Patent GB-320315-A (GB)
Title: Improvements in and relating to means or apparatus for coding and de-coding messages
IPC: G09C3/00
Filed: 1928-04-04
Abstract: 320,315. O'Brien, M. C. M. April 4, 1928. Machines for coding and decoding; hammer-impression arrangements; typewheel actions.-A coding and decoding machine is provided with a series of type-wheels above which is traversed a movable printing-carriage carrying an impression hammer and strip feeding and ink-ribbon mechanism, and means adapted to be brought into co-operative relation with the type - wheels is so arranged that the action of returning the carriage effects a " scattering " or rotary redistribution of the type-wheels and their corelated parts. A stationary carriage carrying an impression hammer &c. is arranged above other type wheels to effect the printing in clear text of the message which is simultaneously printed in cipher. The machine is key-operated, and the key levers 45, Fig. 5, co-operate with an universal bar 44 connected to a vertical rod 74, Fig. 2, provided with cam surfaces 73, 75, 76. In the downward movement of the rod 74 the cam 75 thereon engages a projection on a cam 67 mounted on a square shaft 17 and turns the latter against the tension of a spring 68, and at the same time the cam 73 on the rod 74 allows a pivoted detent 70 to be pulled by a spring 72 into engagement with a projection on the cam 67 to hold spring 68 in tension. On the next depression of a key the rod 74 is moved upwardly, the detent 70 is tripped, and the square shaft 17 is rocked, thereby actuating cam and ratchet devices which operate the impression hammer and effect the feeding of the paper strip and ink-ribbon mechanism. The cam 76 on the rod 74 actuates the escapement 77 of a ratchet wheel 78 on a shaft 19 carrying a series of irregularly gapped wheels 27, Fig. 1, the teeth 28 of which coact with a pawl or stop 14 extending downwardly from the movable carriage. During typing, the shaft 19 with the gapped wheels 27 is rotated intermittently, and the carriage 3, impelled by a spring drum in known manner, travels from the front to the rear of the machine, its progress being controlled by the engagement of the stop 14 with the teeth of successive wheels 27. The key levers 45, Fig. 5, are each provided at their rear ends with a carn face 47 which co-operates with a universal bar 46 at the lower end of a frame 48, Fig. 2, pivoted to swing between lateral supports 60. When a key is depressed the frame 48 is swung on its pivots and a slotted block 50 at its upper end is moved along a helical member 51 which is rotatably mounted and carries a gear wheel 52 engaging a gear wheel 33<a> secured coaxially to the type-wheel 32<a> which prints the clear text corresponding to the key depressed. The gear wheel 52 also engages a gear wheel 88, Fig. 2, on a square shaft 25 which is parallel to a shaft 20 carrying loosely a series of type-wheels 32 and is mounted upon a rocker frame 26, Fig. 1, pivoted on a shaft 22. The rocker frame remains in its lower position during ciphering. A gear wheel 36 slidably mounted upon the square shaft 25 and rotatable therewith is moved intermittently along the shaft by a lug 18 secured to the movable carriage, and during typing is brought into engagement with successive gear wheels 34 mounted in engagement with gear wheels 33 secured coaxially to the respective typewheels 32, which however are rotatably " scattered " or distributed before typing begins, by means of a series of " scatter wheels " 39 mounted on the rocker frame 26. The "scatter wheels " 39 correspond in number to the typewheels 32 and are arranged in integral sets of six upon a shaft 24 mounted within the two ends of the rocker frame and extending the full length of the machine. The peripheries of the "scatter wheels" 39 are provided with irregularly-spaced sets of teeth adjacent to cam faces 40 extending a corresponding distance around one side of the wheels and, in the action of returning the carriage 3 to the front of. the machine by pulling upon a lever 13. the rocker frame is first lifted to bring the teeth of the " scatter wheels " into engagement with the gear wheels 34 which mesh with the gears 33 on the type-wheels. Gear wheels 37 mounted on the rocker frame in engagement with the scatter wheels 39 are also brought into mesh with gear wheels 30 on the shaft 19, and detents 31 are operated to