US2309222A - Telegraph code converter - Google Patents

Description

Jan. 26, 1943.A J. A. SPENCER TELEGRAPH CODE CONVERTER Filed March 22, 1941` 6 Sheets-Sheet l Jan. 26, 1943. v J, A, SPENCER 2,309,222

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TELEGRAPH CODE CONVERTER Filed March 22, 1941 6 Sheets-Sheet 4 .INVENTOR ,mmm ,4. .mf/wip BY MKM Jan. 26, 1943. J. A. SPENCER f TELEGRAPH CODE CONVERTER Filed March 22, 1941 6 Sheets-Sheet 5 INVENTOR. d10/Nif 4. JPENC'-'i Jan. 26, 1943. J. A. SPENCER TELEGRAPH CODE CONVERTER 6 Sheets-Sheet 6 Filed March 22, 1941 ATTORNEY Patented Jan. 26, 1943 TELEGRAPH CODE CONVERTER James A. Spencer, Teaneck, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application March 22, 1941, Serial No. 384,663

(Cl. P18- 70) 8 Claims.

This invention relates to mechanism for converting ycode signal units of one system into those of another system.

In my Patent 2,228,417, issued January 14, 1941, I rdisclosed apparatus for converting signal characters of one type of code into those of another type and particularly illustrated therein means for converting variable-length cable code signals into five-unit uniform-length Baudot code signals, so that a tape perforated with the received cable code signals could be run through a mecha.- nism to transmit signal pulses corresponding to the Baudot code.

It is an object of this 'inventionto convert signals of one system of equal-length code units into signals of another system of equal-length code units.

Another object of theY invention is to provide receiving mechanism that will permit the use of a five-unit code printer with a seven-unit code transmitter.

Another object of the invention is to provide means for converting seven-unit equal-length code signals into five-unit equal-length code signals.

Other objects of the invention will appear in the following description, reference being had to the drawings, in which: v

Fig. 1 is an elevation of a device embodying my invention, the gure being broken in the middle.

Fig. 2 is a plan view of Fig. 1, the middle portion being broken away.

Fig. 3 is a section taken on the line 2-2 of Fig. 1.

Fig. 4 is an enlarged sectional illustration of the five-unit code transmitter taken on the line 4 4 of Fig. 3.

Fig. 5 is a circuit diagram conventionally illustrating the various units controlled thereby and their associated devices.

Fig. 6 is a diagram illustrating the slot formation in the selector levers.

Fig. 7 illustrates the seven-unit code.

Fig. 8 illustrates the five-unit code.

Fig. 9 is an elevation of the seven-unit selector mechanism with the selector bars and certain other parts removed.

Fig. l0 is a partly sectioned elevation taken along the line III-I0 of Fig. 9.

Fig. 1l is a sectional plan View of the eight pulse switch taken along the line Il-II of Fig. 10, certain parts being broken away and others being omitted.

The converter consists'of two side frames I, 2 joined by a base 3 (Fig. 1) and a top plate I.

On the plate 4 are mounted seven selector magnets 5. Each selector magnet has an armature 6 pivoted in the middle at 1, so that its remote end 8 engages (Fig. 10), when the magnet is energized, a selector bar pawl 8 and causes the end of the pawl to enter a notch I0 in its selector bar I2 (Fig. 2). As soon as the pawl is forced into the notch, the latch I3 snaps into place and holds the pawl in its operated position. Deenergization of the selector magnet, therefore, does not destroy the selection set-up.

Figs. 1 and 2 are broken away, but the arrangement will be clear, as all selector magnets and their armatures, as Well as the associated pawls and latches, are alike and are shown in detail in Fig. 10.

In the preferred seven-unit equal-length code system, each letter consists of three units, so that for each character three selector magnets are energized and three selector pawls are forced into the notches of their associated selector bars.

Each selector magnet, when energized, also forces its armature 6 into engagement with a prong I4 on'the eighth pulse cut-out shaft I5, which operates a switch I5a, -shown more clearly in Figs. 9, 10 and l1, for closing the circuit through the eighth pulse relay I5b and the localfunctions distributor LD. Relay I5b is not visible in Figs. 1 and 2, but is shown in the diagrammatic circuits of Fig. 5.V This relay closes the circuit to the eighth pulse magnet I6, shown in Fig. 1 but removed in Figs. 2 and 9. The eighth pulse cut-out shaft and switch are well-known prior art constructions and the operation of the switch thereby will presently be described in detail.

