05-16-2014, 03:30 AM
toptrain Wrote:Where is this conversation going Lutz. Is your statement about Crampton locomotives and directed to the one the Camden and Amboy ran a long time ago. that was a 6-2-0. The Wikipedia link you posted tells a lot about them. What was the fear you speak of ?Frank!
frank
This is a direct reply to Tyson Rayles posting about top heavyness an the fear those locos or even could flip over in curves.
In the middle of the 19th century locomotive constructers were the opinion only a low center of gravity would made a locomotive run stable at higher speeds.
This must be seen in conclusion with the long boiler locomotive especially of British origin. These 2-2-2 had long overhangs front and aft causing vertical swaying too.
The text copied from the English Wikipedia describes how the efforts for a low center of gravity leds to teh Crampton loco:
"...
Meanwhile, the prevailing view was that the centre of gravity should be as low as possible, which limited the size of the driving wheels, and incidentally precluded the use of inside cylinders.
The initial locomotives were of 2-2-2 wheel arrangement to accommodate the extra length. However, with the outside cylinders, the engines were extremely unsteady, swaying from side to side. This led Stevenson to bring the rear wheels forward in the 4-2-0 formation, with the cylinders between the leading wheels. Such an engine was the "Great A" which took part in the Gauge Trials. This however, left the firebox behind the wheels and was therefore limited in size and weight. Moreover, the long rigid chassis made bends difficult to negotiate and damaged the track. The classical long-boiler locomotive, then, was powerful but slow. It was ideal for goods trains, one example surviving as the North Eastern Railways Class 1001.
The opposite point of view was taken by John Gray, who designed a number of engines for the London and Brighton Railway. His engines were the inspiration for David Joy in his design for the Jenny Lind locomotive, which compensated for the size of its boiler by greater efficiency and a pressure of some 120 psi.
The long boiler design, on the other hand, was taken to its extreme by the Crampton locomotive which utilised a larger driving wheel by placing it behind the firebox."
From the German Wikipedia:
"...
Die „Crampton“-Dampflokomotive hat nur eine einzige, weit hinter dem Kessel angeordnete Treibachse mit großen Rädern von bis zu 2,15 m Durchmesser (in Europa). Sie wurde 1843 von Thomas Russell Crampton erdacht. Er verfolgte die Absicht, die Nachteile der von Stephenson entwickelten „Long Boiler“ (Langkessel) zu vermeiden. Diese ragten vorne und hinten über die Achsen hinaus und neigten damit bei hohen Geschwindigkeiten zum Nicken und Entgleisen. Bei der Bauart „Crampton“ ließen sich trotz tiefer Lage des Langkessels große Treibräder für hohe Geschwindigkeiten verwenden. Die besonders tiefe Kessellage wurde damals irrtümlicherweise als wichtig für eine hohe Laufruhe und Laufgüte der Maschine angesehen. Diese Auffassung wurde insbesondere durch die Konstruktionen Karl Gölsdorfs mit besonders hoher Kessellage widerlegt. Dass die Crampton-Lokomotiven tatsächlich wesentlich laufruhiger waren als die „Long Boiler“-Maschinen, lag an der insgesamt besseren Gewichtsverteilung und den nahe dem Lokschwerpunkt angebrachten Zylinder, was dazu beitrug, dass die irrige Meinung bezüglich der tiefen Kessellage sehr zählebig war. Lokomotiven der Bauart Crampton erreichten die für damalige Zeiten sensationelle Geschwindigkeit von 120 km/h.
..."
Here it is about the same, but also remarked, that it was an error the low center of gravity is the main cause for an stable running.
Actually it were the weight of the loco was better spread over all axles and the cylinders were mounted nearer to the center of gravity.
Lateron Gölsdorf build locos with an very high center of gravity which were running stable also at high speeds.
Remember the 4-4-0 American Type loco in the US since 1836. With its 3-point suspension the classic American 4-4-0 is one of the best loco constructions ever made.
Lutz