3657897

Information

• Patent Grant
• 3657897

• References
• Source

• Patent Number

  3,657,897

• Date Filed

  Not available

• Date Issued

  Tuesday, April 25, 1972
  52 years ago

• CPC

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

• US Classifications

  • 405 - Hydraulic and earth engineering