3550389

Information

• Patent Grant
• 3550389

• References
• Source

• Patent Number

  3,550,389

• Date Filed

  Not available

• Date Issued

  Tuesday, December 29, 1970
  54 years ago

• CPC

  • E21D9/0607 - the shield being provided with devices for lining the tunnel

• US Classifications

  • 405 - Hydraulic and earth engineering