Raise boring head with retractable gage cutters
US4194578A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 30, 1978 |
| Grant date | Mar 25, 1980 |
| Priority date | — |
| Expiry date | May 30, 1998 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B44/005
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A raise boring system is provided that allows the raise boring head to be easily and efficiently lowered back through the completed raise hole. The raise head includes a multiplicity of rolling cutters positioned in saddles that are firmly affixed to the body of the raise head. These fixed saddles and rolling cutters comprise the primary cutting stage of the raise head. A multiplicity of retractable gage cutters are located radially outside of the primary cutting stage. The retractable gage cutters comprise rolling cutters positioned in moveable saddles. The moveable saddles and rolling cutters can be selectively withdrawn inside the primary cutting stage. A hydraulic-pneumatic system is provided for withdrawing the retractable gage cutters.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.