GB749927A - Mechanical pencil - Google Patents

Abstract

749,927. Pencil holders. NORTHERN INDUSTRIAL PRODUCTS. Feb. 10, 1954 [March 4, 1953], No. 3879/54. Class 146(3) A propelling pencil comprises a pair of co-operating racks having opposed ratchet teeth, a lead-engaging plunger having a' head extending between the opposed teeth, and means for longitudinally displacing one rack with respect to the other rack, whereby to move the plunger from a position with its head in engagement with a tooth of one rack to a tooth of the other rack. As shown, a movable outer tube 28 Fig. 1, surrounds an inner tube 27, both tubes being slotted and formed with ratchet teeth 32 and 30 respectively. A plunger 36, preferably having a cover 37 to provide slight friction between the plunger and tube 27, engages the rear end of a lead, while its rear end 35 engages the ratchet teeth 32 and 30 so as to hold the lead in projected position. A cap 22, slidable over the barrel 20, is depressed to advance the lead beyond a tip 21 having a slit 26. The cap is connected to the tube 28 by means of an extension 41 of a clip 23. The extension 41 has a hole 42 through which the tube 28 passes, the tube 28 having lugs 44 engaging the lower face of the extension, while the rear end is deformed, such as by forming a lug 51 Fig. 16, to lock the tube 28 and extension together. A spring 55 has its rear end fitted into a notch 43 in the extension 41 and its forward end secured to the barrel, such that depression of the cap 22 causes rotation of the cap 22 and so rotation of the tube 28 with respect to the tube 27. Ears 60 formed on the rear end of the tube 27 prevent retraction of the tube 28 beyond the tube 27; the ears 60 enter cavities 50 on counterclockwise rotation of the cap 22, the plunger end 35 Fig. 1, being free to slide in this position of the ears to permit its retraction in the barrel 20. When the ears 60 are disengaged from the cavities 50, the tubes 27 and 28 are rotated by the spring 55 to engage the plunger end 35. Depression and release of the cap 22 causes the tube 28 to move axially forward and so project the plunger 36, such that the plunger end 35 engages and is locked by the teeth 30 of the tube 27, while the teeth 32 ride over the plunger end 35.