293,080. Marks, E. C. R., (Gardner Calculator Co.). March 21, 1927. Adding and subtracting apparatus. - A multiple-bank lever-operated machine is described wherein counters are shiftable into and out of engagement with respect to detent and actuating elements under the selective control of counter and function keys. Moreover in the process of taking a total or sub-total a special mechanism is provided for producing alignment of the numeral elements of the counter seriatim, the elements having been partially displaced during the entering of the items on account of the action of the transfer - mechanism which may be as described in Specification 272,569. Differential - mechanism.- The stems of the amount keys 215 determine the extent of advance of differential stopbars 615 pinned at 654 to the three-armed levers 610, the forward arms of which terminate in racks 610<c> for actuating the counters of which there are two arranged on upper and lower shafts 403, although accommodation for a third counter is also provided at 410<a>. The stop-bars are normally prevented from advancing by latches 214 moved to release position by the depression of a key in the corresponding bank. With several totalizers.- The shafts 403 supporting the counting-elements are provided with cut-away discs 438, Fig. 19<a>, co-operating with cam plates 419, Fig. 3, pivoted at 405. If a shaft 403 is turned so as to present the cut-away portion of its discs to the cam plates, the counting-elements normally engaged under spring action with the actuating-racks will be removed from such engagement and the counter will, accordingly, be inoperative. The shafts 403 are rotated for the purpose of putting the counters in action by connection with pinions 474, Fig. 16, adapted to be rotated by spring-controlled racks 417. These racks can be depressed singly by the corresponding keys 217 or both together by the centre key 217'. The keys are latched down by a detent 4161, Fig. 2, shaped to provide against the retention of all three keys at once. Varying functions of machine.-On the left of the keyboard is a non-print key 2179, Fig. 2, depression of which rocks a bail 219 to disable the hammers. On the right is a series of keys, Fig. 3, which, commencing at the top, effect respectively, addition, subtraction, error-correetion, repetition, non-adding, sub-total taking and total-taking. The error-key 2172 serves to rock a bail 227, Fig. 1, and thereby the latches 214 to displace the key detents and free the depressed keys. The key 2172 also, through a stud 2511, Fig. 3, rocks a detent 223 to release any of the keys 2178, 2173, 2175 that may have been depressed. The repeat key 2176, Fig. 3, when depressed may be moved rearwardly to lock with the keyboard top plate, 210 and in this position its arm 2176<b> will engage the stud 559, Fig. 20, so as to swing a pivoted hook 221 out of a notch in a stud 263 fixed to the bail 227 and thus break the connection between the lever 220 (rocked ab each operation by the three-armed lever 327, Fig. 3), and the bail 227. Totalizer-engagement, controlling timing of. The cam plates 419 engaged by the shaped collars 438 on the totalizer shafts as described above, are rocked to engage the counting-elements with the actuating-racks by means of a link 321, Fig. 3, pivotally attached to an arm 322 connected by a hub with an arm 325 mounted on the shaft 304. At each end of this arm 325 is pivoted a " flipper " 323, 324, Fig. 10, connected together by a spring 381 and bearing studs 352, 3522, 3525. The operating handle is secured to a shaft 301 rigidly carrying cam arms 316, 320 spaced laterally so that one (316) is in the plane of flipper 324 and the other (320) in the plane of flipper 323. The arm 325 is held by a spring 383 in contact with a stud 353 fixed in a rock arm 326 having a forward extension 326<a> cooperating with the front flipper stud 3522. When the machine is in normal condition with the adding key (2177) depressed the extension engages this stud to prevent the flipper from rocking idly as the cam 320 sweeps past. Consequently when this cam advances the flipper arm 325 is rocked clockwise to force the cams 419 forward and allow springs to shift the counters from the actuating-racks into engagement with the detent combs 413. At the commencement of the return stroke, however, the rear-flipper 324 is engaged by the cam arm 316 and is effective to cause the arm 325 to rock the cam plates 419 and restore the counters into their normal engaging positions to receive the item set up. The subtraction key 2174, Fig. 3, is pivoted at the end of a lever 224 carrying also the adding key, a spring 285 connecting the two keys. If the subtraction key is depressed, it causes an extension of the lever 224 to engage an arm 326<c>, Fig. 10, of arm 326 so as to rock this clockwise and thus render the front flipper 323 ineffective. In the forward stroke therefore the cam arm 320 cannot displace the cam