US2315920A - Impulse operated selector switch for alternating and direct current - Google Patents

Description

E. G. BAKER ETAL 2,315,920

IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECT CURRENT April 6, 1943.

Filed Oct. 8, 1940 3 Sheets-Sheet. 1

g m'sum E CZINVEN 3 CR5.

BY fheciore Obqyarzy April 6, 1943- E. G. BAKER ETAL 2,315,920

IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECT CURRENT Filed Oct; 8, 1940 3 Sheets-Sheet 2 NSUL/Y T ION INVENTOR5.

Edward G B01687" BY fizea0r6 Oqgcuvgn April 6, 1943- E. G. BAKER ETAL 2,315,920 IMPULSE OPERATED SELECTOR SWITCH FOR ALTERNATING AND DIRECT CURRENT Filed Oct. 8, 1940 3 Sheets-Sheet I5 OQG QC DE INSULHT/O/V 75 ga V TIMER 62 PULSE L l/VE LINE KW MM? w HOLD RESET FELHY I Z w Patented Apr. 6, 1943 IMPULSE OPERATEI? FOR ALTERNATING RENT SELECTOR swrrcn AND manor CUR- Edward G. Baker and Thedore Obszarny, Ohicago, Ill., asslgnors to Guardian Electric Manufacturing 00., Chicago, 111., a corporation of Illinois Application October 8, 1940, Serial N0. 360,282

8 Claims.

This invention pertains to selector switch devices for-mechanisms for selectively controlling the make and break" of portions of different electrical circuits or branches of a main circuit. switch devices of this type lend themselves to a relatively wide field of use in the selective con trol directly or remotely of various types of machines and apparatus.

More particularly, the present invention is directed to selector switch devices of the type adapted to be actuated in step-by-step fashion by the intermittent actuation of an electromagnet, operated by pulsations of electrical current,

for selectively completing portions of one or more of a plurality of different electrical circuits, or branches of a main circuit.

One of the primary objects of this invention is to provide a novel and improved form of selector switch of the character indicated, adapted for operation either by alternating or direct current. Another object isto provide a novel form of selector switch of the character indicated adapted for operation by either alternating or direct current under control of a mechanical timing device, which permits selective completion and maintenance of an electrical circuit for a timed interval.

A further object is to provide a novel form of alternating or direct current operated selector switch, controlled by a mechanical timing device, for effecting completion of a portion of a preselected circuit after a timed interval subsequent to completion of another portion of said circuit.

Still another object is to provide an improved unitary selector switch of the type indicated adapted for operation either by alternating or direct current, under control of a mechanical timing device associated therewith; for effecting completion of a portion of a preselected circuit after a timed interval subsequent to completion of another portion of said circuit by adjustment of the selector switch and maintaining said preselected circuit completed for a timed interval.

Other objects and advantages of this invention will be apparent from the following description, taken in connection with the accompanying drawings, in which:

Figure 1 is a plan view of the unitary selector switch embodying the present invention.

Figure 2 is a transverse vertical sectional view through the switch device, taken substantially as indicated at line 2-2 on Figure 1.

Figures 3 and 4 are vertical sectional views through the switch device, taken substantially as indicated at lines 33 and 4-4 respectively on Figure 1.

Figure 5 is a front elevational view of the switch device showing the selector panel.

Figure 6 is a wiring diagram including the electrical circuits for controlling the operation of the Selector switch.

Referring now in detail to the drawings, the

selector switch device embodying the present invention includes a main mounting frame 10 formed as a sheet metal stamping in a generally U-shaped formation. This frame serves as a mounting for and totally supports all elements constituting the switch device so as to provide a unitary structure or assembly.

Connected to the intermediate portion of the U-shaped frame I0, in spaced apart relation thereto, and forwardly thereof is a contact panel H of insulating material which is rigidly con nected to the frame [0 by screws I2 with spacer elements l4 interposed between the panel and the frame as may be seen in the drawings. Said panel is provided with an arcuate series of spaced apart contact buttons it, with the heads of said buttons exposed on the outer face of said panel and including body portions extending through the panel with their inner ends, projecting to the rear of said panel, serving as terminals for connection to conductor wires as indicated at H, which wires it may be understood form portions of different electrical circuits or branch circuits to be selectively controlled.

