US PATENT SUBCLASS 405 / 145
.~.~.~ Discrete independently advanceable earth supporting segments

Current as of: June, 1999
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405 /   HD   HYDRAULIC AND EARTH ENGINEERING

132  DF  UNDERGROUND PASSAGEWAY, E.G., TUNNEL {6}
138  DF  .~ Boring {4}
141  DF  .~.~ Shield {6}
145.~.~.~ Discrete independently advanceable earth supporting segments

DEFINITION

Classification: 405/145

Discrete independently advanceable earth support segments:

(under subclass 141) Method or apparatus wherein each of a plurality of separate soil-sustaining sections is individually moved forward.