. American engineer and railroad journal . eans of a definite loadagainst a lapidarys wheel fed with three-minute emery mixedwith oil. The amount removed by the grinding action was thenascertained by finding the weight lost by the sample. The usualroutine was to take three samples of the metal to be tested andone of soft copper, each specimen measuring 5 millimeters squareby 8 millimeters high. The four were then fixed to the bottomof loaded rods placed vertically over the wheel, so that the centerof each specimen lay on a circle of 11 centimeters radius. Thewheel was then run for two periods
. American engineer and railroad journal . eans of a definite loadagainst a lapidarys wheel fed with three-minute emery mixedwith oil. The amount removed by the grinding action was thenascertained by finding the weight lost by the sample. The usualroutine was to take three samples of the metal to be tested andone of soft copper, each specimen measuring 5 millimeters squareby 8 millimeters high. The four were then fixed to the bottomof loaded rods placed vertically over the wheel, so that the centerof each specimen lay on a circle of 11 centimeters radius. Thewheel was then run for two periods of 10 minutes each at a speedof 800 to 1,000 turns per minute. Taking copper as standard, thefollowing results were obtained for the copper-zinc alloys: age of zinc. Relative wear. Percentage of zinc. Relative wear 0 .816 .881 .905 I 210 .929 Fragile .940 .586 .950 .777 CONSTRUCTION AND MAINTENANCE OF RAILWAYCAR BY OSCAR (Contin tied from page 39.) FREfGHT CARS. In a previous article the general construction of the floor frameof ordinary freight cars was described and subsequent articlestreated of those parts, which, with perhaps slight modifications,are common to most if not all classes; it now remains to describethe different kinds of freight cars which are in use. FLAT OR PLATFORM CARS. The simplest kind of car which can be constructed on the floorframe which has been described is the flat or platform car, whichconsists of the frame, draftgear, trucks and brakes, with perhapssome provision to prevent the material which is carried from fall-ing off the car. These cars are used principally for transportingpieces of freight which are too bulky to put into any other kind ofcar, and which, from their nature, are not liable to be injured bythe weather, and which, from their size and weight, are notlikely to be pilfered. Machinery, stone and lumber are some ofthe
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
