US1999859A - Signal apparatus - Google Patents

Description

April 30, 1935. 5 BEAH 1,999,859

S IGNAL APPARATU S Filed Nov. 5. 1931 8 Sheds-Sheet l 5 51 j INVENTOR- ATTORNEY CZ. E. BEACH SIGNAL APPARATUS April 30, 1935.

INVENTOR ATTORNEY A ril 30, 1935. -c E. BEACH 1,999,859

S IGNAL APPARATU 5 Filed Nov. 5, 1951 s sheets-sheet s INVENTOR ATTORNEY 'c. E. BEAC lH SIGNAL APPARATUS April 30, 1935.

Filed Nov. 5, 19 l 8 Sheets-Sheet J6 a 6hr 673629 fine)? April 30, 1935. -c. E. BEACH SIGNAL APPARATUS Filed Nov. 5, 1931 8 Sheets-Sheet 6 A ril 30, 1935.

c. E. BEACH SIGNAL APPARATUS Filed Nov. 5, 1931 8 Sheets-Sheet 7 April 30, 1935. 'c. .EfBEACH SIGNAL APPARATUS Filed Nov. 5; 1951 s Sheets- Sheet 8 fiiaferal07 hrer 1 592; 5.9%

?aten ted Apr. 30, 1935 PATEN OFFICE 1,999,859 v p SIGNAL APPARATUS Clarence E. Beach, *Brookline, Mass., assignor to The Gamewell Company, Newton Upper Falls, Mass, a corporation of Massachusetts Application November 5, 1931, Serial No. 573,150

44 Claims.

This inventionrelates to signal formulating *or transmitting mechanisms and systems, and more particularly to improvements in apparatus of the type comprising a. series of widely separated signal transmitters connected to a central signal receiving station, for example, to apparatus such as a circuit including a plurality of fire alarm boxes or similar signal transmitters connected to a central signal receiving station. The invention particularly aifords improvements in successive non-interfering signal transmitters as commonly employed for such purposes.

Apparatus of the class to which this invention relates is depended upon-to avoid serious property lossand even inmany cases loss of life itself; accordingly, it is a primary object of the present invention to aiford an especially dependable signaling apparatus and particularly to provide a device of this character which is operable under a wider variety of adverse conditions than has been the case with any device of the general character which has been heretofore provided. Particularly the present invention provides a signaling device adapted to transmit signals over an emergencyline or common return, suchasa ground, if the regular circuit becomes faulty, while-avoiding the closing of such an emergency circuit whenthe normal operating circuit remains. properly conditioned. This invention also afiords a signaling device'arranged to operate when serially associated with similar devices without interference between such devices even if they are simultaneously or substan-- tially simultaneously actuated. Thus the present invention afl'ords an improved type of signaling device of the perfect non-interfering type, as

well as a device having animproved emergencyswitch or ground wirereturn arrangement, and this invention particularly provides for the con- .venient associationof both of these advantaof code signal transmitting call or alarm boxes,

and in which, at a central point or station, the

loop ends are connected through indicating or control devices to a suitable current source. Such, current sources are generally referred to as the central station battery and may be normally free from ground connections so that the faults may develop or threaten in'the circuits or apparatus, so that intended signaling response at the central station may result. from closing and breaking of a connection between. one or the other or both portions ofthe signal circuit and the event that the non-interference magnet or its associated parts become disabled. The funotion and purposes of this magnet and its related parts then being automatically dispensed with during emergency signaling operations. To permit these desirable results, test operations may be carried out in such a manner as to differentiate between a busy condition of the circuit and a malcondition thereof. Furthermore, should the testing operation indicate a malcondition of the circuit, the mechanism is so arranged that it will stop operation after the elapse of acomparatively short interval, thus conserving the energy stored within the motor spring and preventing needless exhaustion thereof, so that the motor may be ready to operate in response 1; a subsequent pulling of the box.

It is still another object of this invention, when the test operations shall point to a busy condition of the circuit, to provide that effects shall transpire progressively to limit the number of times a finally successful waiting or seeking box may repeat its signal. These restrictions vary inversely as the length of the preceding busy period:

for a firstlength of busy period one repetition of a signal shall be deleted; after a slightly longer busy period two repetitions of the signal are deleted; proceeding in like manner, such eii'ects may continue until a transmitter may send its signal but once, without anyrepetition; and, finally, should the length of the busy period extend be yond a second predetermined time limit, the mechanism of the waiting signal box abandons its attempts to seize the circuit and-restores its mechanism to normal, while still retaining enough energy stored in its motor spring for carrying out any subsequent signaling as may be required. in .the regular eventuations of the service.

- A further aspect of this invention relates to the arrangement of the mechanism so that the complete signal may ordinarily be transmitted, even when the current supply is abnormally low, if there is'sufiicientcurrent to permit initial seizure of the linejby the transmitter. Accordingly certain objections which have characterized previous mechanisms of this general type are avoided, since there is little possibility of the transmitter taking possession of the line and sending an incomplete or mutilated code signal, thus giving a .false or wrong alarm indication.

More particularly objects of the invention are: To render the non-interference and succession mechanism ineflective in the event of faflure of this mechanism to be influenced, by adequate energization of the electromagnet, for a time longer than the longest interval between magnet energizations which should occur incident .to the formulation of any signal, to the end that the mechanism may act without the non-interference and succession functions to effect the formulation of the intended code signal notwithstanding any defect or disablement to which the non-interference magnet or its associated mechanism may be subjected; to short-circuit the winding of an busy circuit, without having caused effective response to its signal formulation,

In the drawings: I

Fig. 1 is a front elevational view of improved transmitting apparatus constructed in accordance with the present invention, certain parts being broken away for clarityof illustration;

Fig. 2 is an isometric viewof a portion of the assembly shown in Fig. 1, parts being broken away and removed to show clearly the arrange-. ment of the electrical conducting elements and related parts;

Fig. 3 is a side elevational view of a portion of the assembly shown in 1, certain partsbeing removed;

Fig. 4 is a front elevational view of certain portions of the signaling apparatus, including pormoved and the position of the remaining parts being that which they occupy during a signal transmitting period; i

