Patent GB-550495-A (GB)
Title: Improvements in or relating to apparatus for selectively positioning a typewheel
IPC: H04L17/26
Filed: 1941-07-07
Abstract: 550,495. Printing-telegraphs. CREED & CO., Ltd., and SALMON, R. D. July 7, 1941, No. 8566. [Class 100 (iv)] [Also in Group XL] In apparatus comprising a type-wheel which is selectively positioned under control of a rotatable member or members having rows of stops co-operating with a code-controlled detent' or detents, one or each of the members has a number of separate rest-positions, preferably two positions separated by an angle of 180 degrees, and is allowed to rotate through the angle of separation or is prevented from rotating in accordance with the relation between an element of the code and the rest position. The arrangement enables the speed of the members, and consequently the shock of arrest, to be considerably reduced, since the type-wheel is not returned to an invariable standing- position. In the construction shown in the Provisional drawing, the type-wheel shaft 2 is provided with stop-arms 5, 6 arranged 180 degrees apart and co-operating with a detent 13, selecting-arms 7, 8 arranged 180 degrees apart and cooperating with detents 16, 17, and selecting-members 9, 10, 11, 12 having two, four, eight, and sixteen arms cooperating with detents 18, 19, 20, 21 respectively. The detent 16 carries a pivoted arm 23 which co-operates with a cam 24 and has a finger 25 co-operating with a latch 26 which is carried by a bell-crank 32 and co-operates with a cam 30. A similar set of parts is associated with each of the other detents 17 .. 21, those for the detent 17 being numbered 42, 45, 41, 39, 44, 49. A frame 28, pivoted on a rod 38 and constituting the armature of a magnet 29, has a projection 27 co-operating with the latch 26, and co-operates directly with the other latches 39 ... The typewheel is retained in either of two positions, 180 degrees apart, by engagement of the detent 13 with the arm 5 or 6, engagement being maintained by a bail 14 in the path of the detent. The bail 14 is so arranged that operation of any of the detents 16 .. 21 depresses the bail sufficiently to release any previously-actuated detent. When the first unit of the code is received, a cam 37 depresses the armature 28 and if no current is flowing in the magnet, the armature returns and engages the latches 39 ... and the projection 27 clears the latch 26. Thereupon, the latch 26 is slightly rocked by the cam 30 and maintains engagement with the finger whilst the latch 39 is rocked out of engagement with the finger 41, and the arm 42 is raised by a spring 43. Next, the cam 24 causes the arm 23 to move the detent 16 into the path of the stop-arm 7 and depress momentarily the bail 14. Thereupon, the detent 13 is released by a spring 15 from the stop-arm 5 or 6, and the detent 16 and stop-arm 17 permit the type-wheel shaft to turn very slightly or through 180 degrees according as to whether the stop-arm 5 or 6 is in position. If current is flowing in the magnet when the armature 28 is depressed by the cam 37, the armature is held down, the detent 16 is rendered inoperative, the detent 17 co-operates with the stop-arm 8, and the type-wheel is permitted to turn very slightly or through 180 degrees according as to whether the stop-arm 6 or 5 is in position. The second ... fifth units of the code control the detents 18 .. 21 in the abovedescribed manner. At the end of one revolution of the cam-shaft 1, a cam 34 depresses a restoring- bail 33 for the arms 23, 42 .. , a pin 35 on the bail depresses the bail 14, the detents 16 .. 21 are restored, and the type-wheel shaft rotates until the detent 13 engages the arm 5 or 6. The detents 16 .. 21 may be controlled in the manner described in Specification 529,983 by key-operated combination-bars. In the alternative construction shown in Fig. 1, the shaft 2 of the type-wheel 147 is provided with stop-arms 5, 6 selecting arms and members 7 .. 12, detents 13, 16 .. 21, and a bail 14 having the abovedescribed functions. The detents 16 .. 21 are now associated with translating-mechanism of the kind described in Specification 245,149, [Class 100 (iv)], and .comprising sword-members 61a, 61b carried by levers 62a, 62b which are operated by cams 63a, 63b on a sleeve 1. The sword-member 61a co-operates with either detent 16, 17, whilst the sword-members 61b .. co-operate with one detent only. The sword-members abut on either of a pair of arms 64 carried by a rock-arm 66 in connection with the armature 28 of the magnet 29. If the magnet is energised when a unit of the code is received, the sword-members abut on the left-hand arm 64 and are rocked counter-clockwise, so that the sword-member can operate the detent 16, and the other detents are disengaged from the detents 18 .. 