US2230994A - Retarded switch - Google Patents

Description

Feb. 1l, 1941.

s. F. ARBUCKLE ETAL 2,230,994

RETARDED SWITCH Filed Feb. l5, 1937 4 4Sheets-Sheet. l

Char/e5 E dd/ey ATTORNEYS Febll, 1941- s. F. ARBUCKLE Erm. 2,230,994

RETARDED SWITCH Filed Feb. l5, 1937 4 Sheets-Sheet 2 Feb-V11, 1941- s. F. ARBucKLE ETAL 2,230,994

RETARDED SWITCH Filed Feb. 15, 1957 4 Sheets-Sheet 5 INvENToRs Jamf/e/ F. Awbz/CM? G05/ Cou/fer Char/95 f. 600765/ sa/6% Wm ATTORNEYs Feb. 1l, 1941. s, F ARBUCKLE TAL 2,230,994

RETARDED SWITCH File Feb. l5, 1937. 4 Sheets-Sheet 4 Patented Feb.y 11, 1941 i i UNITED STATES PTENT orties arrancan swrron Samuel F. Arbuckle, Guy H. Coulter, and Charles E. Godley, Highland Park, Mich., assignors to United Lens Corporation, Detroit, Micliu7 a corp poration of Delaware Application February 15, 1937, Serial No. 125.712

, 6 Claims', (Cl. Mit-35) This invention relatesx to retarded switches Figure *l is a sectional detail View taken suband is particularly directed to means for constantially on the line II-ll of Figure 2; trolling the functioning of electro-responsive de- Figure 8 is a sectional detail view taken subvices adapted 'to produce warning and direction stantially on the line IBI- i8 of Figure 2;

signals for automotive vehicles. Figure 9 is a fragmentary detail side view of 5 The invention contemplates the provision of the contacting elements used to produce a tiash a circuit closing means having an adjustable ing action shown in Figure 8;

delayed contact breaking action. Figure 10 is a sectional detail view taken sub- The invention embraceslthe provision o! means stantially on the line -20 of Figure '1; m to produce anvintermittent now of current to Figure l1 is a sectional detail view taken subw electrical devices fora predetermined period of stantially on the line 2l--2i of Figure 2 showing time. the escapement mechanism;

An object of the invention is the provision Figure l2 is a sectional detail viewtaken suboi a current controlling mechanism having ad stantially on the line 22-22 of Figure l1; g5 justable means to produce a ilow of current for Figure 13 is a fragmentary view of the adjust- 15 periods of very short duration. abie spring tensioning arrangement forming a Another object of the invention contemplates part oi the invention; retarded switching means to automatically flash Figure i4 is a sectional detail View taken sub a warning signal prior to and during the time sl'fantially on the line 24--2t oi Figure 7; o@ electro-responsive devices connected thereto are Figure l5 is a sectional detail view taken sub- 20 in operation.` stantiaily on the line -25 oi Figure 8 showing Another object of the invention is 'the pre-4 the means for changing the duration oi? the vision of a control device including visual and hashing action; audible means which will show to the operator rllhe features of the invention have been illus- L the proper or improper functioning of the eleow trated for use with electro-responsive devices 25 troresponsive devices with which the control adapted to produce warning and direction sigdevice is used. nais for Aautomchiles but it is to be understood Further objects and advantages are within the that the saine may be used furthe control oi" scope of this invention such as relate to the any type of electro-responsive device or Wherever im arrangement, operation and functioning of the these features may nud utility. 3o

related elements oi the structure, to various de- The switching means of the invention includtails of construction and to combinations of ing the timing train or clock mechanism used parts, elementsv per se, and vto economies of to produce the delay action for controlling the 'manufacture and numerous other features as circuits for the energiaation of electro-responsive will be apparent from 'a consideration of the devices is enclosed byacasing I0. 35

