3399927

Information

• Patent Grant
• 3399927

• References
• Source

• Patent Number

  3,399,927

• Date Filed

  Not available

• Date Issued

  Tuesday, September 3, 1968
  56 years ago

• CPC

  • E21D23/04 - Structural features of the supporting construction
  • E21D17/02 - Cantilever extension or similar protecting devices
  • E21D17/0206 - Hydraulically operated extension devices
  • E21D19/02 - for use in longwall working
  • E21D23/0017 - Pile type supports
  • E21D23/0047 - without essential shifting devices
  • E21D23/0052 - with advancing shifting devices connected therewith
  • E21D23/03 - having protective means
  • E21D23/0481 - Supports specially adapted for use in combination with the placing of filling-up materials
  • E21D23/06 - Special mine caps or special tops of pit-props for permitting step-by-step movement
  • E21D23/063 - Retractable cantilever extensions therefor

• US Classifications

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