Patent GB-472944-A (GB)
Title: Improvements in type-actions for typewriting machines
IPC: B41J7/02
Filed: 1936-12-07
Abstract: 472,944. Typewriters. FAIRWEATHER, W. C. (Underwood Elliott Fisher Co.) Dec. 7, 1936, No. 33467. [Class 100 (iv)] Type-lever action,s ; keys.-In a type-action mechanism for typewriters, including a set of type-levers, a set of key-levers extending from the key board to a common fulcrum axis, a set of graded upstanding sub-levers connected to the type-levers, and a set of accelerating links connecting the key levers and the sub-levers at graded elevations, the connecting points of the links to the sub-levers and keylevers respectively are at substantially equal distances from the common fulcrum axis, and a restoring spring is provided for each key-lever and an auxiliary spring for each sublever. The key-levers 15 are pivoted on an axis 17 in a comb 18 and guided by a comb 21, and operate sub-levers 34 through links 45. The sub-levers 34 are of graded height and bent inwardly at 49 to conform to the arrangement of the type-levers 23 in their arcuate bearing block 27, so that the links 44 are of uniform length. To equalize the moments between the sub-levers 34 from side to side of the machine the pivot-points 46 of the links 45 are arranged at graded heights. The pivot points 47 are graded, by means of extensions 51 of the key-levers, and the lengths of the links 45 are varied for the different ranks of keys on the keyboard so that (a) the different links 45 all make the same angle in rest position with the lines joining the pivots 17, 47, and (b) with the lines joining the pivots 46, 35 in impression position. The points 46 are arranged on a line lying on a cylindrical surface with its axis at the axis 17, so that each key lever produces the same accelerated movement of the type-lever and is identical in impression and touch. Separate return springs 58 for each key-lever are hooked into serrations 59 in the levers and secured to a shaft 60 carried by arms 62 on a shaft 63. The shaft 63 can be rockect to adjust all the springs by a link 68, provided with sharpedged holes 72 to engage a screw 69 and serrations 67 on an arm 66 secured to the shaft 63. The screw 69 can be adjusted by a nut 71, is flattened at the other end to pass through a slot 75 in a guide plate 76 and hooks on to an anchor plate 79, to which are secured separate return springs 77 for the sub-levers 34. There are therefore universal adjustments for the springs, coarse at 67, 69 and fine at 71, and individual adjustments at 59. The pivots 46, 47 are not provided with large heads, but are rather longer than usual, and the links 45 are retained on the pivots 46 by the springs 77 which are hooked over annular grooves on the pivots. The type segment, to which is connected the support 89 and guide 31 for the type-levers, is raised or lowered for case-shift by bell-crank levers 85. The links 44 move idly about the pivot points 42, and the link 98 connecting the universal bar mechanism 95 with, say, the letter - spacing mechanism 97, moves idly about the pivot 99. To afford adequate clearance between the type-levers 23 and sublevers 34 in the lower case position the typelever segment may be tilted.