'Ihe magnet I6 has an armature I'I engaging push'rod I8, which forces the selector carriage I9 to the left when the magnet is energized. The

operated pawls 9 and the catches I3 are mounted onthe carriage so that thesepawls move their individual selector bars I2 when the carriage is moved by magnet I6. The selector pawls of the unenergized selector magnets will not be forced into the notches of their selector bars and hence their selector bars will not be moved with the carriage.

As the carriage I9 is moved by the armature of magnet I6, it engages the screw I9 on the selector bar return lever 20 pivoted at 2l (Fig. 2). At its extreme movement the return lever engages the projection 22 on trip latch 23 and disengages its catch from lock arm 24 (Fig. 1). Spring 25 forces this lock arm into engagement with the lip 26 on return lever 20 when the eighth pulse magnet I6 is de-energized by the carriage projection 26a engaging the eighth pulse cut-out switch arm 26e. This rotates the bell crank lever 26o, 26d around pivot 26e and opens the switch |5a (Figs. 9, 10 and 11) de-energizing the eighth pulse relay |5b as well as the eighth pulse magnet |6 (Fig. 5). The de-energization is shown as being produced by a separate switch 26h in Fig. 5, to simplify the diagrammatic illustration in that figure. As soon yas the switch arm 26e is moved as described, the projection on 26g moves to the right in Fig. 11 under the force of spring 26h attached to the end of the arm 261' on cut-out shaft I5, the end of the spring being visible in Fig. 9. The circuit of the eighth pulse relay is thus held open by 26g after the carriage is returned and until another selection is made, whereupon the cut-out shaft I5 will be rotated counter-clockwise in Fig. 10. This will move the arm 26g to the left and the switch arm 26o is rotated to closed position shown in Fig. 1l. This rotation is produced by the tension of the spring blade 26j or equivalent means.

When the return lever was moved to the left as first described, (Fig. l) lock arm 24 held the return lever in the operated position while the carriage i9 returned to the right. Just prior to this time the selector bar detent spring 21 (lower left in Fig. 2) snapped into the righ-hand notches 28 of the operated selector bars and retained them in operated position while the carriage returned. The selector mechanism shown herein is of a well-known type used in synchronous printers and the operation is more fully described in my application filed January 2l, 1939, Serial No. 252,119, allowed August 21, 1941.

When the return lever 2U moved to the lefthand position in Fig. 2, projection 29 thereon moved away from spring switch blade 30 and this switch blade, biased to closed position, moved to the rear as shown in Fig. 2, until its contact engaged the contact on the other switch member 3|. This member 3| is shorter than the spring switch member 30 and the projection 29 moves out of engagement with the member 30 but clears the shorter member 3|, shown therebeneath in Fig. 2. The switch is diagrammatically shown in Fig. 5. The contacts on switch members 30, 3| close the circuit to the relay 3|a, which in turn closes the switch to the larger solenoid 32 and closes its own holding circuit. The structure of this solenoid 32 is shown in Fig. 3. This relay is not visible in Figs. 1 and 2, being hidden by the other parts. It may be placed in any location, however.

The solenoid 32 is of the shell type, having a movable core 33, pivoted to an arm 34 fastened to the operating bail 35. This bail has a projecting member 36 which engages the lock restoring arm 31, to which the lock arm trip latch 23 is pivoted (Fig. l) Near the top of the stroke of the member 36, spring 38 forces the lock arm trip latch' 23 above the catch on lock arm 24. At about the time the operating bail engages the limit stop 38a at the upper limit of travel, the adjustable screw 39 thereon opens the solenoid break switch 40, which de-energizes the relay 3io, and the solenoid 32. Spring 4| then pulls the operating bail down to its inoperated position shown in Fig, 1;

As the projection 36 of the operating bail 35 moved to the inoperated position after de-energization of the soilenoid 32, it engaged the lock restoring arm 31, forced it downwards on the return stroke and brought trip latch 23 into engagement with the catch on lock arm 24. This movement released the arm 24 from the catch 26 on the selector bar restoring lever 20 (Fig. 1). Spring 42 (Fig. 2) acting on return lever 20 then forced the selector bars l2 to their original right-hand position. Also, the printing relay switch 30, 3| was opened by the return movement of the projection 29 on the restoring arm.

