US906056A - Axle lighting system. - Google Patents

Description

A. MQGARY.

AXLE LIGHTING SYSTEM.

APPLICATION FILED 00w. 22, 1906.

Patented Dec. 8, 1908.

2 SHEETSSHEET 1 Ir ven tor A/ezamkrM/lm y .lltlorney A. McGARY.

AXLE LIGHTING SYSTEM. APPLICATION FILED 0OT.22, 1906. 906,056, Patented Dec. 8, 1908.

2 SHEETS-$113111 2 an v UNITED STATES PATENT OFFICE.

ALEXANDER McGARY, OF LA GRANGE, ILLINOIS, ASSIGNOR OF ONE-FIFTH TO CHARLES GILBERT HAWLEY, OF CHICAGO, ILLINOIS.

AXLE LIGHTING SYSTEM.

Specification of Letters Patent.

Application filed October 22, 1906. Serial No. 339,997.

To all whom it may concern:

Be it known that I, ALEXANDER MCGARY, a citizen of the United States, and a resident of La Grange, Cook county, Illinois, have invented a certain new, useful, and Improved Axle Lighting System, of which the following is a specification.

My invention relates to the lighting of railroad trains by electricity and has par ticular reference to improvements in electric lighting systems of that class known as axle lighting-systems and characterized by circuits containing a storage battery and by a generator for alternate use, the generator being driven from the car axle, and at times operating to energize said battery.

The practice hitherto generally followed in devising and operating these systems has involved the use of curren't and voltage regulators, and the maintenance of a constant current upon the lamp or working circuit of the system. My investigations and experiments show that such systems are needlessly complicated and that the complication is chiefly attributable to the efforts made to regulate the ,current output and keep the same constant.

In my invention I proceed upon the basis of the known fact that the lamps or other translating devices belonging to such a system will themselves determine the current consumption, and in contra-distinction to the known systems my novel system is characterized by the maintenance of a constant voltage upon the lamp or working circuit of the system, without regard to the varying current flow.

The object of my invention may be briefly stated as being the ovision of an electric lighting system which shall include a dynamo to be driven from a car axle, and a storage battery carried by the car, together with means that shall adapt the same to supply electric current, adequate to the varying demands of the lamp circuit, at a constant voltage. Y

Another object of my invention isto provide an electric system of the class mentioned which, when in operation, shall automatically charge the storage battery in a manner most favorable to longevity.

A further object ofthe invention is to simplify the construction and circuits of electric lighting systems for railroad cars with a view to reducing the initial and the maintenance costs connected therewith.

Patented Dec. 8, 1908.

Other objects ofmy invention will appear hereinafter.

My invention consists generally in the hereinafter described system of electric generation and distribution, comprising a lamp circuit, a duplex generator, a storage battery, and an automatic switch or circuit closer, adapted to connect the battery alone to the lamp circuit when the generator is at rest or running slowly, and also adapted to disconnect the battery from the lamp circuit and connect one of the windings of the generator to the circuit and the other winding to the battery, the battery being cut out of the lamp circuit after the generator is connected to the-circuit and before the generator is connected to the battery.

My invention also consists in an electric windings of said generator, and a compression device for said resistance, operated by a shunt from the lamp-armature circuit; and further, my invention consists in an electric system characterized by a generator adapted to be driven at different times in reverse directions and in an automatic pole-changer operated from the generator shaft or other part, whose rotation is governed by the direction of travel of the ear, and adapted to maintain a constant polarity in the system regardless of the direction of rotation of the generator.

My invention further consists in various details of construction, in circuits and in circuit relations; all as hereinafter described and particularly pointed out in the claims.

My invention will be more readily understood by reference to the accompanying drawings which form a part of this specification, and in which Figure I is a diagrammatic view of an electric system embodying my invention, the

switches thereof being shown in the positions assumed when the storage battery is alone furnishing current to the lamp circuit, the generators being assumed to be at rest or 'with their armatures in slow rotation; Fig.

II is an enlarged detail view of the resistance varying ..means and the circuit closer employed in my system; Fig. III is an enlarged view of the automatic switch or circuit closer Fig. IV is an enlarged view of the pole changer.

