US PATENT SUBCLASS 175 / 253
.~.~ With element holding retaining or severing means inactive

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

244  DF  WITH MEANS MOVABLE RELATIVE TO TOOL TO RECEIVE, RETAIN, OR SEVER UNDISTURBED CORE {3}
249  DF  .~ Core-retaining or severing means {5}
253.~.~ With element holding retaining or severing means inactive

DEFINITION

Classification: 175/253

(under subclass 249) Apparatus including a means to positively hold the core retaining or severing means out of core contact position until a certain condition or manipulation takes place, said holding means generally being deactivated upon the formation of a substantial length of core.

SEE OR SEARCH THIS CLASS, SUBCLASS:

251+, for retaining or severing means actuated upon relative movement between tool and shaft.

271, 275+ and 290, for expansible cutter elements with latch.