Weather and the Railroad

A couple of years ago, during the first good snowstorm we had while I worked for the railroad, I was asked if the railroad took snow days the way some local businesses do occasionally. I think I laughed out loud. The question was an indirect way of asking if I would have some time off as a result of the snowstorm, which would not happen. More recently I was reading an article online about service disruptions to Chicago's commuter rail system during the "polar vortex" that a large part of the Midwest experienced last month. The article was informative but gave only very basic information, but the commentary by other readers is what intrigued me. One particularly upset reader commented that Metra needed to learn how to provide adequate service and stop using the weather as an excuse every time something goes wrong. Now, I do not use Metra, nor am I involved with their public relations department, but the weather can and often does play a significant role in railroading, although the consequences of the weather may be a little less obvious than other forms of transportation.

Since it is February, and still the middle of winter for half the world, we will talk about winter weather. For most forms of transportation, snow and ice can wreak havoc on roads, runways, and basically any surface over which a vehicle operates, by making that surface quite slippery. The same is true for trains, but since trains are on rails, which serve as a fixed guide way, the results are quite different. While cars might slide off the road, trains will generally stay on the rails, although stopping and starting distances will be longer. When snow gets above the rails, it also can decrease the effectiveness of the brake systems. As the wheels travel over snow covered rails, they warm up, and snow sticks to them. Most trains rely on a brake shoe contacting the wheel tread to slow the train. When released, the brake show is very close to the wheel, though not touching it. The snow that the wheels pick up gets stuck to the brakes as the wheels rotate, and it can build up and create a thick layer of snow and ice between the brake show and the wheel. When the brakes are applied in these conditions, the snow and ice must melt off before the brakes become effective. Typically in these conditions, and engineer will set the brakes periodically while running to help curb the build up of snow and ice on the brakes, but some buildup still occurs.

Snow and ice can also affect the brake system in a very different way if any is allowed to enter the air hoses. A large enough amount can create a blockage in the brake pipe itself, interrupting the normal flow of compressed air through the brake system. This situation prevents the normal application and release of the brakes throughout the train. The portion of the train behind the blockage would not respond to any of the engineer's brake operations. If this is a small portion of the train, it may go unnoticed, but if a significant tonnage is behind the blockage, the results could be catastrophic. The chances of such a blockage occurring can be reduced dramatically by blowing snow out of air hoses before coupling them when the train is first assembled. Doing proper brake tests and inspections also helps to catch this condition before it becomes a major problem.

Brake pipe blockages are one problem caused by snow and ice entering the brake system, but even a much smaller amount of snow and ice can cause problems. It is possible that an amount of snow and ice would enter the brake pipe but would be insufficient to block the brake pipe. However, it could get into the control valves on a car and compromise the brakes there. Each car on the train has a control valve, which is basically the brain for that car's brake system. It responds to changes in brake pipe pressure and applies or releases the brakes on that car accordingly. See our air brake page for a more detailed description of air brake system functionality. Inside the control valve is a pair of slide valves, which each work to apply or release the brakes. The slide valves have holes to allow air to flow from one part of the system to another, as necessary for the application and release of the brakes. These slide valves are fairly small, only a couple inches in diameter and a few inches long. The holes are much smaller, some only the size of the head of a pin. It takes very little snow to plug one of those holes and prevent proper air flow. Depending which hole or holes get plugged, the result could be anything from a brake that responds slowly to one that does not apply, or one that does not release. In a long train, a single car not applying is actually not much of a problem usually, however a brake that refuses to release can become serious. If a car is dragged with the brakes applied, the wheels heat up. If the problem goes unchecked for long enough, the wheels can heat up enough to weaken or even destroy them, which can lead to a derailment. If the brakes remain applied hard enough, the wheels may not even turn when the car is moved. As they slide, the rails will wear flat spots in the wheels. Again, if this problem goes unchecked for long enough, it can also result in derailment. One of these days I'll write about the derailment I had that was caused by brakes stuck applied.

Snow and ice are not the only challenges to the railroad during the winter. Actually, the temperature can be a pretty significant challenge as well, particularly extreme temperatures. Before we get to that, let me explain a characteristic of the air brake system though.

On a train, compressed air is pumped into the brake pipe to charge the air brake system on each car and release the brakes. The brake pipe runs the entire length of the train. On the way, the air passes through steel pipe that is attached to the frame of each car and through flexible rubber air hoses that connect the brake pipes on each car. There are countless couplings, fittings, gaskets, and valves that make up the brake pipe. Each valve, fitting, gasket, and coupling is an opportunity for air to leak out of the system. Leakage is normal, up to a point. Since significant leakage can affect the ability of the brakes to function properly, it is measured before a train leaves its initial terminal. There are limits to how much leakage is acceptable. On long trains, the effect of the leakage can be more noticeable. On a train that exceeds a mile in length, it is fairly common to have a pound of two less air on the rear compared to the head end. A couple of pounds makes no noticeable difference in brake system functionality, and it is nearly impossible to avoid. In the summer, when the weather is warm, leakage is minimal, because everything seals up properly. However, as the temperature drops, all those fittings, couplings, hoses, and gaskets tend to shrink up, and as they do so, more leakage occurs. Rubber gaskets become very hard and do not seal couplings nearly as well as in warm weather. The more extreme the cold, the more extreme the leakage.

