Patent GB-712750-A (GB)
Title: Improvements in or relating to calculating machines
Inventor: TURCK JOSEPH ABRAHAM VALENTINE
IPC: G06C7/06
Filed: 1951-01-31
Abstract: 712,750. Calculating-apparatus. FELT & TARRANT MANUFACTURING CO. Jan. 31, 1951, No. 2419/51. Class 106 (1) In a key-driven calculating machine adapted for both positive and negative forms of calculation, ordinal lever actuating mechanisms have two alternative fulcra, and are presettable to pivot about either fulcrum to impart either the true values of the key markings or their complements to the accumulator. Differential mechanism in addition and subtraction.-In the machine shown, each ordinal set of keys 24 differentially rock a bell-crank 56 connected by a link 53 with a totalizer actuating sector 51, the totalizer wheel 22 being advanced through ratchet gearing as the sector 51 is restored by a spring 64. The key stems 36 actuate the bell-crank 56 through the intermediary of a beam 59 centrally pivoted at 58 to the upper arm 57 of the bell-crank. The " 6 " - " 9 keys also engage the arm 57 itself. A lug 60 on the arm 57 overlies the beam 59 and, in addition, a dog 92 pivoted to the bellcrank engages under a pin 63 on the beam so that the beam and bell-crank move as one to register the marked key values. In subtraction, the dog 92 is rocked clear of the pin 63 and a connected latch 67 pivoted to the sector 51 is engaged with a fulcrum pin 66 at the forward end of the beam 59. Actuation of the beam 59 by the lower value keys then rocks it about the pin 66, instead of the fulcrum 56<SP>1</SP> of the bell-crank, and complements of the marked key values are registered. Positive and negative stopbars 71, 72 are selectively coupled to the sector 51 and engage the key-stems to limit movement of the sector to amounts appropriate to the key markings; a coupling link 76 pivoted to the sector is raised or lowered, to engage a pin 78 in one or other of opposed slotted lugs on the stop-bars, by rocking an add/subtract shaft 85 which is also connected to actuate the dog 92 and latch 67. Mechanism for registering zero complements. -In subtraction, depressed keys are retained, and the differential mechanism locked, pending the registering of zero complements in unactuated orders. Except for the " 9 " keys in the tens and higher orders, the lugs on the negative stopbars are formed to enter slots in the stems of depressed keys to retain them. As regards the " 9 " keys, a shaft 189 (Fig. 17), rocked with the add-subtract shaft 85 by means of pins 190 and pivoted fingers 191, thrusts floating levers 175 into notches in the key stems. This limits depression of a " 9 " key to an amount insufficient to actuate the bell-crank 56, but sufficient to lower a lug 183 on the lever to engage in front of lugs at the ends of the positive and negative stop-bars to prevent their forward movement and setting of the corresponding sector 51 and totalizer wheel. A latch 193 retains the depressed levers 175 and " 9 " keys pending the registering of the zero complements. Thus, in orders where a key has been depressed, the differential mechanisms are locked against forward movement, whilst return movement by the springs 64 is prevented by pawls 161 released to engage lantern wheels 43 in the totalizer gear trains by pins 163 on a shaft 164 rocked with the addsubtract shaft 85. A hand-operated shaft 203 is now turned clockwise to enter the zero complements, arms 218 on the shaft lowering connected arms 215 to rock the bell-cranks 56 to advance the sectors 51 through 9 digits in unactuated orders. In other orders the bell-cranks are locked by key depression and spring connections 217 between the arms 215, 218 yield. The sectors 51 are temporarily relieved of their return springs 64 during this phase of operation: the springs are anchored to arms 223 (Fig. 4) on a rock-shaft 224, and are normally held tensioned by a toggle lock 229, 230 (Fig. 5) broken by a connection 235 with the shaft 203. The handle operating the shaft 203 is connected therewith through a toggle linkage which collapses at the end of the forward stroke to permit immediate return of the shaft under spring action. This resets the toggle lock 229, 230 to retension the sector springs 64 and restores the shafts 85, 164 and 189 to release the keys and differential mechanism ; so permitting the sectors 51 to be returned by their springs to enter the set amount into the totalizer. Resetting for addition.-As indicated above, the shaft 85 is restored to the add position at the conclusion of a subtract operation. The shaft 85 is locked in the subtract position (clockwise in Fig. 5) by a toggle lock 133, 134. During 'the forward stroke of the hand shaft 203, a pin 232' on an arm 232 on the shaft 224 strikes a finger of the toggle link 134 and starts to collapse the toggle, a detent 269, released by rearward movement of a link 256 interconnecting the shafts 203 and 164, then holding it extended until completion of the subtract operation and return of the link 256, whereupon the detent 269 is withdrawn, the toggle collapses and the shaft 85 is returned to its normal add position by a spring 139. The shaft is similarly returnable to the add position by depression of an add key 123. Resetting totalizer.-The totalizer is reset by operation of a hand-lever which rocks a shaft 280 (Fig. 5) clockwise to rock the totalizer frame 24<SP>1</SP> to disengage the totalizer. A toggle 285, 286 locks the shaft 280 in the reset position until the next key actuation whereupon one of a series of arms 292 on a shaft 291 is rocked by the corresponding bell-crank 56, and the shaft 291 resets the toggle and restores the shaft 280 through an arm 294 and link 295. Division.-Depression of a division key 121 rocks the shaft 85 to condition the mechanism for entering complements as in subtraction. The shaft 189 is not, however, actuated by this key so that full movement of the " 9 " keys is permitted to enter 9 in the totalizer, the negative stop bars having no lugs for engagement with these keys. The non-return pawls 161 also remain ineffective so that division can be effected by repeated subtraction of a divisor from a dividend. The " 9 " keys are used for entering zeros of a divisor and are dual marked accordingly.