3561223

Information

• Patent Grant
• 3561223

• References
• Source

• Patent Number

  3,561,223

• Date Filed

  Not available

• Date Issued

  Tuesday, February 9, 1971
  54 years ago

• CPC

  • E21D9/13 - using hydraulic or pneumatic conveying means
  • E21D9/0873 - the shield being provided with devices for lining the tunnel

• US Classifications

  • 405 - Hydraulic and earth engineering
  • 299 - Mining or in situ disintegration of hard material