In addition to brake pipe leakage, when air leaves the compressor on the locomotive, it is fairly warm. As it is pumped into the main reservoirs and into the brake pipe, it cools off and becomes more dense. Essentially, a volume of air at room temperature takes up much less space when cooled zero degrees. However, if it must fill the same volume, such as a brake pipe, it still fills it, just at a lower pressure. The combination of colder air and increased brake system leakage means that train length gets limited. In the cold it takes longer for the air brake system to charge, and longer for the brakes to release. It is simply impossible to build the same long trains and expect the brakes to work properly when it is extremely cold outside. Just as a comparison, in the summer in Alaska, Alaska Railroad often runs trains that exceed 8,000 feet in length. Temperatures are warm and it takes less than a minute to apply or release the brakes on a train of that size. In the winter, when temperatures in Fairbanks can dip to -60 or lower, it becomes difficult to operate a train that is 2,500 feet long. The brakes respond much slower, and charging the system, or filling it with air, can take hours instead of minutes.

While trains might not be at much risk of sliding off their intended route of travel during snowy or cold conditions, they face other challenges. The nature of an air brake system is such that it operates better in warmer weather. Many of the measures the railroad takes during the winter are preventive. Whether newspaper readers in major cities want to believe it or not, winter weather has a very real and significant effect on railroading, and is a perfectly legitimate reason for making certain service changes.

Product Review: MagnaLock Brake Hoses

Pacific Western Rail Systems recently announced the release of working air brake hoses in HO scale, from their sister company, North American Railcar Corporation. These are aftermarket detail parts than can be added to a modeler's existing fleet of freight cars, passenger cars, or locomotives. They also announced that they are currently developing a similar product for all other scales, although in the announcement email I received, it sounded as if N scale may be next. Currently, there is no timeline for future releases in other scales.

Several years ago, Steven and I talked about the possibility of making some sort of working brake hoses, using magnets, but we never gave it much thought, and never tried anything. Since then I had thought very little about having working air brake hoses on models, because it is something that has never before been available, and I suppose I had figured it never would be. However, when I received notification of this, I decided I would have to give it a try, and see if it really worked as well as the video that was in the email.

The brake hoses come in packages of ten pairs. Each hose is rubber with a small magnetic cube on the end. One side of the magnet is red, to identify the top. Other than that, the metal is bare and unpainted, and the rubber hose portion is black. The key to making the brake hoses couple properly, regardless of what direction the car is facing, is to make sure that the red side of the magnet is facing up. Once installed, the magnet can be painted or blackened with a permanent marker.

In HO scale, brake hoses are pretty small. This makes installation a bit tricky. Actually, the first installation is so tricky that I wondered if it was really worth all the trouble. It does get easier after a couple of them though. Besides the air hoses, some wire comes in the packaging, which can be used to form a brake pipe, to which the rubber hose can be attached. The wire would simulate the brake pipe on the car. In order to install the wire brake pipe on most cars, the trucks will need to be removed temporarily.

Once the brake pipe is in place, and the glue has had some time to dry, the brake hose gets glued to that. Out of the package, the brake hoses are not all a uniform length. Pacific Western Rail Systems recommends, in their tutorial, that the brake hoses all be trimmed to 3/8 inches. Cars with longer drawbars or draft gear may require brake hoses longer than this to navigate curves though. Once the brake hoses are trimmed to the proper length, they can be glued to the wire brake pipe, or even the coupler box. PWRS recommends using a 3/16 inch spacer to ensure that the brake hoses do not hang too low and hit switch points, frogs, or guardrails when uncoupled.

Once I had a pair of cars fitted with the hoses, I was excited to see if they were worth all the trouble to get them on. Once the glue dried, I placed the two cars on the layout, coupled them together, and then decided that they are indeed worth the trouble of getting them attached properly! It is amazing how such a small detail really adds to the overall appearance. I plan to buy more of them in the future and continue installing them on my freight cars.

Overall I am very satisfied with the brake hoses. I have big plans to install them on everything, although it will be quite some time before that happens! They add quite a lot to the overall appearance of the car and especially to several cars coupled together.

PWRS does provide a written and video tutorial on installation, however it is only available on their website. It is located on the same page as the brake hoses are sold from.

The air brake hoses will be available to the public beginning on Monday, April 1, 2013.

Manufacturer: North American Railcar Corporation
Item Number : 11-AIR-10H
MSRP: $24.98 for 10 pairs
Available April 1, 2013, currently taking reservations.
Reserve and order through Pacific Western Rail Systems.

Engineer Training: Week One

It is hard to believe the first week is nearly over.  It did get a late start though.  Last weekend, I flew from Billings to Kansas City, to attend the classroom portion of the Locomotive Engineer Training Program.  I was supposed to arrive last Sunday, however, due to delays and exceptionally poor customer service of a particular airline, I did not arrive until lunch time on Monday.  Fortunately, the four of us who were delayed had all been in contact with our Road Foreman, in Glendive, and the Training Coordinator, in Overland Park, KS, and we were able to work around the delay.  As it turned out, we mostly missed paperwork.  We went straight to class from the airport, and arrived just in time for lunch!  We spent a little time during lunch getting caught up on the paperwork we had missed, and then by the time the lunch break was over, we were on the same page as the other 12 people, who has all arrived closer to their scheduled times!

This week has consisted primarily of studying air brake systems, in significantly more detail than we ever did in the Conductor program.  Some of it has been a review, but a lot of it has been new information to us.  We have also been studying the basics of train handling, including how to stop and start trains on different types of grades, and different coupler slack situations.  One thing that has been emphasized a lot is to make gradual changes to avoid any violent coupler slack changes.

