Patent GB-191505675-A (GB)
Title: Improvements in Adding and Subtracting Machines.
Inventor: BARR MARK
IPC: G06F7/46
Filed: 1915-04-15
Abstract: 5675. Barr, M., Bell, R. A., and Bramston, M. A. April 15. Adding and subtracting apparatus with operating- means.-In an electric independently-operated adding and subtractiug machine a group of brushes is provided for each denomination, any number of which brushes may be set to bear against one of two cylinders having groups of contacts, whereby, when the cylinders are rotated, impulses are transmitted to counters from which totals may be printed. Fig. 1 is a diagrammatic representation of a machine having a range from 0 to 9 in four denominations. A cylinder b is provided for each denomination with a set of nine contacts a arranged in staggered groups of four, two, two, and one, so that any number from 1 to 9 can be built up by connecting one or more groups in circuit. Opposite each group a is a brush or " putter " c, comprising a rocker placed on a knife-edge 9, Fig. 6, forming the central limb of an electro-magnet the outer limbs of which are constantly energized, while the direction of the current in the coil 10 may be reversed to cause the putter to rock against the cylinder b or to return to its normal position resting on the cylinder 7. In an alternative form, the central limb is constantly energized, and current is supplied to either of the outer coils. One or more of the coils 10 is energized by the making of one or more of the corresponding contacts 1, which are actuated by the numeral keys 2, Figs. 2 and 3. Each key is connected by a bell-crank lever 3 to a sliding bar 4 having one or more pins 5 and levers 6, the number and position of which are such that the values of the contacts 1 made thereby together represent that of the key depressed. Those putters opposite the groups of contacts a corresponding to the contacts 1 affected are therefore rocked on to the cylinder b, so that on rotation of the cylinder, a given number of impulses are transmitted from the contacts a, which are connected to a source of electric current to the group of putters and thence to the counting-mechanism i. Subtraction is performed by addition of the complement of the number to be subtracted, a second cylinder 7 similar to b being provided. The minuend is set up on the cylinder b in the ordinary way and, after rotating the cylinder to operate the counters and returning tte putters, the subtrahend is also set up on the cylinder b, whereupon the contacts a on the cylinder 7 are connected to the source of current and this cylinder is rotated, thereby imparting to the putters in contact with it impulses the number of which represents the complement of the subtrahend; a fixed brush 16 is employed to transmit one extra impulse to the counter of the lowest denomination in order to give the correct value of this complement. The operating or cylinderrotating means may take the form of an electromoter or of manual rack-and-pinion ratchet mecbanism. Selecting denomination.-If a typewriter is combined with the machine, denomination-selection may be by means of a d stributor operated by the typewriter carriage or the like as described in Specification 25,018/10; in other cases, any known arrangement of banks of keys may he e employed. A special distributor t is, however, shown, in which a switch arm u is moved by the typewriter carriage over contacts v, w, x, y connected respectively as shown to the four groups v<1>, w<1>, x<1>, y<1> of putter coils 10. Current is thus supplied, when certain of the contacts 1 are depressed, to the corresponding coils in one of the groups only, according to the position of the switch u, and the corresponding putters thereby rocked. In an alternative arrangement in which the denomination is determined by the sequence in which the keys are depressed, commutators 21, 22, Fig. 8, are mounted on a common spindle rotated by depression of the keys or otherwise in a step-by step manner. The segments 23, equal in number to that of the denominations, are connected one to each set of positioning-coils 14 of the various denominations, the putters being of the second type described above. In the commutator 22, there is a group of segments 24 for each denomination, the number of the first group corresponding to that of the denominations, while in the remaining groups the number is reduced by one in each group. The angular position of the segments 24 in the largest group is one behind that of the segments 23, and the segments 24 are connected to their particular denominational release mechanisms i, that is in the largest group to each device : i and in the smallest group to the units device only. Owing to the intermittent movement of the commutators, the last key of a series that is depressed becomes a units key, while each previous key value depressed moves up one denomination. Error keys and the like.-Correction of error in any particular denomination is effected by placing the switch n, Fig. 1, on the corresponding contact and then depressing a key 17, which sends a reverse current through all the coils 10 of that denomination, whereby all are rocked on to the cylinder 7, the contacts 1 being simultaneously short-circuited. In the modification shown in Fig 8, a commutator 28, having segments 29 corresponding to the number of denominations, and an equal number of brushes 30, connect correction keys 31 to coils 27 each adapted to cause its armature 32 to pass over a contact 33 so as momentarily to energize the return coils 13 of putters. If this type of putter is used in connexion with a distributor t, contacts corresponding to the segments 29 are provided on the distributor, so that the circuits of the return coils of the denomination corresponding to a given position of the arm u may be completed by depression of a special correction key. Totalizing-counters; counting-apparatus with variable-step movement.-The counters d, which may be of the type described in the above-mentioned Specification are actuated by balls released by an electro-magnetic device i, Figs. 1, 4, and 5. The balls are stored in a tube c and are allowed to fall one by one by rockers k, l actuated by the attraction of an electro-magnet i for its armature (not shown). The rockers comprise D-shaped rods so proportioned and arranged that, when the rod l rocks to pass the lowest ball, the rod k projects to stop the next. The balls, as dropped, are held up in the tube q by a bar r adapted, when the proper number has been dropped, to be shifted by a coil s excited by the movement of the switch u on the contact v, so that the balls fall through an aperture in the bar r. Instead of the mechanism described, an electromagnetically - controlled toothed wheel may be arranged to project into the tube e to drop the balls singly. Transfer mechanism.-All the counters d, except that of the highest denomination, may be provided with a " carry point " contact o, by means of which, when each counter reaches its maximum, an impulse is sent to the counter of next-higher denomination and a ball thereof accordingly dropped. Or the zero contact may be employed as carry point, in which case a recess 19, Fig. 4, is provided in the bar r to reject the first ball dropped. Printing totals.-To print the total, the distributor t is employed by setting the typewriter carriage to the highest-denomination and pressing a result key 35, whereupon the contacts v, w, x, y come successively into the printing-circuits, and the typewriter space key is suitably operated. This arrangement may be modified to co-operate with the alternative denomination-selecting mechanism described above.