Mounted on the front face of the panel I I, concentric with the series of contact buttons I6, is an arcuate contact strip l9 having a terminal projecting through the panel for connection to a conductor wire 20 for completing portions of the different electrical circuits including the respective contact buttons l6, as will hereinafter be described.

Said contact buttons l6 and contact strip I9 are adapted to be engaged by a pair of yielding contact arms 22 and 23 respectively as may be seen in Figures 1 and 5 of the drawings. Said arms are formed as extensions of disc members 22a and 23a, which are mounted in engagement with each other between a pair of insulating discs 25 and the assembly of the disc members and the disc insulating members is fixedly mounted on the outer end of a shaft 21 which extends through the panel II and is journalled in a bearing 28 which is rigidly supported on the intermediate portion of the mounting frame It, as seen in Figure 4 of the drawings.

The inner end of the shaft projects within the frame l and has rigidly mounted thereon a ratchet wheel 30 adapted to be rotated in stepby-step fashion for effecting similar movement A of the . contact arms 22 and 23 for sequentially engaging the respective contact buttons l6. Due to the arrangement of the contact arms 22 and 23 it will be apparent that the conductor wire 20 is therefore in series with the particular conductor wire I! corresponding to the contact button engaged by the contact arm 22 at a given time. In other words, when the contact arm 22 is in engagement with any one of the contact buttons IS, the portion of the. electrical circuit connected through said contact button is completed through the contact arm 23, contact strip l9 and the conductor wire 20.

The means for rotating the ratchet wheel 30 in step-by-step adjustments is accomplished by the intermittent energization of an electro-magnet relay 32 supported on one of the legs of the U-shaped frame ill by means of a bracket 33 which constitutes a lateral extension of the field piece 34 of said relay. As may be seen in the drawings, said relay 32 is disposed with its coil in an upright position and hingedly mounted on the upper end of the upright leg of the field piece 34 is an armature 36 normally urged in an upward direction away from the core 32a of the coil of the relay by means of a coil spring 31 which is connected to the rear or heel end of the armature and to a lug extension on the leg of the field piece 34, as seen in Figure 3 of the drawings.

Pivotally mounted at 39 on a vertical axis on top of the armature 36 adjacent said hinged connection thereof is an actuating pawl 40 formed of fiat bar stock and supported directly upon the top of the armature and extending in a direction parallel to the axis of the ratchet wheel 30. The forward end of said bar beyond the armature is twisted at right angles with respect to the main body of the bar so that the lower edge of the projecting portion of said bar is disposed adjacent the toothed periphery of the ratchet wheel 30. The lower edge of the bar 40 in alignment with the ratchet wheel 30, is cut at an incline as indicated at 40a to form a tooth-like surface for insuring proper engagement with the teeth of said ratchet wheel 30. Due to the pivotal connection 39 of said actuating pawl 40 to the armature, said pawl is permitted lateral movement with respect r to the armature.

In order to maintain said actuating pawl in proper position on the armature and for limiting its-extent of lateral movement, we provide a guide in the form of a strap 42 extending over the actuating pawl adjacent the outer or free end of the armature. Said strap is secured to the armature by means of a pair of spaced apart studs indicated at 43.

It is to be understood that relay 32 is adapted to be intermittently energized by pulsations of electrical current which through the action of its armature imparts a step-by-step action to the pawl 40 and ratchet wheel 30 for shifting contact arms 22 and 23 in a step-by-step manner so that arm 22 is sequentially stepped over a series of contact buttons l6 corresponding to the number of electrical impulses imparted to the coil of the relay 32. It is to be understood that said pulsations of current may be supplied directly, or from a remote sending station, and in the latter case suitable receiving apparatus may be employed for use in transferring the wave impulses directly to the relay. Therefore, for convenience said relay 32 will hereinafter be termed a "stepping relay.

