Patent GB-1241487-A (GB)
Title: Improvements in or relating to calculating machines
IPC: G06C1/00
Filed: 1969-10-30
Abstract: 1,241,487. Mechanical calculators; transfer mechanisms. TOPNIT. 30 Oct., 1969 [6 Nov., 1968], No. 53158/69. Headings G4B and G4D. A calculator comprises a housing 1 with two sets of windows 2, 5, for an operand and result respectively, each window of the operand having an associated slide 33, operable by a projection 3, with an attached sprocket 20 which slides axially on a drive shaft 11, 11a and engages with axially staggered ribs 15 on a drive shaft 10, 10a operated through bevel gears 18, 43 by a crank 7, 9; a digit 34 is displayed in each oper- and window by movement of the associated slide 33 which also position its sprocket 20 so that one rotation of the crank 7, 9 rotates the drive shafts 10, 10a one revolution and indexes the sprockets and driven shafts 11, 11a angular amounts according to the slide positions, thus registering in the result windows corresponding digits 24 on dials 23 attached to the driven shafts. The bevel gears 43 have teeth over only half of their peripheries but have pitch circles double those of the gears 18 so that one revolution of the crank 7, 9 produces one revolution of the drive shafts 10, 10a, but the drive shafts are operated during half of the rotation of the crank, lost motion couplings 41 stagger the drive shaft rotations slightly, during crank operation. Carry mechanisms.-Carrying of a number from a denomination to a higher denomination is achieved by a projection 27 on the dial 23 engaging a dog 31 on a pivoted lever 28, depressing the lever and displacing a sprocket 21, axially slidable on the driven shaft 11 of the adjacent dial, so that it is contacted by a tooth 17 on the end of the associated drive shaft 10, and moved one digit. Carrying of a digit through a number of denominational orders is facilitated by the staggered rotation of the drive shafts. A pair of the teeth 17 are provided at the end of each drive shaft 10 so that one tooth of each pair operates the sprocket 21 according to the direction of rotation of the drive shaft during addition or subtraction operations. Replacement of the sprocket 21 to a position out of line of the teeth 17, as shown, is achieved by a projection 16 on the associated drive shaft 10 camming a dog 32 on the lever 28. The dials 23, drive shafts 10 and slides 33 are retained in their index positions by leaf springs 16, 14, 36 respectively. Operation.-The slides 33 are positioned to indicate in windows 2 the required operand. One clockwise rotation of the crank 7, 9 causes the drive shafts 10, 10a to rotate one revolution, in turn causing the driven shafts 11, 11a to rotate angular amounts according to the operand digits, thus transferring the operand to the result row of windows 5. For addition, the number to be added to the first number is indicated in the operand windows 2 and the crank 7, 9 is rotated clockwise one revolution, the result appearing in the result windows 5. For subtraction, the numbers to be subtracted from the first number is indicated in the operand window 2 and the crank 7, 9 is rotated anticlockwise one revolution, the result appearing in the result windows 5. For multiplication, the operand is indicated in the operand windows 2, and the crank handle is rotated clockwise a number of times representing the number to be multiplied with the operand, the result appearing in the result windows 5.