Memoir of Frank Russell Firth

Memoir of Frank Russell Firth

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 edition. Excerpt: ...found in 106, 107; the deflection for a 20-foot chord may be calculated at once sin!IdTM) =--(212) 181. Simple as these formulae are, they maybe rendered 11 more convenient by introducing the number of the og, n. By eq. (206) we have cot iF = 2ri., which substiIed in eq. (208) gives BF=2gn (213) 'wing the chord AF to the outer rail, af = 2r (217) Vl + 4a- Assuming that, for small angles, the tangent offsets vary as the squares of their distances from the tangent point, which will lead to no material error in this case; AB-.BK 11 BF' 1 AB, whence AB = BF+' lJL. ) AB I (218) or AB =:4nrg. BK = V2r. BE ) It is not necessary to determine the degree of curve in ordes to locate the turnout, for having fixed the position of BF, tbl position of af is found by laying off Ba, and Ff each equal tl ig. 'Whatever be the length of the chord af, found by eql (217) or (210), its middle ordinate is always ig, and the ordinl nates at the quarter points, f. ig = T1/. Thus for the statu dard gauge of 4.708 the middle ordinate is 1.177, and the sidJ ordinates 0.883. By the preceding formulse Table XI. has been calculates which gives the required parts of a turnout for various froj when the gauge is 4 feet 8 inches and the throw 5 inchei also for a gauge of 3 feet and throw of 4 inches. For an other throw, only AB must be calculated. For a differeu gauge the engineer will do well to construct a similar tabli adapted to the frogs used on the road. In the table the frog angle is given to seconds, in order that the results may agree, whether found by equations in 180 or 181; but in practice the nearest minute is sufficiently exact. The frogs most used for single turnouts are those from No. 7 to No. 9, inclusive. 182. In case of a more

Product details

  • Paperback | 74 pages
  • 189 x 246 x 4mm | 150g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236503546
  • 9781236503541