The actuating pawl 40 is dimensioned so that its extreme outer end projects into an on opening Illa formed in the intermediate portion of the U-shaped mounting frame l0. Mounted on the outer face of said portion of the frame in registration with said opening, is an adjustable guide block Mb, having a slot or window formed therein for receiving the extreme end portion of the actuating pawl, as may be seen in Figure 3. It is to be understood that said block llb is adapted to be adjusted with respect to the opening Illa for limiting the extent of vertical and lateral movement of the actuating pawl incident to the movement of the armature toward and away from the core of the relay 32. The purpose of providing for lateral movement of the actuating pawl is to permit said pawl to readily accommodate itself to the contour of the ratchet wheel during vertical movement of the pawl in stepping the ratchet wheel and thereby precludes binding of sad pawl and the ratchet wheel which would otherwise occur due to the particular relationship of the pawl to the ratchet wheel.

To insure proper return of the actuating pawl to a starting position for engaging the next tooth of the ratchet wheel for obtaining successive stepping action, we provide a coil spring 45 which is connected at one end to the outer end of the pawl and at the other end to a stud HIc secured to the inside of the intermediate portion of the main frame I0, adjacent the upper end thereof, so that the spring is disposed at an oblique angle, tending to draw the actuating pawl in an'upward and inward direction with respect to the ratchet wheel.

As above set forth, it is intended that the se lector switch be constructed in a manner so that the portion of the circuit completed by engagement of contact arm 22 with a certain contact button 15, corresponding to the circuit selected, be maintained for only a short period of duration, after which the switch device is caused to be readjusted to a neutral or starting position. In order to accomplish this function, a check pawl is pivotally mounted at 5| on the inside of the front or intermediate portion of the frame 10 adjacent the lower edge. Said pawl includes a sharp angularly formed nose 52 for engagement with the teeth of the ratchet wheel 30. The opposite end of the pawl terminates in an arm 53 to which is connected a coiled spring 54, the opposite end of which spring is connected to the lower portion of the adjacent leg of the frame ID, as seen in the drawings. The function of the spring 54 is to normally urge the pawl 50 in a direction to cause the nose portion 52 thereof to engage the teeth of the ratchet wheel 30 and to serve to check or hold the ratchet wheel in various stepped positions of adjustment, but permitting further step-by-step adjustment of said ratchet wheel, by the action of the actuating pawl 40.

Said check pawl 50 is normally held out of engagement with the ratchet wheel 30 by means of a holding and reset relay" 56 which is mounted on the leg of the U-shaped frame I opposite to that upon which relay 32 is mounted. Said relay 56 is termed a holding and reset relay for convenience in description and because of the nature and function of said relay as will hereinafter be set forth. Relay 55 is disposed in opposite relation to relay 32 and has its armature 51 disposed at the lower end of the coil of the relay and hingedly connected at one end on a field piece 58. The armature 51 is normally urged in a downward direction to the position seen in Figure 4 of the drawings by means of a coil spring 59 which is connected to the heel end of the armature and to an extension lug on the field piece 58. Connected to and extending inwardly from one end of the check pawl 58 is a relatively rigid rod 6| having an angularly bent offset portion positioned to engage beneath an insulating panel 62 secured to the lower surface of said armature 51.

It is to be understood that spring 59 of the armature 51 exerts a greater force than spring 54 of the check pawl so that the armature 51 is normally maintained, when the coil of the relay is deenergized, in the position seen in Figure 4 of the drawings, and due to the engagement with the rod 6| said armature holds the check pawl 50'out of engagement with ratchet wheel -30 as seen in Figure 2 of the drawings. As will hereinafterhe described, relay 56 is energized during the period that relay 32 is'being energized by .pulsations of electrical current for imparting step-by-step action, through the pawl 48, to the ratchet wheel 38 and contact arms 22 and 23.

In order that the selector switch may be readjusted to a neutral or starting position after each adjustment for completing a preselected circuit, the ratchet wheel 30 is yieldingly urged in a counter-clockwise direction, or in other words, in a direction opposite to the direction of rotation caused by the stepping action of the pawl 48. For this purpose we provide a coil spring 65 which surrounds a portion ofthe bearing 28 within the frame In with one end of the I spring extending through an aperture id in the intermediate portion of said frame and the opposite end of the spring anchored on a pin 38a carried on the adjacent face of the ratchet wheel. It will now be apparent that as the ratchet wheel is stepped by the pawl 48, spring 65 becomes tensioned, so that upon release of the ratchet wheel by disengagement of the check pawl 56, said spring 65 tends to rotate the ratchet wheel in opposite direction to a starting or neutral position. The ratchet wheel is arrested at a normal or starting position which corresponds also to the starting position of the contact arm 22, as seen in Figure 5 of the drawings, by means of a nubbin 38b carried on said wheel and adapted to engage a projecting shelf portion 66 I of a bracket 61 adjustably mounted on the inner surface of the intermediate portion of the U- shaped frame l so that when the nubbin engages said shelf portion, the ratchet wheel will be adjusted at a neutral or starting position with the contact arm 22 likewise disposed in a neutral or starting position.

