US PATENT SUBCLASS 175 / 215
.~ With tool shaft having plural passages for drilling fluid

Current as of: June, 1999
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175 /   HD   BORING OR PENETRATING THE EARTH

207  DF  WITH ABOVE-GROUND MEANS FOR HANDLING DRILLING FLUID OR CUTTING {9}
215.~ With tool shaft having plural passages for drilling fluid

DEFINITION

Classification: 175/215

(under subclass 207) Apparatus including a tool shaft which is provided with more than one fluid conduit through a substantial portion of its length.