Fig. 6 is a rear elevational view of a portion of electromagnet included in an intended signaling assembly; particularly showing a part of the sigpath in the event of the failure of such magnet to become effectively energized throughout a time longer than the longest intended non-energization interval incident to the formulation of any signal, to the end that in the event of rupture of the.current path through any such m et winding, the intended code signal may nevertheless be transmitted over the'normal metallic circuit, irrespective of the effectiveness of any ground or emergency circuit connection; to provide an emergency common return or ground connection only following the expiration of a time. measured by the rlmning of the train during which the magnet remains deenergized, which time is longer than the longest intended nonenergization period incident to the formulation of any signal, and, at the same time, establish one ormore of the other emergency conditions ,iust

referred to; to assure effective signal formulation in the normal current path, irrespective of eifectiveness of any ground connections, notwithstanding any degree of impairment of the normal line ,,,current strength; to provide -a non -interference mechanisms now known, so long as the normal signaling current path remains unimpaired; to effect conservation of the main spring or other driving power for the transmitter mechanism by provision of means whereby, if the mechanism is nal train .and the escapement mechanism associated therewith;

Fig. 7 is a front elevational view of the signal wheel;

Figs. 8 and 9 are edge views of the same, showing the relationship of the wheel to a portion of the sender arm;

Figs. 10 and 11 are elevational views-of certain parts of the apparatus, showing the position of the same when the signal train is stopped and Figs. 15 and 16 are 'iront elevational views of thesignal wheel, sender arm and the related electrical contact and conductor assembly:

Figs. 17, 18 and 19 are front elevational views of a portion ofthe stop train mechanism and related parts, showing these parts under various operating conditions; Fig. 20 is an isometric viewof the master plate assembly; and 1 Figs. 21, 22 and 23 are typical wiring diagrams. For the purpose of facilitating comprehension of this invention and illustrating a manner or applying the several improvements thereof to a type of mechanism with which those skilled in this art are familiar, the embodiment of this invention shown by the accompanyingdrawings and hereinafter described in detail is one utilizing portions of mechanism such as that of the successive non-interference signal box disclosed in United States Letters Patent to Frederick W. Cole, No. 1,244,587, issued October 30, 1917. Portions of such mechanism which are clearly illustrated and described in said Cole-patent are not always herein described in detail, except in in-- Motor and signal train The motor means and a portion of the signal .train may be similar to that disclosed in the above-identified prior Cole patent, as shown in Fig. 1, the outer end of main spring I is fixed to a stud 2 anchored to the outer frame plate 3 of the assembly, the inner end of this spring being attached to the main shaft 4 (Fig. 3). The ends of shaft 4 are journaled in front and rear plates 3 and 3*, these plates being held in spaced relation by struts Ill. The winding handle 8 may be turned counterclockwise, as viewed in Fig. 1, to

wind the spring I to condition it for imparting a clockwise movement to shaft 4 when the spring is released. A gear I cooperates with a rotating pinion 3 and carries a stop pin I2 for engagement with an arm |4 moving withsaid pinion to prevent overwinding in the manner described in the above-identified patent.

A ratchet wheel 5 secured to shaft 4 engages a spring-pressed pawl 6 that is pivotally mounted on a spur gear 1 free to rotate on shaft 4 (Fig. 6). The gear wheel 1 meshes with a relatively small pinion IS on the shaft l1, which carries the signal wheel l8 (Figs. 1 and 3) A gear wheel 19 secured to shaft |1 meshes with a pinion 2| fixed to shaft 22 and to the escapement wheel 23. The latter engages a speed limiting pallet 24. (Fig. 6) mounted on a pivot 26, arms 21 and 28 extending from this pallet and bearing respective adjustableweights 3| and 32 to affect the speed of the signal train and thus control the speed of the signal wheel I 8.

Manual control A lever 33 is-disposed in front of the, frame plate 3 and connected to a pivot shaft 34, the latter carryinga projection 3B-Which has a camlike engagement with a rocking or master plate 31 to swing the latter clockwise (Figs. 1 and 5). Plate 31 is mounted on a pivot 38 (Fig. 20) that is rotatably mounted between the front and rear plates 3 and 3, while an arm I62 moves with said shaft 38 and has a hooked projection 'engaging the end of retractile spring 52, the opposite end of which is connected to a pin projecting from plate 3. Plate 31 is disposed directly behind plate 3 and has an extension affording a tracer arm 39 (Figs. 10 and 11), which may ride the dished periphery of or enter a notch 42 in a rounds measuring disk 4| that is rotatable on but independently of main shaft 4. A stop dog 40 has a pivotal connection 43 with the plate 31 and is simultaneously shiftable from engagement with the stop pin 44 projecting from gear wheel l9 when the tracer arm 39 is withdrawn from the notch 42, to permit the signal train to start operation under the action of main spring I. When the arm 39 of the master plate moves into the notch 42 of the rounds measuring disk 4|, the

stop dog 40 is brought into the .path of the pin 44 upon the wheel l9 to arrest and retain the mechanism in its inoperative position. When the notch 42 has moved out of registration with the arm 39, the tension spring 52 presses the end of said arm against the flanged periphery of the measuring disk 4|, thus retaining the master plate in its operative or clockwise position and affording brake means for the disk to prevent overrunning thereof.

The stop dog 40 is substantially in the form of a bell crank and has an arm 4|) with a bifurcatedend looselyen'gaging the escapement-wheel shaft 22. The dog also has a slotted bearing portion 40 engaging the pivot stud 43that .projects from plate 31, and cooperating with a coil spring 53 which is looped about a boss concentric with the pin 43. This arrangement affords a clearance between walls of the slot at the end of arm 40 and the shaft 22 and permits the end of dog 40 to snap away from the pin 44 with a positive and rapid movement; thus preventing reengagement of the end of stop dog 40 with pin 44 and assuring positive release of the train irrespective of how quickly the pull handle is released after pulling.

The use of the stop pin 44 upon the gear H3 is particularly advantageous, since the strain from the spring I received by the pin, the dog40 and the related parts is comparatively low due to the gear ratio between gears 1 and I6 and the shafts Signal wheel assembly The signal wheel |8 may be detachably secured by a. set screw 20 to the outer end of shaft 1, thus to permit ready interchangeability (Fig. 5) and is provided with a plurality of teeth 30 in accordance with the distinctive code signal that is to be sent from the individual box. The sender arm or automatic key 9| is pivotally mounted upon the front plate 3, as indicated by numeral 52, and is provided with a lug or fluke 93 (Figs. 15 and 16) which is engageable with the protuberances 30 on the signal wheel. Aninsulating block or abutment 34 secured to arm 9| engages the twin contact springs 61 and 68 (Fig. 2), therebyto set up pulsations in electrical current, as will presently be described, while these springs yieldably urge arm 9| toward wheel l8.

