US2043674A - Calling device - Google Patents

Description

.lune 9, 1,936.

H. F. OBERGFELL CALLING DEVICE Filed April 7, 1934 S4 QM.

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Patented `lune 9, 1936 PATENT OFFICE CALLING DEVICE Herbert F. Obergfell, River Forest, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application April 7, 1934, Serial No. 719,430

14 Claims.

The present invention relates in general to calling devices, or impulse senders, of the type commonly used in automatic telephone systems to enable the subscribers in such systems to transmit digital series of impulses to eiect the proper control over the automatic switches.

The object of the invention is the provision of an improved calling device of the foregoing character. A particular object is the provision of a calling device which is especially suitable for use at the subscribers stations in a party line automatic telephone system which is equipped for measured service, as set forth in detail in the pending application of E. S. Peterson, S. N. 684,477, filed August l0, 1933.

The various features of the invention will be pointed out hereinafter as the constituent parts thereof are described and their operation explained, reference being made for this purpose to the accompanying drawing.

Referring to the drawing, Fig. 1 is a circuit diagram of the essential parts of a system in which the invention may be used.

Fig. 2 is a front view of the dial or calling device, one of which is installed at each party line station.

Fig. 3 is a rear View of the dial, showing the spring assembly.

Figs. 4 to 9, inclusive, are views of the spring operating cam members and associated parts. Of these latter figures, Figs. 4, 6, and 8 are top views of the cam carrying members disassembled, while Figs. 5, 7, and 9 are, respectively side views of the same parts.

In Fig. l, two party line subscribers stations on a ten party line are representedV by AI and All). The line terminates at the exchange in a line switch LS of standard type. Associated with the line at the exchange are ten meters of which two, Ml and M40, are shown. There is also a meter selecting switch S.

The line switch LS and line switches associ ated with other party lines of the kind disclosed herein have access to iirst selectors of standard type by way of trunk circuits such as the trunk circuit T. This trunk circuit includes a number of relays and a small steppingswitch Sl.

The first. selector and other switches are not shown herein as they may be of any suitable type, such as the well known Strowger switches in common use. The system should, however, include means for operating the subscribers meters on successful calls. Meter operation may be by the well known booster method, as shown in U. S.

Patent No. 1,186,823, in which booster battery is momentarily applied to the release trunk when the called party answers. The circuits shown are arranged for this method of operation, but can readily be revised to take care of meter operation by other methods, as, for example, by the well known reverse current method.

The calling device will now be described in detail, after which the manner in which it operates in the party line measured service system illustrated will be explained. This dial or calling device is similar mechanically to the usual dial in common use in automatic telephone systems at the present time, except that it has eleven finger holes instead of ten and transmits a maximum ci eleven impulses instead lof ten impulses. The arrangement of the finger holes and the number-l ingthereof is shown in 1Fig. 2.

The calling device is conveniently manufactured as a modication of the calling device disclosed in U. S. Patent No. 1,642,822, granted September 20, 1927. The calling device shown in the above patent has only ten nger holes but the spacing between the first finger hole and the nger stop is double the spacing required for the transmission .of one impulse. In fact, when the digit one is pulled, the impulse cam is rotated suicient to transmit two impulses, when the digit 5 is pulled, the cam is rotated suicient to transmit six impulses, and so on, the digit nought corresponding to a rotation suiiicient for eleven impulses. The calling device is, however, provided with a cam which rotates with `the number wheel, which ls effective to move the impulse springs out of range of the impulse cam during the last one half rotation thereof, when otherwise it would transmit the last impulse. One impulse is always omitted, therefore, at the end of each series, so that the actual number transmitted always corresponds to the digit pulled on the dial.

Now, the only modification which is required in the above described calling device to make it transmit a maximum of eleven impulses is the omission of the cam which moves the impulse springs out of range of the impulse cam. When this cam is left off no impulses are omitted or cancelled. 'I'he mechanism of the eleven hole calling device, therefore, may be the same as shown in the patent except that the cam referred to is not provided.

