Patent GB-728773-A (GB)
Abstract: 728,773. Calculating-apparatus. FELT & TARRANT MANUFACTURING CO. Nov. 17, 1952 [Dec. 5, 1951], No. 28952/52. Class 106(1). In a normally key-responsive machine rendered key-set for certain kinds of operation, stop means are provided for positively limiting downward movement of the amount keys in such operations and normally inoperative latching means then latch partially depressed keys in set position, set keys determining the extent of subsequent actuation of the accumulater. The invention is applied to the machine described in Specification 566,376 which is normally key-responsive for addition but becomes key-set in subtraction. The subtract key 86 (Fig. 3) substitutes complemental stop bars for the normal stop bars, and sets lock arms 108 (Fig. 4) to hold the clutch hooks 58 of the usual ordinal power trip mechanisms clear of their driving ratchets 73. The parallel motion linkages of the power trip mechanisms thus remain locked with the keys depressed until a key 87 is operated, which swings the lock arms 108 clear so that the clutch hooks are engaged to enter the complement of the set amount into the accumulater. The present machine includes mechanism facilitating division and multiplication, and is key-set also in these operations; the keys are, however, blocked against the full movement necessary to operate the parallel motion linkages, though sufficient to control the stop bars, and an operating key 377 must be depressed to enter a key-set divisor or multiplicand. In division, a key-set divisor is repeatedly subtracted from the dividend until the remainder is less than the divisor in successive series of operations, with a downward denominational shift of the divisor keyboard setting, effected by a shift key 378, between each series. The quotient is registered by the highest orders of the accumulater. Multiplication is by repeated addition of a key-set multiplicand using the operating and shift keys 377 and 378; zero stops are effective to lock the stop bars in unset orders of the keyboard. Setting and subtracting divisor. As in Specification 566,376, normal and complemental stop-bars are adjustable laterally of the machine on transverse supports 125, 127 (Fig. 4). The division key 301 (similarly to the subtract key 86) rocks an arm 119<1> and shaft 121 to shift these supports so as to register the complemental stop bars with the amount key stems 47. The division key 301 also draws a link 342 (Fig. 8) forwardly, a series of ordinal slide bars 351 (Figs. 4 and 8) accompanying the link. These slide bars are threaded through slots in the amount key stems and themselves have clearance notches 354 normally registering with the stems to permit full key depression for key responsive actuation. When shifted by the link 342, shoulders 355 bordering the clearance notches 354 are aligned with the key stems and limit movement of the keys to an amount sufficient to control the stop-bars but insufficient to engage the upper rails 48 of the power trip mechanism. At the same time, spring -actuated stop arms 363 are released to engage under pins 365 (Fig. 2) on the rails 48 positively to prevent movement of the rails. Ordinal key detent bails 328 are also released by the division key to latch set amount keys in partially depressed position, a transverse slide 334 (Fig. 8) and bell-crank 337 connecting the bails with the link 342. The operating key 377, through a bell-crank 379 and link 385 (Fig. 3), rocks a lever 137 and shaft 138 clockwise, and arms 139 on the shaft rock the stop arms 363 clear and operate the power trip linkages to enter the complement of the set divisor into the accumulater. Denominational shift of divisor setting. Mechanism similar to that described in Specification 632,225 is provided for effecting transordinal shift of the keyboard setting. Rockshafts 387 (Figs. 2 and 9) are disposed between the columns of keys, and journalled between transverse bars 388, 389 rearwardly swingable on depending links 392, 396 and 398 by depression of a shift key 378 which then rocks the shafts by displacing a rack 429 meshing with gear segments 428 at the forward ends of the shafts. Loosely mounted on the shafts 387, and located between adjacent key stems, are collars 435 held up to driving pins 436 fast with the shafts by springs 437. Each collar is furnished with a pair of fingers normally disposed immediately to the front of the related key stems, and one 439 normally just below a clearance notch in the stem of the key on its left when undepressed and the other 439<1> level with a notch in the key stem on its right. When the shafts move rearwardly during the initial part of the shift key movement, the collars to the right of partially depressed set keys are able to move with the shafts, their fingers 439, 439<1> entering notches in the stems of adjacent keys so coupling all set keys with the corresponding key in the adjacent lower order. Unset keys are not so coupled to the lower keys, their stems blocking the fingers 439 and preventing rearward movement of the collars 435 which become disengaged from their driving pins 436. During the subsequent rotation of the shafts as the shift key movement is completed, the lower order keys are set in partially depressed position by the pins 439<1>. At the same time, a pin 448 on the additional shaft 427 (see below) shifts the slide 334 (Fig. 8) so tripping the key detent bails 328 to release previously set keys in orders not receiving a new setting. Quotient registering. Transfer across the higher unset (nines entered) orders results in registration of the highest quotient digit by the overflow order of the accumulator. So that succeeding quotient digits shall be registered by successively lower orders, mechanism is provided for automatically actuating the corresponding " 9 " keys sucessively by the shift key actuations. This mechanism comprises an additional rock-shaft 427 (Fig. 9), similar to the shafts 387, disposed to the left of the highest order key stems 47 and provided similarly with a collar 452 and lateral fingers 439, 439<1> adjacent the " 9 " key. Operation of the division key positions a lug 449 on a slide 451 (see also Figs. 3 and 8) clear of the finger 439 so that, when the shafts are rocked by the first actuation of the shift key, the finger 439<1> is effective to depress the highest " 9 " key into key-set position. Subsequent actuations of the shift key result in denominational shift of this " 9 " key setting as with other settings. Multiplication. Zero stops. Multiplication is performed by repeated addition employing the operating key 377 and shift key 378. A multiplication key 457 (Fig. 3) is first depressed and this acts similarly to the division key 301 except that the complemental stop-bars are not substituted for the regular stop-bars which remain active to control accumulation of the set multiplicand. The key 457, by acting on a bell-crank 343 nearer to its pivot 344 than the division key 301 is, however, effective to advance the ordinal slide bars 351 further forwardly. Levers 458 (Fig. 4), connected with the slide bars and bearing pins engaging cam-slots 465 in zero stop arms 466, are now rocked clockwise sufficiently to lower the zero stop arms to block the stop-bars. In their further advanced position, moreover, cam projections 356 behind the shoulders 355 on the ordinal slide bars 351 enter the slots in the amount key stems so that depression of an amount key partially returns the corresponding slide bar for the shoulder 355 to retain the key in key-set position and for the lever 458 to withdraw the corresponding zero stop arm 466. Zeroizing and key release. Interlocks. Mechanism is provided for zeroizing the accumulater and releasing the multiplication and division keys. Spring-actuated detents 304, 471 for these two keys normally engage a flat in a shaft 311. Operation of a release key or zeroizing lever (not shown) rocks this shaft and trips the detents to release either key if set. This also returns the ordinal key latching bails 328, so releasing any amount keys latched in key-set position. An interlock prevents simultaneous actuation of either operating key 87 or 377 and the zeroizing lever or release key. An interlock also prevents actuation of the zeroizing lever whilst an amount key is depressed, but is disabled when the division or multiplication key is depressed. A pendant anchor-shaped blocking member 511 (Fig. 3), similar to the amount key crowding locks 90, prevents simultaneous operation of the operating key 377 and shift key 378. Specifications 601,375 and 640,024 also are referred to.