21. Similarly if the magnet is de-energised, the sword-member 61a can operate the detent 17, and the other sword-members can operate the detents 18 .. 21. The detent 12 is connected by a spring 165 to a pivoted arm 51 which co-operates with a finger 58 on a lever 59 operated by a cam 31. When the detent 16 or 17 is left in engagement with the arm 7 or 8 after all the code-units have been received, the stop arm 5 or 6 obstructs the detent, but when the bail 14 releases the detent 16 or 17, the shaft 2 moves, and the spring 165 enables the detent 13 to snap into position for engaging the oncoming arm 5 or 6. The sleeve 1 is provided with cams 27, 34, 158 for operating the armature 28, the bail 14, and a detent 160 for the arm 66 respectively. The sleeve is coupled to a driving- shaft 127 by means of a ratchet-coupling 129, 128 which is held open by a detent 143 on a rock-shaft 144 in connection with a latch 137. When the startsignal is received, the armature 28 is retracted, a finger 138 releases the latch, the detent 143 is released, and the coupling 128, 129 is closed. Towards the end of one revolution, the detent is restored by a cam 133 and co-operates with a cam-surface on the member 129 to open the coupling. Specifications 473,614 and 534,206, [Group XL], also are referred to. Case-shift'mechanism.-The type-wheel 147, Fig. 1, is secured to a sleeve 60 which is splined on the shaft 2. On receipt of the letter-shift or finger-shift signal, the shaft is set in a pre-determined position, and a projection 152 on the sleeve is placed in the path of a rock-arm 151 or 153 which is moved downwards or upwards by a cam 156 or 157 to depress or raise the type-wheel respectively. The type-wheel is locked in upper or lower position by co-operation of grooves 79 in the sleeve 60 with a roller 80, Fig. 2, on a spring-urged lever 78. Hammer-impression arrangements.-Impression is made on a pair of tapes by a hammer 150, Fig. 2, one tape 167 passing between the folds of an ink ribbon 168 and receiving an impression on the front and back, whilst the other tape passes behind the ink ribbon and receives an impression on the front. The ink ribbon is fed by the mechanism described in Specification 457,821. The hammer is secured to a shaft 97 carrying a fast arm 73 and loose arms 90, 85, the arm 85 being operated by a bail 134 which is operated by a cam 132. The arm 90 abuts on a finger 87a on a bell-crank 87 carried by the arm 85. In operation, the arm 85 rocks the arm 90 counter-clockwise in opposition to a spring 84, the arm 73 is drawn counter-clockwise by a spring 92, and the hammer is retracted. Thereupon, the bell-crank 87 abuts on a latch-member 89 and is released from the arm 90, and the spring 84 fires the hammer. After arrest of the arm 90 by a stop 93, the impression-stroke of the hammer is completed by momentum. When the shift-signal is received, the lever 78 is rocked slightly by the shift-lock roller 80, a latch 82 is released from the latch-member 89, the bell-crank 87 fails to release the arm 90, and the hammer is silenced. When the space-signal is received, a blank on the type-wheel is selected, and a pin 149 thereon rocks a lever 146 for silencing the hammer. Letter-spacing mechanism.-A feed-roller 68, Fig. 2, for the tape 167 is connected to a ratchet-wheel 69 co-operating with a pawl 70 on a bail 95 which normally abuts on a rock-arm 72. During the impression-stroke of the hammer 150, the arm 73 trips the arm 72, the bail 95 is operated by a spring 96, and line-spacing is effected. The arm 85 cooperates with a pin 71 to restore the bail and thereby retract the pawl. When the shift-signal is received, the hammer is not fired and, consequently, tapefeed is prevented. When the space-signal is received, the hammer is blocked, but tape-feed occurs in the above-described manner. If the apparatus is used for typing ciphered matter, a space is automatically inserted after each five characters by means of a pawl 115, Fig. 3, which is operated by the bail 134 and co-operates with a ratchet-wheel 114 connected to the ratchet-wheel 69 and formed with one-sixth the number of teeth on the latter. For normal messages, the pawl 115 is disengaged by means of a slotted link 113 operated by a finger-lever. When the apparatus forms part of a transmitter and receiver and a local record of the messages is not required, tape-feed is suspended and the hammer is silenced by turning a knob 126 in connection with a cam 125 for rocking an arm 120 which is arranged to displace the latch 82, the bell-crank 87, Fig. 2, being thereby prevented from releasing the arm 90. When the send-receive switch is operated, a link 118 releases the arm 120 from the latch, and tape-feed is resumed.