Patent GB-819879-A (GB)
Abstract: 819,879. Calculating-apparatus. ATVIDABEKG-FACIT A.B. Oct. 15, 1956 [Oct. 14, 1955], No. 31375/56. Class 106 (1). A calculating machine, which performs multiplication automatically by the short-cut method, has a rotary actuator which during multiplication moves step-by-step from left to right, the set multiplier controlling the number of revolutions of the actuator starting with its highest order. The actuator thus steps in the same direction as in division. For multiplier digits 1-4, entries of the multiplicand (set on the actuator) into the totalizer are effected additively while for multiplier digits 5-9 (except as stated below), entries are effected subtractively. As operations commence with the highest order multiplier digit, an initial " transfer " operation is performed in the multiplier register to ensure that when subtraction takes place for one multiplier order, an additional add cycle (or one less subtraction cycle) will occur for the next higher order. The invention is applied to a machine as described in Specification 724,043 in which, to perform subtraction, the actuator is shifted laterally by a halfstep but is rotated in the same direction as for addition so that the unoperated pins of each pin-wheel are effective but not the operated pins. Subtraction is thus performed by complementary addition. The multiplier register, into which the multiplier is initially entered, comprises wheels 87 each fast with a cam having a high portion 87a associated with the zero setting, an intermediate portion 87b (digits 1-4), and a low portion 87c (digits 5-9). Levers 92 bear on the cams and their ends 92a in turn determine the positive or negative position of the actuator by engaging a stop 157a carried by the actuator for multiplier digits 1-4 or an offset stop 158 for digits 5-9. When the multiplier digit is zero, the end 92a is raised so as not to stop the lateral movement of the actuator in either position. When an end 92a does arrest the actuator, a carriage 94 on which all the multiplier register mechanism is mounted, moves slightly to the right and when the corresponding multiplier wheel 87 is returned to zero, as described below, the multiplier carriage is restored by a spring. These movements are used to control the automatic operations. During each of the repeated cycles, a shaft 160 is rotated by onethird of a revolution in one direction or the other according to whether the actuator is set for addition or subtraction. Teeth 159 on the shaft thus return the effective multiplier wheel, by one tooth at a time, to the zero position. The initial " transfer " mechanism comprises levers 148 mounted between a plate 149 and an enlarged plate-like portion of a shaft 147. Initially, this shaft, by means of a crank 155, is rocked counter-clockwise through 180 degrees to the position shown in Fig. 2, and an extension 149a of the plate 149 is shifted by a cam slot 150a in a curved plate 150 so as to move the shaft 147 with the levers 148 to the left to the position shown in Fig. 5. After the multiplier has been set in the wheels 87, the shaft 147 is returned clockwise and consequently also to the right, as in Fig. 6. During this movement, in any denomination in which the multiplier wheel 87 registers 5-9 and consequently the end 92b of the lever 92 is in raised position, the lever 148 is rocked counter-clockwise (Fig. 5) to engage, and advance by one digit, the next higher multiplier wheel 87. If a multiplier wheel is thus advanced from 4 to 5, the corresponding entries from the actuator must still be additive and, to this end, each lever 148 is shaped so that when in normal position, it arrests the end 92b of the lever 92 in the positive position, as shown in Fig. 2. When a multiplication has been completed, a clearing bar 153 is actuated to restore any operated levers 148.