Train splits

[NW Mailing List]

Mike:
 
Jeff's answer is of course accurate in its description of the various  
reasons why a train may "split/break in two" but I think there's more to be said 
 about why this results in an emergency brake application.
 
Air brake systems apply the brakes when the brake pipe pressure is reduced  
from its fully-charged level.  If the brake pipe is suddenly fully  
exhausted, which would happen if a train "breaks in two,"  the triple valve  senses 
this rapid loss of pressure and applies emergency brakes, which results  in 
a higher brake cylinder pressure than a normal service brake  application.
 
Although emergency applications should only happen in the event of a train  
separation or a deliberate emergency brake application, unfortunately a  
transient pressure pulse in the brake pipe can also look like a sudden deep  
reduction, inducing an "unintended emergency brake application."  Modern  
systems have reduced this tendency, but it still happens occasionally.
 
Dave Phelps
 
 
In a message dated 10/20/2010 9:10:21 P.M. Eastern Daylight Time,  
nw-mailing-list at nwhs.org writes:

Mike,
 
When a train "breaks in two", it could be one of a number of  reasons. 
Occasionally the air hoses may separate, possibly due to its  hanging to low and 
hitting a road crossing, or some other obstacle  between the rails. There 
are times when a knuckle of a coupler may  break, due to a weak spot in the 
metal, or previous fracture, unnoticed  by the car inspectors. Also, an 
entire drawhead can break for the same  reasons. Of course, a derailment most 
times will cause the train line to  separate, all of which causes an emergency 
brake application.  It does not happen too terribly often, but more often 
than one  might think. 
 
Due to improvements in car construction and modern safety checks,  such as 
dragging equipment detectors, it doesn't happen as often as it  did 50+ 
years ago.
 
Jeff Sanders  

--- On Wed, 10/20/10, NW Mailing  List <nw-mailing-list at nwhs.org> wrote:



From:  NW Mailing List <nw-mailing-list at nwhs.org>
Subject: Train  splits
To: "NW Mailing List"  <NW-Mailing-List at nwhs.org>
Date: Wednesday, October 20, 2010,  6:38 PM

I was curious about something I heard the other  day on one of Winston 
Link's recordings. He was riding in a caboose  descending into Roanoke (I think) 
and the train split in two and went  into "emergency". Could somebody 
comment on what exactly happened and  how often would that occur? Thanks!  


Mike Weeks
Greenville  NC


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