3921409

Information

• Patent Grant
• 3921409

• References
• Source

• Patent Number

  3,921,409

• Date Filed

  Not available

• Date Issued

  Tuesday, November 25, 1975
  49 years ago

• CPC

  • E21D23/0078 - with individual shifting devices
  • E21D23/03 - having protective means

• US Classifications

  • 405 - Hydraulic and earth engineering
  • 248 - Supports