> Any thoughts as to what this valve is, and what it does?
From " The Science of Railways By Marshall Monroe Kirkman" (where else?) (Pretty useful being able to search the contents of books via Google!) "The LeChatelier or Water Brake.—This brake was invented about fifty years ago by a Frenchman, whose name it still bears. It is highly recommended for general use in mountainous districts on account of (1) its efficiency, (2) avoiding the trouble so generally experienced with the driving wheel tires heating and expanding on account of the friction between the brake shoes and tires with the ordinary brake. It is very inexpensive and simple to apply. It is most generally referred to as the "water brake," although it is not water, but wet steam that is introduced into the cylinders. The principles involved are very much similar to those employed in the operation of the Sweeney Air Compressor. When the engine is reversed while running the cylinders are converted into air pumps, and greatly retard the speed of the engine. Before the advent of the air brake it was almost the universal means employed to stop the engine and aid in holding a train. But this method of using the reverse lever had serious objections; as was stated above, the cylinders were converted into air pumps; to fill the vacuum thus created in the cylinders behind the moving piston, hot gases, cinders and smoke from the smokebox were drawn in. This of course was very objectionable and something had to be devised t o supply the place of these hot gases. LECHATEUER OR WATER BRAKK This led to the invention of the water brake by LeChatelier, who used a jet of wet steam in the exhaust ports, which filled the vacuum in the cylinders instead of gases. Construction.—Its construction and application is clearly shown in Figure 96. It is composed of a globe valve a and pipe b which is divided into two pipes c, c, the latter entering the exhaust pipes as shown. The globe valve in the boiler head should be set within easy reach of the engineer and just below the water line in the boiler. In conjunction with the last statement it may not appear clear to some why it is asserted that steam is used in the cylinders, and yet the globe valve connection is below the water line. This is explained by the fact that water will boil under atmospheric pressure or in the open air at a temperature of 212 °F and be converted into steam. When the steam is up to a pressure of 175 pounds the boiling point of the water is 377°F; when it is released into the exhaust ports, the temperature being above the boiling point, it flashes into steam as it enters the cylinders. To Operate.—First cut out the air driver brake. Open the cylinder cocks. Close the throttle valve and open the globe valve of the water brake about a quarter of a turn, then place the reverse lever several notches back of the center of the quadrant, and note the density of the steam by its color as i t issues from the cylinder cocks. If it does not have a damp or dense white color the water valve must be opened until it does; if on the contrary water is thrown from the stack the water valve is opened too wide. Then the reverse lever should be moved backward until the required braking power is exerted; the further back the lever is placed, the greater the retardation of speed. Thus when placed in but the first or second notch back of the center, a very little braking power is obtained; when placed in the extreme back notch it holds the most. To cut out of service again, close the water globe valve, and move the reverse lever slowly to forward motion. If it is desired to use the water brake while the engine is running backward, reverse the operations explained above. " http://books.google.com/books?id=akK4s21j0tMC&pg=RA2-PA219&dq=Le+Chatelier+valve#PRA2-PA216,M1 Pete -------------- next part -------------- An HTML attachment was scrubbed... URL: http://postfix.45mm.com/pipermail/sslivesteam/attachments/20081220/3d958445/attachment.html _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html
