Patent GB-732777-A (GB)
Abstract: 732,777. Calculating-apparatus. FELT & TARRANT MANUFACTURING CO. Aug. 31, 1951 [Dec. 28, 1950], No. 20597/51. Class' 106 (1). A key-responsive machine is adapted for negative actuation by the provision of alternative forward and reverse drives between each ordinal key-responsive mechanism and its corresponding constantly engaged totalizer driving wheel. The invention is applied to the machine described in Specification 435,286, which machine is key-responsive in addition and subtraction, and key-set in multiplication and division whereby, for example, a set multiplicand can be repeatedly entered into the totalizer under the control of a separate multiplier key bank. The invention provides a reversible drive between the key-controlled ordinal actuators and totalizer to avoid haying recourse to the complemental method of negative actuation, and the totalizer transfer mechanism, which is similar to that described in Specification 219,938, is modified to admit of reverse actuation. The totalizer and transfer mechanisms are mounted in a laterally traversible carriage 35 (Figs. 6 and 15) and the condition of the machine is changed. from positive to negative, or vice versa, by drawing forward a spring-returned conditioning lever 250 after placing the carriage in its normal initial leftmost position for amount entering. Reversible drive. As in Specification 435,286, each ordinal actuating sector drives a punion 73 (Fig. 16) which, through the usual ratchet mechanism 50, rotates an add wheel 203 about a shaft 51. The reverse drive is from the wheel 203 and through gears 208, 206 and 205 to a subtract wheel 204 adjacent the wheel 203, the totalizer carriage being shifted slightly by operation of the conditioning lever to change the mesh of an ordinal totalizer actuating wheel 48 from the add wheel 203 to the subtract wheel 204. For this purpose, a notched bar 337 (Fig. 19) for aligning the totalizer carriage with the actuator is adapted for sliding movement over a transverse frame member 335, the carriage accompanying the bar by the engagement of its aligning hook 280 in a notch 281 of the bar. Successive forward movements of the conditioning lever 250, through intermeshing sectors 320, 321 (Fig. 7) and a ratchet pawl 324, turn a cam wheel 325 through successive steps of 60 degrees rotation clockwise. A follower arm 330 for the cam is thereby moved successively to and fro and, through a link 332 and connected leverarms 333 and 341, shifts the aligning bar 337 and carriage to engage the totalizer actuating wheels 48 alternately with the add wheels 203 and subtract wheels 204. A rockable indicator segment 351 connected with the cam follower arm 330 shows how the machine is conditioned. The link 332 is also adapted to engage a locking catch with the zeroizing lever (not shown) when the machine is conditioned for negative operation. Transfer mechanism. As in Specification 219,938, transfer is effected by an escape-controlled torsion spring, tensioned by the lower order totalizer wheel. In the present mechanism, however, a pair of reversely acting springs 218, 219 (Fig. 15A) are employed and provision is made for preloading them in the requisite direction when the add/subtract condition of the machine is changed. The transfer movement from the lower order is introduced into the drive from a totalizer actuating wheel 48 to its numeral drum 43 (Fig. 15) by means of a pair of epicyclic pinions 210, 211 (Fig. 16) carried by a spindle 216 secured to an end cup 217 of the lower order springs. The pinion 210 meshes with internal teeth of the wheel 48, whilst the other pinion 211 meshes with internal teeth of an adjacent wheel 47 connected with the numeral drum 43. A pin 226 on the wheel 47 engages an aperture 227 in the opposite (driven) end-cup 222 of the spring pair so as to tension the spring as amounts are accumulated. Rotation of the driving end-cup 217 is normally prevented by engagement of an escapement lug 230 thereon (see also Fig. 17) with either of two pairs of stop lugs 231, 232 or 235, 236 carried on arms 233 and 234 interconnected by a link 237. At the transfer point, a cam 224, carried round by the pin 226 and engaging dolly-rolls 238, 239 on the arms 233 and 234, reverses the effectiveness of the two pairs of stop lugs so that the end-cup 217 is released for rotation through a half revolution to effect transfer to the higher order. To preload the springs in the appropriate direction when changing from addition to subtraction or vice versa, mechanism is provided for entering ten' into each order of the totalizer after the change-over. As regards the key-operated orders (the totalizer carriage being in its left-most position), a cam on the shaft of the conditioning lever is adapted to move forwardly the lower links of the usual key-operated parallel-motion linkages (see, for example, Specification 435,286) to engage their hooks with the motor-driven wheels so that a full ten-digit movement is imparted to the actuating sectors. The additional orders to the left of the machine are also provided with actuating sectors 71 (Fig. 7) together with the usual motor-driven wheel 90, driving hook 104, friction coupling 75 and interconnecting linkage, but no key-control mechanism. In these orders, the action of the conditioning lever cam is to lower pawls 172 and so engage the hooks 104 with the wheels 90 so that the sectors 71 also are given a full movement. The conditioning lever is also adapted to engage locking arms 312 (Fig. 6) with notched peripheries of the transfer cams 224 to lock them in set position during the entry of the tens, the pins 226 engaging the cams by means of semi-circular slots 225 (Fig. 16) which provide for the ten digit relative rotation. Operation of the conditioning lever automatically adjusts the machine for keyresponsive actuation if previously in key-set condition. Interlocks. To ensure return of the carriage to its left-most position in which all totalizer orders are engaged, the conditioning lever 250 is normally locked by engagement of a fullstroke dog 289 (Fig. 6) over the end of its toothed segment, return of the carriage causing its aligning hook 280 (Fig. 19) to engage and rock a lever 282, which, through a link 286, rocks the dog into effective position unlocking the conditioning lever. A latch '293 also locks the conditioning lever when a lock lever 290 is out of its normal position locking the carriage down with the totalizer engaged with the gears 203 or 204.