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| All Patents in class 175/418 | |||||
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| Number | Date | Patentee | Title | Type | |
| 51,980 | Jan. 09, 1866 | W.W. St. John | Drill-head | ||
| 1,277,970 | Sep. 03, 1918 | N.J. McKenzie | Drilling Bit | ||
| 2,969,846 | Jan. 31, 1961 | R.L. Sandvig | Percussive drill bit for use in reverse flow flushing is soft rock drilling | ||