US1131914A - Electrical installation for lighting, heating, and ventilating railway-carriages and similar purposes. - Google Patents

Description

A. H. BARKER. TION FOB LIGHTING, HEATING, AND VBNTILA TING RAILWAY ELECTRICAL INSTALLA OARRIAGES AND SIMILAR PURPOSES. Arrmcufon FILED NOV.5,1912.

Patented Mar. 16, 1915.

4 SHBETS-SHEET 1.

FIG. I.

I 3 5.? o Imfi ia m av-h I II! FIG. 2.

AIR. DARKRR. ELEO'IBIGAL INSTALLATION FOR LIGHTING, HEATING, AND VENTILATING RAILWAY GABBIAGES AND SIMILAR PURPOSES.

APPLICATION FILED NOV. 5, 1912. 1,131,914. Patented Mar. 16, 1915.

' 4 8HBBTS*SHEET 2.

FIG. 3.

A. H. BARKER. LLATION FOR LIGHTING, HEATING, AND VENTILATIHG RAILWAY GARRIAGES AND SIMILAR PURPOSES.

APPLICATION FILED NOV. 5, 1912.

Patented Mar. 16, 1915.

F, G 5 4 BKEETHHBBT 3- ELECTRICAL INSTA A; H. BARKER. BLEGTBIGAL INSTALLATION FOBLIGHTING, HEATING, AND VBN'IILATING RAILWAY GARBIAGES AND SIMILAR PURPOSES.

ARPLIOATIOH FILED NOV. 5, 1912.

Patented Mar. 16, 1915.

4 SHEETS-SHEET 4.

new.

anmmmhhm UNITED STATES PATENT OFFICE.

ALFRED HENRY BARKER, OF BLACKHEATH, ENGLAND, ASSIGNOR TO J. STONE & COMPANY LIMITED, OF DEPTF'ORD, ENGLAND.

ELE CTBlCAL INSTALLATION FOR LIGHTING, HEATING, AND VENTILATING RAILWAY- CARRIAGES AND SIMILAR PURPOSES.

Specification of Letters Patent.

Patented Mar. 16, 1915.

Application filed November 5, 1912. Serial No. 729,581.

This invention comprises improvements in and relating to electrical installath i w for lighting. heating and ventilating .ailway carriag s and for similar purposes and more particularly concerns those installations or systems wherein a dynamo driven from the axle of a vehicle is titted with a rocking reversing switch which mor to one position or the other. according to the direction rotat on oi the dynamo spindle, for the maintaining constant polarity at the terminals of the dynamo. In such systems it is usual to employ either a governor which closes the main sw itch when the armature has attained a sutlicicnt speed, or an clcctroinagn t solenoid which closes the main switch when the speed is sullicient for (3 \H, purpos of producing a predetermined terminal voltage.

lt preferred to employ a shunt wound dynamo littcd with a demagnetizing series winding which can be connected in a circuit or cut out. or short-eircuited, at will. When the series winding is not active, the dynamo runs as an ordinary shunt-wound machine and the slipping of the driving belt. is relied upon for giving a certain amount ot' regulation of the output. By onnecting the series demaguetizing winding in circuit and by shifting the brushes so as to give them a certain lead. the dynamo is sell regulating and may be driven by a. tight belt or by a po itive gearing. for. not only does the series winding have an increasing dema nietizing cll'cct as the speed increases, but certain of the arn'iature windings.owing to the lead which has been given to the brushes. assist, the series winding in reducing the strength ol the licld produced by the shunt, winding.

l or closing the main circuit when the armature reaches a certain speed and a certain terminal voltage is produced. an ,electzoniagnct or solenoid may be employed which is compound wound with a shunt and series winding. Thus when the shunt winding is sutiiciently energized it closes the main switch, whereupon the circuit is closed through the series winding and the latter assists the shunt winding in holding the main switch tightly closed. .Uponthearmature speed fallng, the switch arm may be pulled off against the attraction of the weakened compound wound magnet or solenoid bye spring, or by a weight carried by the switch lever.

