Stop That Train!

Article from IEEE Spectrum
IEEE is the Institute of Electrical and Electronic Engineers (and I am a member).

http://www.spectrum.ieee.org/mar09/7927

[picture caption] A Norfolk Southern Railway freight train equipped with a new electronically controlled pneumatic (ECP) braking system comes down a mountain. It is the second such train that the company has equipped with ECP brakes.

Synopsis: Electronically controlled pneumatic brakes open the valves on all the cars at once. Plenty of details in the article.

Electro-pneumatic brakes on passenger trains have been around for almost 100 years, first applied to NYC el trains and subways. What is new and interesting is they are being applied to freight trains now. They are being tested on unit trains now and will be used on general service trains as soon as the FRA signs off on them. There is a great web site which shows how EP braking works. It is a British site but it information is clearly and simply presented. Of cource jst like air brakes EP brakes will be slow to become widely accepted. Follow this link for a great explanation of EP brakes as applied to British railroads. http://www.railway-technical.com/ep-brakes.shtml

ex Budd man wrote:http://www.railway-techinal.com/ep-brakes.shtml

Thanks.

The very helpful article at railway-technical.com distinguishes between the ECP systems and the "electro-pneumatic" systems that ex-Budd describes. For one thing, EP is used primarily, perhaps exclusively, on multiple-unit trains, and it relies on a traditional Westinghouse-style triple valve as a separate fail-safe. The ECP systems now running on American freight trains have no such back-up.

Incidentally, I'm the author of the story in IEEE Spectrum, and early on in my research I posed a question on one of these boards about it. Thanks to everyone who helped out.

-Robb

My RR (a commuter line) uses EP Brakes with its MUs and push pull (Loco hauled) consists

The MUs have a 26B - self lapping brake, while the cab cars and locos use a 26E or 30ECDW or Epic non self lapping brake.

While the EPs are noticeable on the MUs as the brakes apply and release much faster, I find the non-self lapping brake with a seperate "EP Hold" position uses the EP brakes to their fullest.

Im assuming the freight locos that will be equipped with the EP controls will use a self lapping brake?

Either way, running a train with EP brakes is MUCH easier and the stopping distances are GREATLY reduced. If it noticeable with a passenger train with a handful of cars, i can only imagine the difference on a several dozen car long freight train.

On the British system the triple valve is by-passed by the application and holding magnet valves. The system I'm familiar with uses the magnet valves to speed up the reduction of brake pipe on each car and to maintain brake cylinder pressure while recharging brake pipe. The 26 control valve (triple valve) responds quicker to brake pipe reductions since brake pipe is being exhausted on each car rather than at the brake valve in the cab.
Now I know the ABDX freight valve has local reduction, but I'm talking about passenger brakes. The ECP still has a brake pipe to supply the train but now braking action is electronically controlled.