Abstract: A balancing mechanism in a conventional, multicylinder engine consisting of a mass linked to the static portion of the engine and dynamically linked to the engine crankshaft in such a manner as to establish an arcuate oscillation of the mass on rotation of the crankshaft for producing a primary harmonic shaking force and a secondary harmonic shaking force in the direction of greatest travel of the mass, and a secondary harmonic shaking force in a direction at right angles to said first-mentioned direction with these harmonic shaking forces adapted to balance other shaking forces developed within the engine. A crank-and-rocker mechanism is utilized in the balancing mechanism and the angular disposition thereof may be related to the position of maximum value of the engine harmonic shaking forces as distinguished from the dead center position of the engine.