In our classroom, we have a train, of sorts.  It is designed to help us understand how the air brake systems on locomotives and cars work.  There are a series of audio visual carts, with all the brake equipment normally found on a freight car.  They are coupled together and have air hoses running between them.  One cart has a locomotive air brake system on it, and a control stand.  The whole thing is connected to a source of compressed air, and manipulating the brake levers on the control stand makes the brake equipment move appropriately.  At the end of this train, there is a Fred.  In class, we have used it only a couple times, but some of us have used it more during breaks or during lunch, to try to figure something out that was unclear to us.  It is a neat setup.  Each of the cars also has air pressure gauges connected to different parts of the brake system, so we can actually see where air is going when we do different things with the controls.

One of the features of a Fred is that it can dump the brake pipe air and put the train in emergency, simply by pushing a button on the locomotive, on a device called Mary.  At lunch yesterday, we were using the train setup in the classroom, and when we got done, one of us had the bright idea of dumping the air from the Fred.  Well, we have all heard trains go into emergency lots of times before, because it happens every time cars are uncoupled or locomotives are removed.  What we did not consider, when we pushed the button on the Mary, was just how loud it would be when done indoors!  There is a delay of a few seconds as the signal is sent, via radio, from Mary to Fred, and while Fred processes the signal.  We pushed the button, and nothing happened immediately, so we figured the Fred must not be armed.  Just as we were shrugging it off and about to walk away, the air dumped.  I think we all jumped about four feet in the air when it happened, despite the fact that we had caused it to happen!  We reset the air, recharged the brake system, and sat down to read over some stuff before our teacher got back.  Once everything was reset, our teacher burst in the door, looked around the room for a second, and finally said, "Alright, which of you plugged the train?"  We all just looked at him, with the most innocent looks we could come up with, and said nothing.  He walked back out to finish his lunch, and that was all we ever heard of it.  We laughed a little after he left, because his office is halfway across the building from our classroom, but he had still heard all the noise.  Oops.

Starting on Tuesday, we have been going to a locomotive simulator for about an hour each day.  We are paired up and work together in the simulator to learn the techniques and practice the tasks assigned to us.  If you have ever heard of or used Train Simulator, a game produced by Microsoft about ten years ago, it is actually a lot like that.  Each simulator is in a small room, which has a mock up of a locomotive control stand inside, and a large screen on the wall where the windshield would be.  When we log in to the simulator, the scenario we are supposed to run loads up, and railroad tracks and some basic scenery appears on the screen.  On the control stand there are a few more screens, and the various gauges, lights, and buttons found on a locomotive appear on them.

On Tuesday, we mostly spent the time familiarizing ourselves with the simulator.  We had some basic tasks to perform, such as cutting out the brake valves, and then cutting them back in, and performing a locomotive air brake test.  Once we were done with that, our teacher had told us to use whatever time was left to play around and get a feel for how the thing operated.  Of course, my partner and I wanted to see how fast it would go, since the screen had indicated that the overspeed was set to 500mph.  We got it to 95mph before our time was up!

On Wednesday we got some practice actually moving the simulated train, according to train handling rules.  It was a pretty basic scenario, we just had to accelerate to 30mph and then stop, but we had to  manage our coupler slack and in train forces.  A little graph on one screen helps us to know what the rest of the train is doing and give us an idea of how smooth the ride would actually be.  For both of us, it was a little rough, and I think on our first attempt at a stop, we would have gotten quite a wallop from those cars bunching up behind us!  Of course, in the simulator, you cannot feel any of the movement, or any of the slack run ins, which is a little disorienting.

Today we got practice starting and stopping on hills.  We each took a turn starting and stopping on an uphill grade, and then again on a downhill grade.  I was more concerned about the downhill trip, because I figured uphill would be easy.  I mean, all you have to do is throttle up to speed up and down to slow down.  I was surprised that I had a harder time making a smooth stop going uphill, and my downhill run had much lower in train forces.  Tomorrow we have a more realistic run to do.  It will about 50 miles in length and take an hour to complete, and the terrain varies from very gentle hills to some longer grades.  That will also be our first scored simulator run, which will start to give us an idea of what we do well with and what needs to get better.  I am a little nervous about it, but only as nervous as you can possibly be knowing it is a simulator, and not the real thing.  I have looked over all the paperwork, track charts, and timetable, and I have written down all the speed restrictions and turnout speeds, so as long as I can keep on top of that, I should be able to finish the run, even if some spots are a little uncomfortable for the simulated freight.

Prototype Railroading: How Air Brakes Work

A few days ago, we talked about how the air brakes on trains came to be.  To many people, they are complicated systems with air flowing back and forth, which by some miracle brings thousands of tons of train to a controlled stop.  Hopefully by the end of the day, they'll be understood a little better.  First of all, let's go over the basics again.

The air brakes on a train operate on the principle that unequal pressures will equalize.  That is to say, if a higher and a lower pressure meet, the lower pressure will increase and the higher pressure decrease until the two are equal.  The brakes in most trains worldwide operate by forcing compressed air through a pipe the length of the train.  The pressure inside that pipe puts air into the system, as well as engages the system when the pressure is changed.  As pressure drops, or when it is lost completely, the brakes apply.  When pressure is added to the system, the brakes release.  They say that a picture is worth a thousand words, so enjoy them.  They're not to any scale, they are simply for reference.

