Train splits

[NW Mailing List]

When I worked on the RF&P(1984-1987) it was standard procedure to make a service reduction and then close the angle cock on the train that we were cutting away from. We never had any accidental releases!

Walt Gay
  ----- Original Message ----- 
  From: NW Mailing List 
  To: NW Mailing List 
  Sent: Saturday, October 23, 2010 8:02 AM
  Subject: Re: Train splits


  " 
  Henry Nase was N&W's head safety man.  When the ABD (W?) brake came out, there
  were a multitude of instructions published.  As I recall, the brake pressure had to be
  reduced to 20 lbs. and the angle cock gently closed.  According to Nase, a hopper 
  train from Lamberts Point was to fill out at Broadway Yard, Petersburg.  Stopping on the
  downgrade from Poe, the brakeman waited for the engineer to signal that the pressure
  was down to 20 lbs., then he slammed the angle cock shut.  The light engines then
  went to City Point Branch Jct. and backed into Broadway Yard.  The valves were
  so pressure-sensitive that the brakes released on the train .  The conductor thought the
  crew had done a remarkable job of picking up - - - - until the cab rounded the curve at
  City Point Branch Jct. and he saw his crew in panic mode.    Harry Bundy "

  That is not quite the way things happened:
      Once you have cut away from the train and exhausted all of the air, when you go back and couple up, it takes a good while for the trainline to pump up. 
      Here is a very basic explanation of what happened in this case. The brakeman was trying to make a quick move by saving the air in the trainline. After the engineer made his reduction, the brakeman not only closed the anglecock on the engines, he also closed the anglecock on the cars. This "bottled" the air on the train that was left standing. 
      The brakes were designed to release when the trainline pressure increased by a couple of pounds over the value of the amount of brake applied. This would result in a quicker release of the brakes in the entire train. It is also very important to keep in mind that there is a pressure gradient in the trainline front to rear.
      So in this case, once the air was "bottled" up, the pressure in the trainline starts to equalize. This in turn increases the pressure on the head end. After this pressure gets above a certain value, the brakes start to release. This in turn causes a chain reaction all through the trainline and eventually all of the brakes release. Next thing you know you're waving goodbye to the Capt'n.
      This is why it is against the rules to bottle the air on the part of the train that is left standing. One anglecock must be left open in order that the pressure doesn't rise and start a brake release.

      In regard to the OWL "BROKE IN TWO!". One thing that hasn't been mentioned is that sometimes lockpins will get shaken up. Slack action would be a good cause of this. Slack runs in and the cut lever swings up lifting the pin. The pin now stays up and when the slack comes out , the train separates. POW!  You are now in emergency.
      The cause of the break-in-two on the recording is unclear. It definately wasn't a drawhead or the car would have been set out. 
      A broken knuckle might seem the most likely cause, however, nothing was ever said about a knuckle or repairing one. A pin coming up is the only other likely cause. However, there is just not enough information provided in the narrative to know for sure.

  Jimmy Lisle


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