Patent GB-439745-A (GB)
Title: Improvements in signal-recording mechanism for start-stop telegraph systems
IPC: H04L17/00
Filed: 1934-06-19
Abstract: 439,745. Type printing telegraphy. GRIFFITH, R. G., Montclair, Crewes Avenue, Upper Warlingham, Surrey. June 19, 1934, Nos. 18092 and 32521. [Class 40 (iii)] In a start-stop transmitter or receiver the cam shaft controlling the selector mechanism for the combination impulses completes its rotation during the time occupied by those impulses and is stationary during the transmission and reception of the start and stop impulses. Transmitter, Fig. 2. When a key 4 is depressed a frame 7 individual to that key is lowered so that its projections 9 tilt the vanes 10 in accordance with a code combination. These vanes transfer the combination to a set of five permutation frames 98 by raising or lowering these. Every key also tilts the trip vane 100 and so lowers the trip frame 99 which trips the latch 104 and so starts the shaft 15. The cam 16 thereon causes a transverse bar 22 to move forward against pointed projections 25 which ensure that each permutation frame 98 shall move definitely to its upper or lower position. The cam 16 also causes five feelers 21 to be advanced against the frames so that they may coact with upper projections 13 and lower projections 14 thereon and acquire positions representing the code combination. The feelers 21 act through bell-crank levers to set up the combination on five selector bars 27, so that the tails 28 of these bars shall or shall not come over the ends 29 of the selecting-levers 30a; the latter of the two states is shown at 28<c>. A cam 106 now acts to trip a catch 3a so that camshaft 1 is started. The selector levers 30a are in turn lifted by the cams 2<a>. If their ends 29 are held by tails 28 they lift the bar 33, but if not the bar 33 is pulled down by the action of spring 35 ; and in every case the bar is so pulled down for the start impulse governed by the first selector lever 30 and cam 2. The bar acts through a bell crank 43 to determine the axial position of a shaft 38 ; this shaft is geared up from the crank-shaft 1, with which it remains in gear in both positions, and carries a cam 39. In one axial position of the shaft 38 the cam 39 engages one horn 40 of lever 42, and in the other axial position it engages the other horn 41. The lever 42 operates the contacts 45 to send the required combination to line. The contactactuating shaft 38 is geared up from the cam shaft 1 in such a ratio that it makes half a revolution for each impulse, including the start and stop impulses. Receiver, Fig. 3, starting. At the receiver the start signal causes the magnet 48 to attract its armature so that a projection 50 thereon acts through bell crank 82 to trip the catch 81 and start the starter shaft 79. Thereafter the cam 85 acts to shift the foot 83 of the bell crank 82 out of the way of the projection 50 so that subsequent movements of the armature shall not be interfered with by the crank 82. The main camshaft 53 is in turn started when a plate 90 trips a catch 95, the plate 90 being itself actuated by a cam 89 on the starter shaft 79. The phase of the starting operation can be adjusted by shifting the mounting of the plate 90 around the axis of the starter shaft 79. Receiver, Fig. 3 ; setting of permutation bars. The permutation bars 76 are set to right or left, in turn, under control of the successively acting cams 77 which act upon projections 78 formed on pairs of vertical levers 71, 72. When the cradle 68 is in the position shown it constrains the lower ends of vertical levers 71 so that any such lever acted upon by a cam 77 moves a corresponding permutation bar 76 to the left, its lower end being held by the side member 69. When, however, the cradle has been tilted counter-clockwise the lower ends of levers 71 are left free and those of the levers 72 are constrained, so that in this case that cam 77 which is in action causes the corresponding lever 72 to move the permutation bar 76 to the right. The setting of the bars 76 is thus determined by the tilting of cradle 68, and this in turn is determined by the signal impulses in the following manner. When magnet 48 is attracting its armature, hook 51 on that armature lies in the path of pin 62 on shaft 55, and so forces that shaft axially to the right; but when the armature is in the released position, hook 65, which is in a different place from hook 51 and is controlled by spring 64, forces shaft 55 axially to the left. According to the axial position of the shaft, cam 58 engages one or other of the arms 59, 61, of a rocker which thus tilts the cradle 68 to one or other position. The permutation-setting shaft 55 is geared up from the camshaft 53 so that it makes three revolutions during the receipt of a character signal, which occupies half a revolution of shaft 53. Modifications of details relating to the setting of the pins 62 by the armature 49 are described in the Specification.