On each locomotive, there is an air compressor, which compresses air for the brakes, as well as other air powered functions on the locomotives, such as the sander, horn, and the wipers.  The air leaves the compressor and goes to the main reservoir, which consists of two large air tanks on the locomotive, used to store air.  From the main reservoir, where the pressure is typically between 120 and 140 pounds per square inch (psi), the air passes through a regulating valve and into the brake system.  The regulating valve can be adjusted to higher and lower settings, but it controls what pressure the brakes will operate at.  For most freight trains, it is 90 psi.  Passenger trains vary, depending on who operates them, but they are usually between 90 and 105 psi.  Think of the main reservoir as a lake, with the regulating valve acting as a dam.  When more water is needed out or the lake, the dam can be opened more, but when the water level downstream of the lake is high enough, the dam can be closed, to allow less water to pass through.

Once air leaves the main reservoir and passes through the regulating valve, it enters the brake system.  The air pipe that goes the length of the train is called, not surprisingly, the brake pipe.  As air enters the system at the locomotive, it flows back, until it has filled the brake pipe in every car, ad the diagram above illustrates.  Now, we are going to take a look at an individual car for a minute.  Looking at the small picture will help understand the big picture.

On each car, there are a few components of the brake system.  The brake pipe runs the length of the car, with a hose on each end for coupling it to the next car.  At each end of the car, there is a valve, called an angle cock, which allows the hose to be closed off if no cars are coupled.  This prevents the pressure from simply escaping out the end of the train.  Connected to the brake pipe on each car are two air reservoirs.  One is for normal braking, and the second one is for emergency braking.  There is a control valve, which actually translates the change in air pressure into a brake application or release, and there is a brake cylinder, which actually provides the braking force.  Braking force is transferred to the wheels by the means of a brake shoe, a composite pad that the brake cylinder pushes against the wheel tread.  (Note: On passenger trains, typically a disc and caliper system is used instead of a shoe against the wheel system.)  Let's look at a single car for a minute.  The following diagram is very basically what the brake system looks like.

The control valve is what allows everything to happen.  In a minute, we will talk about how that works.  The control valve operates solely on air pressure.  There are no electronics that make the control valve work.  It is simple changes in pressure that make it do everything.  When the brakes are released, it allows air to flow from the brake pipe, into the air reservoirs, keeping them full of air, or charge up.  When pressure drops in the brake pipe, the control valve transfers air from the reservoirs to the brake cylinder, thereby applying a braking force to the wheels on the car.  The pressure transferred to the brake cylinder is equal to the pressure change in the brake pipe.  So, if the engineer makes a ten pound reduction, that is to say if the engineer lets 10 psi out of the brake pipe, the control valve will transfer 10 psi to the brake cylinder.  If the engineer then makes another five pound reduction, 5 psi will be added to the air already in the brake cylinder, generating more braking force, and stopping the train sooner.  When the pressure in the brake pipe goes up, the control valve lets the air out of the brake cylinder into the atmosphere, and it then lets the air reservoirs refill from the brake pipe.

Inside the control valve are actually a series of piston driven valves.  The pistons move based on differences in pressures, and when they move, the change the position of valves, which control air flow within the brake system on the car.  As complicated as it sounds, it is actually surprisingly simple, and quite ingenious.  One piston controls air movements under normal braking.  A second piston is to allow an emergency brake application to happen very quickly.  Below are two diagrams of the inside of a control valve.  First we will look at the control valve in the released position.

When the control valve is in the released position, the pressure on either sides of the piston is equal.  The pressure on the left side of the piston is always the same as the brake pipe, and the pressure on the right side is the same as the air reservoir.  When the brakes are released, the increasing pressure of the brake pipe pushes the piston into the above position.  This slides the valve assembly into position to release all pressure from the brake cylinder, releasing the brakes.  It also pushes the piston against a choke valve.  Once that choke valve opens, air pressure can build up inside the air reservoirs, so that there will be pressure ready when the brakes are needed again.  When the engineer lowers the air pressure to apply the brakes, the piston moves, as shown below, which in turn moves the valve assembly.

When the brakes are applied, the pressure on the left side of the piston is lower than the pressure on the right, forcing the piston to the left.  When the piston moves to the left, the valve assembly moves and directs air from the reservoir into the brake cylinder.  The brake cylinder transfers that pressure to the brake shoe, and generates braking force.  Because the pressures on either side of the piston are attempting to equalize, the pressure on the right side, and in the air reservoir, will never drop below the pressure on the left side.  It is simply not possible.  If the engineer reduces the pressure in the brake pipe, on the left side of the cylinder, by ten pounds, then the pressure in the reservoir, connected to the right side of the piston, will also drop by ten pounds.  Those ten pounds of air can only possibly go to the brake cylinder, and so ten pounds of air are used to generate braking force.  Should the engineer reduce the pressure further, then the pressures will again equalize, sending more air to the brake cylinder, and applying the brakes harder.  When the engineer needs to release the brakes, he moves the brake valve in the locomotive to release, and air from the main reservoir flows into the brake pipe.  When that happens, the pressure on the left side of the piston is higher than on the right, forcing the piston to the right, and releasing the brakes.

