. 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 . Fig. 31. Fig. 32. intersects the new tangent. The solution is almost identicalwith that in § 63, a. b. Assume that it is desired to change the forward tangent(as above) but to retain the same radius. In Fig. 32 (i?2—-Ki) cos ^2 =02n; (R2-Ri) cos J2 =02V. x=02n—02n ={R2 — Ri)(cos ^2 — ^^^ ^2) cos i/ cos Jo X (24) The is moved backward along the sharper curve anangular distance of A2 — A2 = d^ — d/. In case the
. 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 . Fig. 31. Fig. 32. intersects the new tangent. The solution is almost identicalwith that in § 63, a. b. Assume that it is desired to change the forward tangent(as above) but to retain the same radius. In Fig. 32 (i?2—-Ki) cos ^2 =02n; (R2-Ri) cos J2 =02V. x=02n—02n ={R2 — Ri)(cos ^2 — ^^^ ^2) cos i/ cos Jo X (24) The is moved backward along the sharper curve anangular distance of A2 — A2 = d^ — d/. In case the tangent is moved inward rather than outward,the solution will apply by transposing Jj ^^^ ^Z Then weI shall have cos iz^cos ij+D D (25) 80 RAILROAD CONSTRUCTION. §69i The is then moved forward. c. Assume the same case as (b) except that the larger radiu^comes first and that the tangent adjacent to the smaller radiuqis moved. In Fig. 33 (R^—Ri) cos i, =Ojn;(E2-7?i)cosii=OiV. x=0in—0in= (7^2—-^i) (cos i/—cos ^i). cos i/ = cos JI X R2-K (26). The , is moved jonvardalong the easier curve an angulardistance of J/ —ii = J2~^2- Fia. 33. In case the tangent is moved inward, transpose as before andwe have cos J/=cos Ji X .R2—R1 (27) The is moved backward d. Assume that the radius of one curve is to be altered with-out changing either tangent. Assume conditions as in Fig. 34. For the diagrammatic solutionassume that i?2 is to be increasedby O2S. Then, since R2 mustpass through Oj and extend be-yond Oi a distance 0,*S, the,locus of the new center must lieon the arc drawn about 0, ascenter and with OiS as locus of O2 is a] so givenby a line Oa/) parallel to BVand at a distance of 7?/ (equalto S .. ) from it. Thenew center is therefore at O2. An arc with ra-dius R2 will therefore be tangentat B and tangent to the olrfcurve produced at new Draw Otti perpendicular to O2B. |
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
