US2729707A - Telephonic apparatus - Google Patents

Description

Jan. 3, 1956 s. D. M KELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 1 Jan. 3, 1956 s, D, M KELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 2 Mum r08 jamue/ 0. d'Ael/eh Jan. 3, 1956 5, D, c N 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 3 Jan. 3, 1956 s MGKELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 4 /Mjzm United States PatetitQ TELEPHONIC APPARATUS Samuel Dunseith McKcllcn, Kensington, London, England Application June 4,1951, Serial No. 229,675 Claims priority,application Great Britain June 7, 1950 12 Claims. ((1179-90) This invention relates to telephonic alarmapparatus for communicating a recorded message to a preselected telephoneline upon receipt of an alarm, as for reporting an outbreak of fire, an attempt at burglary, a rise of flood- Water or the like; such apparatus is currently employed in connection with fire and burglary alarms for the purpose of establishing communication with the fire-service, the police or the residence of a proprietor or manager, and the apparatus may be associated with a phonograph or like sound-reproducing means having a record of a suitable message giving the location of the premises, the nature of the alarm and other particulars recorded in advance. The message will be transmitted over the telephone line after the call has been established in the conventional manner by sending trains of impulses produced by a rotary dialling drum and cooperating contacts; the dialling drum is conveniently driven by the same motor as the record. I

The present invention has for its main object to provide improved means for operation of the dialling drum in order to call the pre-selected line to which the message is to be communicated.

Another object of the invention is to provide a movable support for the dialling drum and its co-operating con tacts, the support being normally locked in a starting position by means of a control device which is releasable by operation of the motor driving the record, this motor starting upon completion or interruption of the alarm circuit, according to the type of alarm employed, that is, with an open circuit which is closed by an outbreak of fire or other emergency, or with a closed circuit which is interrupted by the emergency, the closed circuit type being'generally preferred for burglary alarms.

A further object of the invention is to provide an improved device in which the dialling drum 'is driven by means of a gear-wheel fast with the drum, this gear-wheel being brought into engagement with a pinion revolving with the message record, after the receipt of the alarm has caused the start of the motor driving the record, the gear-engagement being maintained for transmission of the dialling impulses, and the gear-wheel being thereafter displaced from its engagement with the pinion, so that the recorded message can be communicated to the line which has been called by the dialling impulses.

A specific object of the invention is to control in proper sequence all the movements of the support on which the dialling drum, its contacts and the gear-wheel are mounted, by means of a'cam-shaft driven by the motor which starts upon receipt of the alarm.

Other objects and advantages of the invention will hereinafter appear from the followingdescription of a preferred embodiment, given with reference to the accompanying drawings, in which: Fig'. l is 'a plan view of the device as arranged to employa phonograph record of the message, showing the "dialling: drum in its terminal position.

Figs. and 3 are partial plan views, showing the dial- ZJZQJQ? Fatente d Jan. 3, 1 9 56 2 ling drum brought to its starting and intermediate positions respectively by the movements of the rocking lever.

Fig. 4 is a rear elevation of the device, showing the cam shaft which determines the movements of the rocking lever.

Fig. 5 is a section on the line 55 of Fig. 1, showing the drive to the cam shaft and the control device locking the rocking lever in its starting position.

Fig. 6 is a view of the tone-arm control device operated by the cam-shaft, as seen on the line 6-6 of Fig. 4.

Fig. 7 is a detail of a spring drive for reversing the dialling drum at the completion of the dialling operation. Figs. 8 and 9 relate to a modification. A

in the illustrated embodiment of the invention, the movements of a rocking lever 10 carrying the dialling drum are determined by a cam-shaft 11 driven through a Worm-wheel 12 meshing with a worm 13 upon one of the spindles of a phonograph motor. The motor 14 is normally held stationary by a catch 15 engaging with a peg 16 beneath the turntable 17, this catch being disengageable by a relay 18 connected in the alarm circuit and controlling the exchange line. The cam-shaft is shown provided with four cams, viz. a cam 19 which releases the control device and allows the rocking lever to swing about its pivot, a second cam 20 which serves to bring the rocking lever 10 to its starting position (Fig. 2), a third cam 21 which operates a switch to disconnect the instrument after transmission of the recorded message, and a cam 22 which controls the tone-arm 23. i

