Patent GB-721535-A (GB)
Abstract: 721,535. Calculating-apparatus. UNDERWOOD CORPORATION. May 8, 1951 [June 29, 1950], No. 10767/51. Class 106 (1). In a ten-key machine adapted for multiplication and division, repeated add cycling in multiplication is terminated upon movement of a multiplier digit setting member to a subzero position, denominational shift of the multiplicand occuring as the setting member returns to zero, whilst repeated subtract cycling in division is terminated by a concluding add cycle initiated by the occurrence of a negarive remainder in the totalizer. Amount differential. As in Specifications 223,866 and 313,513, [both in Class 106 (i)], nine amount keys are connected to respective push-rods 31 (Fig. 3) in a swinging gate 32 adapted to traverse and set ordinal columns of pins 33. Feelers 39 in a frame 40 traversed with the gate 32 are connected to type bars 35 and engage the set pins to arrest upward movement of the type bars by their actuating levers 42. Positive and negative totalizer setting racks 55, 56 depend from the type bars. Positive and negative totalizer engagement. Normally the totalizer 61 engages one or other set of racks 55, 56. During each machine cycle, a pawl 94 (Fig. 4) on a plate 95 secured to a main rock shaft 96 engages in succession pins 92 and 93 on a cam plate 90, rocking the cam plate and moving a follower link 73 forwardly and then rearwardly to rock a totalizer engagement lever 71 into and out of a central totalizer-disengaged position. Re-engagement of the totalizer is with the positive or negative racks 55, 56 according to the direction lever 71 is moved after being brought to its central position. Normally the link 73 engages a lower pin 77 on the lever and the lever is moved counterclockwise to engage the totalizer with the positive racks 55, but rearward movement of a slide 81, through a spring 80 and lever 78, raises the link to engage an upper pin 76 on the lever 71 so that the lever is rocked clockwise to engage the totalizer with the negative racks 56. The slide 81 is moved rearwardly by the nose 106 of an oscillated subtract frame 104 (Fig. 20) when lifted on its pivots 105 during subtraction or division operations. Non-add. Depression of a non-add key 99 (Fig. 11) releases a blocking arm 101 (Fig. 4) from a slide 102, which then moves rearwardly under control of a part 103 of the ribbon feed mechanism and holds the pawl 94 from engaging the pin 93 of cam plate 90, so that the cam plate 90 and link 73 are not moved to re-engage the totalizer with the setting racks. Multiplication is by repeated addition of the multiplicand according to each multiplier digit in turn and with the multiplicand reduced by a factor of ten after each series of addition cycles. The multiplicand is set on the pins 33, followed by zeros one fewer than the number of multiplier digits, and a slide 110 (Figs. 11, 12 and 23) adjusted forwardly according to the multiplier digit. A series of addition cycles is then initiated by depressing a multiplication key 160 which rocks a multiplication cradle 161 clockwise (Fig. 11) and modifies the normal add operation of the machine as follows. (1) The cradle disables normal power-operation of a rack 193 (Fig. 23) to return the gate 32 and clear the setting pins 33 at the end of each cycle. (2) The back-space key 209 is automatically actuated at the end of the series of cycles to return the gate 32 and frame 40 one step to step-down the multiplicand. An arm 217 (Fig. 23) on a shaft 215 is spring-connected to a bell-crank 219 which is rocked clockwise by a pin 221 on the multiplier setting slide 110 when returned to a sub-zero position at the end of the series of cycles. A hook 212 (Fig. 11) on the cradle 161, when in active position, is clear of a pin 213 on a second arm 214 on shaft 215 so that the arms follow the bell-crank and pin 213 raises the rear end of a link 223 for engagement by a stud 230 on a power-rocked sector 231. Link 223 is drawn rearwardly by the stud and, through connections 224-227, depresses the back-space key 209. (3) Printing is inhibited. The cradle 161, through a link 233 (Fig. 19), rocks a detent 234 clear of a bell crank 235 which can then be rocked by a sector 237 to displace a non-print slide 119 to the left into an active position. Normally, at the start of the return stroke of the main shaft 96 (Fig. 12), a pin 137 on a plate 126 engages a notch 138 on a pawl 136 pivoted to a lever 135, rocking the lever clockwise and the lever rocking a bail 133 to release the impression hammers 54. In its active position, the non- print slide 119 releases a lever 139 for movement by a spring 141 to raise the pawl 136 clear of pin 137 so that the hammers are not released. The non-print slider 119 also obstructs a spring- actuated slide 122 normally operating the platen ratchet-feed pawl 128. (4) A cycle counting bar 242 (Fig. 19) is rendered operative. This bar is similar to the type bars 35 and carries type for printing