| 摘要 |
<p>In a hollow stem auger for earth boring of the kind having spring loaded valve members at the bottom of the stem to permit the passage of test implements such as corers and vane test implements, the auger bit is constructed with a cage formation enclosing the valve member and supporting a bottom ring carrying cutting teeth. Interference of the valve members with a test implement is prevented by using an uncoupleable cylindrical sleeve surrounding the implement which sleeve can be lodged between the valve members to hold them open during use of the implement.</p> |
