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[quote user="Lars Loco"] Hi Michael,as I reread the later part of this thread and postings several times again, the discussion turned to became out what transition-system is better: A mechanical / reciprocating against an electric one.The later one does not care if the power-plant / prime-mover of a locomotive is- a diesel,- gas- coal- hydrogenor...whatever fueled engine, independent they are internal combustions, approach as a turbine or jet engine. The last steam-engines were built with 10-15% machine losses (from the Cylinders), new diesels have less than 10%. This should be done with actual engineering, too, but better? No.'Cause other transition-systems, e.g. hydraulic, never really widely approached, I hardly believe there is a better transition than the electric.Now, you could have the benefit of a:- computer-controlled,- high availability,- rugged and stable system,and even could use the braking energy. Electric-engines turn their energy into the power-net back again (commonly used in Europe and other), why not keep the energy into batteries (which also have become better now), placed into a "Tank-car" as Mr. Modelcar suggested?Steam-engines keep a high potential energy in their boilers, but it takes some time to produce it. With a combustion-engine just start it and off you go...Turbines work in a small frame of load efficiently. Not saying there would not be an application for this, but a limited one.Nowadays, even cars (hybrid) are partly driven with electric-motors, to make them more efficient.Regarding the last posts about TE curves Steam vs. Diesel that:... Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) ...If both engines have same HP they will deliver same HP.I think there is a lot of confusion about particular engine-Types from both sides, the diesel (First Gen., Second Gen., DC/AC) ones vs. the 4-8-4s, 2-6-6-4 and so far. It is pointless to compare them. Yes, steam-engines were magnified machines, sometimes more powerful than that what we have now, but please have a look at my post earlier: The 5600DBHP Y6B N&W engine will just half win against a 4000DBHP GE-4400AC engine, given a speed range of 0-60mph.I did not calculate the area beyond their TE-Curves exactly, nevertheless, we compare technology 50 years apart.Yes, one point is true, with the arrivals of the first and second generation diesels, the railroads were not happy with the speed capabilities of their diesel-engines, because the had to buy many, expensive units to beat steam-locomotives delivering 5000-6000 or more HP. Quite possible that the steamers also had some extra-reserves.Having a lot of respect, that people achieved many years ago, erecting power plants more than 500tons and running about 70mph, anything else than awesome would be totally inappropriate to describe them, but some must wonder, is there really a need to built more than 4000-6000DBHP freight engines? Even the U.P. ( = U.nlimited P.ower) came to the economic conclusion that smaller, but less powerful units than their 5000-6600HP Double-diesel engines are enough. And no, it was not the reason that if one prime-mover fails, the whole locomotive was out of service, it were just rising maintenance costs (frame cracking).As far as I know, most RR nowadays are quite happy with their 4000HP engines. The benefit nowadays is: The better transition of energy.What makes me really think is, how we can use steam as a efficient transition-system? As a turbine? Limited use. Reciprocating/Classic design? The transition-system goes lost while using it.Condensing concepts are also of limited use.While we can debate about various kinds of fuel, burning processes, in my opinion, the electric-transition is the best and there is still place to refine it in future. Lets use Cables near superconductor capabilities and maybe we have transmission systems near 99%. Hard to beat with mechanic.Excitingly waiting your replies!Kind regardsLars[/quote]Lars,You raise several interesting points.  I have some random thoughts I would like to add regarding the difference between steam and diesel regarding what you call transition.  Not to nitpick, but if I understand your use of the term, I would call it transmission.  And I suppose even that term can be somewhat ambiguous.  In its most basic sense, transmission would be the transfer of power from the prime mover to the wheels so all locomotives have it in that sense.  However, in a more specific definition, I see the term as referring to a power transfer mechanism that not only transfers the power, but also, can vary the relationship between speed and torque of a particular power level.As you probably know, diesel locomotives have that kind of transmission just like cars, trucks, buses, bulldozers, etc.  With diesel-electric locomotives, the transmission is electric and accomplished by trading the amperage and voltage, which in turn, trade torque for speed.  I am not completely informed on how this trading torque for speed is accomplished today with AC or even exactly what it is called.  But in the early diesel era, it was accomplished with specific circuit changes between the generator and traction motors, and those changes were called transitions.  So the electrical transmission was accomplished by circuit transition.  But, aside from the method, it was a transmission that accomplished the same thing as any vehicle transmission.  Changing transition electrically was just like shifting gears in a car or truck standard gear transmission. Steam locomotives, on the other hand, are unique vehicles in that they do not have a transmission.  They are direct drive with no ability to change speed and torque ratios.  It is as if they are in high gear all the time.  This is why they do not fundamentally develop high HP or TE at low speeds.  It is just like getting into a car with a standard manual transmission and starting off in 3rd gear.  The engine cannot get up to the RPM where it produces its maximum HP until it gets the car up to 50-60 MPH.Steam locomotives could be built with a transmission, but the added complexity and cost would work against the concept significantly.  What it would amount to would be the reciprocating engine driving into a changeable set of gearing, and from that, the force would be transferred to the wheels.  It could also be done with an electric or hydraulic transmission.  But it makes more practical sense to just make a big, robust 2-cylinder steam engine drive the wheels as its "crankshaft."  Or at least that is the way steam locomotives began their evolution, and they stuck with that premise.  Steam locomotives do have variable cutoff, which shortens the steam admission as the speed increases in order to reduce backpressure, which becomes a larger impediment as speed increases.  In a way, this is like a transmission, and some might argue that it is a transmission.  But since it does not actually change the force/speed ratio, I would not call it a transmission.  Although shortening admission to accomplish the reduction of backpressure would seem to reduce the total force in the piston stroke.  And if reduction of backpressure results in more speed, maybe it is a transmission.
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