The diagrams above only cover normal service brake applications.  Above is the basic system developed by George Westinghouse, in the 19th century.  Because the system works on balancing pressures, having 90 pounds of air available does not actually mean you have 90 pounds of braking force.  The pressures will only equalize, and therefore the pressure that will go to the brake cylinder is considerably less than actual pressure in the reservoir or in the brake pipe.  It would be impossible for the reservoir to completely empty under these braking conditions, unless the engineer emptied the brake pipe.  That is how an emergency application is made.  However, as this system developed, it was realized that the engineer would only usually empty the brake pipe when an emergency arose, and he needed to stop as quickly as possible.  So, an additional system was developed, which is designed to work only when the brake pipe pressure is lost quickly.  Inside the control valve, there is another piston to control that system.  The emergency brake system, just as the normal service brake, is charged when the air is released.  When the choke valve is open, as shown in the first diagram, air can flow into the two air reservoirs.  That builds up a pressure in both the normal service reservoir and in the emergency reservoir, so the air is there when needed.

In the diagram above, we can see that the emergency brake system operates in a similar manner as the service brake.  Again, a piston moves back and forth and controls what the emergency brake does.  However you will notice a few key differences.  There is no choke valve on this piston, because the emergency reservoir is filled only when all brakes are released.  There is no exhaust port on this control valve, because otherwise pressure would be able to escape from the brake cylinder anytime the emergency brakes had not been applied.  This is the same brake cylinder as the service brake uses.  All air exhausted from the brake cylinder goes through the other valve.  Also, this piston has a hole in it.  The hole actually allows air to flow slowly from one side of the piston to the other.  This is what prevents the emergency brake from applying every time pressure drops on the left side, which is whenever the engineer makes a normal brake application.  In normal brake applications, air pressure changes slowly enough that the air can flow through the hole.  When the engineer needs the emergency brake, he empties the brake pipe, and all the air pressure is lost suddenly.  When that happens, the change is too rapid for the air to flow through the hole, so the piston moves, triggering the emergency brake application, shown in the diagram below.

Just as in the service brake, the piston moves to the left, moving the valve into position to allow air to flow from the emergency reservoir to the brake cylinder.  When the emergency brake is applied, the service brake is also fully applied, so the air from both cylinders is directed into the the brake cylinder, which allows for maximum braking force.

Everything described above takes place on each and every single car in a train.  The emergency valve and the service valve are both located in the same unit, and together they are known as the control valve, because they control the flow of air on the individual rail cars.  The flow through the brake pipe is established by the engineer, who has a valve in the locomotive.  He can exhaust air into the atmosphere, resulting in a drop in pressure on the brake pipe, and a brake application.  He can place the brake valve in release, allowing compressed air to flow into the brake pipe, increasing the pressure, and releasing the brakes.  The way the system works allows the pressure to be used to generate braking force, but also allows for any sudden loss in pressure to bring the train to a safe stop, rather than lose the brakes.  The basics of the system have remained relatively unchanged since its invention in the 19th century, however other features have been added to the system.  Features exist now which to help speed up the release of the brakes from car to car, so that the rear end of the train is not still braking while the front is released, as air flows back to the rear.  An emergency application is also expedited by more advanced features, so that an entire train, over a mile long, can have the emergency brakes apply almost simultaneously from end to end.  The entire system is purely pneumatic, and does not rely on any electronics.  Electronics have been added, primarily to passenger cars, to achieve non slip braking, basically anti-lock brakes for a train, but the brake systems even on those cars will function as intended if the electronics fail or are disconnected.  Despite being an old system, it is an extremely reliable system, and there has simply been no need or reason to develop a new brake system.

Note:  All diagrams in this post were created by James Ogden and are copyrighted.  They may be used for informational, educational, personal, or other nonprofit purposes, with proper citation.  Any commercial reproduction or publication outside of these terms is forbidden without written permission.

Prototype Railroading: History of Air Brakes

First of all, I apologize for missing this post on Wednesday.  I was in Forsyth, and normally I would have written a post before leaving, but on Tuesday I got busy with some household projects and completely forgot about it.  Actually, it is okay though, because I really had nothing to write about then anyway.

Today I thought I would talk about air brakes on trains, because I get asked a bit how they work, and trying to explain it makes them sound way more complicated than they really are.  Today we will talk about how they came to be, and in a future post, we will talk about exactly how they work.

Air brakes have not always existed on trains.  Over a century ago, in the middle of the 1800's, trains were stopped by turning a hand brake wheel on each car.  This is where the job of the Brakeman was invented.  Typically there would be two brakemen on a train, one on the engine and one on the caboose.  When the engineer needed to slow a train down or stop it, he would communicate his intentions using whistle signals.  When they brakemen heard the signal indicating that the engineer wanted brakes, the brakemen would go to work, starting at each end of the train and working towards each other.  They would walk on the roofs of cars, and turn each brake wheel as they went along.  When the train was slowed sufficiently and the brakes needed to be released, the engineer would sound a different whistle signal, and the brakemen would walk across the tops of the cars and release the brakes they had applied.  It was a simple system, but it was obviously lacking a few safety features!  At one time, a brakeman was considered the deadliest occupation in the United States.

George Westinghouse is the man who invented the railroad air brake.  Besides the development of the air brake, he is also well known for his pioneering work in the electrical industry.  He recognized that relying on brakemen to stop a train was a very primitive and dangerous system, and he began to work on a system that would allow the engineer to directly control the brakes on the train.  Doing so would eliminate for people to be walking on the roofs of train cars while moving, and it would allow the train to stop faster, if the engineer could control all the brakes on the train at the same time.

