Patent GB-248601-A (GB)
Abstract: 248,601. Ekman, A. May 21, 1925. Adding and subtracting apparatus; governing speed of operation; overthrow-preventing mechanism.-A differentially set machine of the type having a plurality of independently rotatable computing units operable in either direction of rotation comprises means for checking and governing the speed of rotation when this exceeds a predetermined amount. Means are described for effecting transfer, and for zeroizing the numeral drums. As shown in Fig. 4, the end plates 15, secured to the base plate 1, support a shaft 17 carrying a number of independent hubs 26, Fig. 7, to which are attached at one end the, sheet metal numeral drums 27 with integral finger depressions on an extended flange 29. Integral with each numeral drum is a gear wheel 30, and loosely mounted at the same end of each hub is a plate 31 provided with a rearwardly extending tongue 33, Fig. 9, and a depending curved arm 34. The tongues pass between cross bars 21, 22 on balanced arms 19, 20 pivotally mounted on the ends of the shaft 17 and maintained in contact with the tongues by a spring 70. The cross bars 21, 22 are mounted for limited movement between projections 24, 25 nn the end plates 15. Each arm 34 is provided with a pin 35, Figs. 3 and 9, on which is mounted a triangular shaped member 36 and a pinion with toothed portions 37, 38. The teeth 37 gear with the wheel 30 while the teeth 38 are in alignment with the transfer teeth 40 of a disc 39 secured to the adjacent end of the next lower computing unit whereby the transfer is effected. Each triangular member 36 co-operates with the channel-shaped end 60 of a corresponding spring- controlled bell-crank lever 64, 65 mounted on a shaft 58. The bell crank levers are arranged with the upper arms 64 passing between the teeth of a comb on the end of a plate 59 pivoted on the shaft 58 and with the lower arms passing through slots in the horizontal portion 60 of the plate 59. For each numeral added the triangular member 36 is arranged to change one side to that next succeeding against the member 69, the action being completed, if necessary, by the spring 67 of the bell-crank lever 64, 65. If the speed of operation is too great the friction produced tends to rotate the plate 31 so as to lift the tongue 33 until the cross-bar 21 strikes the projection 24 and the triangular member 36 engages the forwardly bent part of the channel end 69, thereby forcing back the arm 64, as shown in Fig. 12, to check the movement whereupon the spring 70 reasserts itself. Finger stop bars 13, 14 are provided at the lower and upper ends of the slotted portion 7 of the casing. The slots have complementary sets of numerals arranged alongside and subtraction is performed by merely reversing the direction of rotation of the numeral drums. Zeroizing mechanism.-The numeral drums are reset by the depression of an operating lever 57 having a toothed sector 53 gearing with a sector in an arm 44 mounted on a shaft 43. The arm 44 is connected to a similar arm 44a by an angle bar 45, 46 which is provided with a number of arms 47 with bent ends adapted when raised to engage tongue portions 41, 42 laterally struck from the transfer tooth discs 39 and effect the return of the numeral drums.