Also, air acts just like water when you close the angle cock. That's why you don't bottle the air anymore. It used to be common practice.

You would be in a hurry so you would pull your train down and stop to set out or pick up a car. You would make a set in the train, the brakeman would bottle the air and cut you off. You would make the move, go back to the train and he would cut the air back in. You would save time by not having to wait to pump the air up which could cost you down the line by a meet or two, etc. When they came out with the new type valves that was the end of that. But some people still did it and paid the price.

When you close that angle cock, the air flowing thru the pipe stops and, like water, bounces back the other way. That is how you get a release and the cars roll away. The first car senses an increase and goes into release. That sends a little air into the brake pipe and the next car starts to release and so it goes until the whole train is released.


Nudge