Drumming Noise Control of a 3-wheeled Pick Up Van by Redesign of Engine-Mounts and Panel Isolation

Attemppts have been made to minimize structure-borne noise of body panels (drumming noise) of a 3-wheeled Pick-Up powered by a 4-Stroke Single Cylinder 175 cc gasoline engine. Vibration measurements at different points on the chassis over a wide range of vehicle speeds could identfy resonance frequencies of the structure. Frequency analysis of Sound Pressure Levels measured near Top Roof of the Pick-Up body showed dominance of the structural resonance. In order to reduce the vibrations at the source, crankshaft balance factor of the engine was optimized. The Body Panels were stiffened and also isolated by rubber pads from the chassis. The engine was respectively disconnected from the chassis at the front and the rear to know their individual contribution towards the drumming noise of the Body Panels. A change-over from the original system of hard rubber pivots to one providing soft mounts in translation drastically reduced the chassis vibrations and thus minimized the structure-borne noise of the body panels substantially.