This is more out of curiosity than anything else. Currently doing the Chicago to Brunswick grain train and noticed something with the braking and wondered whether that's correct in real life. Yeah I know it's taken me a while to notice, haha. I'd apply the brakes up to say around 60% and watch the pressure increase, but if I backed the brakes off to around 40% the brakes stay at 60% and only release once the handle goes to the release position. Is that right?
US air brakes can be difficult to conceptualize. What you should remember is that you can apply them in small increments, but you can’t partially release them. They only release completely; this is a function of the triple valve on the underside of each car. This diagram from Trains Magazine is a great illustration of how that works: From the example above, once the pressure in the brake pipe starts to increase above 80psi, the brakes release. If you don’t let the pipe go back to 90psi and wait for the auxiliary reservoir to recharge to 90psi, you won’t have full brakes for the next application.
Great explanation thank you. As a truck driver im familiar with normal air brake systems but this is foreign to me. It explains why when I've been doing the shunting jobs I back the brakes off without releasing them completely and would still come to a grinding halt
When shunting you're generally better off just using the independent brake- even with a short or light rake of cars. IRL, during shunting they often don't bother to connect up the air hoses, since in general it's fairly light consists at low speeds.