In order to make the finger holes correspond to the modified mechanism a different number wheelY is provided such as is shown in Fig. 2. It will be seen that this number wheel has eleven finger holes, the additional hole being provided.

referring to the dial of the patent, in the space between the finger stop and the No. 1 finger hole. The digit number card behind the dial is so arranged that this new finger hole bears the digit 1. The digits assigned to the other ten finger holes are all rotated one space in a clockwise direction, so that the old No. 1 finger hole becomes No. 2, No. 2 becomes No. 3, and so on. This leaves one finger hole after No. 0 to which the digit 11 is assigned, all as shown in the drawing, Fig. 2. Of course, an arbitrary designation can be used in the eleventh nger hole if desired.

The eleven hole dial described in the foregoing is further provided with certain sets of contact springs and cams for operating them which are required in the party line metering'system and these additional parts Will now be described, reference being made to Fig. 3 and Figs. 4 to 9, inclusive. Fig. 3 shows a rear view of the complete calling device including not only the additional parts referred to! but alsof the oldv parts. This is necessary in order that the complete arrangement mayA be understood.

The contact. springs no-rmally provided consist of-'impulse springs I6r and I'I, and a set of shuntA springs I5', as may beissen by reference to the hereinbefore mentioned patent. These springs are clamped between bushings as shown andflie in a plane above the back of the calling device where theyr can be operated by the cams provided for that purpose. The additional springs provided are a.A pair consisting of springs II) and I'.I andanother pair consisting ofY springs I8 and lo. There is also a member I2 formed somewhat likeA acontact spring. Allv these springs and mem ber |21 are,` assembled along with the impulse springs and shunt springs abo-ve referred to. Springs I U, II, and I8 and member I2 are insulated. in the usual way, but spring I9. is assembled alongside of impulse: spring I'I without any intervening insulation. The four extra springs and the member I2 areoffset. so that. the ends thereof lie in a. plane above the plane of the impulse and shunt springs. The member- I2 supports a piroted` cam I3 for operating contact spring.. H'.

Referringfnow'also to Figs. 8 and 9, the referF ence character 3d; indicates the usuali tapered hub which is usedto attach the upper end of the helical main spring to the nger wheel shaft. The detailed construction of the hub and the associated parts is shown and describedY in U. S. Patent No. 1,615,311, grantedJanuary 25, 1927. It is sufcient to state. here. that the hub. 3I- fits over the end of the main finger wheel shaft` and rotates with it. .To the hub 3i is attacheda member 2'I having agportion; thereof; formed as a cam 30 for operating the shuntjsprings I5. A similar cam 5:1 is. shown in Batent-No. 1,642,822. The cam 53 shown in. this patent is, however, not provided, for reasons previouslyexnianed, andv in place thereof' the. member 2,1 is formed with two pro,- j ections 28 and 29.

Referring now to Figs. 6 and '1, the reference character 22 indicates a disc having two ears 23 and,.24.. The disc 22, as shown in Fig. 3, rests on 'theprojectionsl and 25 and the openings in ears`23 and 24 correspond to the openings. in the projections 28 and 29. Rivets in these openings hold the parts together. The disc 22 carries two camsV 25' and 2.6 `for operating the cam I3, Fig. 3. There is'also a pin 33 projecting from the upper surfaceof disc 22. This pin lies on the circle described'by the holes 34 in member 20 next to be described.

The member 20 is shown in Figs. 4 and 5 and vcan also be seen clearly in Fig. 3. It comprises a disc-like portion corresponding in size to disc 22, and a cam 2I, the latter being provided for operating spring I8. Member 2E) is secured to disc 22 by means of a small machine screw which passes through member 2D into a threaded hole in disc 22. The cam 2i has an enlarged portion with an opening therein so that the screw can be reached with a screw driver. When the member 2D is secured in place the pin 33 lies in one of the openings 34.

