The main engine shaft driven round by the piston is called Crankshaft. Crankshaft converts reciprocating motion of the piston into rotary motion. Crankshaft rotates at high speeds and bears the stresses due to power impulse during power stroke. Counterweight balance the forces caused due to out of balance of the crank offset from shaft axis. Crankshaft of an engine has to be designed for strength and stuffiness against bending and torsion stresses due to gas loads and also to take care of stress due to vibration and provide sufficient bearing area to suit the bearing pressure. Crankshafts have drilled oil passages through which oil flows from the main to the connecting rod bearings. The power impulses tend to setup twisting vibration in the crankshaft. When a piston makes down on its power stroke, it thrusts, through the connecting rod, against a crankpin with a force that may exceed 2 tones and this motion is called torsion vibration. Experimental was conducted on Heavy Commercial Vehicle engine that excessive blow by as well as excessive engine oil consumption and as a result engine sudden stopped after the heavy noise.

PORAG KALITA et al.,International Journal of Computer Engineering In Research Trends Volume 3, Issue 4, April-2016, pp. 152-156