Figure 3.1 Slider-crank Mechanism of IC Engine

A typical crank-slider mechanism as used in an IC Engine is shown in Fig. 3.1. It essentially consists of four different parts viz., frame(i.e., cylinder) ,crank ,connecting rod and reciprocating piston. The frame is supposedly stationary; crank is undergoing purely rotary motion while the piston undergoes to-and-fro rectilinear motion. The connecting rod undergoes complex motion – its one end is connected to the crank (undergoing pure rotation) and the other end is connected to the piston (undergoing pure translation).

We know that the inertia forces are given by mass times acceleration and we shall now estimate the inertia forces (shaking forces and moments) due to the moving parts on the frame (cylinder block).