. The elements of railroad engineering . ravity of the car. The greater the speed of the train,or the sharper the curve, the greater the lateral force and over-turning moment. That the car may be in no danger of leavingthe rails or destroying the track, a flat curve must be taken atvery slow speed. If the speed is to be considerable, the necessarydeviating force must be obtained by canting the track. Canting Formulas. — The conditions that exist are shown inFig. 59. An induced centrifugal force may be said to act hori-zontally at the center of gravityof the car. Gravity measured bythe weight o
. The elements of railroad engineering . ravity of the car. The greater the speed of the train,or the sharper the curve, the greater the lateral force and over-turning moment. That the car may be in no danger of leavingthe rails or destroying the track, a flat curve must be taken atvery slow speed. If the speed is to be considerable, the necessarydeviating force must be obtained by canting the track. Canting Formulas. — The conditions that exist are shown inFig. 59. An induced centrifugal force may be said to act hori-zontally at the center of gravityof the car. Gravity measured bythe weight of the car may besaid to act vertically through thesame point. It is required thatthe resultant of these two forcesshall be normal to the trans-verse surface of the track. Underthis condition there can be no lat-eral pressure due to the centrifu-gal force. The figure shows thatthis condition is secured whenthe tangent of the angle of inclination equals centrifugal forcedivided by weight. This is the mechanical value of the tangent. 108. CANTING FORMULAS IO9 The cross distance between inside of rail heads is the gauge ofthe track, but the distance between bearing points of wheels is alittle less than the distance between rail centers, which, though avariable quantity, may be taken as feet for standard distance between bearing pouits of the trackmans gauge ispractically the distance between rail centers, therefore, this dis-tance will be used in deriving formulas. The difference in levelof the outer and inner rails is called the elevation of the outerrail. The figure shows that the tangent of the angle of elevationequals the elevation divided by the horizontal projection of thedistance between bearing points. This may be called the linearvalue of the tangent. Equating the mechanical and linear valuesfor the tangent of the elevation angle, and solving for the eleva-tion, gives -\ I -^ -^ in which R is the radius of the curve in feet, and 5 is the speedin
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
