frogpipe

Originally Posted by frogpipe

Air Brakes on trains do not require any air pressure to be released.

http://www.railway-technical.com/brake2.shtml



Ergo, while the brakes are applied, the Auxiliary or Brake Reservoir can't be charged while the brake pipe pressure is reduced - as is the case when the brakes are applied.

The link is an excellent document describing the air brake systems on trains, I have only quoted the opening paragraph.

Observe the first 5 minutes of this video.