A member 96 depends from the lower end of the sender arm 9| and normally abuts a stud 91 (Fig. 1) projecting from master plate 31, so that the latter in its normal position holds the lever 9| andfluke 93 out of engagement with the a peripheral portion of the wheel I8. The end of this skirt has an advanced, inclined corner portion IOI. When the master plate 31 initially moves out of its normahp osition 'to release the arm 9|, the edge of skirt I00 engages the fluke 93 and holds the latter spaced from the periphery of the signal wheel I8, while the'contacts of assembly PC remain in engagement under the action of their supporting springs. As shown, the

wheel I8 is provided with a continuously curved,

void or interdental space adjoining the skirt. After the wheel I8 is rotated so that the skirt I00 no longer is disposed adjoining the fluke 93, arm 9I may, under certain conditions, swing toward the wheel, so that, during subsequent revolutions, thelip or inclined corner IOI of the skirt may engage the fluke with a cam-like action, the shield thus being stressed and engaging the inner face rather than the edge of the fluke (Fig. 8), thus permitting said skirt I00 to be rotated past said fluke without'thereby either lifting or supporting said arm 9I.

Electrical connections Referring first to the typical wiring diagram of Fig. 21, it is to be understood that a plurality of boxes or instruments C, D, E, F and G, such as disclosed and described herein, are arranged in series, the parts of the box E being shown diagrammatically. The boxes, as thus connected, are joined by main leads B and H to the respective sides of a central'battery CB, the lead B operating a signal-responsive or recording device A at one side of the battery and the lead H similarly operating a device J. The emergency working switch EW, as shown in Figs. 21 and 23, has a contact K connecting the line section H with the left end or minus terminal of the-battery; but is adjustable (Fig. 23) so that the ground connection or common return CR may be connected to this terminal of the battery by the engagement of elements L and K, while the conductors H and B are then connected through element M with the opposite battery terminal.

' The devices A and J may be capable of transferring signals received from the outlying boxes in any well-known or desired manner, as by visual, audible, recorded or any suitable combination of such forms of signal manifestation.

Fig. 2 illustrates more particularly the connection of the external leads to the individual signal transmitting apparatus and also the arrangement of electrically conductive components of the apparatus. The terminal 56 may be connected to anexterior line section, such as the section B, while a similar terminal 51 is connected to the opposite line section, as thesection H. A third line secto the upper part of the horizontal leg of this angle. Angular contact springs 61 and 68 are secured by terminal post bars H and 12 against the lower surface of this horizontal leg of the manner.

site leg yieldably presses against the first leg, as well as providing a skirt I00 extending beyond insulating angle 66. The springs 61 and 68 are arranged so that their depending legs, which follow arm 9| as previously described, also provide contacts normally engaging similar contacts at the lower ends of springs 62 and 64, respectively, (see Figs. 2 and 15), while the horizontal legs of springs-61 and 68 are turried'up to provide contacts 13 and 16 of the emergency switch assembly, indicated generically by reference characters ES. A spring member 11 is clamped to the block 66 by the terminal member 58 to 'serve as a third contact element of the switch ES, Figs. 1 and 2.

Secured to the master plate 31, a block of insulating material 19 carries a return bent resilient member 8|, the free end of which is bifurcated to form two contact springs 82and 83, normally to engage the respective contact members 6| and 63. The member 8I forms a shunting conductor, and since it is movable with the master plate 31, it normally engages the contactors 6I- and 63, thus joining theline terminals 56 and 51 and shunting out the circuits of the transmitter unit. In a converse manner, when the master plate 31 is, rocked clockwise, the member 8| will be retracted from the line-springs 6| and 63, thereby removing the shunt from the transmitter. This switch is commonly referred to as the box-shunt", and as its actuation occurs only in the .operation to effect an ofi-normal condition of the transmitter mechanism, it will be indicated by the appropriate functional reference characters ON;

On removal of the box shunt as just described, a path may be traced from line terminal 56 over the normally engaged contact springs 62 and 61, terminal post bar 1|, conductor 86 to the two serially connected magnet coils 86, of a master magnet MM, thence over a conductor 81, terminal bar 12, and the other set of normally engaged contacts provided by springs 68 and 66, to the other line terminal 51. Thus, the first two line circuit sections may be joined, at certain times, through the magnet MM in completing a loop circuit, the current in which causes the magnet to attract its armature 88, and thereby "initially condition the transmitter to operate in a standard or normal The non-interference magne MM serves divers major functions and is of universal utility in the present mechanism; accordingly, it

. may also be referred to by this functional term,

master magnet.

Sender arm control assembly The armature 88 normally is drawn away from the magnet MM by a spring I I2 and has integral levers I02 and I03 rocking about a pivot element I04 (Figs. 5 and 11), one of the struts I0 acting as a stop to limit the movement of the armature under the tension of spring II2 (Fig. 1). The lever I02 is movable into and out of the path of a guard pin I06 which extends rearwardly from the upper end of sender arm 9I and which has a fiat surface adjoining the end of arm I02. The lower end of lever I03 provides an outturned ledge I01 movable into the path of a swinging pawl I08 pivoted at II9 (Fig. 13) on the left-hand end, as seen in Figs. 5, 11 and 12, of a latch member I09. When the current flowing to magnet MM is uninterrupted as the signal train starts operation, the ledge I01 is disposed below pawl I08 and the pawl may rest thereon, so that the right-hand end of the latch member is held beneath the path of guard pin I06, despite the tension of spring I28 connecting this end of the latch with the plate 8 (Figs. 5 and 12). Thus, when the armature is pin may be cleared so that sender arm 9| can reciprocate.

The contacts provided by springs 62 and 64 remain in engagement with the sender contacts provided by springs 81 and 68 for an interval sufiiciently long vafter the sender 'arm 9| has started. its movement toward the left in beginning. an impulse formulatiomto permit the guard pin I06 upon arm 9| to pass beneath the righthand end of lever I02 before separation of the contacts occurs. Accordingly, when these contacts separate and effect deenergization of magnet MM, the lower surface of lever I02 rides .upon the upper surface of pin I06 through the remainder of the sender arm stroke toward the left and the return portion of this stroke (Fig. 16) until the contacts of switch PC have again moved into mutual engagement. Thereupon reenergization of magnet MM takes place so that the armature 88 is electrically retained in its portative position. While the armature 86 is thus continually held in its attracted position, the free end of the lever I02 is withdrawn from the path of guard pin I06, and if the latch I09 has previously been withdrawn from the path of said pin I06, it will be held out of such path by the engagement of the lower end of the pawl |08Qwith the ledge I'I carried by the arm I03. The sender arm will therefore be free to operate in response to rotation of the signal wheel I8 so long as the positions of the parts just referred to remain unchanged.