The very first air brake system was a little different than the air brakes of today.  The basic operation of air brakes requires that compressed air be forced against a piston, which in turn transmits that pressure to a brake shoe, generating friction and stopping a train.  Early air brake systems worked on that system, known as a straight air system.  A pipe ran the length of the train, and on each car there was a brake cylinder.  When compressed air was applied to that pipe, it put pressure on each brake cylinder in the train, applying the brakes on every car.  When the pressure was released, the brakes released.  This offered a huge advancement over the hand operated brakes, but there were still some pretty critical flaws.  The biggest flaw with the straight air system is that if cars somehow separate, the pressure is lost in the brake pipe, and brakes release.  When cars are not coupled, or a train splits in two, there would be no air brakes available.

A few solutions were offered to fix the problem of losing brakes when uncoupled.  In some countries, vacuum brakes were introduced.  Vacuum brakes required that a negative pressure be maintained to release brakes.  If the brake pipe became separated, due to the train splitting in two, pressure would be restored in the pipe and the brakes would all fully apply.  Vacuum brakes had the disadvantages of requiring much larger equipment to generate enough braking force, and being very slow to apply and release.  A more popular option was the train air brakes, or automatic brake, which is still in use today on almost every railroad in the world.  Automatic brakes work by requiring each car on the train to have a compressed air reservoir, which is filled up by an air compressor on the engine.  The brakes are still applied by air pressure acting on the brake cylinder, but that air comes from the reservoir on the car.  The brake pipe has constant pressure in it, and a valve ensures that the pressure in the reservoir and the pipe always stay equal.  When the engineer needs to make a brake application, he lets some air out of the brake pipe, making the pressure less than that of the reservoir.  Air is let out of the reservoir and into the brake cylinder, applying the brakes, until the pressures again reach equilibrium.  When the engineer wants to release the brakes, air is added to the brake pipe, making the pressure higher than the reservoir.  The brakes release, and the reservoir pressure increases until equilibrium is reached again.  Whenever the pressures are at equilibrium, the brakes continue doing what they are doing, but when brake pipe pressure is higher, they release, and when brake pipe pressure is lower, the apply.  Next week we will cover in detail exactly how this happens.

As with the other systems, there are advantages and disadvantages to the automatic brake system.  One of the biggest advantages is if a train splits in two, or the brake pipe becomes separated, the brakes fully apply and the entire train comes to a stop.  There are two major disadvantages, although with proper training one can be eliminated.  One disadvantage, which is simply unavoidable, is that having an air reservoir on each car means it takes a considerable time to fully pressurize the brake system.  On a long train it can take eight to ten minutes, even on a good day.  In extreme cold weather, it can literally take hours.  Also, pressure can only be restored to the system when the brakes are released.  Consequently, if an application is made, and then released, it takes a minute for the pressure to restore throughout the system.  If another application is made before pressure is fully restores, there is less pressure available, and therefore less braking ability available.  This is called fanning the brakes, and if done repeatedly it can lead to a complete loss of pressure, and a loss of brakes.  With proper training, fanning of the brakes can be avoided, as can any serious consequences of this disadvantage.

Next week we will talk about how exactly the brakes work.  How exactly they work is actually considerably simpler than it sounds so far.  Basically the thing to remember is that the pressures constantly try to equalize.  When the pressure in the brake pipe is higher than the reservoir, then the brakes release.  When the brake pipe pressure is lower than the air reservoir, then the brakes apply.

Prototype Railroading: Earning a Nickname

(Happy 100th Post!)

Railroading is one of those industries where sooner or later, everyone earns a nickname.  They never choose it.  It is chosen by other railroaders and eventually it just spreads.  It always starts because of a certain event.  As time goes on, people forget the story behind the nickname, but the nickname sticks.  If the stories can be remembered, they're usually pretty good, from a listener's point of view.  For the person who made the story, they can sometimes be embarrassing.  Fortunately, that is not always the case.

Yesterday, I earned my nickname.  People have started calling me "lucky."  For me, the story is not embarrassing.  Looking back, it is actually quite funny, although I was not having quite as much fun as I lived it!

In training, they try to go over as many different situations as possible so that when challenges arise later, as they inevitably will, and you do not have someone watching over and guiding you, you will be able to handle them as effectively as possible.  However, due to the nature of railroading and the length of the training program, it is completely impossible to gain experience in every possible scenario.  That takes an entire career.  As such, there are situations I heard about in training, and talked about, but never actually had a chance to work through and experience.  Yesterday I was able to check a few of those things off the list.

Yesterday, I was assigned to train H-PASGAL9-17A, a high priority merchandise train from Pasco, WA, to Galesburg, IL.  Merchandise trains carry just about anything, and have just about every type of railroad car in them.  Some cars are loaded, some are empty, and everything is mixed in everywhere.  Merchandise trains are well known for often having irregular handling characteristics and sometimes for having a bit of a mind of their own.  That being said, this was supposed to be a straightforward assignment.  The train had been rerouted, and since this was not the normal route, there were no cars to pick up or drop off anywhere along the way.  At the start, it looked like this train would be as easy as a coal train!

We got off to a slow start.  There were several groups of maintenance out working on the line.  We left Forsyth behind the most notoriously slow engineer in Glendive, which did not help the situation any.  We even dragged our feet leaving, so that we would not be too close behind him, but we still caught up to him within about twenty minutes.  It was the warmest day of the week, with highs predicted to be 102 degrees.  We would be moving slow, but at least we were sitting in an air conditioned cab.