The functions of the parts just described may now be considered more in detail. It is intended that the springs I0 and II shall be closed only if the digit 11 isV pulled on the dial and that when closed these springs will remain close-d until the dial returns.V to normal. When the digit 11 is pulled the entire assembly including disc 22 is rotated in a counter-clockwise direction, Fig. 3, and the parts are so designed that as the nger of. the operator approaches the nger stop cam 25:k engages cam I3. Further movement of the nger dial causes cam 25 to rotate cam i3 on its pivot with the result that when the dial has been rotated to the limit the cam i3 will be standing substantially perpendicular to the end portion I4 of' spring II. For safety, the parts shouldl be adjusted so that cam i3 is moved slightly past dead center, as it is required to stay in this position while the dial is returning. The operationV of cam I3. obviously closes spring Ii against spring le.. As the dial returns the cam 25 will engage cam i3 just before the dial reaches normal and the further movement of the dial to normal movescam I3 to its original position as shown in Fig. 3.

Ifany digit of a lower value than the digit il is pulled on the dial the cam I3 will not be operated, for cam 25 will not then reach it.

The springs i8 and i9 are adapted to be closed by cam 2l. To this end the spring I3 may be provided with a bushing which can be engage-d by the cam. This cam presses spring I8 against spring i9 when the dial is pulled down also when it returns. As will presently appear, however, it is, only when the dial is returning that the springs i8 and i9 have any effect. The member 2! is adjustable so. that cam 2i can be made to engage springs i8 during any desired impulse interval While the dial is returning to normal. As shown in Fig. 3 member 28 is set so that cam closes the springs during the last or eleventh impulse interval. By loosening the screw, member il can be raised and rotatedA to position pin 33 in a different hole 34. This circular row of holes and the cooperating pin are provided as an accurate and easy way of adjusting the cam to any desired position.

Referring n ow to Fig. l, it will be assumed that the subscriber at station Aid desires to make a call, and the ensuing operations will be described.

Station AIB is one of ten stations on the party line having conductors 4i and 42 exten-ding te the automatic exchange, As mentioned hereinbefore there are ten meters at the exchange which correspond respectively to the ten stations. When any station makes a call a necessary eperation to be performed before the call can be completed is the selection of the proper meter in order to prepare to record the call. The seleotion is preferably accomplished preliminary to setting up the desired connection and is fasen care of by theV subscribers themselves through the medium of' dialling an additional digit. This extra digit is the digit 11. It may be stated that all the subscribers on the line have instructions to the effect that the digit i1 must be prefixed to all regular exchange numbers.

When the receiver is removed at station A|0, the transmitter is bridged across the line in the usual way, resulting in the closure of a circuit over line conductors 4| and 42 for the line relay 50 of the rotary line switch LS. The operation of the line switch is well known and hence need not be explained. It will suice to say that the operation of the line relay causes the line switch to select an idle trunk leading by way of a trunk circuit such as T to a first selector. If the trunk on which the wipers 53--56 are standing is idle, it is at once seized by the operation of switching relay 5|. If this trunk is busy the wipers are rotated by stepping magnet 52 until an idle trunk is found, the idle condition being determined by the test wiper 55, which picks up ground potential from busy test contacts to keep magnet 52 operating and to shunt relay 5I.

Assuming that the trunk comprising conductor |50-I53 is the first trunk found idle, when the wipers arrive at the contacts associated with this trunk the rotation will cease and the switching relay 5| will operate, disconnecting the line conductors 4I and 42 from the line relay 50 and from ground, respectively, and extending them by way of wipers 53 and 5B to trunk conductors |50 and |53, respectively. As a result of the foregoing line relays |03 and |02 of the trunk circuit T operate over the line from the calling station. Relay |03 closes a circuit at armature ||6 for release relay I 04. The latter relay, on energizing, prepares various circuits which will be described later, and also, at armature |20, places ground on the release trunk conductor |52. This completes the usual holding circuit for switching relay 5| of the line switch.