From the drawings it will be seen that my system comprises three principal circuits aside from the lamp, that is, three circuits which at different times include or are con nected with the lamp circuit, either directly or indirectly. The three principal, or main, circuits alluded to, I designate as battery circuit, lamp armature circuit, and the battery armature circuit. The battery circuit is to supply current to the lamp'circuit, while the armature is at rest or running at a speed too low to maintain sufiicient voltage on the system. The lamp armature circuit is to supply current to the lamps from the armature, after the latter has picked u sufiiciently to supply current at proper vo tage and the battery armature circuit for the recharging of the battery while it is out out of the lamp circuit, and the lamp armature circuit is supplying the current to the lamps direct.

As shown in the drawings, A represents a group ofelectric lamps and B the lamp circuit, whereof B and B are terminals.

0, is a duplex generator having a single armature provided with two windings or sets of coils, D and E. These are wound upon a single core and hence rotate together. The armature winding, D, as hereinafter explained, supplies energy to the lamp circuit, and the winding, E, which contains a greater number of the turns than the winding, D, supplies energy to a storage battery, F, at a greater voltage than that on the lamp circuit.

G represents the field windings of the duplelx generator wound upon a single set of po es.

The armature shaft H is driven from the car axle, I, by a beltor other suitable mechanism. As the armature is driven from the car axle, it is obvious that each change in the direction of move'rhent of the car will cause a reversal in the rotative directionof the armapolarity of the lamp circuit and of the fieldwindings of the generators which are connected to said lam circuit. The office of the pole-changer K 1s to reverse similarly the connections of the battery circuit armature. For convenience, and to avoid multiplicity of parts, I construct the apparatus so that both pole-changers may be operated by a single device. The pole-changers are of the simple two-armed, five pole type. The four arms are connected by a cross bar JK, which carries a block K, and a screw L upon a shaft L is threadedthrough said block. It will be observed that by turning the shaft L the pole changers are shifted. The shaft L should turn only during the first few revolutions of the armature, after the direction of rotation has been changed. That is, the screw shaft should only turn until the contacts are changed, and should then remain inoperative until the direction of rotation of the armature is again reversed. Accordingly, I provide a friction pulley upon the shaft L, and connect it by belt to the armature shaft H. Assuming that the armature has been running in one direction, as soon as it is reversed the shaft L is turned until the polechanger is shifted. Stops, jb, limit the movement of the pole-changer and arrest the shaft L from further rotation, the friction pulley permitting this stoppage without injury to the device.

The lamp armature circuit is traced from the armature, windings, D, through the line d or d, to the pole-changer, J. From the pole-changerit is traced through the lines d to the terminal B of the battery circuit, through the interposed switch or circuit closer M through the lamp circuit B to the terminal B, and thence through the line (i a to the pole changer, returning to the armature through one of the lines (1, d. I speak of the current going to and from the polechanger through one of two lines. son for this is obvious, as which line is the positive "and which the return wire, depends solely upon the direction of the rotation of the armature, and it will also be seen from the foregoing description that the automatic pole-changer, maintains a constant polarity upon the lamp circuit regardless of the direction of rotation of the armature.

The field winding G is connected across the lamp armature circuit, and at points between the pole-changer and the lamp circuit, so as to maintain the field at a constant polarity. The current is traced-from the line (1 through g to the field winding G. ihence it is traced through the line g to a variable resistance N, and then through line 9 to the line (i I will now describe the variable resistance and the manner in which it is operated.

The resistance N comprises a carbon pile held between suitable terminals to which the lines 9 are connected. One of these terminals, 'n, is stationary, whereas the-other is movable and is engaged by acompression lever N. p of the pile N will be varied; according to the degree of com ression exerted tlrereon through the lever N The rea-' It is obvious that the resistance versely, the less the pressure the greater the resistance. To operate the lever N to vary the compression of the pile N, and hence to vary the resistance, I rely upon the well known facts that the temperature of a conductor varies with the square of the current flowing therethrough, and that a body expands indirect proportion to its temperature, I attach one end of a wire of great tensile strength and high resistance to the lever N and the other end to a stationary member, and connect this wire across the lamp-armature circuit. 0 represents the expansible wire, known hereinafter as the hot wire, and o, the stationary connection point. The tension of the'wire' 0 when cold, is sufficient .to compress the resistance N togive it its minimum resistance. The hot Wire is connectedto the lamp armature circuit through wires 0", 0 and y I To prevent rupturing the device, should too reat a strain be placed thereon by the coo ing of the wire 0,

and for other reasons which will appear hereinafter, I make a yielding connection P between the wire 0 and lever N It'will be seen, from the foregoing that as the lamp armature circuit picks -up, a current of increasing voltage will pass through the hot wire 0; and that as the voltage increases the wire becomes more and more heated, with a conse uent proportional expansion of the wire. T is obviously lessens the pres? sure on the pile J and thereby increases the resistanceof'the field circuit. In this manner I regulate the out-put of the main generator and maintain a constant voltage upon a; the system.