Now in practice, if the main switch be closed while the dynamo is stationary or while the dynamo is being driven at a speed lower than the speed at which the main switch should be closed, much damage may be done to the dynamo, for current from the batteries will flow through the dynamo in the direction for running the dynamo as a motor, but inasmuch as the dynamo is prevented from so running by its driving belt or gear, it becomes overheated and the cells of the battery suitor owing ate of discharge. Such ill-timed closing of the main switch may be due to a person meddling therewith, or it may be due to a blow or concussion, or it may be due to a defect, or to sticking oi the armature or core of the switch.

In order to obviate the danger indicated above, the rocking reversing switch is so constructed and arranged that its initial movement in one direction or "the other. under the influence of the frictional engagement of the brushes with the commutator, effects only the closing of the circuit of the shunt field winding and a further movement has to be given to the rocking switch in order to connect the dynamo with the cells. This further movement is produced by electromagnetic means, as for example by means of an elcctro magnet fixed on a suitable training and constructed and arranged so as to attract either one of two pieces of iron or armaturcs carried by the brush rocker. winding oi this magnet is preferably in the circuit; of the shunt tield winding.

These improvements also comprise anraugcments for permitting: of the maintenance of residual magnetism of the field magnets of a dynamo titted as aforesaid, as well as arrangements for preventing overcharging of th battery or batteries in the; ex-

to the excessive ternal circuit. Furthermore, advantageous arrangements for changing over the batteries, when two or more batteries are employed, and for controlling the opening and closing of the main or working circuit are also provided according to this invention.

In order to enable the invention to be readily understood reference is made to the accompanying drawings, in which 2- igure 1 an elevation of the improved rocking switch arrangement as seen from the end of the armature spindle. Fig. 2 is a plan of Fig. 1. Fig. 3 is an elevation of the arrangement shown in Fig. 1 but as seen from the opposite end of the spindle, the arrangement being shown removed from the spindle. Fig. 4 is a detail View of the rocking switch parts. Fig. 5 is a diagram showing the application of a dynamo fitted with the improved rocking switch to a single battery system suitable for a lighting, heating or ventilating installation on a railway vehicle. Fig. 6 is a diagram explanatory of a modified arrangement in a double battery system. Fi modification of the'rocking switch.

In the arrangement illustrated by Figs. 1 to 4 a is a ring for carrying the dynamo brushes b which ring is rcvolubly mounted upon an end framing, or bearing, or upon the armature spindle. This ring a carries two projecting pieces of iron 0 situated a short distance apart which act as armatures for an electro-magnet (Z fixed upon the bearing or mounting comprising a ring frame e adapted to be fixed to the dynamo and having an axially directed bracket or extension ig. 1, terminating in a vertical support 9. This support, carries the bearing 0' of the armature spindle upon which bearing a ball race is formed for receiving a circular series of balls upon which the ring a rocks as seen in Fig. 2. The ring a further supports at diametrically opposite points, axially directed projections or bars it j on the ends of which are mounted respective brushes I). These bars are suitably fixed in recesses in the ring a, and insulated therefrom and the brush holders 7c are carried upon the ends of these bars, spr'ng pressed levers Z being provided for pressing the brushes 7) into contact with the commutator b, Fig. 2, in the known manner. On one side of the diameter which passes through the projections or bars it 7 aforesaid, there is fixed a pair of switch blades or contact brushes m which are so arranged that each member of the pair lies in the patli of a respective projection or bar I; or y. This pair of contacts or blades m is connected with the negative main 1?, Fig. 5, and with one terminal 0 of the shunt winding 7; by the connection 9 ()n the other side of the said diameter there are two pairs of blades or contacts r 8 similarly fitted. Each member of the pair 1* is,

g. 7 1s a diagram illustrating a however, arranged to project farther toward its respective projection or bar it or j, as seen to the right hand of Fig. l and to the left hand of Fig. 4, than members of the pair 8 and, as seen in Fig. 5, the brushes r are connected by the wire t with the other terminal of the shunt field winding Members of the pair 8 are connected with the positivemain u of the system by the connections 1) and w.