Vertical bars 45 are pivoted in the comb 46 and the upper ends a're aligned by comb 46a and positioned adjacent the slotted edges of the seven selector bars |2 by the roller 41 on the operating bail (Figs. 1 and 3). The comb 46a is broken away at the left side in Fig. l so as not to obscure the switch 4|). Only five of the twenty-nine bars are shown in Fig. l. The others are removed for clarity of illustration. The slots in the selector bars are shown in Fig. 5 but not in Fig. l. Five selector bars 48, having aligned back slots (Figs. 3 and 4) for receiving a special lock bar 49, are positioned beneath the seven selector bars. Springs 50, having opposite ends fastened to the sides of notches in bar.; 45 and 49, hold them in engagement with the roller 41 (Fig. 3). The five selector bars 48 are held from transverse movement until the bar 49 is moved from the position shown Each of the bars 48 has notches 59a, into which project one of the ve locking levers 5| of a modified five-unit transmitter (one only being visible in Fig. 4), such as is found on the teletype start-stop typewriter transmitter shown in Patent 1,595,472, issued Aug. 10, 1926 to H. L. Krum. Each of the ve locking levers 5| is adapted to engage the end 53 of one of five contact levers 54a to 54e, inclusive, pivoted at 55. (Figs. 3, 4 and 5). Each of these contact levers has cam projections 56 engaging the periphery of one cam of the five cam discs, each having a notch 58. The five transmitter cam discs engaging the projections 56 are rigidly clamped to the hollow shaft 59 and the notches are so spaced around the shaft as to produce the usual five signal pulses of the standard teletype apparatus in proper time-relation, as indicated diagrammatically in Fig. 5 and structurally shown in Fig. 4. When the cam projections 56 enter the notches 5B, the switches 59a to 59e are closed by the spring action of the switch blades 60. Only one switch is visible in Fig. 4, but all flve have been indicated diagrammatically in Fig. 5. It is the selective closing of the contacts 59a to 59e that sends the pulses in proper time-relation over the line L (Fig. 5) to the printer (not shown), which may be in the same room or at any desired distance from the five-unit transmitter, as will be appreciated.

The sixth cam operates the usual start-stop switch lever 54j which opens start switch 59j (Fig. 5) as soon as its cam projection rides out of the notch in its cam, which it does as soon as the cam assembly starts each revolution.

The seventh cam operates switch lever 54g and opens the switch 59g in the circuit of the selector bar return magnet 60a at the start of each revolution when its projection rides out of the notch in its cam.

Lock loop 6| (Fig. 4) pivoted at 62 between the sides 62a (see also Fig. 3) has a roller 63 engaging a cam projection 64 on a disc fastened to the shaft 59. The locking loop 6| is adapted to be moved as soon as the cam discs in the shaft start rotating in the direction of the arrow to hold the locking levers 5| either in the operated or inoperated position, as the case may be. The operated levers 5| will be located on the right The magnet 69 attracts the pawl 65 when it is energized and thus permits the shaft 59 and the assembly of cam discs to start and, conversely, the de-energization of the magnet permits the pawl to stop the rotation of the shaft at the end of each revolution. This magnet and pawl thus take the place of the usual throw-out lever and stop arm in the standard form of five-unit typewriter transmitter such as shown in said Patent 1,595,472.

Since Fig. 4 is a section, the front side plate 62a is not shown in that figure. The pivot rod 13 of the locking levers 5I, with appropriate spacers, extends across from one side 62a to the other. The unit is maintained in rigid form by crossplate 14 extending from one side to the other. Pivot rod 55 also extends across between the two sides of the transmitter with appropriate spacers to pivot the seven contact levers 54a to 54g in position.

The switch blades 60 (Fig. 3) of the seven switch contacts 59a to 59g (Fig. 5) are mounted on insulation strips fastened to the cross-plate 15 extending from one side frame to the other. Five individual springs 11 have one end fastened to each of the locking levers 5I and the other end to a pin extending from one side of the cut-out portion 16 to the other. There are no locking levers for switch levers 54) and 54g.

The magnet 59 is energized at about the extreme movement of the operation bail 35 by closure of the switch contacts 18 (Fig. 3). An insulated block on arm 34 of the operating bail has a screw 19, which is adapted to engage the upper spring switch blade.

The five-unit transmitter shown in Fig. 4 is r0- tated by any appropriate motor 80 secured to the base of the angle 1I or in any other way. This motor, through a pinion 8|, rotates the worm gear 82 or other appropriate reduction gearing fastened to shaft 83 (Fig. 3), which extends through the hollow shaft 59. This shaft is Journaled in the sides 62a and forms a bearing for the shaft 83.

