3861477

Information

• Patent Grant
• 3861477

• References
• Source

• Patent Number

  3,861,477

• Date Filed

  Not available

• Date Issued

  Tuesday, January 21, 1975
  50 years ago

• CPC

  • E21B17/10 - Wear protectors Centralising devices
  • E21B10/083 - with longitudinal axis
  • E21B10/24 - characterised by lubricating details
  • E21B10/50 - the bit being of roller type

• US Classifications

  • 175 - Boring or penetrating the earth