Normally the actuating cam H3 is at rest be- I neath the projection I21 of lever I09 to prop the latter against the tension of rotator spring I28 (Fig. 12). Slight advance only of the signaling train from normal is sufficient to move cam 3 beyond fluke I21, so that unless otherwise stayed (as by engagement of pawl I08 with ledge I01 when armature 88 is in its portative position), the member I09 may swing to its blocking position,

where its right end is in the path of guard 'pin I66 and where it'encounters the stop pin I34 fixed to the frame plate 3 (Fig. 13). In this position the left-hand end of member I09 supports the depending end of pawl I08 in the path of the intersecting extension I01 of lever I03, and also in the path of the angle I24 at the end of restoring lever I22. A pawl-I I4 pivoted at IIS on plate 3 is engageable by the cam II3. an :instant after it starts rotation, so that when the latch lever I09 is in its blocking position the pawl is lifted and its projection I I'Iis seated or latched on a ledge I I8 (Fig. 14) of the latch pawl I 08, as shown in Fig. 13. The retractile spring continually tends to swing pawl II4 counterclockwise on pivot 6, so

that it tends to project into the path of the actuating cam I3, while the tension spring I26 connects an ear on member I08 with the pivot pin I 2|, that supports latch I09, thus yieldably swinging the upper portion of member I08 toward the projection II! and toward or against a sleeve on armature pivot I04, which acts as a stop.

In order to permit the latching just described,

the dual purpose stud 91 of the master plate 31 projects between the extremes of the bifurcat ed end of the latch restoring lever I22 (Figs. 5 and' 13) pivoted to the frame plate 3 at I23 and serves, in the off-normal position of the plate 31, to rock the lever I22, swinging its upper or free end to the left, so that an angle I24 thereon may be withdrawn from its normal abutment against the lower end of the pawl member I08 (Figs. 1, 5, 12 and 13). This permits the spring I26 to swing the upper end of the member I08 to the right for latching the lifted switch pawl II4, as just described.

When the armature 88 is rocked on the pivot |04-due to momentary energization of magnet MM, the projection I0'I of the lever I03 moves to theright against the depending end of the latch I08 to eifect counterclockwise movement of the latter member, thereby withdrawing the latch-ledge 8 from the keeper I I! of the switch actuating pawl 4. This action completes the cycle of busy test operations for the first round of the signaling wheel I8, and in these operations the ground switch actuator H4 is lifted and latched in an intermediate position and subsequently released to return to normal positionin preparation for meeting other than a busy condition on the line. Description of the latter efiects will presently be continued.

The unlatching of the switch actuator I I4 at this time merely indicates that the only non-)normal condition of the line circuit found to be present the path of the guard pin I06 to keep the sender arm 9| ineffective during the remainder; of this first round.

The busy test operation just described will be repeated at the beginning of each round of the signal wheel I 8, asthe signaling train continues to run, and constitutes successively repeated attempts of the-present transmitter to' seize the. circuit for immediate use. At the end of each round, the cam I I3, in-passing under the tracer I 21 of the sender lock I09, rocks the latter clockwise momentarily to remove the righthand end of this member from the path of the guard pin I06, in presenting the sender arm 9| for possible control acceptance by the signal wheel I8. The completion of the round or cycle of the signal wheel occurs at "a time when the shield 98 supports (as will be hereinafter more fully explained), on its edge, the tracer 93 of the arm 9| to prevent movement of said am toward wheel I8, and since the first round was ineffective to send on account of the busy condition assumed as having been encountered, the lever I09 continues to prop the sender arm 9| in its ineffective position until entire completion of the round. At the latter instant, the shield 90 is again in the position in which it is shown in'Fig. 1, where its skirt I00 supports arm 9| while lever I09 is being withdrawn from the path of the guard pin I06. Therefore, under the continuing operation of the signaling train and at the beginning of the second round of the signal wheel I8, the various parts concerned in the testing operations will be in the same posi-' tions in which they were at the beginning of thefirst or initial round.

The edge of shield I00 has a slightly eccentric [contour at I0 I, so that the advance portion thereof may engage the fluke 93 with a cam-like ac-'= tion, moving the pin I06 slightly to the right out of engagement with latch I09, so that the latter may freely move under the action of cam 3 to its non-blocking position. The pin|06 and arm 9| may occupy any one of five posi- .tions: first, the normal position wherein pin 91 engages tailpiece 96 and the fiuke 93 is slightly spaced from shield 98 (Fig. 1) second, the position wherein the fluke 93 rides on the edge of the shield (Fig. 15); third, the position wherein the pin I06 engages the end of arm I09 (Fig. 13); fourth, the position wherein the fluke engages the top of a tooth of wheel I8; and, fifth, the position wherein the fluke engages an interdental surface of wheel I8. In the first four positions the contacts of assembly PC may remain closed; in the last position thecontacts are separated.

Ground switch control When the armature arm I02 and the latch I09 are disposed in the path of pin I06 due to the armature being in its raised position, the cam II3 may engage the projection I21 and thus rock the member I09 clockwise. The upper surface of the projection III of switch actuator I, if it has remained in its lifted and latched position on the ledge H8 of member I08, will then be elevated to its'actuating position against the lower edge of a projection I36 on a switch latch lever I31 pivotally mounted on frame plates 3 and 3", as indicated by numeral I38 (Fig. 11). The elevation of the left-hand end of member I09 then thrusts the extension III against projection I36 to rock lever I3I counterclockwise. Thus, the switch actuator I ll is lifted in two steps, the first resulting in the latching on ledge II8 (from which it is dislodged if magnet MM is momentarily energized to swing part I'I against pawl I08), the second step occurring after substantially one revolution of cam II3 following the first step and involving the engagement of the cam II 3 with the fluke of latch I09 while the member II l is supported by ledge II8. Ac-

cordingly, the movement of actuator I to rock lever 131 will only occur if the magnet MM has remained deenergized during substantially one revolution 'ofthe shaft II. The upper end of lever I 31 is curved to provide a keeper for retaining cylindrical contactor or switch member I8 in its ineffective position, as shown in Fig. 12. The counterclockwise movement of lever I31 accordingly releases contactor I8 and a projection I39 on the lever engages a protuberance I l0 from the armature 88, mechanically rocking the armature into its portative position (Figs. and 11) The contactor I8 is secured to the end of a lever IlI, a tensile spring I 42 tending to move this lever clockwise about the' pivot l3 carried on master plate 31 (Fig. 5) to thrust contactor I8 into engagement with .contact springs I3, H

