Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

405 OF ENGINEERING FORMULÆ. Stbength of Shafting to Resist Torsion. L = Length of lever in inches, or radius of wheel at which force is applied. F = Force applied in lbs. D = Diameter of shaft in inches, if round. S = Side of shaft in inches, if square. J/FL „ , x . 1» = v ——. for wrought iron. 1 / 00 x for wrought iron. for any other metal. For cast steel.. „ cast iron .. „ gun-metal „ brass .. „ copper .. „ tin .. .. „ lead .. .. for any other metal. Values of K and x. K = 3200 K = 1500 K = 460 K = 425 K = 380 K = 220 K = 170 X — 3800 X — 1800 X = 5-10 x = 500 X — 440 X = 260 X = 200 Supports fob Ordinary Shafting. D = Diameter of shaft in inches. S = Distance of supports apart in feet. S = 4'5 VD2, where power is taken off by rig- gers between the supports. S — 5 • i/1)2, where no power is taken off between the sujjpoits.