.Associated .with the respective relays 32 and 56 are switch devices connected in electrical circuits in amanner for controlling the make and break of a preselected electrical circuit which as above mentioned may be one of a number of main electrical circuits or one of a. number of branch electrical circuits forming a part of the main circuit, and which preselected circuit corresponds to the circuit completed through the corresponding contact buttons l6, when engaged by contact arm 22, due to the step-by-step actuation of the ratchet wheel, as above described.

It is to be understood that each of the different branch or main electrical circuits to be controlled, including the respective contact buttons 16, also include suitable'mechanism adapted to be electrically energized or operated. For convenience in illustration, we have represented in the wiring diagram in Figure 6 of the drawings a plurality of branch circuit portions connected to the respective contact buttons l6, with each oi. said branch portions shown as including a winding or coil indicated generally at 18, which coil, it may be understood, may represent any suitable form of electrically, energized device adapted to be operated when the particular branch circuit is completed through its corresponding contact button by contact arm 22.

The switch devices associated with the respective relays will now be described. Mounted on a bracket 12 attached to one of the legs of the U-shaped frame I 0, immediately above the stepping relay 32, are two sets of switches composed 'of switch fingers l3, l4, and I5, 16 respectively. In the normal inoperative position of the selector switch, switch fingers l3 and 14 have their contact buttons 13a and 14a operatively engaged, while switch fingers l and 16 have their contact buttons 15a and 16a separated, as seen in Figure 3 of the-drawings. Associated with the respective switch fingers I3, I4 and 15, are spring strips 18 for reenforcing said fingers and serving to increase the spring action thereof for urging them to return'to a normal position.

Said switch fingers and strips are mounted between a multiplicity of blocks 19 of insulating material mounted directly upon said bracket 12. Connected to the outer end of switch finger 13 is a plug of insulating material 88 adapted to seat directly upon an arm 82 of a clock type mechanical timing mechanism which is indicated generally at 83. The outer end of switch arm 16 is also provided with a plug of insulating material 84, the lower end of which is adapted to be engaged by the end of switch finger 14, when the latter is moved .to the position seen in Figure 3, by engagement therewith by switch fingers 13, incident to the upward movement of said switch finger through plug 88, by the arm 82 of the timer as will hereinafter be described.

The hold and reset relay 56 has associated therewith a normally open switch including contact fingers and 86, the former being mounted on the insulating member 62 and the latter being mounted between blocks Off insulating material indicated at 81 carried on an extension of the field piece 58, as seen in Figure 4 of the drawings. When the armature 51 is moved into engagement with the core 56a of said relay 56 contact finger 85 is thereby moved into operative engagement with contact finger 86 to complete a portion of an electrical circuit.

The mechanical timing mechanism designated at 83 is of a conventional form and is carried on a mounting plate 88 which is secured by screws 89 to the outer surface of the leg of the frame I, upon which relay 32 is mounted. .While the details of construction of the timing mechanism constitute no part of the present invention it is believed helpful to a better understanding of the entire operation of the selector switch to point out that the arm 82 of the timing mechanism is the main control member thereof, actuated in one direction by the armature 36 as will hereinafter be described. Mounted on said arm is a pivoted pawl 90 which is urged by means of a spring 9| into engagement with the toothed periphery of a ratchet wheel 92 of the mechanism so that as said operating arm 82 is moved in a downward direction by armature 36, the pawl 90 cams over the teeth of the ratchet wheel,

but upon upward direction of movement of said am said pawl tends to rotate the ratchet wheel 92, and the gearing associated therewith. A coiled spring 84 is connected at one end to said arm 82 and at the other end to said mounting plate 88 in a position for normally urging the arm 82 in an upward direction, under control of the gearing driven by the ratchet wheel 82.

