US PATENT SUBCLASS 405 / 141
.~.~ Shield

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.~.~ Shield {6}
142  DF  .~.~.~> With transverse force application feature
143  DF  .~.~.~> Direction control
144  DF  .~.~.~> Door or bulkhead
145  DF  .~.~.~> Discrete independently advanceable earth supporting segments
146  DF  .~.~.~> Lining installation
147  DF  .~.~.~> Seal

DEFINITION

Classification: 405/141

Shield:

(under subclass 138) Method or apparatus wherein a protective member movable with the progress of the work temporarily supports the walls of the corridor to prevent the surrounding material from falling into the corridor during excavation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

283, for shield-type apparatus employed in trench forming.