A clutch member 85 is slidably keyed to the shaft 83 and is pressed by an appropriate spring 88 against. the other clutch member 81 rigidly fastened to the hollow shaft 59. Thus, the hollow shaft 59 is rotated by the motor 80 through the friction clutch for one revolution, after the pawl 55 has been removed from contact with the notch in cam 61 by momentary energization of magnet 59. At the end of this revolution the pawl 85 again stops the rotation of shaft 59 and its connected cams. The friction clutch may be replaced, if desired, by a tooth clutch, as in the usual teletype transmitter.

The motor 80 may have the usual speed control (not shown) for keeping its speed suitably constant. This speed should be such that the shaft 83 will be rotated a trifle faster, say 10%, than the distributors SD, LD (Fig. 5). Thus, at the beginning of each revolution ofthe shaft, 59, the nine cams start in synchronism with the distributor.

The seven-unit and ve-unit code bars I2 and 48, respectively, may be notched in any desired way, but in Fig. 6 I have illustrated in diagrammatic form one way for accomplishing the desired action with the codes indicated in Figs. '1 and 8. I have shown in this diagram only twenty-nine bars 45 for a code consisting of the lower and upper case characters customarily used, but, of course, any other group and arrangement may be employed. In Fig. 6 the seven selector bars I2 and the five selector bars 48', when operated, move from right to left asin Fig. 1.

The operation of my improved converter will now be given, referring more particularly to the diagrammatic illustration in Fig. 5. In this figure the mechcanical parts are shown in light lines, but in certain cases they have been conventionally shown and are not of the exact form shown in the other figures. Also, the selector bars I2 and 48 are shown in side view at the bottom of the figure and are again shown at the middle top in end view. This duplication of parts in the same figure enables one to readily understand the entire operation from Fig. 5 alone.

Let it be supposed that the message characters 25 shares are being transmitted by the distant seven-unit transmitter (not shown) and the seven-unit pulses are being received by my converter from the signal distributor SD. It will also be assumed that the previous character transmitted was a letter, or lower case character. Therefore, before transmitting the pulses for the character 2, a figure shift code will be sent by the distant transmitter. In accordance with the standard seven-unit code, shown in Fig. 7, where dots indicate current pulses, this will consist of pulses in the third, fourth and fifth position of the seven-unit cycle. The third, fourth and fth selector magnets 5 of Fig. 1 will be energized. Only one of these appears in Fig. 5. The catches 9, will then enter the notches of their respective selector bars. This also will close switch I5a and the eighth pulse relay I5b will be energized when the brushes 88 later engage segment No. 8 on the local distributor LD of the assumed multiplex system. This energizes the eighth pulse magnet I6, which moves the carriage I9 and the third, fourth and fth selector bars I2 to the left through Lengagement of the pawls 9 on the carriage with the notches IU in their respective selector bars.

When the carriage reaches the end of its lefthand motion, it will engage the screw I9' and move the selector bar return lever to operated position. At about this time, projection 26a on the carriage opens the switch 2Gb of the eighth pulse relay and the eighth pulse relay and the magnet I6 are cle-energized. In actual construction, as already explained, switches I5a and 2Gb are one and the same switch, but for simplicity of illustration they are shown as two switches in Fig. 5. The de-energization of magnet I8 returns the carriage `to the right under influence of spring 44 (Fig. 2). The return lever 20 is locked in operated position by lock arm 24 and the third, fourth and fifth selector bars are retained in operated position by snap catch 21.

When the return lever 20 reached its extreme movement to the left in Fig. 2, switch blades 30, 3| closed the Contact to the relay 3Ia of the operating magnet 32. Operating bail 35 and its connected parts were thus rotated nclockwise around its central pivot 89 and roller 41 entered the notches in the levers 45. Springs 50 tend to rotate the bars 45 clockwise, but only Vthe lever having a straight line of slots therebeneath can be moved by its spring. In the diagrammatic illustration of Fig. 6, the dark portions represent uncut edges of the selector bars and the white portions the slots.

As stated, the fourth, fifth and sixth selector bars I2 will be moved to the left by the gure shift signal and this will bring a straight row of slots in all the seven-unit selector bars beneath the figure bar 45, which is the second bar from the right in Fig. 6. No other bar of the twenty-nine shown in this figure will have a clear row of slots, so that no others can move.

When the figure bar 45 has substantially completed its movement into the slots of the sevenunit bars I2, the special holding bar 49 is moved to the right by the roller 41 as it rides up the upper side of the notch therein. This withdraws bar 49 from the notches in the back edge of all of the ve-unit selector bars 48. (See the selector bars in the upper middle portion of Fig.

