Study on Vibration and Noise Reduction of Tractor Cab (Part 3)

Elucidation of Generative Mechanism of Solid Borne Sound and Effect of Cab Suspension on Noise Reduction

Abstract

Generation of solid borne sound in a model cab especially in the range of low frequency was clarified theoretically from deflection vibrations of cab walls. The deflection of a cab wall was expressed by a combined function of the 4th degree of freedom of x and y, and a volume change by the deflections of six cab walls made the solid borne sound. A vibration mode of the cab should be however considered because each wall vibrated with a different phase lag. Calculated values of sound pressure level based on this theory coincided with the measured values satisfactorily. The cab suspension system reduced considerablly the sound pressure level in the cab. As same as the case of vibration, the lower the spring rate of suspension system was, the more the effect was.