specification and drawings of a form of the The casing it is preferably made of insulating I invention, which may be preferred, in which: material, such as a phenolic condensation prod- Figure l is a top view of the switching device uct or the like and formed with its back Wall of the invention, wth the cover broken away to removable.- The casing i0 includes a narrow o ShOW the interior details; conduit portion terminating into an enlarged o Figure 1A is a sectional' detail View taken end portion providing a chamber Il of hexagonal Substantially 0n the line H-H 0f Figure 1; conguration having a depth of suitable dimen-1 Figure 2 is a sectional detail view taken subsions for receiving and supporting a frame i5 stantially on the line |2-l2 of Figure 1; carrying the timing train and circuit contacting Figure 3 is Aa sectional detail view taken submeans. Frame l5 forms a removably unitary stantially on the line |3-i3 of Figure 2 looking assembly and comprises hat plates 2| and 22 in the direction of the arrows; of conducting material spaced apart and held Figure 44 is a fragmentary view similar to Figin fixed relation by posts 23. ure 3 showin certain parts of the device in an The plate 2l of frame i5 conforms generally u effective position being a bottom view thereof; to the shape and interior dimensions oi the hex- 50 Figure 5 ls a view similar to Figure 4 showing agonal chamber I4 while plate 22 is preferably the parts of the device in' another effective posiof smaller size and of a rectangular form as tion; particularly shown in Figure l.4 Ozie of the side l Figure 6 is a fragmentary detail view taken walls oi the chamber ilisformed with an opensubstantially ontheline lO-IS of Figure 2; ing I6 for allowing the passage of movable current conducting blade or switch arm 24 which terminates into an insulated end portion forming a manipulation handle 26. The handle 26 operates when moved to the right or left to close and open the circuits controlled bythe switch and also the initiation of the timing train which determines the period of time during which the circuits are operative or inoperative. The switch blade or arm 24 enclosed by the housing l0 is made of current conducting material such as copper or brass. As particularly shown in Figure 3, switch blade 24 is pivotally mounted on a pin 25 fixed to the outer surface of plate 2| and is formed with a reduced end portion 21 forming part of a contacting section -29 and a camming portion 28 adjacent to the pivotal point. The contacting section 29 is adapted to engage either oi the relative stationary spring contact members 3G and 3| insulatingly mounted and supported by plate 2|. The width of the contacting section 29 is such that it cannot be si,- muitaneously placed in engagement with both contact members 39 and 3|, and therefore the switch arm can take the normal neutral position shown in Figure 3 or moved by handle 25 to the right or left to the positions illustrated in Figures 4 and 5 for establishing predetermined circuits.

The plate 2| is provided with curved slots 33 to permit the oscillatory movement of the projections 34 and which extend therethrough and are adapted to be engaged by the opposite side walls of portions 21 and 28 of movable switch arm 24 for the purpose of winding the clock mechanism when the handle 26 is moved and for returning automatically the switch arm 24 to neutral position after a predetermined time has elapsed. An eyelet bushing 35 is mounted around projection 35 to prevent undue wear on the Aparts dueto sliding contact of the projection with respect to camming section 28. The projections 34 and 35 form an integral part of a control switch trip bar 36, the latter being fixedly carried by the rotatably mounted member or stub shaft 31, which is journalled upon plates 2| and 22 as particularly shown in detail in Figures 8 and 14. The member 31 is formed with a longitudinal cut-away fiat portion 31' upon which are also carried for rotation therewith adjacent to control bar 36, a clutch member or disk 40 and a spring retaining disk 4|. Between clutch member-40 and disk 4| is located a bushing 42 and a gear 43, both journalled on member 31 for rotation relative thereto, the main gear 43 being 0f the usual construction and formed with a plurality of spaced radial slots 44 located adjacent to the gear teeth.

The clutch member or disk 40 is preferably of spring metal such as brass and is made with cut-away portions forming three arcuate spacedy fingers 45 and an integral bent projection 41 adapted to be engaged by the control bar 35. As shown in detail in Figure "I, the fingers 45 have theirA ends 45 bent to a suitable angle for engaging the side walls of the sions u of the main gear 43, thus forming a one way driving clutch between clutch disk 48 and main gear 43, the driving connection being present when the clutch disk 40 is moved in a clockwise direction or in the direction indicated by the arrow' shown in Figure 7. Located around member 31 between frame plate 22 and disk 4I is a main coil spring 48 which forms the source of energy for operating the timing'train. The spring 48 has one end engaging the projection 49 forming an integral part of disk 4| and its other end retained by one of the struck-up projections or ears 50 formed on plate 22. Plate 22 as particularly shown in Figure 13, is formed with a plurality of spaced struck-up projections or ears 50 for the purpose of providing means to adjust the tension of spring 48 is initially tensioned.