It will be apparent that when the armature rotates in one direction or the other, the engagement of the brushes 6 with the commutator will cause the rocker a to turn through a small angle until the projections or bars hand j which are in electrical connection with respective brushes Z), are an rested, one by a member of the pair m connected with the negative main 1;. and one terminal of the shunt field winding 72 and the other by a member of the pair 1' connected with the other terminal of the shunt field winding The circuit of the shunt field winding p is thus at once closed but the main circuit or positive connection o w u between the dynamo and the cells .2; remains open as the friction between the brushes 7) and the commutator does not produce suflicient turning moment for overcoming the resistance which the spring contact brushes or blades m and 1 offer to further movement of the rocker a so that the bar 11., or the bar 7', as the case may be, will still not touch the brush a. The turning of the rocker a, however, brings one of the iron ai-niatures 0 close to the suitably'shaped pole or poles 3 of the electroniagnet d whose windings a are preferably in the circuit of the shunt field winding 7) as seen in Fig. As the speed of the armature increases, the dynamo field builds up in the ordinary \vay due. to increase of current in the shunt winding 7) and the electromagnet (1 increases in power until the speed reached at which suificient voltage is generated to allow of safely closing the main switch. At this point the magnet d pulls on the armature c which has approached the pole z as above described and turns the ring a a little fur ther against the resistance offered by the spring contact brushes or blades m and 7 which are engaged by the projections or bars h as aforesaid. T heso contacts or blades m and r are thus depressed or flexed, thereby permitting one or other of the projections or bars It or j to nakc contact with a. member of the remainiri g pair of contacts or blades s and to connect the positive brush of the dynamo with the positive main. the current flowing from the positive brush on the left of Figs. 1 and through the holder and the bar it through the brush on [he left hand and thence through the wires w and '11 Fig. 5. In the latter figure and in Fig. 2, the rocker is seen, for con ven cnce,

in amid position but in actual working conditions it is hard'ly likely that the rocker would ever take up such a position unless springs were applied thereto for the purpose. As long as "the speed remains high enough, the magnet (I will' maintain the parts in this condition, but when the speed diminishes the power of the magnet (l will likewise diminish, until a certain speed is reached at which the magnet (l will not be sutiiciently energized to hold on the armature 6 against the ett'ort of the spring brushes m, r, s and the latter pressing upon the bars 71- and will slightly turn the rocker, thereby shifting the bar h or as the case may be out of contact with the brush 8. Referring to Fig. 1 it will be seen that upon diminution of speed, the bar It would be shifted in this manner out of contactwith that brush 8 which is on the left hand. When this occurs the main circuit is broken and the circuit of the field winding, if it be in shunt will gradually die away until the armature spindle ceases to rotate. If the spindle be then driven in the opposite direction, the rocker will turn through a small angle and first bring the bar 7', Fig. 1, against the brush 1' on the right hand andtlie bar It against the brush m/on the left hant Thus, seeing that the commutator brush (1 corresponding with the bar has changed from negative to positive, the brush 9 will still remain positive and as the commutator brush 6 corresponding with the bar It has changed from positive to negative. the brush m will still remain negative. Therefore the winding 2 and shunt field winding will still be electritied in the same direction as before and the magnet d will act in the same manner as above described. only for this direction of rotation the armature c on the right hand is brought near to the magnet pole 1 by the first nmvement of the rocker and is attracted by the magnet (l for the purpose of completing the main circuit as above described. It is n-eferable in some cases however, to provide a second automatic main circuit closer suitably in the shape of an electromagnetic main switch the l(\'l" armature 1. Fig. 5 of which is primarily attracted by a :iiu'nt winding 2 connected across the mains, one terminal of the winding 3 being connected with the switch part 3 to which the positive main u is connected and the other terminal being connected by the connection 4 and wires 5 and (i with the negative main n. The armature lever 1 car ries zi switch brush 5 which makes contact with the part- 3 and closes the main circuit when the winding 2 is sulliciently energized. A series winding 7, wound in the same direct on as the winding 2, is connected at one end to the b 'ush 50 and at the other end to a terminal 8 from which the positive main u proceeds to the unction between the positive wire 9 of the battery and the positive wire 10 leading to the terminal 11 on the lighting switch.