The lever 10, mounted above the motor casing 24 and adapted to rock horizontally about a pivot 88 under the action of a spring 89, carries the dialling drum 25, which may havea single set of cams for the dialling contacts 26, as in the case where the same digit has to be repeated for establishing the call, for example in dialling 999 in this case, the number of repetitions of the digit is controlled by a cursor 27 engaging with screw-threads 28 upon a boss 29 integral with the drum 25, the axial travel of the cursor as the drum revolves bringing it to the end of the screw-threads, from which it slips into the path of a projection 30 revolving with the boss 29. The resultant movement of the cursor displaces a stop-arm 31 upon which it is pivoted at 32 and which has served to retain the rocking lever 10 in its intermediate or dialling position (Fig. 3) against the action of the spring 89. The cursor 27 is urged downwards by a leaf spring 33 pressing down upon its pivot 32; at the same time, it is urged towards the screw-threads 28 by a light spring 34 connecting it to a detent 35 on the opposite side of the drum, this detent being pivoted on the rocking lever and normally engaged at one edge by another projection 36 revolving with the boss 29 The two projections may consist as shown of two pins of different lengths upon the end face of the boss 29. The short pin 30 engages with the end of the cursor 27 only when the latter occupies a position substantially tangential to the path of the pin after reaching the end of the screw-threads, this position being shown in dotted lines in Fig. 3; the longer pin 36 pushes past the detent 35 at every revolution of the drum during the dialling operation, but will engage the end of the detent if the drum turns backwards.

The stop-arm 31 is itself pivoted upon the rocking lever 10 between its pivot or fulcrum 88 and the dialling drum 25, the free extremity 38 of the stop-arm being guided to engage with a stop 39 for holding the lever 10 in its intermediate position (Fig. 3), a gear-wheel 40 integral with the drum being then in mesh with a pinion 41 on the turntable spindle 42; displacement of the stop-arm 31 by the subsequent thrust of the cursor 27 enables it to slip oil the stop 39 so as to take the gear-wheel out of. mesh with the revolving pinion, this movement of the rocking lever to the terminal position (Fig. 1) being limited by the engagement of the same stop 39 by a stepped surface or recess 43 on the extremity of the arm.

In this terminal position of the lever in which its toe 44 has operated the jack contacts 45 of the pick-up circuit, the cursor 27 drops back to its original position, ready to engage again with the screw-threads 28, but it is held clear by engagement of its heel 46 by a stop-pin 47 on the casing.

At the completion of the dialling operation, the drum seeks to return by the action of an enclosed clockspring 48, until the end of the detent obstructs the second pin 36 and arrests the drum in a position where the plain part of its periphery will engage with the contacts 26. As shown in Pig. 7, the clock-spring 48 is anchored centrally to a peg 49 upon a fixed spindle 50 on which the drum 25 is mounted, the outer coils of the spring engaging frictionally with the interior of the drum so as to turn the latter backwards, up to about one full turn of the drum, after the gear-wheel drive has ceased; the unidi- 5 rectional drive allows the wheel 40 to rotate freely as it is moved past the pinion 41 during resetting of the lever 10.

This resetting can be performed manually, for example by means of a wire drawn out by the attendant; preferably however, an initial short run of the motor 14, after rewinding by the attendant, is arranged to cause the camshaft 11 to bring the rocking lever 10 to its starting position, for which purpose the turntable is temporarily released. As shown, the cam 20 is adapted to engage an oblique face 51 upon a lever 52 pivoted at 53 upon the motor casing, the other end of this lever overlying a rocker 54 pivoted at 55 upon the casing; the underlying end of the rocker is cranked upwardly at 56, so that when 7 the cam 29 operates the lever 52, the latter will depress this cranked end of the rocker 54 and at the same time it will tension a spring 57 connected to the stoparm 31 on the lever 10, sufficiently to overcome the spring 89 which is connected to the toe 44 on the other side of the pivot 88. The movement of the rocker 54 raises a peg 58 at its other end from engagement with the toe 44, so that the lever 10 can swing over to its starting position (Fig. 2) under the pull of the spring 57.