The battery circuit, as before stated, is in service when thearmature is at rest, or running at too low a speed to supply sufficient voltage to the lamp circuit. It is traced 1s from the "storage battery,-F, through the line f tothe circuit closer M, and through said circuit closer and a line f to the terminal B of the lamp circuit, and from the terminal B, to the battery through a line f I The automatic circuit closer M comprises primarily three plates or bridges insulated from 'each other and actuated at the proper time by a solenoid which is connected across the armature lamp circuit. These bridges serve as circuitclosers for the three principal circuits before mentioned, one being located in each said circuit. When at rest, that is, when ,unacted uponby the armature. lamp circuit, it operates to close the battery circuit; and-Whenthe solenoid is energized it operates to cut the battery out -of the lamp circuit and (place it in the circuit of the armature win ingE, and also to place the armature winding D inthe lamp circuit. In

plished will now be described.

: M. To the core is attached a rod, m, which other words, the circuit closer M serves to. replace '-the battery by the d means and manner in which t is accom- M represents'the solenoid having a core,

amof The p the resistance of the field is preferably of insulating material, and upon this rod are located the closers proper or bridges. As before stated, I provide a bridge for each of the three principal circuits; thus the bridge,fm, serves to close the battery circuit; a bridge, dm, the lamp arma- -ture circuit, and a bridge, cm, the battery armature circuit. The bridge, fm, is adapted to engage the contacts, mfm; the contact, m, being connected to the lamp terminal, B, through the line f, and the. contact m being connected to the battery by the linef. As illustrated in the drawings, thebattery circuit is closed, and the batter is supplying the current to the lamps, W ile the dynlamo is at rest. When the circuit closer is in t e will flow from the battery F, through the line f, contacts m fm, m, and thence through line f to .the lamp circuit B, returning through the line f At such times the lamps will be supplied from the battery, F, and from there only. Y'Vhen the rod, m, is drawn up by the solenoid the bridges dm and em engage'respectively contacts m m m and m These last two represent the duplex armature windings, D and E respectively, and thecircuits established when the circuit closer is raised are easily traced, they having been mapped out hereinbefore. To avoid a momentary flicker of the lights, when the battery is cut oil and the dynamo thrown in, it is necessary to close the lamp armature circuit before breaking the battery circuit. It is also obviously necessary to break the battery circuit before closing the batteryarmature circuit. To this end the bridges fm and dm are slidably mounted ,on the rod m, while the bridge em is rigid therewith. The bridges fm and dm are held apart by a spring M and stops dm andfm limit their movement apart. These stops, dm, fm are a slightly greater distance apart than the position shown in the drawings, current pairs of contacts m, m and m m. Consequently, one circuit represented by these bridges is always closed before the other is broken. When the circuit closer is down, as illustrated in Fig. III, the bridge fm seats against the contacts m, m and the stop dm holds the bridge (Zm out of engagement with the contacts m m. As the rod m is drawn upwardly, the spring M seats the bridge dm on the contacts m m, and also maintains the engagement of the bridge fm with the contacts m, m With further upward movement of the rod m, the stop fm raises the bridge m, thereby breaking the battery circuit an a slight additional movement closes the battery armature circuit by seating the bridge em on the contacts m m". p

The hot wire 0, besides being used to vary G to maintain a constant voltage on the system, is also used to automatically close the circuit through the solenoid M. The lever N carries a conthe levers, through a line m oid circuit is bridged across energized irrespective main circuit through the contacts m m adapted to engage a lever S; these parts constituting a circuit closer for the circult of the solenoid, M. S is alimiting stop for the lever S, and the contact, B, only engages the levers when and after the hot wire, 0, has been expanded by a flow of current 'therethrough. The

solenoid M is connected with the lamp, armature circuit by a line m7, and its opposite terminal is connected with As the solenthe terminals of solenoid M may be the armature, ,D, the