connect the wheels 30 to their adjacent rack wheels 27. During the returning of the carriage rotation is imparted to the shaft 24 of the " scatter wheels " 39 by a gear train driven by a sprocket wheel 78<1>, Fig. 3, (not shown) actuated by a chain which connects the movable carriage to its driving-spring. The gear wheels 34 are normally held against rotation by pawls 35 which, however, are released during the periods that their lower ends are engaged by the cam surfaces 40 on the " scatter wheels "39, and are released when the lug 18 on the travelling carriage strikes a lateral arm 35<b> thereon. The typewheels 32 are thus re-distributed in a manner determined by the setting of the " scatter wheels." Two separate settings of the "scatter wheels" are arranged for, namely a " zero " or initial setting which may remain unaltered, and a " message setting " or key-word particular to each message sent. The " zero " setting is effected with the rocker frame in its lower position. In this position a gear wheel 55<a>, Fig. 3, (not shown) on the rear end of the shaft 24 is engaged by the first wheel of a set of five gear wheels each of which is secured to a dial wheel 63<a>, Fig. 7, provided with indicia around its periphery and is mounted loosely on a supporting shaft. A knob 59 at the front end of shaft 24 is then rotated until the desired character on the first dial is opposite an index mark, a corresponding rotation being transmitted to the first set of " scatter wheels "39 by a radial dog 42, Fig. 5, on the shaft 24 engaging gear teeth 41 on the inside wall of the " scatter wheels." The shaft 24 is then moved longitudinally by rotating a shaft 58 disposed at right-angles to it and carrying a gear wheel 57 meshing with a grooved portion 56 of the shaft 24, thus bringing the gear wheel 55<a>, Fig. 3 (not shown), into engagement with the gear of the second setting-dial, and bringing a dog 42 on shaft 24 into engagement with the teeth 41 within the second set of " scatter wheels " 39. The successive letters of the 11 zero " setting are thus set upon the dial wheels 63<a>, with a corresponding setting of the " scatter wheels " 39, after which the shaft 24 is again moved longitudinally to disengage the gear wheel 55a. The " key word " of a message is set up in a similar manner through a gear wheel 55 on shaft 24 controlling a group of dials 63, Fig. 7, at the front of the machine, after the carriage 3 has been returned to the front and while the rocker frame is still in its raised position, the " scatter wheels " 39 being then engaged with the type-wheels 32 through the gears 34, 33. The frame 26 is lowered before ciphering commences, by operating a catch 13<b> on the front of the machine. Before setting the machine in a condition to cipher or decipher a revolution counter 89 at the front of the machine is first zeroized. Tn deciphering a message the " message setting " dials 63 are first set to the key word, and the keys are actuated to type the ciphered message on the tape of the type-wheel 32<a> of the fixed carriage, the clear text then being typed on the tape of the movable carriage. To control the frequency of vowels in a ciphered message each type-wheel is provided with two bands of characters, one consisting of the five vowels repeated four times, and the other consisting of the consonants. A small shift movement may be applied to both carriages, or a slight longitudinal movement may be imparted to the type-wheel shafts by a device common to the vowel key-levers. Line-spacing mechanism.-The grouping of a message into five or ten-letter groups is effected by increasing at intervals the extent of the feed of the paper strip, which is controlled by a rocking-lever 10, Fig. 1, actuated by the oscillation of the square shaft 17. The lever 10 is connected to a pivoted plate carrying a pawl 12 engaging a ratchet wheel 6<a> on one of a pair of co-operating strip-feeding rollers, and an arm carrying a pawl 11 is connected to the lever 10 and engages a ratchet wheel 8 on an ink-ribbon spool 7. To divide a message into ten-letter groups the lever 10 engages a ten-toothed ratchet wheel on the shaft 17, one tooth of the ratchet being higher than the others at one part of its width so that it imparts a greater movement to the lever. By moving the lever laterally the engagement with the higher part of the tooth is not obtained, and the strip is fed uniformly.