Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

219 OF ENGINEERING FORMULAE. Resistance of -Tkains. W = Weight of vehicle without wheels and axles w = Weight of wheels and axles. D = Diameter of wheels on tread. <1 = Diameter of journal. F = Coefficient of axle friction. - stiy -018 with oil, or '035 with grease. f = Coefficient of rolling friction. ’ = say '001. R = Resistance of vehicle. / d \ R=/(\V + w)+^WF5J- Resistance of Curves. (‘ Trans. Inst. Civ. Eng.,’ vol. xxxi., Morrisou.) W — Weight of vehicle. R = Radius of curve. D = Distance of rails apart from tread to tread. L = Length of rigid wheel base. F = Coefficient of friction of wheels on rail. W F (D + L) Resistance due to curve — — • The coefficient F will vary according to the weather from '1 to "27.