' of the closing of the The solenoid is therefore always in readiness various parts of the as to raise the circuit closer against the tenwire 0. A spring 19 to operate the circuit closer M, and the device are so constructed sion of the s ring M whenever the armature has attained sufficient speed to supply 1 a current of sufiicient voltage for the amps. This 0 eration of the solenoid, however, does not ta e place immediately upon the starting of the generator or at an indeterminate time, for the reason that the circuit is not closed through the solenoid M; until the flow of current from the armature D has caused sufficientexpansion of the hot wire 0 to permit the contact R to engage the switch lever S, As previously stated the exfpansible or hot wire is the means employed or controlling or determining the action of the circuit closer, and said wire is so proportioned that its sufiicient expansion will occur only when the armature 1) has reached the minimum speed that will enable it to supply current I e requisite voltage. The construction of this portion of the device as a whole is shown in details in Fig. II, wherein it will be seen that aspring NS, connects the levers N and S, tending to draw themtogether, and another and weaker spring, S tends to draw the levers away from the stop S. The lever N presses upon the carbon pile N and carries a spring'case 1 Within the case P is a rod p, and plunger 1) The rod works freely through an opening in P, and is' attached to the free end of the hot between the plunger 1) and the end of the casing E, tends to draw the lever N away from the lever S; that is, the plunger is fixed except as moved by the expansion and contraction of the hot wire;

and the spring, acting from the stationary lunger p, forces the lever N away from the connected to the contact W. l changer ,the current is traced through the e the. end of the casing pansion or slack of wire until an adjustable nut p upon the rod P seats itself on the end of the casing P; the spring meantime maintaining pressure on the compression resistance. The nut p is so positioned that it will engage the, lever casing P, when the voltage upon the hot wire, due to the full energization of the main field and the more rapid rotation of the armature, has closely approached the number of volts required upon the lamp circuit, and a slight increase on the hot wire circuit (thereafter operating to. further expand the wire-O) will cause the release of the lever N, andpermit the contact R to close upon the lever S. This action closes the circuit containing the solenoid M and the operation of the circuit closer follows immer ately, the effect being to cut out the battery and place the main armature D in the lam circjuit. At the same time, the armature It is connected with the battery and will begin to recharge the same.

The operation of the automatic switch with relation to the armature E is as follows: One of the terminals of the armature windings isconnected to the contacts In and k of the pole changer K, and the other terminal is From the ole e to the contacts m cm, and m, of the circuit closer M and thence to the battery F, returning through the line 6 When the solenoid M is energized the battery is cut out of the lamp circuit and connected with the armature winding E to be recharged therefrom. i

For the purpose of tapering the battery charge I introduce resistance 0. The effective resistance varies with the current flow. Consequently, when the potential ofthe battery is low it will be charged at a high rate by a current of relatively low voltage, and as the capacity of the battery is approximated, the voltage of the charging current Wlll be increased, thereby insurmg ER in the line the completeness of the charge and protecting; the battery from injury. The special merit of this portion of my apparatus is that its operation and regulation are wholly au- .tomatic. Reverting to the controller; it has-been seen that the spring exerts its maximum ressure upon the resistance N when the wire is cold and it willbe evident that as the hot wire expands and thus lessens the spring ressure, the effective resistance of the mass N will be increased, and this will result in weakening the field of the generator and reduce the output'of the lamp armature. In this measure the temperature of the hot wire will i be reduced and the same will tend to reduce the resistance N and cause the restoration of the armature output. This operation so far as it concerns the reduction of the outputof l the main generator does not begin to have circuits of the lamp sequently the main field is weakened.

practical eiiect until the lamp armature has een placed in the lamp circuit.

It will now be understood that the further movement of the lever N, which occurs after the switch N S closes, is slight, but is suflicient to vary the resistance N to such an extent as to vary the strength of the field G in response to slight variations in the length of the wire 0, and thus compensate for changes in the speed of the generator armature and in the load upon the lamp circuit. The result is a substantially constant voltage upon the lamp circuit, which constant voltage is maintained irrespective of the current consumption and. irrespective of variations of car speed, so long as the generator speed does not fall below the minimum. When a drop in speed does occur, the hot wire, which is in direct connection with the lamp circuit, will at once respond and its contraction will result in opening the automatic switch cir= cuit, whereupon the storage battery will be instantly restored to the lamp circuit and will remain therein until the generator speed again rises to the point at which the controller and switch operate to close again the and charging armatures. In practice suitab e circuit breakers are provided in the various circuits for the purpose of cutting ofi the lamps when desired and to prevent battery leakage, when the system is at rest, but such switches and the manner of their use being well known, it has been deemed unnecessary to either show or describe them.

