GB581590A - Improvements in typewriters and like machines - Google Patents

Abstract

581,590. Typewriters. BRUMHILL, C. W., and PATEMAN, A. Sept. 14, 1944, No. 17556 [Class 100 (iv)] In a typewriter the type-bars 10 are of the end-thrust lever-operated type and are associated with weights 30 which complete the stroke by momentum, each bar 10 being supported and operated by a lever movable about a fixed pivot lower than the bar, and guided by a curved cam track to produce a substantially rectilinear final movement of the type block 45. Each bar 10 is connected at 35 to a lever 14 pivoted at 15. The keylever 17, pivoted at 18, is connected to a lever 20 pivoted at 21 by a link 19, the nose 22 of lever 20 engaging under a pin or roller 23 on a bell-crank lever 24 pivoted at 25. The lever 24 is connected to the lever 14 by a link 26 and to the lever 20 by a tension spring 27. A two-armed lever 29 carries the weight 30 on one arm, and the other arm is connected by a link 31 to a pair of toggle arms 33, 34, arm 33 being connected at 35 to the lever 14 and bar 10, and the arm 34 being mounted on a fixed pivot 36. A tension spring 38 connects an extension of the lever 29 to the lever 20. The type-bar 10 has an arcuate slot 42 or a cam track engaged by a pivoted follower 44 or a roller in a fixed guide 13. When the key-lever 17 is depressed, the lever 14 is rocked about pivot 15 to thrust the bar 10 towards the platen 12, but not in contact therewith. The arms start to straighten and swing the weight 30 forward, which by its momentum 'completes the forward movement of the bar 10. The track 42 and general design of the mechanism ensures that the final movement of the type block 45 is substantially rectilinear. The springs 27, 38 return the mechanism to inoperative position. Each type block 45 has two characters, and case shift is of the basket shift type by mounting the pivots 15 and 36, guide 13 and type-guide 55 (not shown) for vertical movement. Adjustment of individual type bars to obtain equal impression is by an eccentric device 49 which adjusts the length of toggle arm 34. Felt stops 39, 40 and an adjustable resilient stop 41 are provided for the arms 34 and key-levers 17. Locking, due to excessive movement of the toggle-arms 33, 34, is prevented by a tail 47 on lever 29, which engages a lug on link 31. In a modification greater leverage is given to the weight 30 by mounting it on a short link which connects the link 31 to an extension of the lever 14 to form a toggle, which straightens as the weight swings. The slot 42 in the type-bar 10 is open to facilitate disengagement from the guide 13.