William Suddards Franklin

“ The hastened precession on the one hand quickly alters the condition of balance of the car so as to limit the departure of the axles of spin from a line at right angles to the length of the car, and the steady and unhastened precession, on the other hand, insures the complete return of the axles of spin to a line at right angles to the length of the car. ”

“ The arrow S in the vector diagram represents the spin-momentum of the axle and drivers at a given instant, S' represents the spin-momentum at a later instant, ΔS represents the increment of spin-momentum, and T represents the torque which must act upon the axle because of its precession. To exert this torque the outer rail must push up with an excessive force against the outer driver, or, in other words, the outer driver must be forced downwards against the outer rail with more force than that which is due to the locomotive alone as it is rounding a curve. ”

“ The rotation of a wheel on an axis is called spin, and the axle upon which the wheel rotates is called the axle of spin. The spin of a wheel may be completely represented in both magnitude and Fig. 1. direction by an arrow drawn parallel to the axle of spin, pointing in the direction in which a right-handed screw would travel if turned with the spinning wheel, and having a length which represents the number of revolutions per second of the wheel. ”