The line relay |02 is connected to ground through the secondary winding of the dial tone transformer shown and hence as soon as the connection is extended to the trunk circuit by the line switch the calling subscriber will receive a tone indicating that he can commence dialing the desired number. As before stated, the digit 11 must be prexed to all numbers and therefore the dial is first operated in accordance with this digit.

When the digit 11 is pulled the dial is rotated in a clockwise direction, see Fig. 2, and the cam assembly as shown in Fig. 3 will be rotated in a counter clockwise direction. At the beginning of the rotation cam 2| forces spring I8 momentarily against spring |9 but this is of no effect for springs I andv II are not closed. As the rotation is completed, cam 26 engages cam I3 and operates it as described hereinbefore, with the result that spring II is forced into engagement with spring I0 and held there. As can be seen from the circuit drawing this prepares a circuit for grounding the upper line conductor 4I by spring I8 on the return movement of the dial. It may be mentioned also that at this point that the rotation of the dial also results in the rotation of cam 30 which permits the shunt springs I5 to close and short circuit the transmitter and the receiver.

When the dial returns to normal the impulse cam is rotated. This cam momentarily separates spring IS from spring I1 eleven times, thus producing the well known circuit interruptions or impulses by means of which the numerical switching operations are controlled at the exchange. Line relays |02 and |03 both respond to these interruptions, relay |04, however, remaining in operated position because it is slow to release. The rst time relay |03 falls back it closes a circuit for stepping magnet |34 in switch SI which extends by way of grounded armature IIB, armature I|9, armature |32, and winding of magnet |34 to battery. Switch S| therefore advances one step. Line relay |02 falls back with relay |03 and closes a circuit for slow acting relay |01, the circuit extending from ground by way of armature 03, armature II3, armature II1, and winding of relay |01. Relay |01 operates and remains energized throughout the time relay |02 is responding to the interruptions of the line circuit. Relay |01 closes a circuit for relay |08 which operates and locks itself to the release trunk conductor |52 at armature |3|. Relay |08 also opens the original circuit of the stepping magnet |34 at armature |32 and the circuit of relay 01 at armature |30. However, the contacts at these two armatures have already been shunted by the operation of armatures |29 and |26 of relay |01. Line relay |03 therefore continues toY send impulses to magnet |34. It will be noticed that olf normal springs |36 are closed at the rst step of switch SI, but relay |01 holds open the circuit of release magnet |33 at armature |21. At the same time that it sends impulses to switch SI, the line relay |03 sends impulses to the meter selecting switch S over the following path: Ground at |30 or |26, armature ||5, armature |8, armature |22, conductor wiper 54, conductor 44, and winding of stepping magnet to battery. The switch S is therefore advanced along with switch SI. On the first step of switch S the off normal contacts 3 are closed. The circuit of release magnet 4 is however held open by slow acting relay 6, which operates in parallel with magnet 5 and holds up during impulses.

The relays operate as described with the result that after ten interruptions of the line circuit have been produced ten impulses will have been transmitted to magnets |34 and 5 and switches SI and S will have advanced to their tenth positions. The impulse cam next produces the eleventh interruption. At this time cam 2| closes springs I8 and I9, these springs remaining closed during the time impulse springs I6 and |1 are opened by the impulse cam. The conditions during the eleventh interruption are therefore moded by the grounding of the upper line conductor 4I. As a result relay |02 alone responds, relay |03 being held up over the temporarily grounded line lconductor 4|.