When the rocking lever 10 has been brought to this starting position, the turntable is stopped by reengagement of the catch 15, leaving the apparatus ready for operation as soon as the alarm circuit energizes the relay 18 to release the catch 15 and connect the apparatus to the exchange line by the jack contacts 59; a short delay,

variable if desired, may be allowed before the further rotation of the cam-shaft 11 causes the cam 19 to release the control lever and start the dialling operation.

The control lever 60 is adapted to rock over one edge of the motor casing 24, being pivotally mounted on a bracket 61; its dependent arm 62 is engageable by the cam 19 and its upper arm supports a peg 63 which extends normally up into the path of the lever 10, adjacent to the end where the rotary drum is mounted, so as to lock the lever in its starting position (Figs. 2 and 5). When the control lever is operated by the cam 19, it moves the peg 63 clear of the rocking lever to allow the latter to swing to its intermediate position (Fig. 3); the control lever is held in this released position by the action of a leaf spring 64 which has been pressing against the edge of the upper arm and now slips over it to prevent return of the lever after the cam 19 has passed. This leaf spring is so arranged that during the return of the lever 10 at the resetting operation, it drags the leaf-spring 64 clear of the control lever 60 to allow the latter to bring its peg 63 back into position for holding the lever 10 in the reset or starting position, after which the leaf spring returns to press against the edge of the control lever.

The position of the lever 10 maybe displayed by a semaphore device mounted behind the front panel 65 of the apparatus, as shown in Fig. 1, with a coloured disc visible through a window in the panel and carried by a lever 66 pivoted at 67; the other arm of the lever has an inclined upper edge 68 engaged by a wire 69 projecting from the lever 10, so that the resetting of the latter lifts the semaphore disc into place behind the window. Upon the same panel 65, there is mounted a push-button 7% for operating jack contacts 71 to energize the relay l3; when the apparatus is to be reset after an operation of the alarm, the motor 14 will be rewound by means of a handle and the button will then be pushed to start the turntable, the motor being allowed to run until the cam 20 has brought the rocking lever 10 to its starting position (Fig. 2). As soon as this is heard to have occurred, the button 70 will be released, leaving the apparatus ready for operation, with the semaphore disc visible to show its condition.

The tone-arm 23 supporting the pick-up is returned to its starting position with the needle in contact with the record, before transmission of the recorded message, the cam 22 having one face which serves to raise the tonearrn spindle '72; at the end of this upward movement, the spindle is caused to swing the tone-arm back to the starting point of the record, the tone-arm then falling to bring the needle into contact with the record as soon as the opposite face of the cam allows the spindle to descend again. Preferably the tone-arm 23 is lifted and swung at least partly back to its starting position by the preliminary movement of the camshaft 11 at the setting of the apparatus.

As seen in Figs. 4 and 6, the cam 22 engages with the rounded foot 73 of a slider 74 having two bosses 75 in which the spindle 72 is rotatably mounted; a sleeve 76 secured to the upper end of the spindle carries the tonearm 23 The slider 74 is supported in guides 77 upon a standard 78 having a U-shaped bracket 79 secured thereto; the middle portion of this bracket is slotted out to receive a peg 8t) fixed in a collar 81 secured upon the spindle 72. The width of the slot 82 limits the swing of the tone-arm, its lower edge being horizontal and its upper edge 83 inclined; when the spindle is lifted by the cam 22, the peg contacts with this inclined edge 83 and forces the spindle to turn so as to swing the tone-arm to the starting point of the record. The descent of the spindle, when the cam 22 passes from under the slider 74, takes place vertically under control of a pivoted latch 84 of substantially sector shape, normally held with one edge parallel to the sides of the slot 82 by a light spring 85; as the peg 80 travels up the inclined edge 83 of the slot, it lifts this latch until clear of the bottom corner thereof, whereupon the latch snaps down behind the peg, so that the peg and spindle can only descend vertically.