About an hour into the trip, the air conditioner began blowing warm air.  This happens from time to time, especially when the locomotive is idle.  If the locomotive thinks it is idle, it turns off the air conditioner after a while to save energy.  Fixing it is easy, you just move the air conditioner switch to a different position and then back, and it lets the locomotive know you are still there.  That is exactly what we did, however, the warm air continued to flow.  We tried that a couple more times, with no additional success.  Finally, just to get air moving, we propped the front door open and opened the side windows.  That forces air through the cab.  While it was not any cooler, at least it was moving air, and it made the cab somewhat bearable.  At different stops along the trip, we tried different things to get the air conditioner working again, but we were unsuccessful, and the broom held the door open the rest of the way to Glendive.

Eight hours later, we were still on the move, and crossing the Powder River.  The dispatcher called us up on the radio to let us know that the mechanical department had spotted a hot journal bearing.  They told us what car it was on and which axle and we stopped as quickly as we could to look at it.  The journal bearing is at the end of the axle, and it is what supports the weight of the car.  The axle turns in the journal.  If they are working properly and lubricated properly, they only warm up a little.  However if there is a defect in the journal bearing, it can generate more friction, and therefore more heat.  If allowed to continue to operate, it can start fires along the railroad, and it can cause the metal to heat up enough to weaken it and cause the axle to break, resulting in a derailment.

Once we came to a stop, I grabbed my radio, infrared thermometer, and the work order, showing all the cars and their contents, and then I stepped off the train.  My engineer started to pull up, so I would not have to walk, but another problem presented itself.  He moved the train about three car lengths and then we heard a loud hiss, indicating that the emergency brakes had applied.  The engineer let me know the pressure at the rear of the train showed zero.  The air brake pipe had come apart somewhere.

At that point, I walked back to the car with the hot journal bearing.  I figured I would deal with that first, and then try to sort out why the train had gone into emergency.  Once I got to the indicated hot axle, I zapped it with the thermometer.  The journal was 168.8 degrees, which is warm, but not beyond the normal operating range, especially on a day as hot as it was.  I concluded that it was defect free.  When the indicated axle comes up okay, the policy is to check twelve axles ahead of and behind the indicated axle, just to make sure one of them did not set off the detector.  I did that, and found that they were all in the 150 to 170 degree range, so nothing was wrong there.  I figured the hot journal bearing was a fluke, and I began walking.  I still had to determine why the train had lost all air brake pressure and gone into emergency.

The train was 6,414 feet long, or about 1.25 miles.  That is a long walk, even in the shade, when it is 102 degrees outside!  Once the computer reset itself from the emergency brake application, the engineer placed the brake handle in release.  The brakes would only release if the pressure could build up to 90 pounds per square inch and then be maintained.  As the pressure started to build, the air flow meter indicated a leak.  It indicated that we were leaking about 100 pounds per minute, which is quite high.  That is a good indication that something came apart where it should not have.

About 50 cars back, or half the length of the train, I heard a hissing.  Air was leaking.  As I got closer, I found that some air was leaking out where the hoses from two cars were coupled together.  I stopped for a minute to check it out, but determined that that was not the problem.  It was a small leak, and small leaks like that are actually quite common and really do not effect overall braking or handling.  I kept walking.  About 70 cars back, I began to hear another leak, but it was more of a wooshing noise.  It sounded like a much bigger leak. As I cam around the bend I noticed that there was about 75 feet between two cars in the train.  Something had come apart where it was not supposed to!  The 83rd car was the source of the wooshing noise.  The hoses, and cars had uncoupled.  When the cars uncoupled, the hoses came apart, letting all the air pressure out, causing the unexpected emergency brake application.  When I walked around the end of the 83rd car, I instantly saw the problem.  The coupler was missing its knuckle.  I had no idea where the knuckle was, although I could see exactly where it had broken off.

I let the engineer know what I had found, and then I closed the angle cock on the 83rd car, so he could start getting the air pressure back up on the front part of the train.  Then I got to work getting the remaining pieces of the knuckle off the car.  This was a little more difficult than removing a whole knuckle, because there was nothing left to grab.  Finally the biggest piece fell out, and the coupler was ready for a new knuckle.  The only problem was the new knuckle was on the locomotive, over a mile away.  About the last thing I wanted to do was walk that mile again, and then walk it a third time carrying a 75 pound hunk of steel!  Fortunately for me, the track inspector who had been following us overheard our predicament on the radio and offered his help.

The broken knuckle, after extracting it from the rest of the coupler.
Photo by James Ogden.

The track inspector drove to the locomotives, which were sitting by a highway, and picked up the knuckle and some water for me.  While he did that, I climbed up a hill to the nearest road, and met him in a pull out.  All I had to do then was hike back to the train with the new knuckle.  That was downhill, so gravity did part of the work.  Where the hill was steepest, I just tossed the knuckle down and let it roll.  I met it at the bottom.  Despite the walking saved by the track inspector, I was still completely exhausted by the time I got back the train!  Rather than walk aback the seven cars to the broken coupler, I asked the engineer to pull up.  By this time, it had been long enough that the air pressure had recovered in the front portion of the train, and he was able to move.  Once he moved the train, I installed the new knuckle, ensure that it was working properly, and then hopped on for the ride back to the rear portion of the train.  Once back there, we coupled the pieces of the train back together, made sure the coupler would hold, and then I coupled the air hoses again, so the entire train would have brakes.