When relay |02 falls back alone it closes a circuit for relays |05 and |05 in parallel, said circuit extending from ground by way of armature IIG, armature II4, and windings of relays |05 and |05 to battery. Relay 05 is slow to pull up and cannot operate responsive to a standard length irnpulse such as is delivered by relay I 02 under control of the dial. Relay |05 operates, opens the impulsing circuit for magnet 5 of the meter selecting switch S at armature |22, and locks itself over a circuit including ground, armature |21, armature I24, and armature |23, A branch of the locking circuit extends from the upper end of the upper winding of relay |05 by way of armature |25, wiper |35 of switch SI, tenth contact in bank, and winding of relay IOI tobattery. Relay |0| energizes and locks itself to the grounded release trunk conducto-r |52 at armature Ill. At arma.-

qture I I0 relay I0| supplies ground to the locking circuit of relay |05, as the original ground is to .be shortly removed' by the falling back of 'relay Relay |0| also disconnects the line relays |02 and |03 at armatures |02. and ||2 and connects the incoming trunk conductors |50 and |53 to automatic trunk `conductors |55 and |56', respectively, extending to the first selector.A The line and release relays (not shown) of the selector accordingly energize and the latter supplies a holding ground to the release trunk conductor |52. At the trunk circuit the deenergization of linerelay |03 is followed by the deenergization of relay |04 which breaks the circuit of relay Hl?. The latter relay, on falling back, closes a circuit for the release magnet |33 of the switch Sl is therefore'restored to normal, whereupon the circuit of release magnet |33 is broken at olf normal springs |36.

Relays |0|, |08, and |05 remain energized throughout the connection, the first two being locked to release trunk conductor |52, and the last named relay being locked to ground at armature ||0 of relay IGI. It will be recalled that the energization of relay |05 opens the impulsing circuit to magnet 5 of the meter selecting switch S at armature |22. 'At the same time a circuit is .closedv at armature |.2| which extends ground to conductor |5| by way of resistance |60. The resistance is high enough to prevent the operation of magnet 5, but the relay E is held up. The meter selecting switch therefore remains with its wiper 2 standing on the tenth contact, with the result that meter MI'B isconnected to conductor i3 and to release trunk conductor |52.

The calling subscriber at station A| 0 may now dial the digits in the desired number, and the first selector which has been taken for use together with other switches will be operated in the usual way to complete the desired connection and signal the called subscriber. When the called subscriber answers, a booster battery is momentarily inserted in the circuit of the release trunk conductor |52.. The increased voltage operates the connected meter Ml!) to register the call. When the subscriber at station A| 0 replaces his receiver the bridge across the line is broken and the connection is released in the usual manner. The removal of ground from release trunk conductor |52 permits the switching relay of the line switch LS to restore and permits the energized relays in the trunk circuit T to fall back. Relay l0| disconnects ground from conductor |5|, whereupon relay 6 falls back. This closes a circuit for release magnet 4 of switch S, which restores the switch to normal, springs 3 opening in normal position to open the circuit of magnet 4.

It will be understood that although in the calling device at station A||l the cam 2| is set in the position shown in the drawing, Fig. 3, with the pin 33 in the tenth hole, at the other stations the cams corresponding to cam 2| are set differently, in fact, each cam has a different setting corresponding to the number of the associated station. At the No. 1 station, for instance, the cam is set with pin 33 in the rst hole. `The operations which take place when the subscriber at station Al makes a call will now be briefly explained. The station apparatus at A! is not shown in detail but is the same as at station A|0 except for the diierent setting of cam'2l.

The results which follow the removal ofthe receiver are the same as previously described. When the preliminary digit is pulled in the dial the cam such as |3 is set in the described manner in order to prepare for grounding the negative dises the digit ll.

