. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . to turn the point, it ii necessaryto protect the point by some form ofshoe. Several forms in cast iron havebeen used, also a wrought-iroli shoe,having four straps radiating fromthe apex, the straps being nailed on tdthe pile, as shown in Fig. 70 (6). Thecast-iron form shown in Fig. 70 (u)has a base cast aroUnd a recess on the top of the base re-FiG. 70. ceives the bottom of the pile and pre- vents a te
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . to turn the point, it ii necessaryto protect the point by some form ofshoe. Several forms in cast iron havebeen used, also a wrought-iroli shoe,having four straps radiating fromthe apex, the straps being nailed on tdthe pile, as shown in Fig. 70 (6). Thecast-iron form shown in Fig. 70 (u)has a base cast aroUnd a recess on the top of the base re-FiG. 70. ceives the bottom of the pile and pre- vents a tendency to split the bottom of the pile or to force theshoe off laterally. See § 167, par. 23. 165. Details of design. No theoretical calculations of thestrength of pile bents need be attempted on account of the ex-treme complication of the theoretical strains, the uncertainty asto the real strength of the timber ijsed, the variability of thatstrength with time, and the insignificance of the economy thatwould be possible even if exact sizes could be computed. Thecaps are generally 14 feet long (for single track) with a cross-section 12X12 or 12X14. Spht caps would consist. 202 BAILEOAD CONSTRUCTION. § 166. of two pieces 6X12. The sway-braces, never used for lessheights than 6, are made of 3X12 timber, and are spiked onwith I spikes 8 long. The floor system will be the same asthat described later for framed trestles. i66. Specifications for timber piles (Adopted 1909 byAmer. Rwy. Eng. Assoc). 1. This grade [railroad heart grade]includes white, burr, and post oak; longleaf pine, Douglasfir, tamarack, Eastern white and red cedar, chestnut. Westerncedar, redwood and cypress. 2. Piles shall be cut from soundtrees j shall be close-grained and solid, free from defects, such asinjurious ring shakes, large and unsound or loose knots, decayor other defects, which may materially impair their strength ordurability. In Eastern red or white cedar a small amount ofheart rot at the butt, whic
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