Once all the work was done back there, it was time for the hike back to the head end of the train.  By then I was completely exhausted, and completely drenched in my own sweat.  I started hiking, and I immediately went for the second locomotive, because it had working air conditioning!  I sat in there for a few minutes and just enjoyed the nice, cool, refreshing air!  Once I had a couple minutes to cool off, I walked up to the lead locomotive, and we got underway again.  We finally arrived in Glendive nearly 12 hours after we had departed Forsyth.  It was a long day, but I guess it was one of those that turned into experience.

When we arrived at the yard in Glendive, we relayed the entire story to the crew van driver, and he was the one who decided that my nickname should be "lucky."  His reasoning was that typically knuckles break six to ten cars back, and I got one 83 cars back, on my first one, on the hottest day of the week, when the air conditioning was not working, and while trying to inspect a hot journal.  The really bizarre part is that the train was headed downhill.  Irony is what he was going for I guess.

Prototype Railroading: Air Brake Tests

This week, we have been back in the classroom.  In about a week and a half, we have our first exam, which is the Hostler's exam.  A Hostler is someone who is qualified to move locomotives not attached to cars.  Typically this is done in yards and locomotive servicing facilities.  In order to take the Hostler's exam, we have to know how to do all the different air brake tests and safety inspections, as well as how to operate locomotives in consists of multiple units and alone.  We also have to be able to identify what all the controls are and what they do inside all the different locomotive types.

In the classroom this week, we have been going over all of that.  Air brake tests have been the primary topic, because there are different tests for different situations.  A consist of locomotives gets tested differently than locomotives connected to cars, and they all get tested differently than a train that was previously tested or has been connected to a source of compressed air within the last four hours.

The biggest and most elaborate test is the Class 1 Air Brake Test, or the Initial Terminal Air Brake Test and Safety Inspection.  This is an inspection of the entire train of locomotives and cars.  Once the air pressure has been built up in the whole train, a brake application is made, and the Conductor walks the entire length of the train and checks to make sure all the brakes applied properly.  At the same time, the Conductor does a safety inspection, which includes things like making sure the hand brakes are released on all cars and the angle cocks are open.  The angle cocks are valves on each end of each car which allow the compressed air to flow from one car to the next, when open.  Once the Conductor has walked the entire length of one side of the train, the brakes are released, and the walk back begins.  This time the Conductor is checking to see that all the brakes released properly and are not sticking on any car.  Depending on the length of the train, this test can take quite some time to do.  The first one I did was on a train which was just over 7,000 feet long.  Later that same day, I had about 30 cars that were untested at the front of a train, so only those 30 had to be inspected.

When locomotives are coupled, with no cars attached, they must also have a brake inspection.  Locomotive have two types of air brakes, called the Automatic Brake and the Independent Brake.  The Automatic Brake, when applied, applies to all the locomotives and cars in a train, if coupled to cars.  The Independent Brake only applies the brakes on the locomotives.  Both of those must be tested, and then the air system must be tested for leaks.  Once that is done, the locomotives can be moved or coupled to cars.  Locomotives receive a safety inspection every day they operate, which is every day, with only a few exceptions.  A qualified Engineer must perform the safety inspection.

When cars and locomotives have had their Class 1 Air Brake Test and their Locomotive Brake Test, and the train is uncoupled for some reason, there is another brake test that must be done.  When the train is coupled back together, an Apply and Release test must be performed.  This is the simplest one.  The Engineer makes a 20 psi brake application.  The End of Train Device (ETD) measures air pressure in the brake pipe and relays that information to the locomotive.  Once a drop in pressure of at least 5 psi is indicated by the ETD, the brakes have applied on the rear end of the train.  Then the Engineer releases the brakes.  Once the pressure has increased 5 psi in the ETD, the Engineer knows the brakes have released at the end of the train. Many years ago, before ETD's, the crew in the caboose would have monitored an air pressure gauge and relayed that same information to the engineer by radio or signal.  Today, all that information is monitored and relayed to the engineer on a little computer display in the locomotive cab.  That, basically, is why you almost never see cabooses (cabeese?) on today's freight trains.  (There is a much longer explanation to why the caboose is gone, but basically a computer replaced it.)  If a locomotive uncouples from some cars and leaves them standing, with no source of compressed air, for more than four hours, the cars must have another Class ! Air Brake Test.

That is a brief summary of the air tests.  When a train leaves its initial terminal, all the brakes must be functioning properly.  Any defective car must either be fixed or set out before the train leaves.  If defects develop during the trip, the train may continue, provided that efforts have made to correct the problems.  Under no circumstances may the train operate with less than 95% of the brakes working.  If enough defects develop that less than 95% of the brakes work, the crew has to start setting cars out of the train so the mechanical department can come fix them.

Brakes are very important on trains!  The first air brake system was developed in the 1860's, in the United States, and it has been improved upon over the decades since then.  Even the early, primitive systems were a major step towards safer rail transportation.  Today's brake systems work exactly as George Westinghouse designed them to work over a century ago.  Some of the exact details have changed, but the principle remains the same.  The Westinghouse Automatic Air Brake, and the Janney Knuckle Coupler were two of the biggest improvements in railroad safety, and continue to contribute to that.