There are two different load sources acting on the
crankshaft. Inertia of rotating components (e.g.
connecting rod) applies forces to the crankshaft and this
force increases with the increase of engine speed. This
force is directly related to the rotating speed and
acceleration of rotating components. Variation of angular
acceleration and angular velocity of the connecting rod
for the engine speed of 3600 rpm is shown in Figure 3.
The second load source is the force applied to the
crankshaft due to gas combustion in the cylinder. The
slider-crank mechanism transports the pressure applied
to the upper part of the slider to the joint between
crankshaft and connecting rod. This transmitted load
depends on the dimensions of the mechanism.