You say that the D&S placed straight air on their equipment. Is this a dual system like some of the logging lines (like the West Side in California) and mining operations used or did they remove the automatic system?
A straight air system is like the very first air brake systems where the engineer put air into the pipe to put the brakes on.
Automatic Brakes is the system that has been used for over 100 years with the train line pipe charged always with brakes applied when the brake pipe pressure is reduced. This also will cause the brakes to go on when the train brakes in two.
I sure hope that they put on a dual system.