3397543

Information

• Patent Grant
• 3397543

• References
• Source

• Patent Number

  3,397,543

• Date Filed

  Not available

• Date Issued

  Tuesday, August 20, 1968
  56 years ago

• CPC

  • E21D23/12 - Control
  • E21D23/00 - Mine roof supports for step- by- step movement
  • E21D23/0047 - without essential shifting devices
  • E21D23/0052 - with advancing shifting devices connected therewith
  • E21D23/0418 - Positioning devices and stabilizing means for the props
  • E21D23/06 - Special mine caps or special tops of pit-props for permitting step-by-step movement
  • E21D23/142 - Measuring the advance of support units with respect to external points of reference
  • E21D23/144 - Measuring the advance of support units with respect to internal points of reference
  • E21D23/16 - Hydraulic or pneumatic features

• US Classifications

  • 405 - Hydraulic and earth engineering