Automatic lead advancing mechanism for a mechanical pencil
AssigneeJ. S. Staedtler GmbH & Co.
InventorEngelbert Brunner
Life of this patent
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Abstract
An automatic lead advancing mechanism for a mechanical pencil has at its writing point a lead guide tube which is movable axially against a clamping member to cause radially movable components of the clamping member to clamp the lead therein during the writing position of the pencil. The lead guide tube moves axially inwardly against a force exerted by a compression spring interposed between the clamping member and a thrust member, a portion of which is engaged by the lead guide tube and another portion of which has a beveled surface engaging a correspondingly beveled surface on the clamping member. The co-acting beveled surfaces exert both axial and radial forces to the clamping member.
Claims18
An automatic lead advancing device for a mechanical pencil comprising an axially movable lead guide tube, an axially movable clamping member having a central passageway there through for lead and having radially movable components to clamp the lead therein, a plurality of arms projecting axially from a face of said clamping member directed to a writing point of the pencil, inwardly directed stop claws on the ends of said axially projecting arms, a compression spring within said axial arms and having one end acting upon said face of said clamping member and another end acting against means operatively connected to said lead guide tube, and means between said compression spring and said stop claws for transmitting both radial and axial forces through said axially projecting arms and said stop claws to said clamping member whereby the clamping member is in an unclamping position with respect to a lead therein when the pencil is in a non-writing position.
Dependencies are inferred from the claim text.