A dolly "sandwich" packing incorporating polystryrene chips, polyurethane, and resin-bonded fabric pads, topped with a rope coil within the driving helmet, together with detailed attention to numerous potential sources of noise have enabled noise levels on the rig to be reduced to 70-80 dBA at 15 m. The complete unit (MK. 11 hammer) weights 7.75 tonnes, is lifted by double rope sling and positioned on the pile for driving. The composition of the "sandwich" dampens noise without significant loss of energy transmission. By isolating the hammer from its guide tube by means of wooden spacers, there is no metal-to-metal contact between weight and frame, and neither is there any between weight an pile (by virtue of the dolly sandwich). To limit the helmets travel and return to its original position after an impact, four shock absorbers are fitted linking anvil block and the lower collar frame assembly. A close fit between pile section and leg guides is an essential feature of the noise reducing provisions. Other noise reducing measures are also briefly outlined.

  • Availability:
  • Corporate Authors:

    Foundation Publications Limited

    7 Ongar Road
    Brentwood CM15 9AU, Essex,   England 
  • Authors:
    • Patey, D R
  • Publication Date: 1976-1

Media Info

  • Features: Figures; Photos;
  • Pagination: p. 20-21
  • Serial:
    • Volume: 9
    • Issue Number: 1
    • ISSN: 0017-4653

Subject/Index Terms

Filing Info

  • Accession Number: 00131575
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 16 1976 12:00AM