United States Patent 2427330
Inventors:
Lloyd, Spencer
Publication Date:
09/09/1947
Other Classes:
166/215, 285/2, 285/123.11, 285/307, 285/396, 285/922
International Classes:
E21B43/10; E21B43/02
US Patent References:
| 1242539 | N/A | | | |
| 0891065 | N/A | | | |
| 0387675 | N/A | | | |