At about the extreme movement of the operating bail 35, magnet 69 on the five-unit distributor is energized by closure of contacts 18. This removes pawl 65 from engagement with cam disc 61 and shaft 59 for simplicity, shown identical with shaft 83 in Fig. 5, with its associated cams starts rotating counter-clockwise. The lug 56 of lever 54j rides out of its notch on the cam disc and this immediately opens the start-stop contacts 59j. This produces the socalled start pulse (no current) in the outgoing line L. At about the same timelever 54g rides out of the notch 5B in its cam disc and this opens switch 59g and de-energizes restoring magnet 60a and it no longer holds the five selector levers 48. Springs 1l then rotate the first, second, fourth and fifth locking levers 5I clockwise and these move the first, second, fourth and fifth selector bars 48 to the left as the slots therein permit this, as shown by Fig. 6. The third selector lever engages the figure shift bar at |00 and it and its switch lever cannot move.

The operation of the first, second, fourth and fifth locking levers 5I released contact levers 54a, 54h and 54e and as their cam notches 58 move over their cam projections 56, contacts 59a, 59h and 59e will close and transmit pulses to line L in the first, second and fifth time position in the five-unit cycle.

Slightly before the next energization of operating magnet 32 for the message character 2,

shaft 59 and its associated cams will have been stopped by pawl entering the notch in stop cam 61 (Fig. 4). Thus, when the seven-unit pulses for the character 2, which as shown by Fig. '7 consist of pulses one, two and seven, have operated the first, second and seventh selector bars I2 in the way previously shown, the bar 45 will move into the aligned notches in all seven of the selector bars I2 as soon as the printing magnet 32 operates and elevates the roller 41. Only the first, second and fifth of the five-unit selector bars 48 can be moved to the left, as indicated by the code in Fig. 8 and the slot diagram of Fig. 6. Movement of the first, second and fifth bars will transmit the pulses in the first, second and fifth time position over the line L to the printer. This is the signal for the figure 2.

When the first, second and fifth pulses are sent out,by the distant seven-unit transmitter for the character 5 the vertical bar 45 for this character will enter the slots in the seven-unit selector bars as shown by Fig. 6. This will permit only the fifth selector bar 48 to move to the left. This will close switch 59a and send out the fifth pulse only over line L in the fiveunit transmission, which, as will be noted from the code diagram in Fig. 8, is the correct fiveunit code signal for figure 5.

A letter shift will next be sent from the distant seven-unit transmitter. By inspection of Figs. 7 and 6 it will be seen that signal pulses two, three and four of the seven-unit code will cause the second, third and fourth selector bars I2 to move to the left. This will permit all of the five selector bars 4B to move to the left. Thus, all five signal pulses of the five-unit code will be transmitted. which Fig. 8 shows are the signals for the letter shift in the five-unit code.

The distant seven-unit transmitter will next send out pulses three, six and seven for the letter S, which will move the third, sixth and seventh selector bars I2 to the left. This will permit movement to the left only of the first, and third selector bars 48, which will operate the first and third locking levers and send out the appropriate signal for the letter S, in accordance with the five-unit code.

It will be clear from the description and the drawings how the seven-unit signals for the remaining letters H, A, R, E and S, in the expression assumed, will be transmitted and converted to the live-unit code signals and it Will not be necessary to explain the operation further.

In Fig. 5 only one selector magnet 5 is shown. The six other selector magnets not shown are connected to conductors 9| to 96 inclusive.

I have disclosed my improvement in connection with a multiplex system in which the local functions of the described channel take place during the receipt of signals over the other channels, as in the usual practice, but, of course, It may be used in single channel systems without. change, except such changes are necessary in the local functions operations, such as are disclosed, for example, in my said application Serial No. 252,179.

Having described my invention, what I claim l. In telegraph code converters, a set of selector bars, means operated by received signal pulses in one code for selectively moving said bars, a second set of selector bars, a transmitter operated by movement of the bars of the second set comprising a plurality of cam discs and switch levers operated thereby, and means controlled by the selective movement of the bars of the first set for selectively moving the bars of the second set, the selective movement of the last-mentioned bars causing the transmitter cams to operate said switch levers to send the same character in a different code.

2. In telegraph code converters, a set of selector barsy means operated by a received signal in one code for selectively moving said bars lengthwise, a second set of selector bars, a transmitter operated by lengthwise movement of the bars of the second set comprising a. plurality of cam discs and switch levers operated thereby, and means controlled by the selective movement of the bars of the first set for selectively moving lengthwise the bars of the second set, the selective lengthwise movement of the last-mentioned bars causing the transmitter cams to operate said switch levers to send the same character in a different code.