In operation, assuming that the apparatus has been reset with the tone-arm raised and swung over to the starting point of the record, the lever 10 being in its starting position, the alarm circuit will cause the relay 18 to connect the instrument to the exchange line by way of the contacts 59, and to disengage the catch 15 beneath the turntable; the motor 14 can then drive its mechanism for revolving the turntable and the cam-shaft 11 will begin to rotate. After a short delay, for example ten seconds, as determined by the angular setting of the cam 19, the control lever 69 will lower its peg 63 and allow the lever 10 to rock under the action of the spring 57 until it reaches its intermediate position (Fig. 3); the lever is arrested in this position by the abutment of the stop-arm 31 against the pin 39. As the gear-wheel 4i) revolves, the cams upon the periphery of the drum 25 successively engage with the dialling contacts 26 and transmit the coded impulses three times; during the three revolutions of the drum, the cursor 27 advances along the screw-threads 23 until it reaches the top, whereupon it rocks over to bring its extremity into the path of thepin 30. Consequently, at the completion of this third revolution of the drum, the pin 30 causes the cursor to move the stop-arm 31 sidewaysgia rela'tion-tothe pin 39, the leverlo being thus tree to rock'to its terminal position (Fig. 1); the gear wheel 40 is then clear of the revolving pinion, the stopa'rm 31 engages the pin 39 within the stepped recess 43, and the detent 35 engages the pin 36 so as to hold the dialling drum in correct position for its next operation. As soon as the rocking lever reaches its terminal position, its toe 44 engages the jack contacts 45 for'the pick-up circuit; by this time, the cam 22 will have lowered the tone-arm 23 to bring the needle down upon the re v'olving record and the transmission of the message will begin. The message may be repeated two or more times upon the'rec'ord to allow for delay in establishing "or answering the telephone call.

In order to disconnect the telephone line and pick-up circuit after the transmission of the recorded message, the carn'21 nowoperates to close contacts 36 which cause the relay 18 to free the catch 15, thereby arresting the turntable, and to restorethe jack contacts 59 to their original p'osition. Alternatively, the customary slowing down of the motor 14 at theend of the record may be utilized by providing a lever which engages with the speed disc 87 of the governor; this lever'will have a short forked arm which rocks as the motor speeds up, thereby dragg'ing a spring pawl at the end of its longer arm across the hump of a spring contact controlling the circuits, for example through a suitable relay, but when the motor slows down towards the end of the record, the forked lever will return the pawl across the humped contact, the pawl acting positively in this direction of movement to depress the spring contact and establish the relay circuit.

The rotary dialling drum having peripheral cams for repeating the same large number of impulses at every revolution may be fitted in the known manner with'a sleeve or shield which cuts 01f some of the cams from engagement with the co-operating contacts, so as to reduce the number of impulses in each train. Where the telephone call to-be established requires the use of diiferent digits instead of repeating the same digit each time, the rotary drum may be arranged to provide for the several digits on two or more'sets of cams, the drum being for example displaced axially in relation to the contacts between its rotary movements by any convenient means. i

Figs. 8 land 9 illustrate a modified dialling drum 90, in which the screw-threads 91 engaged by the cursor 27 are formed with peripheral cams 92 upon the crests of the threads for engaging the dialling contacts 26; the latter are mounted upon a finger 93 which is carried by the same pivot 32 as the cursor and travels longitudinally of the drum at the same time as the latter. The number of cams on the several threads may be the same or difierbut, as requ'ired'by'the digits to be transmitted, and the number of screw-threads may also be as required, accordin'g to the number of le'tters-and/ or digits in the call-sign. The pivot 32 is pressed downwards by a leaf spring 33 and the cursor 27 is urged towards the threads by a light spring 34; the finger 93 is also urged towards the threads by a light spring 94, its movement into the grooves being limited by a fixed post 95 so that the springs 26 engage properly with the cams.