As particularly shown in Figures l, 1-A and 2 inclusive, a gear train and an ecapement mechanism are associated with the main gear 43 for the purpose of permitting the torque produced by the tensioning of spring 48 to expend itself at a predetermined rate of speed. The gear train consisting of the pinion 52 in mesh with gear 43 and mounted on shaft 6| to impart movement thereto. Shaft 6| also carries a gear 62 and a flash wheel 63, the latter having teeth orcon tacting projecting surfaces 84 for a purpose which will hereinafter appear. The gear 52 is in mesh with a pinion 64 mounted on a shaft B5 which imparts motion to a gear 66 also mounted on the shaft 65 journalled on plates 2| and 22 The gear B6 is in engagement with a pinion 81 mounted on a shaft 58. A toothed wheel 59 also mounted on the shaft 58 is adapted to be rotated by pinion 61. A flutter or escapement wheel 10 carrying angularly displaced pins 1| and 1I' adapted to engage alternately the teeth of the wheel 59 is mounted on a balance shaft 12 pivoted on adjustable bearings mounted on plates 2| and 22. The teeth of wheel 69 are so shaped and the pins 1| and 1|' are so placed with respect thereto so as to permit only a timed intermittent motion of wheel 69. rIhis gear train which is actuated by the unwinding action of the spring 48 is timed by the action of the flutter wheel 10 which oscillates by the rotative action imparted on the pins 1| and 1| by teeth of wheel 59, allowing with each oscillation thepassage of one tooth of the wheel 59, the arrangement not only serving as escapement mechanism but also producing a distinct audible sound or buzzing action for the purpose of indicating that the gear train is in operation.

The projection 49 of spring actuating disc 4| as shown in Figure 8 is with one of the teeth 84 on the ash wheel 53 acting'as stop means for the gear train when the switch blade 24 is in its central position. When the spring 48 is placed under tension by movement of lever 28 to right or left, as particularly shown in Figures 4 and 5, the rotation of the spring actuating disc 4| caused by said movement moves the lug 49 out of engagement with the teeth 84 on the flash wheel 63 thus allowing the rotation of the gear train until theprojection 49 once more engages a tooth 84 of the wheel 63. Gai-tied by the plate 2| by means of an insulating plate is a spring contact member 82 the free end ofwhich is adapted to be engaged by the teeth of the flash wheel 63. As particularly shown in Figure 9 wheel 53 is formed with three rows of spaced teeth 84 in order. to not only compensate for wear but provide suitable contact surfaces. The lfree end of the relatively station.' ry spring contact 82 is movable towards and away from the teeth of wheel 33 by flexing member 82 through the use of a threaded member 85 carried by the insulating plate 80 having an end contactingwith contact member 82 as shown in Figures 8 and 15. This arrangement provides means to produce which l also adapted to engage flashes of very short duration highly effective for producing eilicient signals visible under adverse conditions and also permits changing the length of time or duration of engagement of contact 82 with wheel teeth 84 thereby regulating at will lthe duration of the flash produced by the engagement of contact 82 and projections 84.

The conducting frame plate 2| when in position in the insulated switch casing I is connected through a suitable fuse (not shown) to the live or ungrounded terminal of a storage battery or other suitable source of energy. The switch blade 24 is in electrical contact with plate 2| by the pivot pin 25 and when 1t is moved to the right or left engages the spring contacts 30 and 3| controlling the electrical ilow of current to the devices connected to the contacts.

As particularly shown in Figure 3, spring contacts 30 and 3| are formed integral with the bus bars |00 and|0| supported on the plate 2|I by blocks |02 and |03 of insulating material. Bus bars |00 and |0| are connected to the light source terminals carried by the base of a lamp bulb |04 acting as a tell-.tale device. The lamp bulb |04 is removably carried by projection I8 of casing |0 and as particularly shown in Figures 1, l-A and 2 inclusive, is enclosed by a removable translucent cover |05 of suitable material which protects the lamp bulb from damage and is preferably of a color to project a. colored light giving a definite tell-tale indication when the light source is energized.

Suitably spaced from the plate 2| by means of posts |06, |01, |08 and |09 is a removable plate ||2 ofinsulating material carryingA a movable contacting member or spider ||4 pivotally mounted as at ||5. A pin ||6 of insulating material mounted on the lever 24 and the same is adapted to engage slot ||8 on a central kprojec- 4tion of spider ||4. The spider ||4 has two outwardly extending fingers |20 and |2| the ends of which are formed to selectively contact with portions |25 and |26 of the bus bars |00 and |0| when the spider I4 is moved to the position illustrated in Figures 4 andA 5 by the action of the manipulating switch arm 26. The spider ||4 is so arranged that when the switch arm 26 is in its central position iingers |20 and |24 are out of engagement with their respective contacting surfaces |25 and |26 as shown in Figure 3.