The free end of lever I 31 has an inclined end engaging the contactor I8, such end being so formed that during movement of the arm I responsive to spring 2, as the contactor I8 passes along said inclined surface it will cause the arm I3I to swing somewhat in a counterclockwise direction and thereby act through the extension I39 moving with said lever I31 and the flexible strip 0 associated with the armature 88, to firmly hold said armature and its associated assembly in portative position and, at the same time, to stabilize contactor I8 in engagement with the contact springs I3, ll and 11. While the armature assembly is thus maintained in its portative position, the ledge I 01 carried by the lever I03 is disposed in the path of the lower end of the pawl I08 and thereby prevents the descent of the latch lever I09 at times when the support of the cam I I3 is withdrawn from the projection I21 of said latch lever; with the result that neither the free end of said latch lever I09 nor that of the arm I02 will be disposed in the path of the pin I06, and the arm 9| will be free to move in response to the rotation of the signal wheel.

Stop train and related control mechanism A pawl cam l6 fixed to signal gear shaft IT has a notch l5 engageable with a pawl l8 that is pivotally mounted on a rotatable member lI in loose assembly with the shaft, II (Figs.- 5 and 14). A spring 50 engages the pawl l8 and thus tends to retain the opposite end of the latter in engagement with the recess l5, to hold the clutch in its closed or operative position, so that the members l6 and H may be caused to rotate as a unit with the signal wheel shaft I1 and the members fixed thereto. Member l'I carries a gear lI which meshes with a wheel 5I amxed to the measuring disk lI upon the main shaft l (Fig. 3). When the clutch l6-l8 is closed, the signal and stop trains operate together to bring the rounds disk H to its normal position sothat spring 52 (Figs. 5 and will rock plate 31, and cause arm 39 to reengage the notch l2, and the stop dog l0 to engage the stop pin ll.

The signal and stop trains preferably have such a gear ratio that the measuring disk lI normally makes one revolution during four revolutions of the signal wheel I8. Under certain conditions, however, the clutch l6- l8 is open so that the signal train continues in motion while the movement of the stop train is interrupted.

Accordingly the signal wheel may continue rotating and tests of the circuit conditions may be made through the armature and latch mechanism, while the rounds or measuring disk lI remains stationary at one point of its path.

A skipping dog I29 (Figs. 4 and 14) loosely swung on the pivot shaft I0l is continuously stressed clockwise by a rotor spring I3I extending from the dog about a boss concentric with shaft IN and having its remote end connected to a pin upon the armature lever I02. An arm I32 projects forwardly from dog I29 to engage a sloping extension or fluke I33 on the upper edge of the left-hand end of latch lever I09, so that the lower extremity of dog I 29 may swing downwardly to engage the pawl l8 when the right-hand extremity of the latch lever is raised 1 to its blocking position. Accordingly, the lower end of the skipping dog I 29 is then disposed in the path of the pawl 48 so that it may engage the pawl after the shaft I I has made substantially onerevolution, thus to disconnect the clutch elements 46 and 48 and cause cessation ofmovemerit of the members 41, lI upon the shaft l1, and of the measuring disk M and its gear 5! upon the main shaft l, the end of stop arm 39' engaging the dished periphery of the measuring disk under these conditions to act as a brake and prevent accidental forward movement of the same as the clutch is held out.

-wheel I52 at cessive advancing steps thereof, both of the shoulders I66 and I61 of the holding pawl incidentally purpose, the stepping and I 9 may engage ratchet teeth on a counting wheel I52 that is loosely mounted on main shaft 4, advancing this wheel one step (Fig. 17) under the control of a click element I53 and against the tension of a spring I54 which is adapted tobe wound on a grooved hub I56 on the counting wheel. Spring I54 is secured to the element I53 and to a stepping pawl I51 pivoted to ratchet I58, this spring serving the triple purpose of drawing the ratchet wheel to its normal position, yieldingly retaining the pawl I51 against a stop pin I59 on the sideof the ratchet wheel and stressing the holding pawl or click element may engage teeth of the counting wheel I52. The

engaging the end of the retractile spring 52 for plate 31.

An aperture I BI in the body of the pawl I 53 receives the angled extremity I63 of the arm gage the teeth of the counting ratchet wheel I52,

will then be retained by engagement of the end of the pawl I53 with the long I64. During the second round of the mechanism, the pin 44 engages the next lower or eleventh tooth of the counting ratchet I52 in advancing it a second step, whereupon it is retained by engagement of its last tooth I 69v with the last ledge I61 or the holding pawl I53,

may dually engage teeth ing wheel as advanc operate in holding it on succeeding steps,

which its of the tracer 39.

and

of advancing the disk notch 42 will be inretaining the counted (Fig. 18).

presented in the path The interdental space between the long tooth I64 1y ride the point of t to the stepping pawl I51.

"rake the attend- I52 is less than a full step,

the holding pawl I53 may not fall ini but merehe next ratchet tooth of this e spring I 54 will cause backi it is checked by the holdthe tooth of the ratchet on which it was previously seated; During such retraction of the wheel is moved backward I52, the stepping pawl I51 in preparation for 'a new scribed the pin 44 engages the long tooth I64 ping dog I29 so that the clutch 46-48 is reendog again engages the pawl revolution of the rounds gaged, causing the member 41 and gear 41 to rotate with the shaft I1 and causing a quarter disk 4I. Thereupon if the current cond'tions are such thatthe skipping dog I29 remains in the same position, the 48, the-clutch 49-48 is opened, and for two successive additional rounds the member 41 is stepped along by engagementof the stepping pawl I51 with the toothed portion thereof. At the end of the second succeeding round the skipping dog and pawl are again disengaged, the clutch 46-49 is again closed, and the measuring disk makes another quarter turn. The same sequence of operations may be repeated at the end of two more rounds so that the measuring disk 4| completes its final quarter revolution, whereupon the arm 39 reenters the notch 42, thus causing the dog 40 to be carried into the path of the pin 44 to thereby terminate the operation of the mechanism. 9

Whenever the mechanismis brought to rest under any of the various circumstances herein described, through the stop dog 40 being moved into the path of the pin 44, the accompanying clockwise movement of the plate 31 in carrying the arm 39 into the notch 42, correspondingly swings the arm I62 so as to changethe relationship between the angled extremity I63 of said arm and the aperture I6I in the body of the pawl I53, from that shown in Fig. 18 to that shown in.