As shown in Fig. 8, the cursor 27 and finger 93 are coupled together with lost motion by a peg 96 projecting from the cursor into a notch upon the boss 97 of-the finger, so that the cursor can swing over the top of the ,drum after reaching the end of the screw threads, while the finger 93 still remains engaged therein at a lower level; on'the subsequent return of the cursor, when it is pushed back by the revolving projection 30, so as to displace the stop- arrn 31,11; previously described, the cursor acts to swing the finger 93 away from the dialling drum so as to lift the contacts 26 clear of the cams thereon, the cursor and finger then descending to their original levels under the pressure of the spring 33.

It will be understod that the rotary dialling drum may beureadilyfi-removed and replaced. :by another having a different arrangement of cams, whenever it is desired to provide for communication with a different subscriber-7s line.

What I claim is:

1. In telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheel fast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable'by rotation of said motor-driven record, means .for retaining said support in a starting position wherein said gear-wheel is clear of said pinion, means for moving'said support .toa dialling position wherein said gear-wheel engages with said pinion, means .for retaining said support in said dialling position during transmission of the dialling impulses, and means for displacing'said support from said dialling position after transmission of said impulses.

2. In telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pro-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheelfast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion'rotatable by rotation of said motor-driven record, means for retaining said support in a starting position wherein said gear-wheel is clear of said pinion, means for moving said support to a dialling position wherein said gear-wheel engages with said pinion, means for retaining said support in'said .dialling position during transmission of the dialling impulses, means for displacing said support from said dialling position after transmission of said impulses, and'a cam-shaft controlling said support-retaining, moving and displac: ing means, said cam-shaft being driven by said motor simultaneously with said pinion.

3. In telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a rockable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation of said motor-driven record, means for retaining saidsupport in a starting position wherein said gear-wheel is clear of said pinion, means for moving said support to a dialling position wherein saidgear-wheell'is centered upon astraight line joining the pivotal axis of said rockable support to the axis ofsaid pinion, said gear- .wheel meshing with said pinion insaid dialling position, means for retaining said support in said dialling position during transmission. of the diallingimpulses, and means for displacing said support from said dialling position after transmission ofsaidimpulses.

t. In telephonic alarm. apparatusof the class described, including a call transmitter and 'aim'otor-driven record of a message .to be communicated to a pre-s'elected line after calling, a' call transmitter comprising a dialling drum, contacts co-operating with said drum, agear-wheel fast'with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation of said motor-driven record, means for .retaining'said support in a starting position wherein said-gea'r-wheel is clear of said pinion, meansforzmoving said support to a dialling position'wherein said gear-wheel engages with said' pinion, means for retaining said support in said dialling position during transmission of the dialling impulses, screw-threadsfast with said drum, -a spring-controlled cursor" engaging with, said 'screwth'r'eads and travelling therealong during rotation of said'drum', 'and mea'ns for displacing said support from said dialling position when said cursor reaches the end of said screw-threads.

5. In telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call.transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheel fast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation of said motor-driven record, means for retaining said support in a starting position wherein said gear-Wheel is clear of said pinion, means for moving said support to a dialling position wherein said gear-wheel engages with said pinion, a stop-member attached to said support, a fixed abutment for said stop-member, said stop-member engaging said abutment to retain said support in said dialling position during transmission of the dialling impulses, screw-threads fast with said drum, a spring-controlled cursor engaging with said screw-threads and travelling'therealong during rotation of said drum, and means rotating with said'drum for engaging said cursor when it reaches the end of said screw'threads and causing it to shift said stop-member in relation to said abutment, said moving means then displacing said support from said dialling position.

' 6. In telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheel fast with said drum, a movable support for said drum, con tacts and gear-wheel, a pinion rotatable by rotation of. said motor-driven record, means for moving said support to a starting position wherein said gear-Wheel is clear of said pinion, means for retaining said support in said starting position, means for moving said support to a dialling position wherein said gear-wheel engages with said pinion, means for retaining said support in said dialling positionduring transmission of the dialling impulses, i

means for displacing said support from said dialling position after transmission of said impulses, and a cam-shaft controlling said support-moving, retaining and displacing means, said cam-shaft being driven by said motor simultaneously with said pinion.

