Patent GB-191028362-A (GB)
Title: Improvements in and relating to the Differential Actuating Mechanism of Computing Attachments for Typewriters.
Inventor: HOWIESON JOHN THOMAS
Filed: 1909-12-29
Granted: 1911-01-30
Abstract: 28,362. Howieson, J. T. Dec. 29, 1909. Adding-apparatus. - Relates to the singlebank motor - operated adding and subtracting machine, constituted by the combination of a calculating-mechanism with the numeral keys of a typewriter, of which the denominationselecting and column-spacing mechanisms are described in Specification 30,426/09, the transfer and reversing mechanisms in Specification 28,058/10, and the spring-motor driving-mechanism in Specification 28,363/10, and deals more particularly with the means whereby the depression of a key releases the motor and controls the differential rotation of the numeralwheel actuating-shaft thereby. The mechanism comprises a rotary controller for the differential movement, operated from the keys through the ageucy of slide-bars, and carrying a number of stop-bars which are interlocked with each other, and are adapted to unlock the main driving- shaft, to stop it after a predetermined rotation, and to relock it, the mechanism clutching one of the numeral wheels to the actuating-shaft being locked in position meanwhile. Provision is also made for compelling a full stroke of a key and for ensuring that one key only shall be depressed at a time. Keyboards ; full-stroke mechanism; keyboard interlocks. - Each numeral key of the typewriter is connected by a rod 38, Fig. 23, with a cam disk 31, pivoted on a fixed rod and carrying:-(1) teeth 34, 35 for engagement with a wheel 41, which, as the key is depressed and released, is fed forwards in the same direction owing to the alternate engagement of the teeth on the cam-disk; (2) a tappet cam 37 for engaging a bell-crank lever 45, 46 adapted to depress a universal bar 50 and thereby clutch the selected numeral wheel to the actuating-shaft; (3) an edge cam 36 whereby longitudinal movement is imparted to one of a series of nine slidebars 61 controlling the motor and the differential mechanism. The partial depression of a key produces a rotation of the wheel 41 insufficient to bring the next recess opposite to the tooth 34, whereby the return is prevented until the stroke is completed. In order that the depression of one key may lock all the others against depression, each cam-disk has a slot 164 of which the narrower portion engages slots 160, Fig. 21, in a tube 158 over which the larger part takes freely; within the tube are cylindrical pieces 162 having sufficient play to admit the thickness of one disk only. Selecting denomination; interlocking. - The spring motor is connected with and continually tends to drive a sleeve 74, Fig. 45, having a locking-wheel 84 normally held against rotation by a pawl 86 subject to a rotary controller constituted by disks 88, 89 and sleeves 87 all in one piece and loose upon a shaft 73. Mounted in radial slots of the disks are nine stop-bars 91 of the form shown, which are pressed outwards and towards the locking-wheel by spiral springs between pins on the shoulders of the stop-bars and projections 101 on the end of the sleeve. The longitudinally-moving slide-bar 61 presses by means of a spring pawl 70 thereon against the inclined shoulder of a stop-bar, forcing it in sufficiently to bring the whole width of the bar into the slot and to allow the spring to slide the bar towards the locking-wheel. Simultaneously the heel 149 of the stop-bar moves an inner sleeve 146 in the same direction, thereby bringing the collar 147 beneath the extremities 98 of all unoperated stop-bars and holding them against movement, and at the same time releasing the locking-wheel by the following mechanism. A compound spring - controlled lever 144, 151 engaged by a collar 145 upon the inner sleeve is rocked so as to press a spring- pawl 153 against an horizontally-moving spring lever 133, whereupon the catch 132 frees a finger 131 upon a U-shaped rock-lever 111, 112, Figs. 41, 46, rotating upon an horizontal rod 114 and connected with a locking-dog 118, the lower end of which presses upon the extremity of the locking-pawl 86 to maintain it in engagement. The rock-lever is also connected to the upper end 122 of a short lever 123, which is pivoted in the centre and engages at its lower end with a slide 127 normally spring-pressed rearwards ; these connexions result in a normal forward tendency of the rock-lever, so that upon the depression of a key and the operation, through the proper slide-bar and stop-bar, of the catch 132, the rock-lever swings forwards, and in so doing frees the locking-wheel by camming upwards the locking-pawl, and displaces the holding-arm 118 thereof, while the rearward movement of the slide 127 carries a stop 130 out of the path of a stop-bar resting against it. The rotary controller thereupon moves round until the projected stop-bar meets a roller 116 upon and resets the rock-lever, and in consequence reapplies the pawl to the locking-wheel and holds it firmly in place, the stop 130 simultaneously coming forward to present its inclined surface to the projected stop-bar, which is reset and arrested thereby. When the pawl 86 rises to release the locking-wheel, a bar 163 interlocks with and prevents movement of the universal bar 50 determining the clutching of a numeral wheel to its actuating-shaft. Varying functions of machine.-In the machine described there are two totalizing- counters, each with its own denomination selecting means, either or both of which may be driven from the single set of motor and differential-actuating parts.