Patent GB-1004383-A (GB)
Abstract: 1,004,383. Mechanical calculators. MONROE CALCULATING MACHINE CO. Aug. 22, 1963 [Sept. 7, 1962], No. 33245/63. Heading G4B. A four rules calculating machine of the ten key type has a row of decimal point type members and a pair of independently settable decimal point position selecting members which, for example during multiplication, are set to the required numbers of decimal digits (i.e. digits after the decimal point) in the multiplier and multiplicand. The members control correct positioning of the decimal points when the multiplier and multiplicand are printed, and also position the decimal point in the product through differential gearing, the number of decimal digits in the product being equal to sum of the numbers of decimal digits in the multiplier and multiplicand respectively. The machine may be of the " pin box " type or, as shown, may be provided with a selector carriage 2 (Fig. 5c) which, starting from its right-hand position as shown, is indexed stepby-step to the left under the action of a spring 75 controlled by an escapement 87, 88. At each step a sector gear 80 is rotated through a distance depending on which digit key is depressed to enter a digit in the corresponding actuator wheel 20. In the correct ordinal position the decimal key is depressed which causes a shaft 146 to be rotated until a tooth 145 connects through a rack 120r, a carriage 120 for left shift together with the carriage 2. If the number being entered is a whole number, the decimal key is not depressed, but connection of the carriage 120 to the carriage 2 occurs when any suitable function key, e.g. the multiplicand entry key, is depressed. Aligning decimal points in successive multiplicands &c. (Figs. 5b, 5c). The machine is particularly designed to perform a series of similar operations, e.g. a series of multiplications of a multiplicand having at most three decimal digits by a multiplier having at most two decimal digits to give a product having at most five (three + two) decimal digits. For the multiplications referred to above a dial 7 is rotated by hand to indicate the number three and a dial 6 is rotated to the number two. A stepped barrel 98 is rotated through the same angle as dial 7 through gears 7g, 108, a stepped barrel 97 is rotated through the same angle as the dial 6 through gears 6g, 105, 106 and a third stepped barrel 99 is rotated through an angle equal to the sum of the rotations of the dials 6 and 7 by means of a differential 112. The rotations of the barrels 97, 98, 99 cause corresponding lateral movements of sliders 65, 64, 63 along yokes 60, 59, 58 respectively, i.e. sliders 65, 64 are moved two and three steps from their normal leftmost position against the action of springs 64s, 65s and slider 58 is moved five positions to the left from its normal rightmost position. If for example a multiplicand having only two decimal digits is to be entered, the digits are entered, most significant digit first, in successive leftmost wheels of carriage 2 as it is stepped to the left until the decimal key is depressed connecting the carriage 120 for movement with the carriage 2; then the two decimal digits are entered with corresponding shifts of both carriages. Carriage 120 is now two steps from its rightmost position and the multiplicand entry key is depressed moving a stop 103 on the carriage 120 into the path of the steps on the barrel 97 and at the same time releasing the carriages 2, 120 for further left shift. Since barrel 97 has been rotated through three steps, the carriage 120 can move a further step to the left before the stop 103 engages the third step 97a on the barrel 97. Further left shift of the carriages, 2, 120, is then prevented and carriage 2 is correctly positioned above entry racks 18, i.e. as though a zero had been added to give the desired three decimal digits in the multiplicand. Similar arrangements exist using the barrel 98 to enter the multiplier, and an additional stop 104 is provided to enter a dividend in conjunction with the barrel 99. Multiplication, division, addition, subtraction (Figs. 1a, 1b).-These are stated to be performed in known manner. The multiplier or quotient is stored in gears 30 and a row of toothed actuators 26 are set to the multiplicand or divisor by rotating them through a corresponding number of teeth and then, as carriage 27 bearing the actuators is stepped transversely, a counter gear counts out the numbers stored in successive gears 30 as the actuators 26 are driven round by means not shown. A second set of actuators interspaced between the gears 26 have teeth complementary to those of the gears 26 and are used for subtraction. Printing and decimal pointing (Figs. 1a and 5b).-During the first part of a revolution of a drive shaft driven through a one revolution clutch, racks 18 are engaged with set gears 20 of carriage 2 and are moved differentially as they zero the gears. Corresponding settings are transferred from the racks 18 through gears 39, 40 to type wheels 19 mounted on pivotally mounted hammers 35. Those racks 18 which have been released cause corresponding ones of a row of pawls 48 to be pivoted clockwise (Fig. 1a into the path of a release bail 49 which is thus lifted to release corresponding locking bars 45. A restore bail 44 is also pivoted clockwise to release the hammers. Thus the racks 18 which have moved forward have set their type wheels 19 and prepared the corresponding hammers for release when firing bail 43 is released during the forward dwell of the racks 18. Mounted on each hammer, to the right of its respective type wheel, is a decimal point type member 21, normally held in an inoperative position below the level of printing. The type members are mounted for vertical sliding movement relative to the hammers 35, and are brought into operation when corresponding rockers 53 are engaged with and lifted by the bail 49 as it releases the locking bars 45. The desired rocker is moved into the path of the bail 49 by one of the three sliders 63, 64, 65 advanced by arms 67.