accepta line 4| Yon the return movement. When the dial returns, relays |02 and |03 fall back responsive to the first line interruption and the latter relay delivers an impulse to switch SI and also an impulse to switch S, advancing these switches one stepeach. During the second interruption cam 2| closes springs i8 and |9, grounding line conductor 4| and thus preventing line relay |03 from falling back. Relay |05 is therefore energized and locked up, opening the impulsing circuit to magnet 5 of switch S. Ground is supplied to relay 6 through resistance |50. During the third interruption springs I8 and I9 are not in engagement as cam 2| has passed on, so that the third and succeeding interruptions operate the line relays |02 and |03' in the normal way. The latter relay resumes the transmission of impulses to 4switch SI but sends no more impulses to swich S because of the fact that relay |95 has operated. Switch S therefore is left standing with its wiper 2 in engagement with the rst contact, thus connecting up the No. 1 meter. Since eleven inten ruptionsf are produced, and since the effect of one is lost by holding up relay |03, just ten impulses will be delivered to switch SI, which is thus ad- 'f vanced to the tenth contact in its bank. Wiper at this point closes the circuit of relay |0| and the ensuing operations are the same as described.

l'rom the foregoing the manner in which the corresponding meters are selected responsive to calls from the other stations on the line will be readily understood. Each subscriber always pre- Eleven interruptions are always produced therefore, effective to control the trunk circuit T, and during one interruption, which one depends on the station calling, the negative line is grounded to operate relay e5 and stop the meter selecting switch S. Switch SI continues to operate responsive to the remaining interruptions and delays the operation of relay Hit unt-il the preliminary series of interruptions is iinished.

In any measured service system some consideration must be given to the possibility that some subscriber will attempt to put through a call without going through the required operations, with the object of defrauding the company. The mechanical construction of the calling device herein shown positively requires that the digit ll be prefixed to each number called. Unless this digit is prefixed the cam I3 is not operated, and unless cam I3 is operated no grounding of the line 4i canoccur during the impulse transmission. Without such grounding of the line relay |05 cannot be operated and relay |0| cannot be operated to connect the line through to the iirst selector. In order to prevent tampering with the calling device the instrument may be sealed, or preferably, a drop of sealing wax may be placed over the screw which retains cam 2| in position. Thus any attempt by a subscriber to change the setting of cam 2| so as to charge his calls to a diierent subscriber can be defeated, or at any rate, will be detected on the next inspection.

However, a subscriber may attach wires to the line terminals of his instrument and to the ground terminal and attempts to simulate the operation of the calling device, applying the ground during vsome random interruption or during some interruption which will not result in selection of his meter, if the setting of the meter cam 2| is known. The fact that switch Sl must receive ten impulsesmakes `it rather difficult to obtain any results this way, as any momentary cessation of the impulses for a longer period than the normal spacing will let relay |01 fall back, releasing switch SI. As an added precaution relay |06 is provided. This relay, it will be recalled, is slow to pull up and will not energize in the normal operation of the system. However, in attempting to get through the trunk circuit T by manipulating wires, the operator is liable to ground the line for too long a period and any substantial increase in the length of the impulse delivered to relay |95 results in the energization of relay It in parallel with it. Relay |05 is thus prevented from locking up because relay |06 is slightly slow to release and will hold the locking circuit open at armature |24 until after it is opened at armature |23. Unless relay |05 is locked up, relay mi cannot be operated, even if the switch SI is successfully stepped around, and the line cannot be extended through to the rst selector.

The invention having been described, the particulars as to which the protection of Letters Patent is desired will be pointed out in the appended claims.

What is claimed is:

1. In a calling device of the type which includes a setting member and in which impulses are transmitted upon the restoration of the setting member, a contact member, means responsive to the operation of said setting member in accordance with certain digits for transmitting impulses without actuating said contact member, means responsive to the operation of said setting member in accordance With another digit for actuating said contact member, means for retaining said contact member in actuated position, and means eiTective upon the completion of the restoration of the setting member for restoring said contact member.

2. In a calling device, a dial, a shaft on which said dial is supported, a pair of contact springs, a pivoted member for operating said springs when rotated, said pivoted member being arranged and adapted to tend to remain in its normal position until rotated and to remain in its rotated position until restored, a cam on said shaft for rotating said pivoted member responsive to a predetermined movement of the dial, and another cam on said shaft for restoring said pivoted member upon the return of the dial to normal.

