2772870

Information

• Patent Grant
• 2772870

• References
• Source

• Patent Number

  2,772,870

• Date Filed

  Not available

• Date Issued

  Tuesday, December 4, 1956
  68 years ago

• CPC

  • E21C27/22 - by rotary drills with breaking-down means, e.g. wedge-shaped drills
  • Y10T408/85985 - Plural tools moved by diametrically opposed screws

• US Classifications

  • 299 - Mining or in situ disintegration of hard material
  • 175 - Boring or penetrating the earth
  • 408 - Cutting by use of rotating axially moving tool