Winston,
I certainly would not disagree with your points of starting a train in today’s
modern railroading. My comments were from first hand experience in the 1970s
when we still had waycars and lots of friction bearings.
Leo Phillipp
> On May 9, 2020, at 12:20 PM, Winton <runextra@gmail.com> wrote:
>
> The idea that one cannot start a heavy train without taking slack is a
> railfan myth in today's context. In fact I'd go so far to say that you canNOT
> use slack to start a heavy train today. In the old days of cold brass
> bearings and slow releasing air brakes you could use the take-slack method to
> start a train but not anymore. Roller bearings and faster releasing air
> brakes has made slack-starting on a grade impossible. To use the slack method
> you need to be able to get the entire train moving forward before the rear
> end cars release. If you don't then the rear end will roll backwards and you
> are going to be in two (or more) pieces. To prevent breaking in two while
> starting you can only accelerate (stretch out) the head end at a certain rate
> or you will break it in two from jerking the cars into motion. With todays
> fast releasing brakes the brakes will release faster than you can safely
> stretch the train. Thus you get the roll back and kapow!. Besides, slack
> starting one car at a time is not necessary and has not been necessary since
> the 1960s. If you have enough loco power (Tractive Effort) to pull the train
> up the hill then you've got more than enough power to start the train
> entirely stretched, no slack. In my 41 years as an engineer I've routinely
> started hundreds, maybe thousands, of tightly stretched 15,000 ton trains on
> 1%+ grades with no problems. It is all just physics. Lighter trains on
> steeper grades like 2% are similarly started without slack. Tieing handbrakes
> on the rear cars to hold the slack in today would be impossible. You can't
> walk across the tops of cars to set & release hand bakes. There is no caboose
> & thus nobody back there anyway.
>
>
>
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