ous parts such as main bearing journals, rod journal, crank am, buring, counter balane ed weight and flywheel end. The crankshaft revolves in bearings located in the engine crankcase but the number of bearings used usually depends on the number of cylinders in the engine. and the design of the engine Mechanically, a crankshaft without spec ial balanced weight would have severe vibration when revolving In order to reduce or eliminate surh vibration, it must be provided with counter balane ed weights that (x- tend radically from the crankshaft centerline in the opposite direction of the crank anmr. Im that way, the fores acting on the crankshaft are balanced and vibration is reduced The md joumals are bored hollow in order to reduce the erankshaft inertia. Drilled diagonally through the: crank arms ure oil holes to supply 04 Fig 1-4 The crankshaft raik haf frmi erd 2-frond main joumal 3 oil peuwsupe helr 4-erumk pin 5-emank wHl il passage plug 8-isil pasage g-eruu k lrft eMlar 10--flywheel 11-Aywheel gear ring 12--flywhed lock plate 13--clutch staft tearin 14--rm ar main brug half shell 15--oil EVe 16--cTankshaft thrust 17-renunl main beiring half shell 18--bearing hall shell 1y--trcnt main bearing half whell The flywheel is a relatively heavy metal wheel, which is firmly attached to the crankshaft. Its func tion is to help the engine to nn smoothly by absorbing some of the energy during the power stroke and re leasing it during the: other strokes Because uf its rotation the flywheel acquires kinetic energy when the flywheel speeds up, it stores additional kinetic energy, and when it slows down it gives back that energy. The anlount of energy that a flywheel will store for a given change in speed depends on its inertia, which, in lum, depends on its mags and its elective diameter. The heavier the flywheel or the larger its diameter the smaller will be the speed changes. For an engine of a given horsepower, single cylinder engines require large flywheels to keep the momentary sptd variations. While multi-cylinder requ flywheels can do it. In practice the automobile engine is usually multi-cylinder engine. Flywheels however, because of its inertia, an cessively heavy flywheel will cause the engine to accelerate and decelerate slowly. For this reason, heav duty or truck engines have large and he avy flywheels, while racing engines or high performance engines ave light flywheel