3490244

Information

• Patent Grant
• 3490244

• References
• Source

• Patent Number

  3,490,244

• Date Filed

  Not available

• Date Issued

  Tuesday, January 20, 1970
  54 years ago

• CPC

  • E21D23/0069 - without essential advancing shifting devices
  • E21D15/44 - Hydraulic, pneumatic, or hydraulic-pneumatic props
  • E21D15/586 - the props being pre-loaded
  • E21D23/06 - Special mine caps or special tops of pit-props for permitting step-by-step movement

• US Classifications

  • 405 - Hydraulic and earth engineering