Fig. 19, andthereby causes said pawl I53 to swing away from the ratchet I52. Said ratchet will thereupon be rotated counterclockwise, by its spring I54, until it is restored to its normal position where its long tooth I54 engages the intermediate tooth I56 of said pawl I53.

It is evident that the signaling apparatus may transmit three rounds of the signal through the pulsating contact assembly PC, if the rounds measuring disk has been moved one-quarter of stored in the a revolution before transmittal of signals through this assembly is permitted; If the rounds wheel or'disk has moved one-half a revolution before the transmitter receives possession of the line, two rounds of the signal will be transmitted, and if the disk has moved three-quarters of a revolution, only one round will be transmitted. Accordingly, this arrangement results in the repetition of the signal for a smaller number of times after a determined period of delay, the number of repetitions being reduced as the period of delay-is prolonged until but-a single round of the signal may be transmitted, and ultimately-the mechanism may be conditioned so that the signal will not be sent at all, but the signal train will stop to conserve some of the potential energy main spring I for a subsequent operation.

' Ordinary operation circuit is in normal condition and no other transmitter associated with that circuit is in opera-. tion, the apparatus will operate in the normal.

immediate transmittal of the signal. Pulling of the handle 33 swings the master plate 31, in a clockwise direction, removing the stop arm 39 from the notch 42 in the rounds disk 41 and snapping the stopdog 40 out of the move the stop dog path of the stop and stepping pin 44 on gear I9 (Fig. .11). Movement of the plate 31 also disengages the contacts of switch ON and removes the pin 91 from the tailpiece 95 of the sending arm 93, as well as swinging the angle I24 at the end of latch restoring lever I22 to the left, away from the depending end of pawl I08. As soon as the-stop dog 40 is removed from the pin 44, and the arm 39 is retracted from notch M, the signal train starts turning, due to the release of energy from main spring I. The shunt connection provided by member 8| with its contacts 82 and 83 is disconnected by opening the switch ON so that current flows through the contacts of the pulsating contact assembly PC, the arms H, 12, and the connections 94 and 81, whereby magnet MM is energized. Armature 88 is thus immediately 68 as soon as its tailpiece was released from engagement with the pin 91. The energization of magnet MM raises the arm I02 so that the guard pin I06 may pass under the end of this arm. When the shaft I1 starts rotating from its normal position, the cam II3 moves out of supporting engagement with the fluke I21 carried by latch lever or guard I09, so that the lower end of pawl I08 may engage the ledge I01 of armature lever I03, which has been moved by energization of magnet MM into the proper position to receive the lower end of the pawl. Thus the rightpath, and the energization of the armature holding the arm I02 above its-path. As soon as the fluke 93 leaves the skirt I00, it may engage the periphery of the signal wheel, opening the contacts of switch assembly PC so that the magnet .is no longer energized. However, under these 08 is mechanically held conditions, the armature in its portative position, due to the end of lever I02.resting on pin I05. As one of the teeth 30 moves the arm 9| to its switch closing position, the contacts of assembly PC are again momentarily closed to energize the magnet MM to permit the armature to be electrically retained in portative position before its mechanical support provided by the parts I02 and I06 becomes inoperative. Thus the electric pulsations are sent over the line or electrical loop provided by conductors B and H, so that the signal devices A and J in the main station may be'energized to indicate and/or record the signal being transmitted.

The skipping dog I29 is held out of the path of pawl 48, due to the position of latch lever I09, so that the clutch 46-49 remains in its closed condition. Accordingly the gear 41 rotates with shaft I1, so that the rounds disk makes one revolution in four-revolutions of the shaft I1 and the signal wheel. Accordingly four rounds of the signal are transmitted before the notch 42 again receives the stop arm 39, thus permitting the plate 31 to return to its normal position and to 40 into engagement with the pin 44 (Fig. 10).

switch ON is closed, the stud 91 reengages tailhand end of arm I09 is locked in its depressed Simultaneously the shunt piece 95, and the projection I24 at the end of arm I22 swings against the lower portion of pawl I00 positively to return the latter to its inoperative position.

Due to the ratio of gears 1 and I6, the shaft I1 .Operaflon when transmitters are four in interfering relatimzship its portative position, so that the ledge I01 on the arm I03 will engage the lower end of pawl I08 and thereby prevent the ledge I I8 from being carried by said pawl into is If, however, the, magat a time when the dog I I4 H3 as just described, upon the path of the angle I I1 while the dog I in its elevated position. net MM is deenergized member H4, first step of its movement.

During-the beginning of each successive round of the signal wheel and sender arm .9I to move to the left unless otherwise prevented. At such times, however, the fluke 93 engages the edge of skirt I 00, thus preventing such a movement of the arm and p session by other transmitters,- or if pulsations in current similar to busy signals cause momentary energization of magnet MM. For example, the shaft Thus, as described above, after one or substantially one revolution of the shaft II, the pawl 4 may engage the skipping dog I 29, which is engaged, the clutch 4 648 is opened and member 41 with its pinion 41, the gear 5| meshed therewith, and the rounds disk 4| may remain stationary, although the signal train continues its movement. However, each rotation of the gear I9 causes the pin 44 to engradual movement action of retractil'e arm I32 carried end of said pawl ter of a revolution,

such position in the path of the lower end of pawl I08, engaged by said pawl to thereby support latch arm I09 in its elevated position after said am has thereafter been next raised by the action of cam II3, so that the right-hand end of said arm will be moved downwardly to a position where it will no longer be disposed in the pathof pin I06 and restraint will be terminated. I09 will also carry I33 moving therewith into engagement Such movement of said arm the sloping extension or fluke with the thereby move the the path of the pawl may then be closed, wall operate in the as the occurrence just described takes place when the notch 45 in'the disk 46 has just passed beyond the free end of the pawl 48, the closing of the clutch 48-48 will not become efiective until the signal wheel I8 has thereafter completed nearly a full revolution, round of the signal. After this, but three additional rounds will be sent from the transmitter, since the disk 4I had already made a quarter of a revolution at the time the skipping dog I29 was positioned to permit closing of the clutch 46-48, and since no more than one round is sent out to each quarter revolution of the disk.

