. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . the braces becomes very small; and the scantling of thebraces will be reduced to about 6x7 inches. RODS. The weight upon the first set of rods is the same as thatupon the end sets of braces; in the present case 800000 -i-2 = 400000 on each side truss, and 400000^2 = 200000on each end; and if there are five rods in each set, each rodbears 40,000 lbs. Referring to the
. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . the braces becomes very small; and the scantling of thebraces will be reduced to about 6x7 inches. RODS. The weight upon the first set of rods is the same as thatupon the end sets of braces; in the present case 800000 -i-2 = 400000 on each side truss, and 400000^2 = 200000on each end; and if there are five rods in each set, each rodbears 40,000 lbs. Referring to the table on p. 146, oppo-site to 31,410 lbs., is the diameter 1 flinches; whence thefirst set must contain five rods, of 1|^inches second set decrease in size as the weight is lessened bythe two end panels. The nut and washer for the rod arealso found in the same table. COTUNTERBRACING. 180. When a load is placed on the point C, fig. 64, thetruss tends to sink at that point, and a corresponding risetakes place at C This motion changes the figure A B C E,from a rectangle to an oblique angled figure; the diagonalE B being shortened, and A C lengthened. This motion is^ 152 HANDBOOK OF RAILROAD CONSTRUCTIOX. Fig. easily checked by the introduction of the counter braceEB. The action which this timber is called upon to resist,being caused by the moving or variable load on one panel,the brace must resist the load coming thereon, (say fifteenfeet,) and is thus the same size as the brace at the centre ofthe span. The counter braces may be so confined between thebraces, at the intersection, as not to move laterally or verti-cally, but must not be fastened to the braces; because theaction of the separate timbers is thus trammelled. The manner of adjusting the braces and counter bracesFig. 67c. ^o ^he chord is shown in fig. 67 C. It was formerly thecustom to abut the bracesagainst a block on one sideof the chord, and to screw therod against a block on theopposite side ; the
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