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[quote user="CShaveRR"] I'd have to check the book (which I have), but I don't think John Kneiling advocated less structural strength as one went further back in his integral trains.  In fact, he advocated mid-train power.  Today we have distributed power, often shoving against the rear of the train.  I'd rather have the drawbars be just as strong for anything that could happen with the slack back there.The drawback with dedicated trains is that if one part breaks down, the whole thing is lost for a time (including the power, if I remember Kneiling's stuff right).  Despite the fact that locomotives spend too much time idling as it is, the loss of power and cars isn't going to be tolerated.It's possible, now that railroads have come up with a way of changing out wheels without breaking the train, that you'll see some sort of compromise along these lines--cars similar to today's articulated in units of five or six, with drawbars between them.  It won't save much weight, but it would save moving parts, and eliminate a bit of slack action.As for a separate line to bleed an entire train, I don't see a need.  One rarely has to stand and wait for the air to bleed completely any more--just gve the bleeder rod a push or pull and move on.  If a whole train is being bled off, it's most likely in a yard where the train is being walked for inspection anyway, so no time is being lost by the manual bleeding.  And if a hand brake (more likely plural) has to be applied to a cut of cars being left somewhere, I'd rather have the air applied at the time to give me a hand cranking it up--impossible if everything's going to be bled off.[/quote]I would have to check back into my Trains collection to refresh my recollection of what all Kneiling had to say in relation to this matter.  I have never seen his book, only his columns in Trains.  I recall him often making the point about loose-cars needing to have the strength necessary to withstand being first out in a long train.  So the dedicated consist was a way to fix the position of each car so it could be designed only as strong as necessary.  In the case of a 100+ car coal train, the difference in tractive load between the first car and the tenth car, for instance, would not be that great.  It would therefore probably not be practical to make tiny incremental reductions in strength to each car.  By the time you got to the tenth car, you might only have reduced the weight on that car by 200 pounds.  So you would probably have cars designed to specific strength classes that correspond to their position in a train.  The first ten cars, for example, might be identical, and of the class for the number-one position.  The next ten cars would be for the number-two position class, and be slightly lighter.I do recall Kneiling advocating distributed power in a dedicated train-set.  I believe he viewed it as somewhat of an extension of the concept of reducing the strength from the front to back of the train.  Distrubuting the power tends to eliminate the need to distribute the strength.  Either approach could reduce the tare weight, or both approaches could work together with each contributing to the cause.You mentioned the need for car strength to withstand slack as well as tractive force, and that slack can affect cars regardless of their position in the train.  That is true, but with a dedicated train-set, one of the other major advantages is that there is no slack.  Slack is a product of the automatic coupler with its operational tolerance, and there would be no automatic couplers in a dedicated train-set.  Another major advantage of the dedicated train-set is its ability to utilize a superior electric or electro-pneumatic brake system.  Because the cars in the dedicated train-set do not have to interchange, they can be freely upgraded with non-standard brake systems.  In a loose-car train not only is there slack forces, but also those forces are further exacerbated by the irregular affects of conventional air brake operations.  The destructive braking/slack forces are eliminated in a dedicated train-set because it has no slack and it has perfectly distributed braking throughout.The bleed line would not be utilized to bleed cars that were being set out.  They would be left with the air set as usual, so the mechanical advantage for applying a hand brake provided by the air set would still be available.  The bleed line would be to bleed cuts of cars that are going to be switched.
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