As soon as one or other of the brushes 8 is electrified by the bar it or 7', thereby electrifying the positive main u, current flows through the connection 3, shunt winding 2, connection 1 and wires 5 and 6 to fl e'negative main n, and when sufficient ele'ctro-motive force is generated by the dynamo this shunt winding 2 pulls on the armature 1, or sucks in a core if a solenoid is used, and causes the brush 50 to contact with the terminal 3, thereby closing the main circuit to the battery w and lighting switch, the flow of current through the series Winding 7 causing the magnet to be more strongly energized and to hold on the armature 1 with great firmness.

If desired, the electro-magnet for operating the rocker may be polarized.

The main switch magnet or solenoid comprising the windings '12, and '7 advantageously inclosed in a casing the lid of which may be fitted with a contact for completing the circuit of this magnet only when the lid is in position, so that the removal of the lid puts the magnet out of action.

To provide for possible loss of the residual field of the dynamo an additional contact 12 may be arranged upon the main lighting switch and this contact may be connected by a wire 13, seen in Fig. 5. with the shunt field winding 1) by way of the wire t, so that, as shown, the wire 13 is connected at a point between the field winding 1) and the winding of the rocking switch magnet d which is conveniently included in the circuit of the shunt tield winding 1) as aforesaid. This contact 12 is so arranged as to be engaged by the lighting switch bar or 'bladc, not shown, when the latter is turned to the verti cal position in Fig. 5 for putting the lamps or other consuming devices 14 in circuit, whereupon current from the battery ;r passes by way of wires 9 and 1t) and contact 11 not only to the lamps but also by way of contact 1'22 and wires 13 and t to the shunt field winding thereby energizing the latter and producing an initial field. lamp 1.) may be inserted in this connection 13 which lamp not only acts as a resistance but also as an indicator. The, initial lield may be insured however in other ways undlan advantageous method is that indicated in Fig. 5). according to which a high resistance 1 such as that provided for example by a volt meter coil. is connected across the terminals of the main switch. Thus when the. latter is open a very small current can pass from the battery :r, through the wire 9, connection 8, series winding 7, resistance 16, terminal contact 3, positive main u, wires w and t to the brushes 8. To insure that the current shall be con-- it b ducted to the shuntwindings p in all conditions of the roehing switch, as for example when the bar it or j is touching only the corresponding brush r, or is touching no brush at all, a second high resistancel7 is connected between the brushes 8 and r so that the current from the battery can continue from the brush 8 tl'irough resistance l7,-brush r, winding 2, wire t and shunt windings ;0 back to the negative main. Of course when the dynamo generates a voltage the latter will oppose the electroinotive force of the cells and the small current from the battery will disappear as the speed rises.

There may be as stated series turns 18 on the field magnets which, at one end may be connected with the junction between the wires 1: and w and at the opposite end may be connected by wire 19 with a terminal 20 a rranged near a suitable terminal 21 of the wire 11;. When the plu 22 is inserted, shown, between the terminals 20 and 21, the series turns 18 are short circuited and ha e no eil'eet but when the plug is removed the working ;-urrcnt flows from the brush 8 to the iiositive main u by way of wire '11, series turns 18, wire 19, and terminal 20, instead oi by way of wires r and to terminal 21 and plug 22- as bei'orc.

Whcn the dcmagnctiizing series turns 18 are eil'ectirc so that the dynamo becomes silt regulating and maintains a constant voltage or output at various speeds as hereiubet'orc referred to, the brushes Z1 and bars ft and j may be allowed a greater amplitude oi ()iii'llillil'lil by removing from the ends of the. l

/i j the liners h and 7', Figs. 1 to. l. which arc cured by the studs 71 1". Indccd any desired amplitude of swing or oscillation of the brush rocker may be secured by liners of ditlercnt. thicloicsses so that the dillircnt conditions may be accurately pr0 'ided for.

