Patent GB-256791-A (GB)
Abstract: 256,791. Buschmann, T. E., and Claus, C. E. A. Aug. 24, 1925. Adding and subtracting apparatus; attachments to typewriters ; differential mechanism. - In a machine in which the values determined by depressing the numeral keys is transmitted to an adjustable pinion displaceable relatively to a stepped cylinder adapted to be driven by a spring or electric motor, the pinion is adjusted by means of levers arranged in staggered relation on a shaft and acted upon by camplates moved by the keys, cam plates also serving to clutch the motor to the stepped cylinder. Two forms of cam plates are described in one of which means are provided to adjust the plates in any one of three positions for computing, punctuation, and printing only respectively. This adjustment may be effected manually or automatically through the totalizer. Means are also described for preventing the simultaneous actuation of a plurality of keys and for cutting out the motor circuit when the machine is set for recording only. In the form shown in Figs. 3 and 4, the cam-plates 2 are mounted by means of bridge pieces 3 on a shaft 4 and each is formed with a slot for engagement by a pin 1 on the corresponding numeral key 32 and with a curved surface 2b and a slot 2a engaged by a corresponding roller arm 6 on a shaft 7. The arms 6 are arranged at different angles on the shaft 7 so that when the shaft is rotated by the depression of a key a corresponding angular movement is imparted thereto which movement is transmitted through the gearing 8, 9, 10, 12 to a vertical shaft 11, Fig. 5, which effects in a known manner the adjustment of the pinion with respect to the stepped drum. At the same time the movement of the cam-plate 2 through a surface 13 thereon rocks a shaft 15, Figs. 5, 10 and causes an arm 16 at the end thereof to rock a lever 17 to raise the shaft 11 to close the clutch connecting the source of power with the stepped cylinder. After the partial depression of a key locking of the other keys is effected by a pin 19 on the cam plate engaging a corresponding lever 20 to throw the ends 21 of the other levers into the notches 22 on the other cam-plates. In the form shown in Figs. 12, 15 the cam-plates are formed with the upper closed portions 45 having a tappet-shaped stop member 46 and a relatively movable stop member 47 pivoted on the shaft 4 and connected to the member 46 by a pin and slot. The camplates are adjustably mounted on the shaft 4 so that in the position shown in Fig. 12 depression of a key 32 engages the bevelled end of the stop members and rocks the cam plate to set the adjustable transmitting pinion as described above. The raising of the shaft 11 to engage the driving clutch members is effected by a ratchet wheel 52 which is actuated by a pawl 53 on an arm 54 'integral with the cam plates and is adapted to rock a roller arm 56 on a shaft 55, Fig. 14<a>, which carries a toothed sector 58, Fig. 21, engaging a pinion 59 meshing with a toothed portion 60 on the shaft 11. In the punctuation position shown in Fig. 15, the keys are locked against depression by reason of the engagement of the pin 1 with the end of the stop member 47. In the printing or non-computing position the cam plate is moved to such a position that the pin 1 on the depression of a key moves freely in the portion 51 of the upper part 45. The adjustment of the cam-plates to any one of these positions is effected by the rocking of a shaft 64 having arms 63 engaging projections 61 on the can plates. The shaft 64 is provided with an arm 82. Figs. 23, 24, to which is attached a link 81 pivoted to a sleeve 80 surrounding the shaft 11. The sleeve is operated by a slide 75 through racks and pinions 76 - - 79, the slide being connected to a bell crank lever 70 having a one-way action stop 66 co-operating with the underside 83 of the totalizer 65 on the travelling carriage. A notch 84 in the underside of the totalizer indicates the punctuation position 'and serves to rock the shaft to lock the keys. To adjust the cam-plates manually a key 87 is provided the depression of which through an arm 85, Fig. 17, rocks the shaft 64. The shift key employed to change over from small letters to capitals may also be utilized to shift the cams to the non- computing position by providing a pin 92 on the shift-key lever 91 adapted to engage a bar 93 connected to an arm 94 on the shaft 64. The shaft 64 also carries an arm 97 connected by a link 98, Fig. 27, to a mercury tilting switch 95 for the motor circuit.