Brake line pressure


Dave Nelson
 

I’m in a discussion elsewhere on the subject of routine brake line pressure in freight trains.  He suggests 90 PSI.  I’m thinking 80.  Anyone know the norms of the late steam era and if it was different than the modern age was it a mandated change… and if so, when?

 

Dave Nelson


Dennis Storzek
 

I will have to check my steam era Soo Line air brake rules book, but as I recall during the steam era 70 psi for freight and 90 psi for passenger were common. Keep in mind that that automatic air brake equipment functions on the pressure differential from the pressure the system was initially charged to. System pressure was determined by the setting of the locomotive feed valve. Higher pressures did not result in higher braking force, but did effect the time required to release the brakes and recharge the system. The higher pressure aids recharge time on today's longer trains.

Dennis Storzek


Robert Allan
 

In my years on the MoPac, we were at 80# brakepipe pressure. UP was at 90# so several years after the merger, we aligned with the system standard.

Bob Allan


Dave Parker
 

I know the original query was in reference to the "late steam era", but FYI my 1918 Westinghouse brake handbook gives 70 psi as the standard for the train-line pressure.

Dave Parker
Riverside, CA




Dennis Storzek
 

As promised, I dug out my Soo Line Air Brake Rules book, but unfortunately, it slightly post dates the steam era: December, 1962. However, here are the pressures specified at that time, all numbers are PSI:

AIR COMPRESSOR GOVERNOR -130-140
FEED VALVES, PASSENGER SERVICE - 90
FEED VALVES, ALL OTHER CLASSES OF SERVICE EXCEPT ORE SERVICE - 75
FEED VALVES, ORE SERVICE - 90
FEED VALVES, SWITCHING SERVICE - 70

As one can see, the pressure setting was variable with the service, and as the feed valve was in th cab, the engineer was expected to ensure it was set properly for the service.

Dennis Storzek


Dave Nelson
 

Very interesting.  Thanks Dennis, this will raise some issues for our sim software.

 

Dave Nelson

 

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Dennis Storzek
Sent: Tuesday, May 08, 2018 5:39 AM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Brake line pressure

 

As promised, I dug out my Soo Line Air Brake Rules book, but unfortunately, it slightly post dates the steam era: December, 1962. However, here are the pressures specified at that time, all numbers are PSI:

AIR COMPRESSOR GOVERNOR -130-140
FEED VALVES, PASSENGER SERVICE - 90
FEED VALVES, ALL OTHER CLASSES OF SERVICE EXCEPT ORE SERVICE - 75
FEED VALVES, ORE SERVICE - 90
FEED VALVES, SWITCHING SERVICE - 70

As one can see, the pressure setting was variable with the service, and as the feed valve was in th cab, the engineer was expected to ensure it was set properly for the service.

Dennis Storzek