The operation of my invention is as follows': When the car that is equipped with my system is at rest, and also after the car has been started, but before the generator s eed has reached the required minimum, the attery is in circuit with the lamps, the bridge fm. of the automatic circuit closer serving to close the circuit through the lamps and battery. The armature being rotated, the hot wire which is in closed circuit with the armature winding D, will be heated. Meantime the armature Winding E remains idle as its circuit is open at the contacts m and m. As the speed of the armature increases, the energization of the main field increases and the pressure increment upon the circuit of the hot wire 0, will cause further expansion thereof. This condition will continue until the hot wire has been sufficiently expanded to permit the closing of the switch N, S, which closes the circuit of the automatic circuit-closer M. Incidentally the efi'ective resistance of the pile N is increased and con- It should be noted that this weakening of the main field takes place only when the current from the generator has acquired sufficient volt-age properly to supply the lamps; and that the weakening of the field is in proportion to the increase of voltage thereafter.

In this manner the voltage on the entire system is kept constant, for the hot wire '0 responds to every change of potential upon the lamp armature and in so doing causes the battery circuit, and lastly, closing the battery armature circuit, all as hereinbefore described in detail. The lamp circuit is now supplied with energy from the armature winding C, and'the current flow in the battery will be reversed, the same being charged with current from the armature winding, E, the resistance ER in that circuit operating in the advantageous manner herembefore set forth.

The operation of the automatic pole changer J, K has been fully described in connection with the detailed description of its structure, therefore it is sufficient to repeat here that with every reversal of the direction of rotation of the generator, the pole-changer is shifted, thereby maintaining a constant polarity on the entire system.

various modification; ofmy invention will suggest themselves to one skilled in the art, I do not confine my invention to the specific constructions herein shown and described.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An electric system, comprising a working circuit, in combination with a storage battery, a direct current generator having a variably driven duplex armature one part of which is devoted to said working circuit, and the other to said battery, means for maintaining the output of said generator at a constant voltage when running at or above a certain speed, and means automatically operative, when the armature attains sufiicient voltage, to connect the respective parts of said armature successively to the lamp circuit and to the battery, and disconnect the battery from the lamp circuit intermediate said successive steps; and conversely, operating to disconnect the same from and connect the battery with said working circuit, when 11 the voltage of said armature output falls below a certain predetermined voltage, sub stantially as described.

2-. In an electric system, a storage battery and a working circuit suitably connected, in combination with a variably driven, constant voltage generator comprising two direct current armatures within a single field and means automatically operative, when the armature attains sufficient voltage, to consai nect the respective parts of said armature successively to the lamp circuit and to the battery, and to disconnect the battery from the lamp circuit intermediate said successive steps, and conversely, operating to disconnect the same from and connect the battery with said Working circuit, when the voltage of said armature output falls below a certain predetermined voltage, substantially as described. I

3. In a system of electric generation and distribution, a working circuit, in combination with a storage battery, a generator having a duplex armature and means automatically operating to connect one of the windings of said armature to said working circuit, to disconnect said battery from said working circuit after said connection has been made, and to connect the other of said armature windings to said battery after said battery has been disconnected from said working circuit, and means for varying the strength of the field to maintain a constant voltage-on the system, substantially as and for the purpose described.

4. In an electric system of the class described'a working circuit, and a storage battery suitably connected thereto, in combination with a variably driven generator having a duplex armature, means for automatically disconnecting said battery from said working circuit and connecting one of the windings of said generator to said circuit and the other to said battery, a pole changer interposed between said generator and said battery and means mechanically connecting said pole changer with a moving part of said generator to operate said pole changer to maintain a constant olarity on said system, substantially as escribed.

5. In an electric system, a generator provided with a duplex armature, in combmation with a storage battery for connection with one of said armatures, a lamp circuit for connection with the other armature, means connecting said lamp circuit with the field windings of said generator, current varying resistance provided in the circuit of sal fie d windings, means automatically operative for connectin said lamp circuit with its armature and with said battery at different times, and ole changers for maintaining the polarity of said lam circuit and said battery circuit, and there y maintaining the polarity of the 'field of said generator, substantially as described.

