Noise control is brought about by the use of acoustic materials in the engine compartment, the prevention of engine noise entering the cab and the reduction of sound levels within the cab by absorption. A significant reduction can be obtained by a slower engine fan speed and the fitting of sound absorbent material under the bonnet. A high proportion of noise is reflected up through the vehicle floor. Examples are given of acoustic floormat materials and their use. The engine can be mounted on rubber blocks which, when deformed in shear and compression, ensure that the forcing frequency is greater than the vertical natural frequency. The cab can be isolated from the chassis but in this case impact testing is needed to ensure adequate safety. The efficiency of in-cab sound absorption material is generally poor below 500 hz. Despite the increased numbers and types of acoustic materials available, it is necessary to maintain a flexible attitude towards product engineering because each vehicle has its own problems. Noise control should be able to incorporate technology from other industries. /TRRL/

  • Corporate Authors:

    Trade and Technical Press, Limited

    Crown House
    Morden, Surrey SM4 5EW,   England 
  • Authors:
    • Edwards, D J
  • Publication Date: 1977

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00174118
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Jun 28 1978 12:00AM