The insulating plate ||2 is .provided with spaced openings adapted .to accommodate the ends of metal posts |06, |01, |00 and |09, inclusive, and is removably held in position by means of screws |50, |5|, |52 and |53 which are received on threaded openings formed on the end of each post. The screws |5|! to |53, inclusive, serve as circuit terminals for securing conductors to the different elements of the switching mechanism. The screw |50 .serves as a connecting terminal for contact 30 and the bus bar |00 while screw |5| acts as a terminal for establishing a connection to contact 3| and bus bar |0I. The screw |52 serves as a terminal to establish a connection to both the spider member I|4 through member |54 contacting therewith the spring contacting element 82 through post |09.

The screw |53 serves as a terminal for a conductl ing plate |51 secured to the outer surface of the insulating plate ||2 as particularly shown in Figure 6. The conducting plate |51 is formed with a bent projection |58 passing through an opening |59 formed on the plate ,for the purpose of engaging and establishing an electric contact with raised portion |56 formed on the switch arm 24 when the same is in central position as par- .ticularly shown in Figures l--A and 2. It should be noted that this engagement of projection |58 with the vswitch arm raised portion |56 does not take place whenever the switch plate 24 is moved to the positions shown in Figures 4 and 5.

The circuit controlling mechanism or retarded switch including the time gear train and flashing means actuated thereby is particularly adaptable to use with a signalling device forming a unit serving to produce tail-light, stop and back-up warning signals, as well asdirection signals by the use of a plurality of light sources in association with electro-responsive means operable to move shutters for producing outlines of directional arrows. The particular construction of these signalling devices is fully disclosed and described in co-pending application Serial No. 740,400, iiled August 18, 1934, now Patent No. 2,141,188 of December 27, 1938.

The operation of the retarded switch when used with signalling devices for vehicles can be summarized as follows: If the user of the switch such as a driver of the vehicle desires to make a right hand turn it will only be required to move the switch operating handle 26 to the right.

When` the switch blade 24 located in right position, the other parts of the switch will be moved into the positions shown in Figure 4, it

being remembered that the latter is a bottom l view of .the switch and therefore the switch blade 24 will appear in opposite relationship, as compared with Figure 1. As shown in Figure 4 the switch blade 24 directly connected to the battery by frame plate 2| is moved into electrical engagement with Contact 3|, `thus establishing a ow of current to an electric right hand turn indicating device or other suitable electro-responsive devices connected to post or terminal 5L In addition the movement of switchv blade 24 to the position shown in Figure 4 winds up the main spring 48 by moving the projection 35 of the trip bar 36 rotating thereby shaft 31 which cause to override the slots 44 of gear 43, concurrently moving the lug 49 of the spring disc 4| out of engagement with the teeth 84 on the flash wheel 63. When this movement is completed the gear train will start its rotation due to the force storaged by the winding up of spring 48 as the clutch lingers 45 Ywill rotate the gear 43 by their engagement with the slots 44, rotating the flashing gear 63 and causing teeth 84 to engage the spring contact'82, causing the intermittent energizetion of suitable electro-responsive devices connected to lterminal |52 such as light sources producing light flashes of very short duration attracting the attention of observers to the signalling device.

It will also be noted by referenceto Figure 4, that the contacting spider |4 has' been rotated by the movement of blade '24 into a position Where one of its arms |20 is in contact with the portion |25 of the bus bar |00. This contact exists for a shorter durationthan that of the switch blade 24 with the stationary contact 3| as the returnmovement of the blade 24 causes spider I4 to rotate and break such contact prior to .the break of switch blade contact. While this contact is made it forms a parallel circuit including the tell-tale device |04 bridging contacts 82 and 84, this circuit includes from spring contact 82, the conducting plate |54 connected to spider finger |20 in engagement with contacting portion |25 of bus bar |00 to the terminal of tell-tale light |04 in engagement therewith and from the other light terminal by means of bus bar to contact 3| in engagement with switch blade 24 to switch plate 2| and hence to contact teeth 84. It is important to note that when this parallel branch circuit is established and the contacting teeth 84 and spring contact 82 are out of engagement the tell-tale light |04 is connected in series with the electro-responsive devices or the light sources connected to terminal post |52 and due to the total resistance of the circuit the current flowing is only suiilcient to energize the tell-tale device. However, when this branch parallel circuit is bridged by the engagement of the iiash wheel teeth 84 with spring contact 82 full energization of light sources connected to terminal post |52 takes place and the tell-tale light |04 is rendered ineffective, thus causing a flashing action of the light sources or the electro-responsive devices connected to post |52 and alternate flashing of tell-tale light |04. This particular arrangement of circuitconnections not only inform the switch operatoror l driver by the flashing action of tell-tale light |04 v that the light sources or the electro-responsive devices connected to post |52 are operating properly, but should the light sources or electro-responsive devices connected to post |52 become inoperative or the circuit rendered ineffective such defects will be indicated, as under such conditions the tell-tale |04 will not be energized to produce a ilashing action. This circuit arrangement will also indicate the ineffective operation of the flashing wheel or teeth 84 to make contact with spring contact 82 as the tell-tale will remain lighted, indicating an-abnormal operating condition of the system.

