<div class="htmlview paragraph">The unknown characteristics of the bending vibration coupled with torsional vibration (hereafter called“coupled torsional, bending vibration”) are investigated from the experimental and analytical viewpoints. The torsional and bending vibration stresses of the crankshafts of a 6 cylinder, in - line engine and an 8 cylinder, V - type engine are measured first in order to investigate experimentally the characteristics of the coupled torsional - bending vibrations.</div> <div class="htmlview paragraph">Next, the displacements, moments and stresses of the torsional and bending vibrations of the above - mentioned crankshaft are calculated by 3 dimensional, forced vibration analysis of the crankshafting of the V 8 engine using the transfer matrix method, which has been developed by the authors.</div> <div class="htmlview paragraph">Finally, the experimental results are compared with the corresponding calculated results and the characteristics of the bending vibration stresses coupled with the large torsional vibrations are made clear.</div>