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.