In order to Iprevent any interference with the production of the .flashing of light sources or the electrical devices connected to lpost -|52 when the same are also controlled by the oper-ation of any other switch such as the well-known stop switch used in an automobile, the energization of the light sources through the closure of stop switch or auxiliary switch is also controlled by the switch blade 24 by connecting to the post |53 Ithe end of the conductor which is normally connected to the lite battery terminal so that when the blade 24 is moved to produce direction signals the circuit for lthe ilow of current to the stop switch or the auxiliary switch is open by moving the raised portion |58 from contacting vengagement with finger |58 of plate |51. However, this circuit is normally closed when the switch blade 24 is in its central position whereby the closing oi the auxiliary switch drtstop switch fully controls the lightsources to produce stop light signals.

The unwincling action of spring 48 causes the switch blade 24 to be gradually moved back toward its central position by lthe projectionA 35 of trip bar 36 contacting tion 28 of the switch blade 24, and will cause, rst: to move out of engagement the finger |20 with contacting .portion |25 interrupting the circuit to the tell-tale light |04 through the use of the insulated connection IIB between spider |I4 and switch blade 24, andsecond. to interrupt the engagement of switch blade contacting portion 29 with stationary contact 3| and concurwith the camming por',

rently moving the projection 48 o! spring disc 4| into engagement with a tooth 84 of wheel 83 to stop the gear train whereby the switch blade 24 and associated parts are in the position shown in Figure 3. In the embodiment shown, due to the position of one end of spring 48 in the fourth struck-up ear 50 of plate 22, the return action to central position of blade 24 is timed through the gear ltrain and escapement mechanism to require a period of approximately 15 seconds, a vperiod long enough to complete the average turn, and during this length of time the signalling devices are maintained energized and at the same time the light sources or ldevices connected to post |52 are intermittently ashed by the periodic engagemen-t of teeth 84 of flashing wheel 63 with spring contact 82 and after this .time has elapsed engagement between contact portion 28 and stationary contact 3| is broken, interrupting the flow of current .to the devices connected to switch post stopping their operation as well as that of the devices or li'ght sources connected to post |52 As hereinbefore pointed out, when engagement between projection 49 and -teeth 84 takes place, the spring contact 82 is vout of engagement with any of the flashing wheel teeth 84, so that when the switch blade 24 is in a central position no current is passing to the light source or devices connected to .post |52 through the spring contact 82. It should be noted 4that when the switch blade 24 reaches its centr-al position, the engagement of projection |58 with switch blade raised por-tion |58 takes place andthe light sources or devices connected to post |52 are capable of being energized by movement of the auxiliary switch such as a stop switch or transmission switch.

If the switch opera-tor such as a driver of a vehicle.' desires to' indicate his intention to make 1 a. left hand turn or energize the electrical device connected to the switch post |50 the switch handie 26 is lmoved to the left causing the switch blade 24 and associated par-t movable therewith .to take the position shown in Figure 5 wherein it can .be seen that switch blade contacting portion 28 is in engagement with contact 30 thus establishing a flow of Acurrent to the signalling apparatus or electro-responsive devices connected to post |58 so as to indicate that a turn to the left is going to .be made by the vehicle. The movement of switch blade -to the left will cause: the engagement of finger |2| with contacting surface |26 and by the engagement of switch balde portion 21 with trip bar projection 34, the rotation of shaft 31 causing the clutch fingers 48 to move counterclockwise -to override the slots 44 and simultaneously move the projection 48 out of engagement with the flash wheel teeth 84 winding up spring 48 to impar-t rotating torque to gear 43.