7. 1n telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheel fast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation ofsaid motor-driven record, means for operation of said drum comprising a gear-wheel fast with said drum, a

movable support for said drum, contacts and gear-wheel, a"

a pinion rotatable by said motor, means for retaining said support in' a starting position wherein said gear-wheel is clear of said pinion, means for moving said support to a dialling position wherein said gear-wheel engages with said pinion, means for retaining said support in said dialling position during transmission of the dialling impulses, screW-threads fast with said drum, a spring-controlled cursor engaging with said screw-threads and travelling therealong during rotation of said drum, said cursor controlling the co-operation of said dialling drum with said contacts, and means for displacing said support from said dialling position when said cursor reaches the end of said screw-threads.

8. ln telephonic alarm apparatus of the class described, a dialling drum having peripheral cams representing a digit to be dialled repeatedly by continuous rotation of said drum, screw-threads fast with said drum, a springcontrolled cursor engaging with said screw-threads and travelling therealong during rotation of said drum, and means for interrupting the rotation of said drum when said cursor reaches the end of said screw-threads.

lit)

9. In telephonic alarm apparatus of the class described, a dialling drum having peripheral cams representing a digit to be dialled repeatedly by continuous rotation of said drum, a gear-wheel fast with said drum, a movable support for said drum and gear-wheel, a pinion for driving said gear-wheel, a stop-member for retaining said support in a position wherein said gear-wheel engages with said pinion, screw-threads fast with said drum, a springcontrolled cursor engaging with said screw-threads and travelling therealong during rotation of said drum, said cursor being mounted on said stop-member, and means carried by said drum for engaging said cursor when it reaches the end of said screw-threads, said engaging means then causing said cursor to shift said stop-member from its retaining position.

10. In telephonic alarm apparatus of the class described, a dialling drum having peripheral cams representing a call sign to be dialled by rotation of said drum, screw-threads fast with said drum, a spring-controlled cursor engaging with said screw-threads for relative axial travel during rotation of said drum, and means for interrupting the rotation of said drum when said cursor reaches the end of said screw-threads.

11. In telephonic alarm apparatus of the class described, a dialling drum having peripheral cams representing a call sign to be dialled by rotation of said drum, screw-threads fast with said drum, a spring-controlled cursor engaging with said screw-threads for relative axial travel during rotation of said drum, a clock-spring in frictional engagement with said drum, said clock-spring being wound up by rotating of said drum, and means for interrupting the rotation of said drum when said cursor reaches the end of said screw-threads, said clock-spring then acting to rotate said drum in reverse direction to obtain an inoperative position of said peripheral cams.

12. in telephonic alarm apparatus of the class described, including a call transmitter and a motor-driven record of a message to be communicated to a pre-selected line after calling, a call transmitter comprising a dialling drum, contacts co-operating with said drum, a gear-wheel fast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation of said motor-driven record, a clock-spring having frictional engagement with said drum, said clock-spring being wound up by rotation of said drum by said pinion and tending to rotate said drum in reverse direction, means for retaining said support in a starting position wherein said gear-wheel is clear of said pinion, means for moving said support to a dialling position wherein said gear-wheel engages with said pinion, means for retaining said support in said dialling position during transmission of the dialling impulses, and means for displacing said support from said dialling position after transmission of said impulses, said gear-wheel rotating said drum in reverse direction to overrun said clock-spring when said gearwheel engages with said pinion during return of said support to said starting position.

References Cited in the tile of this patent UNITED STATES PATENTS 1,867,500 Denzler July 12, 1932 1,974,551 Tuscher et al. Sept. 25, 1934 2,036,420 Lowry et al. Apr. 7,1936 2,099,913 Tuscher et al. Nov. 23, 1937 2,131,565 Lauersdorf Sept. 27,1938 2,161,525 Mountstephen June 6,1939 2,276,954 Pritts et al. Mar. 17, 1942 2,358,586 Newell Sept. 19, 1944 2,469,278 Sears May 3,1949 2,537,599 Mountstephen J an. 9, 1951

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