The shunt windings may be connected to the pair of negative brushes m through a variable resistance as shown in Fig. In tirir suitable arrangement one terminal oi the windings ,o is connected by a wire 23 with a tern'iinai i l. and through a resistance :35 with the terminal 0. 'hen the plug 26 is inserted between the terminals 0 and 21, the resistance :5 is short circuitcd and when the plug 26 removed. as shown, the re sistance 25 is ctl'ectirclv in circuit with the shunt wiihlings y. and coi'isequently the dynamo will require a higher speed in order to generate thc criti al voltage than is the case a hen the plug JG inserted and thc resistain. 52?. short ri r-uitcd. The terminal 0 is conncrted wi h the pair of brushes in by the u irr whirl; may. include the resistance "1 and tlia lat inn}. be norn'ially short cirwar d as h rcinu'l'tcr described.

to probt the i'aittcry against an elect rd magnetic srait h may be provided, having its winding 21) con nected across the terminals of the battery .70. This switch may be thus connected, only when the lighting switch is turned off which is the arrangement illustrated in Fig. 5, wherein one terminal of the winding :29 is connected by wire 30, connection 31 and wire to a contact 33 on the lighting switch, a diametrically opposite contact 3-1 on the lighting switch being connected by wire 35 with the positive main u. The up posite terminal of the winding is counceted to the negatiie main n by wire 36 connection 37 and wire 6. \Vhen the \olt age rises unduly, which is an iinlication of the completeness of the charge, the magnet winding :2!) becomes suiliciently encr ized for pulling on the armature 38 This action may be utilized, as shown in Fig. for lifting the switch brush it) from the contact 40 and this opening of the switch may be arranged to break the connection between the dynamo and the battery, or to insert the re sistance in the circuit of the shunt field winding 7, and so reduce the strength of the field. The latter arrangement is illustrated by the drawings, the insertion of the resist ance 2S being, accomplisl'icd by connecting the terminals 0 and 41) by a wire 4.1 and. by connecting the brush '19 with the comm tion 37 by the flexible wire 42. Normally, the: c it'ore, when the brush 3! rests on the contact 40, the resistance :28 is short xii-rail d by the wire 41, connection to. brush Fill. flexible wire 1-13, connection 37, wire ti, and negati e main 1;, which is connected to the negative pair oi switch l'n-usl'ies m. soon are the voltage is sutliciently raise-d. due to the com plction of the charging of the battery, and the armature 38 and brush in are l' aforesaid, this short circuit connection is broken and the resistance 28 becomes efi ectile in the circuit of the Slllillt winding and reduces the strength of the livid to the desired cxtcut. it will be rradily un lcr stood that this overt-hargc-prercnting mag net opcratcsonly when the lamps -l l o other consuming device are not in use that is to say wheir the switch bar conne ts aiross from the contact 32} to the c ntact ll in is but would otherw lee be tor oii' po-ii'i n.

The 5}hlt'lil may Ya n tin single batter; type a. 1. in rm. :3, of lhr doobb batter rim o'- r ho n in hog. l lattcr rose a suitable inc-ch r" nnurnctic device is prmiilnl ore: (in: ballerina; w ulul .r' inl n nzomrr, either ach rim:- that th din; n of rotation oi the m o-zrl ore is ('l'ianged, or Le h l li t that the il xaiwno is connected up to the bdtories .1, .r' or d sroiiiicctiwl therefronr in placoof such a. changeover switch, the pair oi" blades iercii'ibctm'e desc ibe-l, whi l: stand oil n: th ir L'Uillfj on the until a ent wltuge lid/n been gm; ii-ism no i:

so h r employed to accomplish the change-over each time that the direction of running is reversed. To this end the blade members 8, s, of this pair, instead of being directly connected together or made in one, are separated as by insulation 61 Fig. 6 and are connected through a lamp resistance 62. One battery it is connected with one blade member s and the second battery :17 with the other blade member s as shown. In this way it is arranged that when the dynamo runs in one direction, one battery, for example the battery Fig. 6, is charged directly by the dynamo, whereas the other battery as Fig. 6 may only receive current occasionally through the resistance 62 by way of brush 3, wire 9, resistance 62., and wire 9. \Vhcn the dynamo runs in the other direction the connections of the batteries are interchanged with the well known result. In order that the current from the dynamo to the lamps 14 must always pass through the lamp resistance 62, a fixed pair of brushes 8 is arranged in relation to the brushes 8 s and is connected with the lamp switch 141 as shown. Consequently when the bar j is pressed against the brush 8, as shown, so as to flex the latter, the corresponding brush .9 has its contact with the brush 8 broken so that current can only pass to the lamps 1 from the bar 7' by way of brush a wire 9, resistance 62, wire 9 brush 8, brush 8 wire 14:0 and switch 141. The path of the current. when the bar h flexes the brush .9 will be readily understood.

