"Stretching " your train.

I would like to run my trains in TRS 2006 as prototypically as possible, and as such, I have a few questions regarding "stretching" the train.
I have seen before departing on a trip, the engineer will apply some sort of brake and then advance the engines forward to remove all slack from the train.
My questions: Is this, indeed, to remove all slack and why would the engineer do it? Or is this a test of the train's brakes through all the cars in the consist? Or is it for another reason? How would I go about doing this "stretch" in TRS 2006 with my trains?
Can anyone help me with these questions? Thanks.
CharlieLima

An engineer will slowly take out the slack, so that when he pulls, it doesn't rip couplers and break knuckes from dozens of feet of slack action on a 125 car train.

I made a 4 mile long train and tested out how much slack was in it...it took 4 grids from when the loco first started to move, until the last car began to move.

You are limited to your field of view, so you really won't see much of your slack action, unless your route doubles back on itself.

That is the reason we do it, and just to add to you're question. The brakes are already released when we take the slack out, for a real train the way we can tell the tail end is moving, is we have a display on our screen to tell us when the marker/e.o.t. on the end of the train starts to move, and what direction it is going.

Thank you for your replies. This info really helps. So the practice is: release the brakes, start slow, eliminate slack and pick it up from there. Thanks

CharlieLima

charlielima said:

Thank you for your replies. This info really helps. So the practice is: release the brakes, start slow, eliminate slack and pick it up from there. Thanks

CharlieLima

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The draw bar will break if to much tension is applied to it suddenly. the coupler is attached to the draw bar, the draw bar is attached to the railcar or engines or there units.

Damon:wave:

You can also think of it as an easier way move a train. When an unstretched train starts to be pulled by an engine, the engine really only has to move one car at a time. By the time the slack between the first and second car is taken out, the first car is already moving and the engine and the first car brings the second car up to speed. This is repeated for each car in turn until the last car is added to the moving set of cars. The delay between cars is not much but it is there.

Now imagine if there was no slack. The engine would have to move the entire train at once. The strain on the couples would be tremendous and something would probably break. Plus the engine would have to be very powerful to get things moving, much more power than would be needed to keep the train moving. There would also be a question of adhesion. Wheel slip would be a real problem.

Not so...the practice you are describing is similar to "backing into er" and pulling with violent slack action..this practice is prohibited on RR's.

A 125 car train stopped upgrade on the Horseshoe Curve can get er going but it takes repiticious small tugs until things get rolling.

Pulling with slack action damages cars severly.

Yes so, in the USA it is frowned upon because their trains are given enough power to start the train no matter what, in other parts of the world trains are given just enough power to get the job done, so if the train is going through flat country it will have its limit for starting on the flat, necessitating the method of starting described by martinvk, neither method is right, neither is wrong, its just the way it is

Cheers David

Edit:- this method was used during the steam days all over the world due to the fact that a steam loco is at its least power at a near standstill.

I don't get much slack at work, because out train set that were using now is articulated, but the steam coaches can generated some serious slack if your not careful how you apply the throttle. We don't have train brakes, so you just have to be easy on the throttle when you take off, in case the car's decided to move forward on you

cascaderailroad said:

...pulling with violent slack action..this practice is prohibited on RR's.

...
Pulling with slack action damages cars severly.

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If it was violent then yes, the potential for severe damage is high.

In my description there would not be any acceleration until the last car was moving and all the slack was taken out. Therefore from each car's point of view, the acceleration from standing still to moving would be the same. Only once the whole train was moving as a unit would acceleration towards road speed start.

That's the theory. If it was actually done this way in practice is another story. If the engine started to accelerate before the last car was moving then it would get increasingly violent towards the end of the train.

Hi All: Now think of what could take happen when your rolling down a hill..Thats where some times Dynamic braking comes in to play..Now to go even farther..How about what happens when have a long freight, part of it is going uphill and part of it is going downhill..Are we not having fun now..