3. In telegraph code converters, a set of selector bars, means operated by a received signal in one code for selectively moving said bars. a second set oi' selector bars, a transmitter operated by movement of the bars of the second set comprising a plurality of cam discs and switch levers operated thereby, means for holding the bars of the second set from movement, means for releasing v the holding. means after selective movement of the bars of the first set, and means controlled byv said selective movement of the bars oi.' the first set for selectively moving the bars of the second set upon release of the holding means, the selective movement oi' the last-mentioned bars causing the transmitter cams to operate said switch levers to send the same character in a different code.

4. In telegraph code converters, a set of selector bars, means operated by a received signal in one code for selectively moving said bars lengthwise, a second set of selector bars, a transmitter operated by lengthwise movement of the bars of the second set comprising a plurality of cam discs and switch levers operated thereby, means for holding the bars of the second set from movement, means for releasing the holding means after selective movement of the bars of the first set, and means controlled by said selective movement of the bars of the rst set for selectively moving lengthwise the bars of the second set upon release of the holding means, the selective lengthwise movement of the last-mentioned bars causing the transmitter cams to operate said switch levers to send the same character in a different code.

5. In electric telegraphs, a plurality of selector levers, a set of movable selector bars extending across said selector levers and notched normally to form a discontinuous slot adiacent all said se- Y lector levers and to form a continuous slot adjacent diierent ones of said levers upon movements of different groups of said bars, means responsive to signal pulses for moving said different groups.

selector levers, a latch normally holding the bars oi.' the second set from movement by said springs, means for moving a lever into the aligned notches of both sets of bars upon operation of the firstmentioned means, means for thereafter releasing said latch whereupon the bars oi' said second set having the extended slots are moved by said springs and the remainder are held from movement by the said moved selector levers and means operated by the last-mentioned bars for transmitting signals.

6. In electric telegraphs, a selector lever, .a movable notched selector bar extending transversely of said leverand normally having its notch out of line with said selector lever, means responsive to a signal pulse for moving said bar to align said notch with the lever, a second movable notched selector bar extending transversely o1' said lever and normally having its notch aligned with said lever, the last-mentioned notch having a portion extending beyond one side of said leverto permit longitudinal movement of the second selector bar when the lever is positioned therein, means for moving said lever into the aligned notches of said bars upon operation of the mst-mentioned means, means for moving the second bar in a longitudinal -direction to decrease said extending portion of the slot, a rotataible cam, a signal switch, an arm adapted to open the switch when engaging the rotating cam, means for holding the arm from engagement with said cam, said means being connected to move with the second bar to disengage said arm and permit it to engage said cam for opening and closing said switch by engagement therewith.

7. In electric telegraphs, a selector lever, a movable notched selector bar extending transversely of said lever and normally having its notch out of line with said selector lever, means responsive to a signal pulse for moving said bar to align said notch with the lever, a second movable notched selectorbar extending transversely of said lever and normally having its notch aligned with said lever, the last-mentioned notch having a portion extending beyond one side of said lever to permit longitudinal movement of the second selector bar when the lever is positioned therein, means for moving said lever into the aligned notches of said bars upon operation of the first-mentioned means, means for moving the second bar in a longitudinal direction to decrease said extending portion of the slot, a rotatable cam, a signal switch, an arm adapted to open the switch when engaging the rotating cam, a pivoted lever having a hook at one end for holding the arm from engagement with said cam, said pivoted lever having the other end connected to move with the second bar to free said arm and permit it to engage said cam for opening and closing said switch by engagement therewith.

8. In electric telegraphs, a selector lever, a movable notched selector bar extending transversely of said lever and normally having its notch out of line with said selector lever, means responsive to a signal pulse for moving said bar to align said notch with the lever, a second movable selector bar having a portion extending beyond a side of said lever to permit longitudinal movement of the second selector bar wh'en the lever is positioned therein, a latch normally holding the second lbar from movement, means for moving the first lever into the aligned notches of said bars upon operation of the ilrst-mentioned means, means for releasing the latch, means for moving the second bar in a longitudinal direction to decrease said extending portion of said slot. a rotatable shaft, a cam.. a clutch between the cam and shaft, a signal switch operated by rotation of the cam, means for holding the cam from rotation and means for releasing the cam-holding means upon release of said latch.

" JAMES A. SPENCER.

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