Patent GB-566376-A (GB)
Abstract: 566,376. Calculating-machines. FELT & TARRANT MANUFACTURING CO. Sept. 16, 1942, No. 13077. Convention date, Sept. 17, 1941. [Class 106 (i)] A calculating-machine includes mechanism for actuating an accumulator in accordance with the values of and in response to the depression of digital control keys, control means for rendering the key-responsive mechanism key set, and means operable by the control means for conditioning the mechanism to actuate the accumulator in accordance with the complemental values of the keys depressed. Keyboard.-The keyboard comprises the usual ordinal keys, but without the usual complemental markings. The machine is ordinarily key-responsive and performs additive operations, but at the depression of a minus key 86, the machine becomes key-set for subtractive operations by automatic complemental addition, the operation being concluded by operation of an equals key 87, which restores the machine for additive operations. Addition.-In any denomination, operation of a key 24 depresses a parallel motion bar 48 and link 55, Fig. 2, in the manner described in Specification 344,868. A dog 67 on the bar 48 depresses a spring-pressed lever 72 which has a spring connection urging a hook 58 to engage a continuously power-driven wheel 73, which, pulls the hook and its associated link 59, and through a yieldable clutch 63 depresses a gear sector 42 in an idle stroke to an extent controlled by the usual digital control bar halted differentially by the depressed key. A latch 66 pivoted on the link 55 engages a projection 76 on the dog 67 to hold the dog and the parallel motion mechanism depressed until a projection on a guide member 60 releases the latch 66 and the parallel motion mechanism. rises under spring notion, the lever 72 releases the hook 58 from the gear 73 and the link 59 and gear sector 42 return to initial position under the action of a spring 46 to enter the amount previously set. The depressed key is released by the withdrawal of a tooth 82 on a bar 81 attached to the bar 48. As described in U.S.A. Specification 2,043,021, no two keys of the same denomination can be operated simultaneously. Transfer is effected in the manner described in Specifications 148,292 and 154,603, [both in Class 106 (i)]. Subtraction.-Subtraction is effected by automatically adding the complement, the keyresponsive nature of the machine being automatically changed to key-set. The minus key 86, Figs. 1, 5, 7, operates a parallel motion bar 89 and link 255 and is locked down by a latch 266 engaging a dog 267, and also by a tooth 91 on a bar 92 moving with the bar 89. A projection 93 on the bar 92 prevents operation of the equals key 87 before the minus key. Key 86 rocks a lever 95, Fig. 7, clockwise so that a pawl 98, spring-pressed counter-clockwise, engages a pin 105 to rock a shaft 107, whereby lock arms 108 engage lugs 111 on all the hooks 58 to prevent their engagement with gears 73 during the subsequent setting-up of the subtrahend. Key 86 also rocks a lever 119, Fig. 15, and a rock-shaft 121 to displace bars 125, 127, Figs. 2 and 15, laterally across the machine to remove the ordinary digital stop bars 112 from alignment with the stop portions of the keys 24 and to substitute nines-complemental stop bars 113 in all denominations except the lowest where there is a tens-complemental stop bar 113<1>. A slot 40 in the stem of each key 24 allows non-interference of the complemental stop bars 113, 113<1> when in inoperative position. The subtrahend is then set up, the keys being held depressed by the teeth 82 on the bar 81. Depression of the equals key 87 completes the subtractive operation. Its stem rocks a lever 128, Fig. 7, so that a pin 133 rocks the pawl 98 clockwise to disengage the pin 105, allowing the shaft 107 to return to normal position, so that the hooks 58 in those denominations in which keys have been depressed drop into engagement with the wheels 73. The lever 128 also rocks a lever 137 on a shaft 138 which carries upright arms 139 which engage pins 141 to urge forward the links 55 so as to engage the remaining hooks with the wheels 73. The gear sectors 42 are thereupon set according to the complement of the subtrahend, the complemental stop bars in which no ordinal keys have been depressed receiving the full stroke of 9 or in the units order 10 ; and this complement is added when the sectors 42 return under the influence of the springs 46. Overflow.-The usual overflow wheel 150, Fig. 1, is provided, but the usual subtraction lever is omitted, and an additional adding mechanism corresponding to the other denominations is furnished, but without the ordinal keys, the yieldable clutch and the gear 73. A lock-piece 154, Fig. 5, spring-pressed clockwise, normally overlies a pin 157 on the guide member 60 of the next lower order, and in additive operations, the overflow denomination is unaffected except by transfer. At the operation of the minus key 86, however, a pin 146 on the link 255 rocks a lever 148 bearing a pin 153 which depresses the lock-piece 154 pivoted to the guide member 260 of the overflow order, so that this member 260 is taken along with the member 60 of the lower order and as there is no yieldable clutch the associated gear sector is given a maximum movement of 9, at the end of which a pin 277 on the member 260 releases the latch 266 to allow the parallel motion mechanism and the key 86 to return to normal position. This operation can take place only when the operator has released the key 87. Key interlocks.-The projection 93 on the bar 91 prevents operation of the key 87 before the key 86, operation of which moves the bar 91 to remove the stop and, by depressing the bar 89, causes a forward-extending arm 159 on the latch 266 of the overflow order to engage a lug 161 at the end of a lever 162, Fig. 5, which rocks slightly forward. Operation of the key 87 rocks the latch 266 so that the arm 159 swings below the lug 161 and the lever 162 returns under spring action to maintain the latch 266 in inoperative position, Fig. 7, with its arm 275 to the rear of the projection 276 of the dog 267 so that the dog cannot be relatched until the bar 89 has returned to original position and again been depressed by the minus key. The machine is thus automatically reconditioned for additive operations. Specification 551,994 and U.S.A. Specifications 767,107 and 2,018,933 also are referred to.