. Railway mechanical engineer . o the statistics of the American Iron & SteelInstitute, the- tonnage of rails produced in the United States in1920 was 2,604,116, an increase of 400,273 tons, when comparedwith 1919, a decrease of 340,045 tons as compared with 1917—the best war year—and a decrease of 898,664 tons as against the 1920 tonnage, only 142,899 tons were made by theBessemer process. The Automatic Control of Locomotive Cutoff Tests on Big Four Demonstrate Its Pressure as Actuating Force Utilizing BY E. S. PEARCE Mechanical Engineer. Cleveland, Cincinnati, Chi
. Railway mechanical engineer . o the statistics of the American Iron & SteelInstitute, the- tonnage of rails produced in the United States in1920 was 2,604,116, an increase of 400,273 tons, when comparedwith 1919, a decrease of 340,045 tons as compared with 1917—the best war year—and a decrease of 898,664 tons as against the 1920 tonnage, only 142,899 tons were made by theBessemer process. The Automatic Control of Locomotive Cutoff Tests on Big Four Demonstrate Its Pressure as Actuating Force Utilizing BY E. S. PEARCE Mechanical Engineer. Cleveland, Cincinnati, Chicago ■& St. Louie LOCOMOTIVE drawbar pull is the result of steam pres-sure on the pistons. Variations in the amount of drawbar pull with changes in speed re the result of variationsin the average pressure against the pistons, and changes inthe average pressure against the pistons are the result ofchanges in the quantity, pressure and temperature of thesteam admitted to the cylinders at the beginning of the Mikado Locomotive Equipped for Automatic Control of Cutoff Graphically, the relation of quantity and pressure arerepresented by the indicator card. As shown by Fig. 1, steamis admitted to the cylinder from the point of admission A tothe point of cutoff B, at a pressure of P lb. At the point Bthe amount of steam in the cylinder, for all practical pur-poses, is the amount used in the development of the work ofone stroke. From B the steam expands the remainder of the The exhaust or back pressure, P2, varies directly with theadmission pressure Plr the length of cutoff, speed and theability of the boiler to supply steam at the rate required tomaintain Pr It varies indirectlv with the size of exhaustports and passages. Fig. 1 shows the value of back pressure when a constantcutoff is used through a range of increasing speeds as com-pared to the changes that take place in the admission pres-sure. The admission pressure falls off with increasing speeddue principally to
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
