. The elements of railroad engineering . s. i .GGl 8,803 If 102,368 tV .837 11,133 HI 109 760 t 13,754 n 117 600 1 1TIT 1G,G21 111 ^1 G 125 440 1 . 19,779 2 133 728 1 3T6 23,296 2i 142 912 1 26,880 H 160 384 H 30,912 n 178 528 1 2. Go 35,168 n 198 016 ItV 37,632 H 218 176 H 42,336 n 239 456 ItV 47,264 H 261 G32 n 52,192 3 284 928 1t\ 57,568 H 315 840 If 63,168 3i 366 464 ItV 68,992 3f 420 448 n 75,264 4 478 464 1 9 81,536 4i 508 4
. The elements of railroad engineering . s. i .GGl 8,803 If 102,368 tV .837 11,133 HI 109 760 t 13,754 n 117 600 1 1TIT 1G,G21 111 ^1 G 125 440 1 . 19,779 2 133 728 1 3T6 23,296 2i 142 912 1 26,880 H 160 384 H 30,912 n 178 528 1 2. Go 35,168 n 198 016 ItV 37,632 H 218 176 H 42,336 n 239 456 ItV 47,264 H 261 G32 n 52,192 3 284 928 1t\ 57,568 H 315 840 If 63,168 3i 366 464 ItV 68,992 3f 420 448 n 75,264 4 478 464 1 9 81,536 4i 508 480 1| 88,256 H 570 080 111 95,200 if 635 040 The load which each king-rod sustains we found to be,500 lb. A rod which would safely sustain this load 1262 RAILROAD STRUCTURES. with a factor of safety of (I would break under a load of8,500 X G = 51,000 11). Referring to the table, we find in the column headedBreaking Sticss, the number most nearly corresponding to51,000, which is 52,li)2 lb. This stress calls for a rod. RAILROAD STRUCTURES. 12G3 1;^ in. in diameter, which is the diameter we specify for king-rods. The stress in the rafters produces a shearing stress along the grain of the tie-beam at the footing of the rafter. This stress is equal to r /, or 7,800 lb. We find in Art. 1809 that the working stress for shearing along the grain in yellow pine is 400 lb. per sq. in., and to resist a shearing 7 800stress of 7,800 lb. it will require ^ = sq. in. There must accordingly be sufficient space between the foot of therafter and the end of the stringer to give a superficial areaof at least in. As we have made this distance 12 in.,giving a superficial area of G X 12 = 72 in., there is noquestion of the security of this joint. The bolts /, t passingthrough the tie-beam at the foot of the rafter serve only tokeep the rafter in place. The needle-beam projects 4 ft. 3 the truss, as shown in detail at .^. A brace ii runsfrom this projecting need
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
