Air brake chalk board What is he talking about??? Part 1 in Tales of the Jointed Track

A train passes by you. The locomotives blast by, and car after car passes. Is this thing ever going to end ? The the last car with an odd looking device on the draw bar ( the ETD) or a locomotive(s) DP.

How do we brake these monsters ? Whether level grade or Mountain territory, the air brakes play an important key in controlling and stopping a train.

Simply, it is air pressure opposing air pressure. Air is invisible, as we breathe, and its like that on the locomotives and the in train. How the engineer sees it is with the gauges on the control stand and on the ETD, or and a caboose gauge ( if you have one) verbally given to you by the car men or by the train crew on the rear end.

When I had trainees, or fireman working toward promotion to engineer, I stressed air. I told them its important, and one day, you’re gonna need to know how to use it. Since I was mountain grade, it was critical to learn, and how and why it operated. Tonnage, load versus empty ratio, how many cars, how many tons, train length. Terrain, signal indication, a slow order out there, or a bunch of them ? Taking a siding?, either by train order or track warrant?, or under CTC dispatching. Do you have to stop and line your self in? Are you on a grade where you need to balance the grade, to stay in control. Air and the corresponding brakes are a major tool in your decision making, and planning.

How do you covey the idea and the principles? I surely was a deer in the headlights look when I started, but once it clicked it made a lot of sense. No, I don’t expect you to be air brake experts after reading this, but will give you a basic idea, of how trains slow and stop. Other than blocking you at your “favorite’ railroad crossing.

The first thing is where does the air come from. Yes, it is all around us, at atmospheric pressure. The railroad braking system, cannot operate at atmospheric pressure. The air compressor is the means for gathering air to operate the brake system. Each individual locomotive has an air compressor, and they work individually, or in tandem, when hooked up in a consist. So if you have 4 units, the Main Reservoir hose connection, between each locomotive, will supply all the needs to the lead unit. The air will flow toward the lead locomotive, and also keep the Main Reservoir supply system charged, via piping and check valves .

There are two main reservoirs on a locomotive. The No.1 main reservoir, uses that air for whistle ( Horn ) wipers, bell, and air operated associated equipment as, shutters and/or air operated magnet valves or relays . The No.2 is the air braking and storage of air and charging of the air braking system. Who has precedence over the other? It is the the No.2, Number one is an overall storage tank, and there is a check valve between them. The No.1 will always flow to the No.2 and the check valve will insure that there is no back-flow. The No.2 main reservoir flows to the air equipment. There are reducing valves and “chokes” that bring the air pressure to operating pressure. A regulating valve or what we called a feed valve, reduced 140 lbs of main reservoir air to the operating brake pipe of 90 lbs for freight or 110 lbs for passenger. The equalizing reservoir and the P2A application valves in the service portion of the locomotive, will charge and the associated piping will allow a transition to charge, apply and release the air brakes .

Part 2 will try to explain on how this all works