1920450

Information

• Patent Grant
• 1920450

• References
• Source

• Patent Number

  1,920,450

• Date Filed

  Not available

• Date Issued

  Tuesday, August 1, 1933
  91 years ago

• CPC

  • E21C25/66 - Machines for making slits with additional arrangements for drilling

• US Classifications

  • 299 - Mining or in situ disintegration of hard material
  • 173 - Tool driving or impacting