3850000

Information

• Patent Grant
• 3850000

• References
• Source

• Patent Number

  3,850,000

• Date Filed

  Not available

• Date Issued

  Tuesday, November 26, 1974
  50 years ago

• CPC

  • E21D9/0607 - the shield being provided with devices for lining the tunnel
  • E21D11/08 - with preformed concrete slabs
  • E21D19/04 - for use in drifting galleries

• US Classifications

  • 405 - Hydraulic and earth engineering