3621661

Information

• Patent Grant
• 3621661

• References
• Source

• Patent Number

  3,621,661

• Date Filed

  Not available

• Date Issued

  Tuesday, November 23, 1971
  53 years ago

• CPC

  • E21D23/0095 - Temporary supports at the driving front
  • E21D23/0091 - at the junction with the working face

• US Classifications

  • 405 - Hydraulic and earth engineering
  • 248 - Supports