If the line should still remain busy, the counting ratchet wheel I52 will continue its tooth-bytooth movement until the long tooth I64 is engageable with the pin 44, which throws the hooked or raking ratchet I52 into engagement with the toothed field I12 on the disk 41 (Figs. 4 and 18), thus member 41, the parts being so proportioned that the wheel I52 is advanced less than a movement corresponding to a single one of its ordinary teeth, so that the ratchet element I53 permits a slight backward movement of the wheel I52 under the action of spring I54. In the course of the next revolution again engages t e 48, so that the clutch 46-48 whereupon the mechanism hooked ratchet I51 again to engage the toothed,

field I12, thus moving the disk 41 far enough to disengage the pawl-48 from the skippin dog I20, permitting when the notch 45 is next presented to the free 48 near the conclusion of the next revolution of the gear I9, the member 41 with its gear 41 ,will be caused to rotate for one revolution, thus turning the measuring disk M for a quarter Thereafter, if

session of by may be sent by the signal wheel after the notch 45 is presented to the free end of said pawl.48, since the measuring disk has made one-half a revolution. .11, however, the line remains busy,'

I51 therewith, whereupon 48-48 is again closed and the disk 4I turns another quarso that thereafter but a of movement of the arm SI normal manner. Inasmuch and has thus sent a.

clutch 46-40 to close, so that single signal round will be given if the line is released to the transmitter. After two more rounds, which result in another closing of the clutch 48-48, the shaft I1 enters its final round, the disk 4| passes through its final quarter revolution, and then the notch 42 is again presented to arm 30. The transmitter may gain possession of the line to send a signal until the cam II3 leaves the fluke I21 of arm I08 at the beginning of this final round, corresponding to the final quarter revolution of the disk 4|.

The arrangement just described will also be effective to prevent interference between two transmitters should both transmitters be operated at the same time or, in effect, simultaneously. Under these conditions the sender contacts PC of both transmitters may at first operate in synchronism, as in any case of normal operation. If, for example, the two transmitters have signals presenting similar digits, when the initial teeth of the wheels I8 0! the respective transmitters are withdrawn from their respective fiukes 93, both transmitters may at first op- .erate in synchronism. For example, assume that one transmitter sends signal pulsations according to the formula 2-3-5, and assume that the other transmitter sends a signal 2-2-5;

' may operate together until upon the line will mitter sending the signal longer than the interval between consecutive strokes of any numeral, so that the movement Emergency operation V when there is a break in thelinecircuit so that current may not be received by the magnet MM even momentarily, as, would be the case where the line under a busy condition, the mechanism automatically operates to close an emergency line which normally may be in the form of a connection to a common return conductor, such as the ground. when the box is pulled under these conditions, the initial position of the parts may be the same as described above in connection with a busy test or when boxes are in interfering relation. The skirt I00 is in blocking relationship to the fluke 03, thus preventing the movement of the arm 8I to a position where the contacts of assembly PC will open.

the shaft I1 starts rotation, the cam II8 leaves the fluke I21 0! the latch arm I00, mitting the latter to rock counterclockwise under the action of spring I28, so that the end of arm I09 is disposed in blocking relation to guard pin I06 to prevent movement of sender arm 9| when the skirt I00 passes out of engagement with (Fig. 13). The cam II3 under these conditions is effective in lifting the ground switch actuator II4 to a position where the projection the second circuit is Thereupon the I 1 thereof is latched over the ledge H8 upon the left-hand line section H between the boxes E and pawl-108, the projection I24 of restoring arm I22 F, the emergency switch ES having been closed When the cam H 3 has substantially completed of the battery CB while transferring the termione revolution, during which the clutch .46-48 ha] of the line section H to the right-hand termihas been disengaged, the skirt I00 is supporting ha] of the battery. Under these conditions curfluke 93, and cam H3 engages the fluke I21 of rent may flow from the right-hand terminal of the latch-lever I09, rocking the latter clockwise, the battery through the lead B, conductors 62, so that the switch actuator H4, which is now 61, 13, 18, 11 and 58, to the common return or ari line current), w l be fted o a p s t on effective in actuating the signal-responsive dewhere it engages the lever I31, lifting the latter vice A against the tension spring H5 so that the switch emergency switch ES permitting the pulsing into m may sw n ab u its piv t 43 to mov whichever one of the two line connections may con a tor. 8 into e a m nt with nta ts be closed, or, if both are closed, pulsing into them 5 and h s cl sing the ground or emergency simultaneously. Obviously if the line break had it he lifting o latch also moves d occurred at point Y (Fig. 21) rather than at point 9 away rom pawl 48 (Fi 4), so hat clutch x, the operation of the transmitter through its 45-48 is reengaged and rounds disk 4| starts ground switch ES would be similar to that just tati wh n the n t h 45 has a ain e n p described, the receiving device J rather than the sented to the free end of said pawl 48. device A being actuated.

Under these onditions t e inclined end of As a further example of possible faulty circuit member I31 has a cam-like e gagem With the conditions, let it be assumed for convenience of eyllndrieal pp t r the eon aot r 73, thus description that a short circuit is due to the acting as a prop to hold mature 8 n D joinder of ,point X with point Y of the line seet v Position g l), the armatu e being tion B and that it is desired to signal from the moved and h d by projection on arm intermediate box E and, furthermore, that the gaging h m r p n Further switch EW has been moved to its alternate position of the cam 3 Will thereupon withdraw 1t tion for emergency working (Fig, 23) When the from engagement with the fluke I21, thus p rswitch ES closes under these conditions, one side lnitting m [0 o m v responsive to the \of the line will be provided by the ground conspring until t lower end of the l nection or common return CR, while the opposite thus preventing movement of said lever to posit rs B and H in parallel.

