GB824000A - Improvements in or relating to propelling pencils - Google Patents

Abstract

824,000. Propelling pencils. BARRY, T. F. H. March 13, 1956 [April 18, 1955] No. 11082/55. Class 146(3) In a propelling pencil of the kind in which the propulsion of the lead is effected by relative rotation between a helix and a lead propelling part which engages in the helical slot of said helix, said helix is held with one end against an abutment, and is restrained against rotation relative to said abutment by a projection on the one engaging in a recess in the other so that said relative rotation between said helix and said lead propelling part is adapted to be effected through relative rotation between said abutment and said lead propelling part, said projection being adapted yieldably to ride out of said recess in the event of overwinding so, as ,to ensure against damage due to overwinding. The leadholder 7 is carried on a stick 6 having at its rear end a projection 10 which extends through an axial slot 9 in a hub 1 secured to an actuating knob 2 and into the helical slot of a helix 4 comprising a wound flat strip which abuts at its front end a collar 5 on the hub and at its rear end has a projection 14 extending into a notch 13 in a bush 3 screwed into the barrel (not shown) of the pencil. On rotation of the knob the lead 8 is advanced or retracted, its advancing movement being limited by the projection 10 engaging the collar 5 and its rearward movement by a rod 15 engaging the knob 2. On continuing to rotate the knob 2 after the lead is fully retracted, the projection 14 is forced out of the notch 13 to compress the helix 4, which then rotates with the lead-holder 6. On continuing to rotate the knob 2 after the lead-holder is fully advanced, the projection 14 prevents rotation of the helix 4, the projection 10 rotating outside the forward end of the helix and compressing the latter. When the forward movement of the lead-holder is stopped by the converging inner walls of the point portion of the pencil, the stick 6 continues to move forward against a spring 16 to eject the lead. According to the Provisional Specification, the notch 13 is V-shaped, thus allowing continued rotation of the knob 2 in either direction to force out the projection 14 and rotate the helix 4.