The Effect of the Damping of the Throws on the Torsional Vibration of the Crankshaft System of an Internal Combustion Engine

In the Journal for October, 1923, I gave the following formulæ for the frequencies in torsional vibration of the crankshaft system (see Fig. 1) of a direct drive engine having equal throws and equal journals, viz.:—1and2where3c=torsional stiffness (the CI/L) of an “equivalent journal”;p=polar moment of inertia of the “equivalent pulley” of a throw;r=ratio of the torsional stiffness of the shaft between the airscrew and the first “ equivalent pulley,” to that of an “ equivalent journal “;n=number of throws.