tion where its free end would be disposed in the If th r is an open circuit, for example, at the path of pin I05 and final y Clearing the P of left of point X on the line loop, and if the sevmovement of said pin; t f end o armature ered end of the line which extends to the right of p ojecti n 39 mov it m I31. Thus tion' of their emergency switches ES; in other when the skirt I00 passe o of engagement t -words, performing as if the circuit was completed the fluke 93, the-sender 9| is free to move to its through it or al path, except in that the recircuit opening position and may oscillate sultant signal will be manifested onlyby receivresponse to the Co our of the Wheel intering device A. The boxesat the other side of the mittently closing the contacts of assembly PC in break namely boxes F and h ill response to eng g m nt w the teeth 301115 quire the closing of their' respective emergency tribnt d p h Wheelh movement of switches ES to apply a ground connection, wherearm I09 caused its slopin extension I33 to act by the left-hand circuit may be closed and sigagainst he al'ln carried by the Skipping naling effect may be manifested on the receiving I29 to s ing id o to itsinoperative'oosition device J. If, for example, there should be cirand thereby permit closure of the clutch -48, t openings t 5 t t points X and Y th whic closure becomes efieetive when the notch box E would become isolated and in a hopeless 45 is then ne t Presented to the free d of the condition. However, the remaining boxes G F paw 48 following Substantially revolution (if-the D and C could still operate after their emergency signal wheel '8, SO that the rounds dlSk I will or grounding switches had been automatically thereafter Comp e the final three-fourths of its closed. Under these conditions, if an attempt is revolution while the emergency Switch is made to operate its box E, the emergency switch closed, and t e contacts of assembly PC will act will be closed at the end of the first revolution of to formulate four signal rounds, the formulation thesignal wheel 3 and t movement of th of one of which will occur prior to the presenta- 9 permitted, during t f ucceeding tion of notch 5 o p w 8 as just expla drounds of the signal wheel will not cause response The emergency Switching arrangement of either instrument A or J. Since, however, the fective t permit proper transmittal of the ig-, clutch 46-40 has remained closed, the rounds nal under many malconditionsof the line, a few disk 4 t t continually during t five revo of which will be pointed out to S w the general lutions of the shaft l1 and wheel l8, so that it utility of this switching arrangement. For ex-' is returned-to a position where the notch 42 reample, referring to Fig. 21, let it be assumed that ceives the stop arm 39 while the stop 40 simultathere hasbeen a line break at the point X in the neously engages the'pln 44. Accordingly under 75' sponse of either mally positioned, such grounding will not alter the responsiveness of devices A and J to signals from any of the boxes, even if of low resistance. If, during the effectiveness of such a low resistance ground of the external circuit, the central oflice switch EW is positioned as shown in Fig. 23, signals from-boxes to the right of such ground connection will be responded to by device A and those from boxes to the left of such ground will be responded to by device J; so that, if such ground connection developed atX, device A would respond to boxes C, D and E and device J would respond to boxes F and G.

Should low resistance ground connections develop at two or more points, or should a low resistance ground connection develop at one point and a break occur at another point, signals from any box or boxes situated in the circuit between such defects would fail to cause redevice A or J. For example, should the circuit be grounded at X and at Y or broken at X and grounded at Y, or vice versa, any one of such conditions would render the devices A and J unresponsive to box E, irrespective of the positioning of central office switch EW.

The arrangement of emergency switch ES permits shunting or excluding the magnet M from the circuitso that a break in the magnet winding or in the immediate electric connections or the like does not prevent emergency working of the transmitter. Furthermore, this arrangement also is advantageous, since it requires relatively less current, since energization of the magnet is not required when working under emergency conditions, thus permitting operation with a weak current.

Operation with optional circuit arrangement Fig. 22.shows a typical type of circuit which may be employed rather than that shown in Fig. 21, the differences in the circuits being in the arrangement of the central station portion CS. In the circuit arrangement shown in Fig. 22, which forms a portion of the subject matter of my copending application Serial No. 573,151, filed on even date herewith, the leads H and B correspond to those shown in Fig. 21 and may be connected to the signal boxes in exactly the same manner. The left-hand or primary winding of a transformer T may be connected to any suitable current source (not shown) which, for example, may be the commercial city lines, while the secondary winding of transformer T is connected across the input diagonal of a rectifier bridge or network RN. The latter comprises four rectifier units U, V, W and Z, so that one-half wave of a current cycle may cause the upper terminal of the secondary winding of transformer T to be positive and the current may. flow through rectifier unit W, receiving device A, lead B, serially connected boxes C, D, E, F and G, lead H, re-

.ceiving device J, and rectifier V to the lower terminal of the secondary winding. During the next half cycle the lower terminal winding of transformer T may be positive, so that the current may flow outward from rectifier unit Z, thence over the same loop to return over rectifier unit U. Thus each half-cycle of the alternating current supply may be rectified in the network RN to provide a uni-directional pulsating current for the line loop and the devices therein rather than the direct current source CB of Fig. 21. I.

The central station CS, when having an arrangement such as shown in Fig. 22, requires no special switching or circuit changes for emergency working. For example, it may be assumed that an opening in the line section H has occurred at a point X, such as shown in Fig. 21, and that subsequently the box E has been pulled. After one round of the signal wheel the emergency switch of the box is closed in the same manner as already described, so that during one-half cycle of the alternating curren current may flow from the lower terminal of transformer T through the rectifier unit Z, the serially connected device A, and stations in the line section B to the active signal initiating station, thence through the pulsing contact assembly PC of that station and its switch ES to the ground or return CR, whence the current will be received over the manifesting device R in the central station CS, thereupon passing to the upper terminal of the secondary winding. f the transformer. During the next half cycle the direction of electromotive force will be such as to urge current flow toward the upper terminal of the transformer secondary winding T, from which parallel paths to the active station will be provided through manifesting device R and the ground or return CR, and through rectifier unit W, device A and line section B; but no return path will be provided from the active station to the lower terminal of the transformer secondary winding.

As another example of the emergency working of the arrangement shown in Fig. 22, in combination with boxes of the type disclosed herein, let it be assumed that the line loop sections B and H are connected by contact of points X and Y at either side of the transmitter E, thus shortcircuiting this transmitter. Under these conditions when the upper terminal of the, transformer T is positive, current may flow therefrom through the rectifier W, line section B into the line section H and thence return through the rectifier unit V to the opposite terminal of the transformer, while current may also flow throughthe device R, emergency conductor CR, switch ES of box E, and thence through conductor H and unit V. When the lower terminal of the transformer T is positive current may flow through the unit Z, the line section B, to the contacting point of X and Y, a portion of the current then flowing through the leads 62 and G4, the contact members I3 and 14, to the emergency switch ES and thence through the lead 11 to the common return CR from which the device R may receive the signals, the current then passing to the upper or negat've terminal of the transformer. It is thus evident that under these conditions the signal device R will be actuated by alternating current impulses received from the signal box E. i

Obviously the wiring diagram shown inFig. 22 is but a typical example of a circuit arrangement which may be used advantageously with a signal box constructed in accordance with the present invention; in fact, it should be understood

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