US PATENT SUBCLASS 172 / 721
.~ Non-rectangular, symmetrical type

Current as of: June, 1999
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172 /   HD   EARTH WORKING

681  DF  TOOL, STANDARD OR CONNECTION {32}
721.~ Non-rectangular, symmetrical type {8}
722  DF  .~.~> Earth breaking part and separately attached wings {2}
725  DF  .~.~> With separable vertical cutter on centerline
726  DF  .~.~> Having separable parts jointed at centerline
727  DF  .~.~> With attached runner or depth gauge {2}
730  DF  .~.~> Winged
731  DF  .~.~> Lateral extent decreases upwardly
732  DF  .~.~> Triangular blade
733  DF  .~.~> Constant height and V-shape

DEFINITION

Classification: 172/721

(under subclass 681) Apparatus comprising an earth working element symmetrically arranged with respect to the line of draft, i.e., parts on opposite sides of the line of draft are mirror images of each other and are arranged at the same position longitudinally of the line of draft.

(1) Note. Patents are classified here by disclosure when a claim includes any detail of the shape of the earth working element.

(2) Note. An earth working element all parts of which lie in a single plane and which is of square or rectangular shape when viewed both in plan and front elevation is not included under this definition.

(3) Note. An earth working element which is square or rectangular when viewed in both plan and front elevation and whose intersection with any vertical plane transverse to the line of draft results in one or more straight lines is also excluded from this definition. Thus, for example, an ordinary scraper blade which is straight, transversely of the line of draft and curved in end elevation, is excluded.

(4) Note. An earth working element which is symmetrical due merely to an arrangement of earth working fingers, tines, blades, or the like is not classified under this definition. See subclass 766 for such earth working elements.

SEE OR SEARCH CLASS 37, Excavating,

198+, for a V-shaped plow for railway snow excavation, subclasses 266+ for a V-shaped plow for roadway snow excavation and subclasses 366+ for symmetrically shaped plows for ditching.

111, Planting,

83, for lister plows; subclass 111 for a runner-type opener claimed in combination with a plant setting machine; subclasses 124 and 125 for shoe- and runner-type openers respectively, used in combination with a liquid or gas soil treatment; and subclasses 152 and 153 for shoe- and runner-type openers respectively, claimed in combination with seed depositors.