VIBRATION formerly was classed as such without much thought as to the determination of its sources, Mr. Taub states, and then came isolation of the various causes. The first two vibrations to be segregated and vigorously attacked were the secondary inertias of reciprocating units and torsional vibration. The development of the six-cylinder engine was among the earliest attempts to eliminate secondaries, and it was also the earliest producer of torsional vibration.
Dynamics, combustion roughness, torsional roughness and structural weakness, are a few of the contributing causes of engine roughness. Consideration must be given to all these factors if an engine is to be considered inherently smooth, and each is analyzed.
Engine mountings should have low resistance to rotation about the longitudinal principal axis and to rotation about the vertical axis through the center of gravity, together with minimum shift of affective principal axis and vertical axis. The kind of material used in engine mountings should be determined after considering the overall characteristics of the mounting and the durability of those characteristics.