

Every time I had the privilege of riding behind 765 with you at the throttle, it was always a smooth ride.  I never saw any beverages spilled in the coaches!  
Thank you very much!

How were you able to provide that smooth ride during the 2013 trips around horseshoe curve, especially in such an environment with grades?  Does having the diesel along change things for the engineer?
Grades don't pose a problem for controlling slack, especially going uphill! Coming down, the same principle applies. Gentle applications of the air and just a little throttle to keep everything stretched. The 765 was a flatland locomotive, so it does not have drifting valves. We have to work a little throttle all the time when we're moving in order to keep the cylinders lubricated.

When we've had a diesel along behind the 765 it has usually been for stretching the coal mileage. The train handling process is the same...stretch brake the train and modulate the throttle (steam or diesel)  to stop. We have an "MU Box" which we use to control trailing diesel(s) from the cab of the 765. This is what it looks like.

This MU box was built for us by Jack Wheelihan, who worked for EMD at the time. You know him as "Hot Water" here on the forum. Ours ALWAYS works.

Here's the EMD builders plate on the box...a little worn but still there:

Do you set up  the brakes on the diesel just like it was  a piece of rolling stock or can you also bail off the independent on the diesel  in case of a emergency brake application. How does that work? 

Gregg posted:

Do you set up  the brakes on the diesel just like it was  a piece of rolling stock or can you also bail off the independent on the diesel  in case of a emergency brake application. How does that work? 

Main line steam locomotives of today (SP 4449, NKP 765, UP 844, and UP 3985 for examples) have had their air brake systems modified so that the air MU functions are piped through the tender and the auxiliary tender so that full independent air brake MU is accomplished with any trailing diesel units, just like MU'ing two or more diesel into a consist. Thus, Independent Application & Release, as well as Actuating, functions are train lined. 

What is the port which looks like a 25 pin serial connection on the right side of the MU Box?  

Rich, I love the comment that your box always works!  The concept is around 40 years old, the first being built for AFT/SP 4449.

Dominic Mazoch posted:

What is the port which looks like a 25 pin serial connection on the right side of the MU Box?  

That's where the MU cable connects. It is MUCH larger and heavier than a 25-pin serial connector. That connector is about 5" wide.

I'm guessing the MU box in the picture is no longer in use  and been  replaced with one that has a dynamic brake feature ?  I can see  things could get very  busy with trying to run the steamer & diesel at once. (I think I would flip the generator field switch to "off" and leave it there.)( I can't multi task.)

Thanks for informative replies.. Very interesting.

Gregg posted:

I'm guessing the MU box in the picture is no longer in use  and been  replaced with one that has a dynamic brake feature ? 

Nope. The 765 folks STILL use that same MU Control box. They really have no need for adding dynamic brake control, as they primarily use the trailing diesel to "stretch/reduce" coal consumption.

I can see  things could get very  busy with trying to run the steamer & diesel at once.

Not really.

(I think I would flip the generator field switch to "off" and leave it there.)( I can't multi task.)

Then you would never make a good qualified steam locomotive Engineer, as there is LOTS, and LOTS of "multitasking" involved.

Thanks for informative replies.. Very interesting.

 

What is the function of the generator field switch?

RJR posted:

What is the function of the generator field switch?

All diesel electric locomotive have a switch, that is train lined, to energize or de-energize excitation of the main generator, i.e. the "Generator Field". With out current passing through the Main Field Coils of the main generator (or ANY generator for that matter) , the generator with NOT produce any output. Thus, "dropping the Generator Field switch", unloads all the trailing units, regardless of diesel engine speed. 

Hot Water posted:

RJR posted:

What is the function of the generator field switch?

All diesel electric locomotive have a switch, that is train lined, to energize or de-energize excitation of the main generator, i.e. the "Generator Field". With out current passing through the Main Field Coils of the main generator (or ANY generator for that matter) , the generator with NOT produce any output. Thus, "dropping the Generator Field switch", unloads all the trailing units, regardless of diesel engine speed. 

Oddly enough, the dynamic brake will still work with the generator field switch down.