Re: Train Accident in Blue Mountains

[krel4203@netconnect.com.au (Krel )]

On Fri, 10 Dec 1999 11:05:50 +1100, John MacCallum
<engineman@ozemail.com.au> wrote:

>
>
>Russell Norton wrote:
>> 
>> When starting the IP on a downhill grade in the mountains, the independent
>> brake (loco brake) is not fully released, to keep the entire consist bunched
>> until dynamic braking is started. This is to maximise passenger comfort, as
>> there is a fair amount of slack in the IP consist.
>
>Do not NR's reduce Dynamic Braking to a level similar to set up
>if Brake Cylinder pressure is detected?
>
On an NR the DB does not reduce unless BC pressure is 100kPa or above.
So on starting on a down grade the DB is engaged (full) then the
independent gradually released until it is below 100kPa, at which
point the DB takes over and keeps the train bunched. The independent
is then gradually released and the DB reduced until the train begins
to move.

>On an 81 class and other GM units this is the case so that it removes
>the possibility of skidding the wheels due to the combined Dynamic 
>Brake retardation and Brake Cylinder Pressure induced Retardation.
>
>It would therefore be a pointless excercise as when you finally did
>release the Independent Brake the Loco's would run away from the train
>thus defeating the Purpose of the exercise. Is it not better to 
>stop on the Automatic but bunch the train up using Dyno and then just 
>before stopping applying the Independent to keep the Train bunched
>as the Dynamic looses effect. Then when it is time to move off release
>the auto and then after a delay of a few seconds the Independent so
>that the train moves off bunched up. Then when selecting Dyno again
>there is almost no noticeable Train shock.

Cheers

Krel


VGR website http://www.castlemaine.net.au/~vgr/

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