Fundamentals of Railway Curve Superelevation
By Jeffrey G. Hook
Web Site Page 1 of 3 4-20-2010
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Effect of Centrifugal Force.
Railway locomotives and cars, hereafter referred to as rolling stock, when rounding a curve develop what is commonly referred to as centrifugal force that acts in the direction away from the center of the curve. If the rails of the curve are at the same elevation (zero cross level) the combination of the centrifugal force Fc and the weight of the rolling stock W will produce a resulting force Fr that does not coincide with the center line of track, thus producing a downward force on the outside rail of the curve that is greater than the downward force on the inside rail. The greater the velocity or the smaller the radius of the curve becomes the resulting force Fr will move farther away from the center line of track. Over turning velocity is approached when resulting force Fr approaches the outside rail. Drawing DRTRK13, Figure A, illustrates the basic concept described. Lateral displacement of the center of gravity permitted by the suspension system of the rolling stock is not illustrated.
Definition of Centrifugal Force.
1. The apparent force that is felt by an object moving in a curved path that acts outwardly away from the center of rotation. 2. An outward force on a body rotating about an axis, assumed equal and opposite to the Centripetal Force and postulated to account for the phenomena seen by an observer in the rotating body. See other reference sources for detailed explanations of Centrifugal Force and Centripetal Force.