Patent GB-190919550-A (GB)
Title: Improvements in Calculating Machines, especially Designed for use in connection with Typewriting Machines.
Inventor: FAIRWEATHER WALLACE
Filed: 1909-08-25
Granted: 1910-08-25
Abstract: 19,550. Fairweather, W., [Underwood Typewriter Co.]. Aug. 25. Adding and subtracting apparatus; attachments to typewriters.-Relates to computing-attachments for typewriters adapted to sum both horizontal and vertical columns in book-keeping &c., and to sum simultaneously the results thus obtained, and further to take account of positive and negative items. A number of totalizers are employed, together with a grand totalizer. The machine is of the single-bank, key-actuated type in which the successive denominations are selected by a lateral movement of the master-actuating wheels. Differential mechanism.-The machine forms a support for the typewriter, the numeral keys of which are connected by suitable links to the differential segments 10 mounted loosely upon a shaft 11, and each adapted to engage one of the nine receiving pinions 16 fast upon a shaft 14, from which the movement is conveyed to the master actuating-wheels 5, 6 splined upon the shaft 4 and adapted to actuate one of the totalizers A ... F, or the grand totalizer G. ratchet mechanism renders the return of the keys inoperative. Transfer mechanism; detent mechanism.-Figs. 16 and 17 show the annular wheels which effect the transfer upon the totalizing-counters, the numeral wheels of which receive their actuating movement through receiving-wheels 39, Fig. 11, with which the master-actuating wheels engage in turn. A single tooth 24<d> upon the lower wheel engages a broad internal pinion 36 which also gears with a toothed ring 37 upon the higher wheel. For the purpose of preventing excess movement at actuation, each of the differential segments carries a projecting wedge-ended finger 60, Fig. 20, adapted to finally strike and arrest a corresponding spurwheel upon the shaft 14 ; the receiving wheels of the totalizing-counters are also controlled by starwheels 64, Fig. 11, engaging with detents 62 carried by a spring drum 63 having means for adjusting the tension of its spring. Selecting denomination.-The master-actuating wheel 5 is free to slide upon the shaft 4, but the fork which carries it is attached below to an endless flexible band 74, passing over guide-pulleys 75 and over a driving pulley 76 provided with pins for positive engagement with slots in the band and driven from the typewriter carriage in such a manner as to transmit a magnified linear movement to the band. The grand-totalizer masteractuating wheel 6 normally moves with the band, owing to the engagement therewith of a catch carried by the wheel fork, and in its passage to the right winds up a restoring spring ; when the fork reaches the stop 92, the catch is released and the spring carries the actuating-wheel backwards into engagement with a special receiving-wheel to the left of the highest of those belonging to the grand totalizer. At this moment the other master actuating-wheel is in engagement with the corresponding wheel of some one of the other totalizers. Adding and subtracting.-A reversing-mechanism 17 ... 20 is inserted between the shaft 14 of the differential mechanism and the shaft of the actuating-wheels, with a finger lever 22 for adjustment. The numeral wheels of the totalizing-counter have two sets of numerals, distinguished by colour &c., which progress in opposite directions and are assigned to positive and negative values, respectively, the numerals of the two sets being either side by side or alternating. Movable apertured shutters 102 over the numeral wheels determine which series of figures shall be read. In order automatically to adjust the shutter for any totalizer when its indications pass from positive to negative, the highest numeral wheel of each group is provided with a single tooth adapted to rotate a spur-wheel to the left thereof, and thereby moves the shutter and also communicates a unit movement to the lowest numeral wheel of the series. Full-stroke mechanism.-The links by which the numeral keys rotate the differential segments may merely abut beneath the keys, in which case a system of eccentrics mounted upon a manuallyoperated shaft may be provided for disengaging the computing-mechanism from the typewriter. In the case, however, in which these links are pivoted to the key-levers, the full-stroke arrangement shown in Fig. 20 may be employed, wherein the double-ended spring-pawl 120 upon the segment travels over the fixed ratchet sector 119, and is reversed at the end of the stroke by the projection 123 upon the sector in order that the lower tooth of the pawl may engage the lower half of the sector during the up-stroke of the key-lever.