Patent GB-222450-A (GB)
Title: Improvements in mechanical pencils
IPC: B43K21/00
Filed: 1924-07-30
Abstract: 222,450. Wahl Co., (Assignees of Wahl, J. C.). Sept. 26, 1923, [Convention date]. Pencil holders.-In a pencil holder of the screw-propelling type, means are provided to disengage the propelling-mechanism when a lead is exhausted, so that the follower can be returned by a direct longitudinal pull in order to insert a new lead. The pencil casing comprises an outer barrel 1, Fig. 1, with an inner shell 2 which is provided with an internally screwthreaded portion 3. The upper ends of the barrel and shell are provided with interengaging beads 5, 4, and the lower end of the shell tapers to a conical shoulder 2b having a tubular extension 2<a> terminating in a feed tube 6 upon which is screwed a ribbed steel tip 7 to prevent relative rotation of the shell and barrel. The follower comprises a crosshead 17 carrying a follower wire 21 movable longitudinally within a tubular actuator 8, Fig. 5. One side of the crosshead is provided with screw-threads 20 and projects through a longitudinal slot 10 in the tube 8 to engage the screw-threads 3 of the shell. The other side 30 of the crosshead is smooth and is guided within a channel member 13, Figs. 6 and 7, which is slidably disposed within the tube 8. The lower end 15 of the channel member is bevelled and projects through a rectangular aperture 11 in a shoulder 8<a> at the lower end of the tube 8, the aperture being disposed in the plane of the slot 10. The projection of the end of the channel member is limited by retaining shoulders 14 cut in the side flanges to engage the sides of the aperture 11, and the travel of the member in the opposite direction is limited by a disc 27 secured within the tube 8. The lower portion of the channel member 13 is provided with a reetangular slot 16 into which the smooth side 30 of the crosshead slips when it is projected to its extreme forward position, thereupon disengaging the threads 20 on the other side from the internal threads of the shell 2. The tubular actuator, together with the internal channel member and crosshead, can then be withdrawn from the casing. The slot 16 receives the end 30 of the crosshead only when the crosshead is at the extreme forward position. This is ensured by pressing inwardly a portion 13<a> of the channel member, so that if the actuator 8 is pulled when the crosshead is in an intermediate position the friction between the narrowed portion of the channel and the stationary crosshead causes the bevelled end 15 to project through the aperture 11 in the shoulder 8<a> of the actuator, and the slot 16 is then in such a position that the threads 20 of the crosshead cannot be released. In the normal position, as shown in Fig. 1, the end 15 of the channel member abuts against the shoulder 2<b> of the shell 2 and ensures the correct position of the slot 16 to release the mechanism when the lead is exhausted. The upper end of the tube 8 provides a receptacle for spare leads and has a triangular slot 22 which is closed by a loose sleeve 23 provided with a corresponding slot 24. The slots can be placed in alignment by rotating the sleeve to a position determined by a detent on the sleeve moving within an inclined guide slot in the tube 8. A tubular eraser holder 12 is screwed upon the end of the tube 8 and is covered by a cap 28 which also forms the operating head of the pencil.