the multiplier digits. It is adapted to be lifted step-wise during successive cycles but its holding pawl 243 is normally tripped, to prevent advance, by a pin 256 on a power-driven plate 241 engaging a hook 254 linked with the pawl. The detent 234, when rocked by the multiplication cradle 161, raises the hook 254 clear of the pin 256 so that the pawl 243 maintains the advance of the bar 242 to count successive cycles of a series. (5) The multiplication key 160 rocks a cradle 173 (Fig. 11), and an arm 174 of the cradle then clears a pin 176 on an arm 177 carrying a feed-pawl 271 for the multiplier slide 110 so that the slide is restored step-wise during successive cycles. (6) A retaining latch 178 for the arm 174 also retains a clutch release spindle 181 to maintain the drive until the series of multiplying cycles are completed. During the first cycle of the series following setting of a multiplier digit on slide 110 and operation of multiplication key 160, the totalizer remains disengaged, the non-add key 99 being operated by the key 160. A roller 260 (Figs. 11, 12 and 23) on plate 126 rocks a lever 261 spring-connected to the lever 177 (now freed by arm 174) so that feed pawl 271 returns the slide one step. The counter bar 242 is raised to bring " O " into printing position by means of a spring-urged slide 276 (Fig. 19) upon release by the bell-crank 235 operating the non-print slide 119; the slide 276 moves forwardly under control of a stud 279 on plate 241, rocking a lever 250 to an advanced forward position in which a feed pawl 283 engages teeth 244 on the counter bar 242, raising it one step and the pawl 243 holding it. A lost-motion connection between the slide 276 and lever 250 prevents full return of the lever so that, whilst the feed pawl 283 is disengaged in readiness for the next cycle, the holding pawl 243 remains in engagement. Succeeding cycle of the series follow automatically upon the first, and the action is similar except that the totalizer is engaged to accumulate the multiplicand, the non-add key having been restored at the conclusion of the first cycle. The last cycle of the series commences with the multiplier slide 110 back to zero and, in this position, the slide releases a lever 116 (Fig. 12) which thereupon moves under spring action to block the non-print slide against movement to active position so that, after the cycle counting bar 242 has been raised a final step, the printing mechanism is effective to print the multiplier digit and multiplicand. During this cycle, the multiplier slide 110 is moved back one more step into a sub-zero position in which it is held temporarily by a detent tripped at the end of the cycle, whereupon a roll 293 on a spring-urged arm 294 restores it to normal. In the sub-zero position, the slide 110 causes actuation of the slide 223 to backspace the gate 32 to step-down the multiplicand, the slide 223 also rocking lever 250 to release the cycle counting bar 242 which thereupon returns to normal. The slide 110 also trips the latch 178 to release the clutch control spindle 181 and arrest the drive. Operation for the succeeding multiplier digits is similar but, in the case of the last digit, the gate 32 and frame 40 are fully restored. Moreover, during this last series of the cycles, the units type bar 35 becomes operative and its upward movement is used to reset the multiplication cradle 161. In its movement the units bar 35 (Fig. 11) releases an arm 305 and shaft 303 for counterclockwise rotation by a spring 304 when an arm 301 on the shaft is also freed by rearward movement of a link 157 upon restoration of the slide 110. An arm 310 on the shaft 303 lowers a link 312 which is then moved rearwardly by a stud 314 on a power-driven arm 315, the link 312 disengaging the latch 166 allowing the cradle 161 to restore and parts controlled by it to revert to normal. Division is by repeated subtraction of the divisor from the dividend until an overdraft occurs and then the divisor is added back once. Further such operations are made on the remainders in one continuous process, and with the diviser reduced by successive factors of ten, until all the quotient digits have been determined, whereupon control mechanism halts the process. Operation of the division key, after setting the dividend in the totalizer and the diviser on the pins 33, rocks a division cradle (not shown) forwardly. This cradle embraces the multiplication cradle 161 (Fig. 11), which it carries forwardly to prevent restoration of the gate 32, to permit actuation of the non-print slide 119 and to render the cycle counting bar 242 operative as in multiplication. The division cradle itself moves forwardly a link 330 (Fig. 22) to rock a bell-crank yoke 334 clockwise. This displaces a slide 336 to cause the left-hand upturned end 341 of a lever 338, centrally pivoted thereon, to be engaged by a cyclically-operated rod 48 (see also Fig. 3) so that a slide 344 connected to the lever engages stops