From: gl4317@yahoo.com   
      
   In article ,   
    Larry Sheldon  wrote:   
      
   > Thank you so much.  It looks like it might be competitive with what so   
   > would say is my favorite, the Mallet inverteds of my youth.   
      
      
   Here is a side view of a broad gauge Beyer-Garratt used in India:   
   http://sundar.brinkster.net/PClass.jpg   
   from this web page:   
   http://sundar.brinkster.net/Garratt.htm   
   It will help you see how these are put together, though the articulation   
   joints aren't obvious.   
      
   The Mallet style articulated locomotives had a long boiler, but it is   
   possible to get better heat throughput in a shorter, fatter boiler.  The   
   advantages seen on narrow gauge lines were certainly a factor, but those   
   same advantages worked on standard gauge lines as well.  Toward the end   
   of steam in the USA they were really pushing the limits on what could be   
   done with a locomotive where the driving wheels were directly under the   
   boiler.  The bigger the driving wheels the more speed you get at a given   
   RPM, but the smaller the boiler was able to be and thus the less power   
   available to move at speed.  The Garratt design didn't put anything   
   under the boiler or firebox.   
      
   This was certainly an advantage on narrow guage, but it was an advantage   
   anywhere.  Australia, Brazil, India and possibly Argentina used them on   
   their broad gauge lines.  In the side view you can see how low they   
   dropped the fire box below the boiler, now that the wheels are out of   
   the way.   
      
   Also, there were certain limitations with the Mallet design, among them   
   they really were not that flexible while the Beyer - Garrett had a   
   rotating engine piece at each end with the boiler in the center.  This   
   made them a bit more like the flexibility allowed with a rotating truck   
   at each end of a diesel or electric locomotive.   
      
   Thus, while the USA had the largest articulated locomotives on earth, a   
   Beyer Garratt design holds the world's speed record for an articulated   
   steam locomotive.  The Mallet style locomotives could be operated at   
   reasonable speed on really well built track, but they were rarely really   
   intended for fast passenger service as a regular assignment.  Due to   
   their stability at higher speeds, there were Beyer-Garratt designs   
   intended for day to day use on fast passenger trains.  In fact, before   
   electrification came to Sao Paulo broad gauge commuter service they used   
   a high speed 4-6-2+2-6-4.  Sure, from time to time a USA Mallett style   
   may have worked a long intercity passenger train, but daily commuter   
   service would have been unthinkable with them.   
      
   Also, with the weight of the water tank and fuel (coal, oil, or wood   
   were all used in these) directly above the engine, the weight of that   
   also contributed to the tractive weight of the locomotive.   
      
   All of these features made them quite popular in many parts of the   
   world, but oddly enough not very many of them were used in Europe, and   
   none were used in North America.  Asia, Australia, Africa and South   
   America found them very useful, however.   
      
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