An Autonomous Pneumotronic System for Enhancing the Braking Capability of Long Freight Trains

Trains brakes are pneumatically actuated and use the same pneumatic line for power and signal transmission. This simple architecture presents limits for long trains since the last vehicles brakes receive a very delayed command and the train speed must be limited. Solutions were proposed using a signal transmission line parallel to the pneumatic line. These systems, though effective, present drawbacks and are of difficult implementation as retrofits. A solution is described, which leaves the braking system unchanged, but reduces the time delay in the signal transmission by adding a pneumotronic unit at the pneumatic line end. This unit analyzes the pressure time history, recognizes the precursors of new braking commands and issues inputs to a valve at the pneumatic line end mirroring the commands to the master valve. The rapidity of the braking action is enhanced, thereby allowing a more uniform braking and a speed increase of long freight trains.