Patent GB-327883-A (GB)
Title: Improved action for typewriting machines
IPC: B41J7/02
Filed: 1929-05-06
Abstract: 327,883. Fairweather, W. C., (Underwood Elliott Fisher Co.). May 6, 1929. Type-lever actions.-A noiseless action particularly for machines employing an ink ribbon comprises a type-bar pivotally supported by a front lever and a rear lever which is connected by a link to a sub-lever actuated with accelerated motion by an arm on a key-lever; the type-bar is normally folded down and depression of the key-lever unfolds and floats rearwardly the typebar, the supporting-levers being so arranged that during the final part of the rearward movement the type-bar moves more slowly than the supporting-levers. Separate hamgers may be provided for the series of actions. In the action shown in Fig. 1 a type-bar 24 provided with types 25 is pivoted at 36, 37 to levers 22, 23, the lever 22 being connected by a link 20 to a sub-lever 19 having a curved tread 18 engaging an arm 13 on a key-lever 12. The planes of movement of the set of pairs of levers 22, 23 are radial to the printing point 43, the levers being pivoted on curved rods 38, 65 mounted in slotted segments 39, 56. The sub-levers are arranged radially and are pivoted on a curved rod 21 mounted in a slotted segment 27. The sublevers increase in length from the centre to the sides of the set, and the widths of the set at the top and bottom are approximately equal to the widths of the sets of type-levers and keylevers. The key-levers are pivoted on a straight rod 14 mounted in a slotted bar 16, the arms 13 being in the same planes as the sub-levers. The middle sub-levers have necks 29 passing over the bar 16. Guide-combs 30, 31, 35, 41, and 46 are provided for the key-levers, sub-levers, levers 22, and type-bars, the guide-comb 46 engaging lugs 45 on the type-bars. A slotted dust-guard 47 is arranged over the segment 39. Returning- springs 51, 53, connected to the key-levers and levers 22, normally hold the key-levers and types in contact with cushions 58, 59. To prevent knocking at the pivots, the type-bars are connected to springs 60 and are formed with counterbalances 64. On depression of a keylever, the associated lever 22 and type-bar are rapidly swung upwards, and when the types are adjacent to the platen 44, the levers 22, 23 and type-bar swing slowly rearwards to effect noiseless impression, the speed of the types during the final part of the impression swing being only about half that of the levers, since owing to the convergence of the levers the type-bar rocks relatively backwards. The key-lever has initially a great leverage, the arm 13 and tread 18 engaging with little rolling until the type-bar has made a substantial swing. During the remainder of the swing, the arm rolls on the tread and reduces the leverage, and during the final part of the swing, the arm and tread engage with little rolling movement and maintain a uniform leverage. The action shown in Fig. 8 includes the same elements as that described above but is rendered more compact and easy-running by employing a short type-bar 70 and short supporting-levers 68, 66, the lever 68 being about half the length of the corresponding lever 23. Moreover the pivot 69 of the lever 68 is considerably higher than the pivot 67 of the lever 66, and the pivot 72 of the type-bar is substantially to the rear of the pivot 69. Each pair of levers 68, 66 is mounted on a separate hanger 75 having arms 77, 78 carrying the pivots 69, 67, and a stem 76 for engaging a slot 79 in a segment 80, shoulders 86, 89 on the stem engaging the front and top of the segment. The set of hangers is secured by means of a segmental plate 83 which is clamped to the front of the segment by means of bolts 81 each being arranged between a pair of stems and being formed at the sides with flats to permit removal of either hangers when the nut 85 is slackened. The levers 68 consist of a doubled blank, the pivots 72, 69 being riveted to ears 92, 106, and the upper end 107 of the hanger being reduced to pass between the ears 106. A thin fin 96 on the type-bar works in one of a series of guide-slots 97 in a segment 98. The arms 78 have arcuate fingers 100 engaging guideslots in lugs 101 on the levers 66. A spring 60 for preventing knocking at the pivots is connected to the type-bar and a pin 90 on the hanger. Letter-spacing mechanism. - A universal bar 123, Fig. 1, in the path of lugs 122 on the abovedescribed sub-levers 19 is carried by a rock-shaft 125 which is connected to an adjustable forked link 133 engaging a pin 131 on the dog rocker 129. The lugs 122 can be filed or bent for adjustment and are formed of different lengths and arranged at different heights to impart uniform movement to the universal bar. Any key-lever can be rendered silent by removing its lug.