As may be seen in the drawings, said operating arm 82 is normally disposed in. a position immediately beneath and in engagement with the lower end of the plug 88, associated with switch finger 13. Said arm is adapted to be moved in a downward direction incident to the attraction of the armature 38 to the core 32a of the relay 32, and for this purpose the strap 42 for holding the actuating pawl 88 confined on the armature includes a forwardly extending leg 42a, positioned to extend immediately above said operating arm 82 so that when said armature is attracted to the core of the coil of the relay 32, said arm 82 is moved downwardly, and when said arm is freed of the pressure of the armature, through the leg extension 42a, said arm is drawn upwardly by the coiled spring 88 under control of the gearing of the timer mechanism.

It is to be understood that the gearing of the timer mechanism and the tension in the coil spring 94 are so corelated that when the arm 82 arrives at the position seen in Figure 2 of the drawings, the forces are substantially balanced. In other words, the position of the parts is then such that the arm 82 has imparted sufficient movement to plug 88 for shifting switch finger 13 into engagement with switch finger 14 and the latter through the plug 84 has moved switch finger 16 out of engagement with switch finger 15, as seen in Figure 3 of the drawings.

It will be apparent that during the period of pulsating action of the armature 38, due to the intermittent energizing of relay 32 by pulsations of current, the operating arm 82 of the timing mechanism is substantially held in a position out of engagement with the plug 88 so that switch fingers 13 and 18 are in open position, while switch fingers and 18 are in engagement to complete portions of an electrical circuit.

This delay action of arm 82 as regards the switches composed of fingers 13, 18 and 15 and v 18 is due to the gearing of the timing mechanism a which requires an interval of time for return of the arm 82 to its uppermost normal position, substantially in excess of the time between pulsations of current imparted to the relay 32. fore, the arm 82 is permitted to move upwardly under timing control of the gearing when pulsations of current to the relay 32 cease, and effects a time delay action of the switches.

It will now be seen from the wiring diagram represented in Figure 6 that the switches composed of switch fingers 13 and 14 and 85 and 88, respectively, are connected in series in the main electrical circuit, while the switch composed of switch fingers 15 and 16 controls the supply of current to the "hold and reset relay 58 from an auxiliary circuit which for convenience may be a low voltage circuit. If desired, the main electrical circuit could be connected as a part of the low voltage circuit but generally the main circuit is preferably of higher voltage for the proper operation of the devices to be actuated in the branch circuits of the main electrical circuit.

The circuits of the selector switch will now be briefly described as follows. The coils 18 are Thereshown connected in the branch circuits of the main supply circuit which includes conductors designated as lines #I and #2. This circuit includes a main conductor wire I88 for connecting the current supply line #I to the switch finger 13 and a conductor wire I8I connects switch finger 14 to switch finger 85, and a conductor I82 connects switch finger 88 to the conductor wire 28, which is connected to the contact strip I9, throughcontact arm 23 to the contact arm 22, to a predetermined contact button I8, corresponding to the preselected branch circuit to be energized. Conductor wires I1 complete the branch circuits through the respective coils 18 to the other main current supply line #2.

When the selector switch is in inoperative position no current is permitted to flow through the main circuit including conductor wires I88, Ill, I82 and the supply lines #I and #2 since the switch composed of members 85 and 88 is normally in open position. While pulsations of electrical current are imparted to the stepping relay 32 for effecting selective adjustment of the contact arm 22 with a desired contact button I8 by the action above described, the main circuit, due to operation of the switch fingers 13 and 18, remains open during the period that pulsating current is supplied to said relay 32.

As above mentioned, said switch fingers 13 and 14 become separated due to the attraction of the armature 36, through the leg extension 42a of the guide strip on said armature engaging the arm 82 of the mechanical timing device, so that said arm relieves the pressure on the lower end of the plug 88 and thereby permits switch finger 13 to yieldingly move out of engagement with its cooperating finger 18, and which, as also above mentioned, permits closing the switch composed of switch fingers 15 and 18, which results in energizing the hold and reset relay 58 which is connected in an auxiliary circuit including conductor wires I85, I88 and I81. Energizing of said relay 58 attracts armature 51 and moves switch finger 85 into engagement with finger 88 for completing a portion of the main circuit.