3. Ina calling device, a main shaft on which a dial is carried, a pivoted member supported adjacent said shaft, a cam on said shaft for rotating said member when the dial is turned a predetermined amount, a spring contact member actuated by said pivoted member, the said members being so related that the pressure of said spring member holds the other member in actuated position, and another cam on said shaft for restoring said pivoted member upon the return of the dial to normal.

4. In a calling device, a rotatable dial, a spring for returning said dial after it has been rotated, an impulse sender actuated a number of times during the return movement depending on the extent of the rotation, and a contact device actuated only when the said dial is rotated suincient to send the maximum number of impulses.

5. In a calling device, a setting member, a pair of contacts closed at the end of a predetermined movement of said setting member, means for holding said contacts closed during the restoration of said settingmember, a pair of contacts closed only at a predetermined point in the restoration of said setting member, and a circuit including said pairs of contacts in series.

6. In a calling device, a rotatable dial, a spring for returning said dial after it has been rotated. impulse sending means operated a number of times during the return movement of the dial depending on the extent of the rotation, a second impulse sending means operated only once during the return movement, and adjustable means having a number of fixed positions, for varying the point in the return movement at which the operation of said second sending means takes place according to the position in which said adjustable means is placed.

'7. In a calling device, a rotatable dial, a spring for returning said dial after it has been rotated, impulse sending means operated a number of times during the return movement of the dial depending on the extent of the rotation, a second impulse sending means operated only once during the return movement, two circuits over which the two sending means send impulses, respectively, and means whereby the second circuit is rendered effective only upon a particular amount of rotation of the said dial.

8. In a calling device, a rotatable dial, a shaft for said dial, means for returning the dial and shaft to normal after the dial is rotated, impulse sending mechanism driven by gears from said shaft during the return movement of the dial, additional impulse sending mechanism operated directly by a member attached to said shaft during the return movement, and means for securing said member in any one of a number of set positions to predetermine the point in the return movement at which the said additional sending mechanism is operated.

9. In a calling device, a rotatable dial, means for returning said dial after it has been rotated, impulse springs, means for separating said springs a number of times during the return movement of the dial depending on the extent of the rotation, and means also operated during the return movement to ground one of said springs at a time when it is separated from the other spring.

10. In a calling device, a rotatable dial, means for returning said dial after it has been rotated, impulse springs normally closed, means for separating said springs a number of times during the return movement of the dial depending on the extent of the rotation, impulse springs normally open, and means for closing said springs once during the return movement, the closing taking place concurrently with a particular opening of the said first mentioned springs.

11. In a calling device, a rotatable dial, means for returning said dial after it has been rotated, a rst impulse contact, means for actuating said first contact during the return movement of the dial a number of times which depends on the extent of the rotation, a second impulse contact, and means for actuating the second impulse contact during the return movement only after at least one actuation of the first contact has been effected and terminated, and for terminating the said actuation of the second impulse contact prior to the iinal actuation of the rst contact.

12. In a calling device, a rotatable dial, means for returning said dial after it has been rotated, a rst impulse contact, a second impulse contact, means for actuating the rst contact during the return movement to send a number of impulses which depends upon the extent of the rotation, means for actuating the second contact coincident with one of the said actuations of the rst contact, and selecting means for predetermining the actuation of the rst contact with which the actuation of the second contact coincides.

13. In a calling device, a rst contact, a second contact, means for producing a series of actuations of the first contact, means coincidentally effective for producing an actuation of the second contact, and means adjustable to any one of a number of xed positions for predetermining, according to its adjusted position, the position in the series of actuations of the rst contact to be occupied by the actuation of the second contact.

14. In combination, means for generating a series of impulses, means coincidentally eiective for generating another impulse during said series, and means adjustable to any one of a number of fixed positions for predetermining, according to its adjusted position, the position in the series to be occupied by said other impulse.

HERBERT F. OBERGFELL.

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