UNSTOPPABLE

[bcnPete]

I will go see it or wait for the DVD but for entertainment, you can't beat the 'Silver Streak' with Gene Wilder and Richard Pryer, on board a runaway train....and its got one hell of an ending

[Edwin_m]

Is that correct about vacuum brakes? I always thought that the vacuum was raised to release the brakes which accounts for problems loco men sometimes had with dragging train brakes when the locomotive ejector was not creating sufficient vacuum.

 

We're both right. Vacuum was used to release the brakes so they would start dragging if the pipe pressure rose. However there had to be a "store" of vacuum on each coach to provide the brake force - in the vacuum system this is in part of the brake cylinder itself rather than a separate reservoir (Wikipedia has more details). Just as with an air brake this could leak off with time or be released manually by "pulling the cord" if a vacuum-braked wagon was to be run in an unfitted train.

[Arthur]

We're both right.  Vacuum was used to release the brakes so they would start dragging if the pipe pressure rose.  However there had to be a "store" of vacuum on each coach to provide the brake force - in the vacuum system this is in part of the brake cylinder itself rather than a separate reservoir (Wikipedia has more details).  Just as with an air brake this could leak off with time or be released manually by "pulling the cord" if a vacuum-braked wagon was to be run in an unfitted train.

Thanks Edwin, that makes sense.

 

 

Arthur

 

 

[PhilJ W]

Is that correct about vacuum brakes? I always thought that the vacuum was raised to release the brakes which accounts for problems loco men sometimes had with dragging train brakes when the locomotive ejector was not creating sufficient vacuum.

Quite so. All brake systems nowadays are required to be 'Fail Safe'. The vacuum or air pressure holds the brakes 'OFF' so a loss of either vacuum or air automatically applies the brakes.

 

 

 

[Edwin_m]

Quite so. All brake systems nowadays are required to be 'Fail Safe'. The vacuum or air pressure holds the brakes 'OFF' so a loss of either vacuum or air automatically applies the brakes.

 

Please see my posts above for reasons why this might not be the case, as in fact happened in the incident on which this film was based, despite the brakes officially also being failsafe.