6. In an electric system, a generator provided with a duplex armature, in combina tion with a storage battery for connection with one of said armatures, a lamp circuit for connection with the other armature, means connecting said lamp circuit with the field windings of said generator, current varying resistance provided in the circuit of field windings, means automatically operative for connectingsaid lamp circuit with its armature and with said battery at different times, and pole changers actuated by the rotation of said duplex armature for maintaining the polarity of said lamp circuit and said battery circuit and thereby maintaining the polarity of the field of said generator, substantially as described.

7. In an electric system, a generator proits armature and wit said battery at different times, and actuated from the lamp circuit armature, and pole changers actuated by the rotation of saidv duplex armature for maintaining the polarity of said lamp circuit and said battery circuit and thereby maintaining the polarity of the field of said generator, substantially as described.

8. In an electric system of the class described, a working circuit, and a variably driven generator suitably connected thereto, in combination with a pole changer interposed between said generator and said worklng circuit, and operated by the rotation of said armature, sa1d pole changer comprising a two arm switch, a yoke connecting said arms, a lug on said yoke, a shaft screw threaded through said lug, and means connecting said shaft with the shaft of said genfrom said working circuit after said ,circuit has been closed, substantially as described.

10. In a system of electric generation and distribution, a working circuit, in combination with a storage battery, a generator, means automatically operating to connect the armature of said generator to said working circuit and to disconnect said battery from said working circuit after said circuit has been made, and means for varying the strength of the field to maintain a constant voltage on the system, substantially as described.

11. In a system of electric generation and distribution, a working circuit, in combination with a storage battery, a generator, and means automatically operating to connect the armature of said generator to said working circuit and to disconnect said battery from said working circuit after the first said circuit has been closed, said means comprising a solenoid connected with said armature circuit, a core having a suitable extension, and a pair of circuit closers on said extension and having relative movement thereon, substantially as described.

12. In a system of, electric generation and distribution, a working circuit, in combination with a storage battery, a generator, and means automatically operating to connect the armature of said generator to said work distribution, a working circuit, in combinaing circuit and to disconnect said battery from said working circuit after said circuit has been made, said means comprising a support, contacts arranged upon said support in pairs, a reciprocating member, circuit closers upon said member and having relative movement thereon, and a solenoid connected with said armature circuit for actuating said reciprocating member, substantially as described.

13. In a system of electric generation and tion with a storage battery, a generator, and means automatically operating, to connect the armature of said generator to said working circuit and to disconnect said battery from said working circuit after said circuit has been closed,.said means comprising a support, contacts arranged upon said support in pairs, a reciprocating member, circuit closers slidably mounted upon said member and spring pressed apart, stops for limiting the movement of said circuit closers, said stops being at agreater distance apart than said pairs of contacts, and a solenoid for actuating said reciprocating member, substantially as described.

14. In a system of electric generation and distribution, a working circuit, in combination with a storagebattery, a generator, and means automatically operating to connect the armature of said generator to said working circuit and to disconnect said battery from said working circuit after the aforementioned circuit has been closed, said means comprising a support, contacts arranged I upon said support in pairs, a reciprocating member, circuit closers slidably mounted E upon said member and spring pressed a art, g stops for limiting the movement of sai ciri cuit closers upon said members, said stops being at a greater distance apart than the distance between said pairs of contacts, a s ring operating to move said member in one irection to connect the battery with the working circuit, and a solenoid connected with the armature circuit for actuating said 'member to disconnect the battery from the working circuit and connect the armature therewith, substantially as described.

15. In a system of electric generation and distribution, a working circuit, in combination with a storage battery, a generator having a duplex armature, and means automatically operating when the armature attains suflicient voltage to connect the respective parts of said armature successively to the amp circuit and to the battery and to disconnect the battery from the lamp circuit intermediate said successive steps, said means comprising a support, contacts arranged upon said support in pairs, a reciprocating member, a pair of circuit closers slidably mounted upon said member and spring pressed apart, stops for limiting the movement of said circuit closers, said stops being at a greater distance apart than the respective airs of contacts, a third circuit closer rigid y secured to said member, and a solenoid for actuating said member, substantially as described.

In testimony whereof, I have hereunto set my hand this 17th day of October, 1906, in the presence of two subscribing witnesses.

ALEXANDER MoGARY.

, WILLIAM H. READER.

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