It will now be apparent that no current is permitted to flow through the main circuit including conductor wires I88, IM and I82, and lines #I and #2 during the period that the contact arm 22 is being stepped from one contact button to another.

Due to the fact that relay 58, as above mentioned, functions as a "hold and reset relay" and is energized during the time that pulsations of current are being supplied to the stepping relay 32, the check pawl 58 is freed by the armature 51, which is attracted to the core 580 of the coil of the relay 58, and thereby disengages the rod 6| so that the pawl 58 under influence of spring 54 operatively engages the teeth of the ratchet wheel 38 and maintains the same in stepped positions of adjustment.

Immediately upon cessation of pulsations of current being supplied to the relay 32, the armature 88 is released and moves to its upper free position by coil spring 81, and such movement of the armature through the leg extension 8211 frees the operating arm 82 of the mechanical timing device 88 so that said arm 82 in a time delay action, after lapse of an interval of time, again forcibly engages the lower end of plug 88 and moves switch finger 13 into engagement with switch finger 14, thereby completing the preselected electrical circuit, including the main electrical circuit, for a predetermined timed interval which timed interval is determined by the mechanical timer 83. As said arm 82 continues to move upwardly, after completion of a preselected circuit through the switch fingers 13 and H, motion is transmitted through switch finger H and plug 84 for moving the switch finger I6 out of engagement with switch finger l5, and

when this takes place the auxiliary circuit for" member 62 reengages the arm 6|, associated with the check pawl 50, and thereby shifts said pawl out of engagement with the ratchet wheel 30,

whereupon the spring 65 then returns the ratchet wheel together with the contact arms 22 and 23 to normal or neutral starting position.

The construction represented in the drawings may be understood to beespecially suitable for use with alternating current, and for this purpose the stepping relay" 32 is provided at its head with a copper slug 320, the function of which is to act as a shading ring for eliminating chatter and buzzing. It is to be understood, however, that when this selector switch is intended for use with direct current, the stepping relay 32 shall be of modified form having proper characteristics for use with direct current.

It will now be apparent that by virtue of the construction described there will be no arcing as a result of the contact arm 22 moving from one contact button to another during the stepping action since no current flows through the main electrical circuit, including the branch circuits, until the selector arm is arrested for a short interval of time in engagement with a predetermined contact button of a preselected circuit, after which period of time current is permitted to flow through said preselected circuit for a limited period of time, under control of a mechanical timing device, and after which all circuits are then broken and assume a normal inoperative condition.

Although we have herein shown and described a preferred embodiment of our invention, manifestly it is capable of modification and rearrangement of parts without departing from the spirit and scope thereof. We donot, therefore, wish to be understood as limiting this invention to the precise form herein illustrated and described. except as it may be so limited in the appended claims.

We claim as our invention:

1. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, means for shifting said arm into engagement with a predetermined one of said contacts for completing a portion of a preselected branch circuit, switch means for controlling said main electrical circuit, and mechanical timing means for controlling said switch means, said timing means and first mentioned means being interconnected to effect energization of said timing means upon operation of said first mentioned means, and said timing means being rendered operable upon discontinuance of operation of said all) first mentioned means, whereby said switch means is controlled to eiTect energization of the preselected branch circuit in delayed timed relation, subsequent to engagement of said arm with the contact of the preselected bra-nchcircuit.

2. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, means for shifting said arm into engagement with a predetermined contact for completing a portion of a preselected branch cir-' cuit, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electro-magnet in said auxiliary circuit for controlling said normally open series switch, and mechanical timing means for controlling the other two switches in such correlation to each other as to cause the auxiliary switch and electromagnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, said timing means being responsive to and operated by said first mentioned means, whereby said switches are controlled in a manner to effect energization of the preselected branch circuit for a predetermined limited time, in de layed timed relation, subsequent to engagement of said arm with the contact of the preselected branch circuit.

3. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, electrical impulse operated electromagnetic means for shifting said arm in step-bystep fashion into engagement with a predetermined contact for completing a portion of a preselected branch circuit, switch means for controlling said main electrical circuit, and me chanical timing means for controlling said switch means, said timing means being responsive to and rendered operable by said electro-magnetic means, whereby said switch means is controlled to effect energization of the preselected branch circuit in 4. In a selector switch, the combination of a 4 plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, electrical impulse operate-d electromagnetic means for shifting said arm in step-bystep fashion into engagement with a predetermined contact for completing a portion of a pre selected branch circuit, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electro-magnet in said auxiliary circuit for controlling said normally open series switch, and mechanical timing means for controlling the other two switches in such correlation to each other as to cause the auxiliary switch and electro-magnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, said timing means being responsive to and operated by said first mentioned means, whereby said switches are controlled in a manner to efiect energization of the preselected branch circuit for a predetermined limited time, in delayed timed relation, subsequent to engagement of said arm with the contact of the preselected branch circuit.

5. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, means for shifting said arm into engagement with a predetermined contact for completing a portion of a preselected branch circult, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electro-magnet in said auxiliary circuit and arranged for controlling said normally open series switch, the other two switches being interconnected for correlated actuation, and mechanical timing means for controlling said other two switches, in such correlation to each other as to cause the auxiliary switch and electro-magnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, said timing means being responsive to and operated by said first mentioned means, whereby said switches are caused to be actuated in a manner for effecting energization of the preselected branch circuit for a predetermined limited time, in delayed timed relation, subsequent to engagement of said arm with the contact of the preselected branch circuit.

6. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, electrical impulse operated electromagnetic means for shifting said arm in step-bystep fashion into engagement with a predetermined contact for completing a portion of a preselected branch circuit, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electromagnet in said auxiliary circuit and arranged for controlling said normally open series switch, the other two switches being interconnected for correlated actuation, and mechanical timing means for controlling said other two switches in such correlation to each other as to cause the auxiliary switch and electro-magnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, said timing means being responsive to and operated by said impulse operated electro-magnetic means, whereby said switches are caused to be actuated in a manner for effecting energization of the preselected branch circuit for a predetermined limited time, in delayed timed relation, subsequent to engagement of said arm with the contact of the preselected branch circuit.

I. In a selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, electrical impulse operated electromagnetic means for shifting said arm in step-bystep fashion into engagement with a predetermined contact for completing a portion of a preselected branch circuit, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electromagnet in said auxiliary circuit and arranged for controlling said normally open switch of said pair of switches, the other two switches being interconnected for correlated actuation, and mechanical timing means responsive to and operated by said impulse operated electro-magnetic means, said timing means being positioned for controlling said other two switches in such correlation to each other as to cause the auxiliary switch and electro-magnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, whereby said timing means is caused to be energized during actuation of the impulse operated electro-magnetic means and rendered operative after cessation of operation of said impulse operated electro-magnetic means to effect energization of the preselected branch circuit for a predetermined limited time, in delayed timed relation, subsequent to engagement of said arm with the contact of the preselected branch circuit.

8. In a unitary self-contained selector switch, the combination of a plurality of contacts connected in separate branches of a main electrical circuit, a movable contact arm, electrical impulse operated electro-magnetic means for shifting said arm in step-by-step fashion into engagement with a predetermined contact for completing a portion of a preselected branch circuit, a pair of switches connected in series in the main circuit, one of said switches being normally open and the other normally closed, a separate normally open switch connected in an auxiliary circuit, an electromagnet in said auxiliary circuit and arranged for controlling said normally open switch of said pair of switches, the other two switches being interconnected for correlated actuation, and clockwork type mechanical timing means having an arm positioned to be engaged by the armature of said impulse operated electro-magnetic means, said arm of the timing means being so positioned to control operation of said other two switches in such correlation to each other as to cause the auxiliary switch and electro-magnet of the auxiliary circuit to be controlled during an overlapping interval of the two series switches, whereby said mechanical timing means is caused to be energized during actuation of the impulse operated electromagnetic means and rendered -operative after cessation of operation of said impulse operated electro-magnetic means to effect energization of the preselected branch circuit for a predetermined limited time, in delayed time relation, subsequent to engagement of said contact arm with the contact of the preselected branch circuit.

EDWARD G. BAKER. THEDORE OBSZARNY.

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