Air Brake Condensate

NW Mailing List nw-mailing-list at
Mon Dec 28 15:49:50 EST 2020

On 12/28/2020 8:30 AM, NW Mailing List wrote:
> A friend of mine asked me in the winter how did the railroads keep air 
> brake condensation from freezing the triple valves especially during 
> the steam era.  I did not have an answer nor did I ever think about 
> it.  Is/was this a problem?
> Sam Holben
> Virginian Rail Fan
     The big problem was not the triple valve, it was the vent valve. 
The vent valve you might recognize as a round dish-like piece. Anytime 
the air was down close to freezing and the train went into emergency, as 
in cutting off from the train to do work, the air vented through that 
valve. The sudden drop in air pressure also dropped the air temperature 
and the thing would freeze open. When it did, you couldn't get any air 
past that car to the rear to pump the brakes off. Sometimes, they would 
reset themselves after blowing for some time. I have also had some luck 
making a normal brake application down to zero and got them to reset. If 
not, someone would have to walk the train and beat on it to get it to 

Jimmy Lisle

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