When the movement of the switch blade 24 to the left is completed the torque action on' gear 43 will cause the engagement of clutch fingers 45 with slots 44 of gear 43, to start the rotation ol' the gear train whereby the flash wheel teeth 84 are moved into engagement with spring contact 82 causing the light sources or electrical device connected to post |52 to produce lighting liashes of very short duration for attracting the attention of observers that a left turn direction signal is Vbeing produced by the signalling devices. When the switch blade 24 is moved to the left" position the branch or parallel circuit formed across the flash wheel teeth 84 and spring conall v accesos islfied bereiten a oii'ection i telwtale lit tias. iwoiucecl s the driver an .e the ation oi tl merely, the invention coniprehencline vanam tions thereof.

.nat we claim.

i. In combinationswitching means in open cizfcuit position being .manually operable to selectively temporarily complete an elecn tric circuit for 'the energization ol an electron responsive device; a mechanism rendered operm able by the .movement of said switching means to circuit completing position; means actuated by said mechanism in engagement with d man@ ually operable switching means for moving the same to its normal open circuit position after a predetermined `period of time; a. spring beine placed under tensionrby the movement of said manual switching means to circuit coinpletins1 position for actuating said mechanism.; and means for holding said spring in rlierent posi tions to change the tension set up in said spring by the movement of said switching' means Whereby the time period. of actuation of said mecha nism for moving the switching means to normal open circuit position is varied..

2. In combination, a plurality of spaced contacts; a switch member manually movable to selectivels`7 and temporarily engage either of said contacts to complete an electric circuit for the ,energizaton of an electro-responsive device; a

timed operated mechanism adapted to be set in motion by the movement of said switch member to contact engaging position; means driven by saisi mechanism' in engagement with said switch. member tor returning` 'the same to the neucircrit position after e. predetermined period o spring initially andes" tension for actuating mechanism and. loe-'lng wound by the ino" 1.

sltlon; and means for "nolclh'ig saisi -f l ont position" to change its i? wlriereby the e pernos?) ci' actnatsc. mechanism can ce changed.

plete electric electro Ai.espoiwve eievice;

a positions cham the time period is che ation, sn c position be selectively tric c enit onslve device; a time@ device rendered 'ivy the movement of switching; te c it completing position; means actuated device in en "agement with saisi mannahy l able switching sans f moving the to cuit Anen position a circuit mailing' c including stationair e einher having a j' ,s in a staggered e", the rotatable ine; ist." timed fe ce cause v to cally engage station. cc c "if t i"elogi intermittent new oi our@ y. s means we during tile perico salti til eel device cessation., 3 t

lin combination. means nomas in. openciicnit position beine mairuallf,r oper e to selectively and temporarily complete an el ce tric circuit for the energization of an electrcserm e5 sponsive device; a mechaniism set into operation by the movement of switching means to cie1m cuit completing position; means actuated by said mechanism for returning said manually operable switching means to circuit openposltion after a predetermined period o time; a stationary cons tact; a rotatable contact member cooperatii'ig With said stationary Contact both o said contacts being connected in series with said switching means, said rotatable Contact member heine driven by said timed mechanism to periodically engage said stationary contact for causing an' in termlttent energization of the electro-responsive device; and means to change the initial position of the stationary contact with respect to the. rotatable contact member for changing the duration of the periods of energization ofthe electroresponsive device during the time Said mechanism is returning said manually operable switchu lng means to circuit open position.

6. In combination, switching means normally in open circuit position being manually operable to selectively and temporarily complete electric circuits for the energization of a plurality of electro-responsive devices and a tell-tale device, the latter located within observable distance from the switch operator; a timed mechanism set into operation by the movement of said switching means to circuit completing position; means actuated by said timed mechanism for returning said manually operable switching means to circuit open position after a predetermined period of time; a stationary contact; a rotatable contact cooperating with said stationary contact, said contacts being connected in series with said switching means, said rotatable contact being driven by said timed mechanism to periodically engage saidstationary contact for causing an intermittent energizationof the electro-responsive device and successively establishing a. circuit in which the tell-tale device located within observable distance from the switch operator is connected in series with one of the electro-responsive devices for indicating to the switch operator by the intermittent energization of the tell-tale device the proper functioning of the other electro-responsive devices.

SAMUEL F. ARBUCKLE.

GUY H. COULTER..

CHARLES E GODLEY.

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