plates and counters and the item is consequently subtracted on the downward travel of the actuating-racks. In the return stroke, however, the flipper 323 is held rigid by a hook portion 326b of the arm 326 and therefore the cam arm 320 is able to rock the flipper arm 325 clockwise to force the counters out of engagement. At the end of the operation a stud 350, Fig. 3, on an arm 318 engages the arm 322 and restores the flipper mechanism and the counters to normal position. The non-add key 2175. when depressed, effects through an extension 2175b, Fig. 3, meeting pin 3525, a clockwise displacement of the rear flipper sufficient to place its stud 352 out of the path of the cam arm 316. The front flipper backed as in normal adding operations by the arm 326 remains effective for the forward stroke so that the counters are disengaged at the commencement and remain so until the termination of the operation. Printing totals and sub-totals.-Depression of the total key 2178, Fig. 3, retained depressed by a pivoted latch functioning also for the sub-total and non-add keys, rocks the amount key releasing-bail 227 and thus the latches 214 so as to free the differential stop-bars 615. A portion 2178<a> on the key also engages a stud 3527, Fig. 10, to rock the arm 326 clockwise and thus to throw the rear flipper entirely out of action and permit one-way novement only to the front flipper. In the forward stroke of the main operating-mechanism therefore, both flippers are inoperative and the counter remains in gear to transmit its accumulated amount to the actuating-racks and so to the type. In the return stroke the front flipper cannot rock clockwise owing to the position of the hook 326<b> and in consequence the flipper arm 325 is rocked clockwise by the cam arm 320 to disengage the counter so that it remains cleared. The subtotal key 2173 when depressed engages by a toe portion a pin 3528, Fig. 10, to rock the arm 326 clockwise sufficiently to put the rear flipper out of action and to free the front flipper for idle. movement in both directions. The operation of the handle will therefore have no effect on the position of the counter which consequently remains in gear throughout both strokes. Alignment of counting and printing elements in total-taking. Owing to the nature of the transfer-mechanism the counting elements do not necessarily stand at their definite, digit positions and in taking a total or sub-total therefore each of these elements is first restored to its true position before the digit value is transmitted to the printing-mechanism. A shaft 607, Fig. 7, is provided with a number of spirally disposed pins 6511, one for each denomination and is adapted to be given a complete rotation by a, spring-controlled sector 618 when this is released by a latch 620. Depression of either the total key or subtotal key rocks an arm 621 carried by the latch 620 so as to free the sector. Under the action of the spring 681 and controlled by the dash-pot 6741 the shaft 607 therefore commences to rotate. First a pin 6701 fixed in the shaft departs from its position supporting the arm 671 so that a shaft 609 rocks slightly clockwise to liberate arms 613 having stops 613<b> for co-operation at zero with pins 457 on the counting-elements. The arms 613 although freed do not move into operative position, for a rearward extension of each arm is stopped by resting upon a latch 617, Fig. 1, serving as intermediary between the restoring cams 318 on the main shaft and the actuating- racks. When, however, the shaft 607 has rotated sufficienfly, the first pin 6511 displaces the corresponding latch 617 to free both the stop arm 613 and the actuating-rack so that under the action of its spring the latter rotates the counting-element until it is stopped at zero. The next pin 6511 coming round performs a similar release in the next higher denomination and so on throughout the counter. Interlocking. To prevent operation of the machine if the total or sub-total key is only partially depressed a pivoted yoke 627, Fig. 12, is linked with an arm 6270 pivoted at. 304. At the upper end of this arm is a roll 639 which, with an incomplete key depression, engages a hump 314a on the full-stroke pawl 314 and so places a stud 373 on the pawl in the path of a notch in the end of the full-stroke ratchet 315 carried by the cam arm 320. To prevent operation of the machine while the total-correcting mechanism is operating, the rear end of the, sector 618, Figs. 7 and 13, while this is in course of movement, keeps a bail 6271 displaced clockwise so that a one-way dog 6272 maintains the full stroke pawl in the path of the notch in the end of the ratchet. When a total-taking has been initiated by depression of the corresponding key 2173, 2178 operation of the machine is essential and for this purpose the following mechanism is provided. Within the bail 6271 is another bail composed of arms 6274, 6276, Fig. 12, joined by a hub 632. Whe