LOCOMOTIVE FUEL CONSUMPTION AND THE SPEED DIAGRAM. COPYRIGHT, 1912, BY A. K. SHURTLEFF. LOCOMOTIVE FUEL CONSUMPTION. The largest primary account in the operating cost of the average railroad is "Fuel for Road Locomotives." Locomotive fuel consumption can be divided as follows: (1) Fuel used for work. (2) Fuel used account of leakage of water and steam, and for steam used for brakes, whistling, etc. (3) Fuel used for re-evaportion due to radiation. (4) Fuel used at enginehouses, "firing up," etc. The tables in the American Railway Engineering Association Manual of 1911 provide for fuel used under the first three headings during the period of maximum effort. Two tons of coal per hour is the average that can be properly handfired by a single fireman in a modern freight locomotive, through the long periods of maintained effort required in making the schedule with the maximum train. The tables referred to, however, provide for any practical amount of fuel consumption, but it is rare, even with a relief fireman, that over five thousand pounds of coal will be fired during the period of maximum work by a freight locomotive. No accurate mathematical method can be fixed for estimating locomotive fuel consumption. Details of construction, condition of the locomotive and the "personal equation" of both the engineer and fireman introduce variables which materially affect the question. Single tests may show what might be expected under like conditions, but for the student of economics in railway location or operation, averages must be considered. The personal equation of the fireman probably is the greatest variable, and for the same man will vary widely on different trips. No economic study can be of value that does not consider the average efficiency of the laborer. The fuel used by locomotives while drifting or at rest is a material amount of the total consumption. At the 1904 convention of the American Master Mechanics' Association, some valuable data was presented covering *Published by permission of the author. twenty-one tests over an engine district on the Atchison, Topeka & Santa & Fe Railway and twenty-four tests on the Norfolk & Western Railway. From this data the accompanying tables, covering fuel used at rest, were obtained. The tables are arranged in the order of delayed time for each locomotive, and a study of the coal used as compared with the time delayed will show the variable character of the personal equation and the necessity of following the rule of averages in estimating economies. Coal used per trip "firing up" at enginehouses, average of 15 tests.. ..515 lbs. per 1,000 sq. ft. H. S. The fuel loss by radiation depends on the temperature of outside atmosphere, area of boiler exposed and quantity and quality of boiler covering. The exposed area varies and is not one of the items given with locomotive dimensions. With modern locomotives there is from 4.75 to 5.75 sq. ft. of exposed area to one square foot of heating surface. The proportion of this outside area insulated against transmission of heat varies. Evaporation is from heating surface, and, owing to the variables and un determined area of boilers exposed, the losses will be based on heating surface. The heat loss from radiation is the total loss when locomotive is not working, less the loss due to leakage and use of steam and water for other purpose than work. In the Atchison, Topeka & Santa Fe tests, it would require 34.7 lbs. of 11,000 B. T. U. coal per 1,000 sq. ft. of H. S. to evaporate the 282 lbs. of water used per hour idle from a feed water temperature of 65 degrees to a boiler pressure of 200 lbs. Coal used per trip "firing up" at enginehouses; average, 24 tests.. .501 lbs. per 1,000 sq. ft. H. S. The Norfolk & Western tests do not give the water and steam losses while at rest. In ninety-seven tests at the St. Louis Exposition testing plant, the average steam loss per hour per 1,000 sq. ft. of heating surface was 151 lbs. These locomotives were probably in as good or better condition than the average road locomotive and the Norfolk & Western |