Question - Why Total Reliance Is Placed On Frictional Grip In Conventional Built Up Crankshaft On Main Engine ?
Answer -
Frictional grip is the usual method of crankshaft construction for built-up crankshaft. This grip is subjected to the full torque of the engine output, and hence subjected to high torsional stresses. If there are any defects at this joint, then the resulting stress concentration would trigger a crack and possible shaft failure.
To minimise the possibility of such defects, then only a frictional grip is permitted under Classification Rules for crankshaft construction, hence pins, keys, etc are not allowed.