In some cases the electromagnetically op erated main switch may be dispensed with and the electromagnet (I, which operates the rocker in the manner aforesaid, may be relied upon to close the main circuit through the brush 5 when the speed. and therefore the voltage. is sutlicient to permit of the dynamo being connected up to the main working circuit with safety. \Vith this arrangement the rocker is operated by the magnet (l to bring the bars h or into contact with one or other of the brushes 8 at the proper voltage and the circuit is held closed so long as current is delivered by the armature. As the speed is reduced, the voltage at the dynamo terminals is correspondingly decreased until it falls to the voltage of the accumulator: at this moment the armature ceases to have an output and it the. magnet (I, does not readily deenergizc or, if the magnet armature sticks. a current may flow back from the batteries to the dynamo which will at once allow or cause the armature to fly ol't' and the rocker to return to the position in which the connection of the dynamo with the 'v orking and battery circuits is broken.

In a modification of the last named arrangement. the magnet 11 has some series turns wound upon it, so that, as shown in Fig. 7, the working current proceeding from either of the brushes 8 first passes around the series turns before flowing to the working circuits. Moreover a third pair of brushes 3 is provided and so arranged that one or other of its members is engaged by the bar It or the bar j, as the case may be, after the brushes r s have been successively engaged thereby. This double brush 63 is connected by wire 64 with a point in the shunt winding 2 of the magnet d. The action therefore, is as follows Upon the armature revolving in one direction or the other the rocker moves in a similar direction and brings the bar it, or the bar j, first against one of the brushes 1" thereby completing the circuit of the shunt winding p and magnet winding 3. As the speed increases the magnet (Z becomes more powerful and, when the armature speed and the strength of the field magnetism are such as to insure the required output, the bar it or j is moved a little farther by the action of the magnet (l on the rocker so as to touch one of the brushes .9 and comi'ilete the main circuit. Supposing that any appreciable flow of current to the working circuit then takes place, the series turns on the magnet (l will more strongly energize the latter and the rocker will thus be turned a, little tan ther by the magnet d thereby bringing the bar it or into contact with one of the brushes 63 which will result in short circuiting the winding 2 up to the point at which the wire 64: is connected. ()1, of course, the winding 2 may be entirely short circuited. The magnet (l in spite of the short circuiting of the winding 2, is still powerful enough to hold the rocker in the position in which all of the three brushes 7' s and 63 touch the bar it or 1'. The complete or partial short-circuiting of the mag net winding 2 cfiects a reduction in the resistance of the circuit of the shunt winding p, thereby avoiding or counteracting, the drop in voltage which otherwise takes place when a shunt wound dynamo, work ing on open circuit, is closed on o a. working circuit.

I claim-- 1. In a reversible dynamo. an automatic switch gear comprising. a ro king ;--uppmt, switch parts thereon. contact. ii; ii=hl 1n the paths f said SWlilli parts. a part revolving with the dynam amuiture and adapted to more said switch parts iinst certain of said contacts, fricti n engaging means between said support and rm'olving part, and electromagnctic cleans operative upon said rocking support in unison with said frictional engaging means and adapted to give said support an :Hltllilnlitll move ment for etlerting the closing of a circuit.

2. In a reversible dynamo, an automatic switch gear comprising, a rocking support,

commutator brush holders on said support,

brushes in said holders, switch parts on said support, contacts mounted in the respective switch parts, means operative upon same direction as by the engagement commutator.

3. In a reversible dynamo, an, automatic switch gear comprising, a brush rocker, switch parts thereon connected with respective brushes, cooperative switch contacts in the paths of said switch parts in different relative positions so that certain of said parts and contacts come into engagement upon the initial rocking of said brush rocker in either direction, and electromagnetic means operative upon said rocker to bring about the complete engagement of switch parts and contacts.

In a reversible dynamo, a rocking brush holder, reversing switch parts carried thereon and connected with respective brushes, switch brushes variably arranged in the paths of said switch parts and electromagnetic means operative upon said holder in the same direction as said holder is turned by the engagement of its brushes with the commutator in either direction of running, and circuits successively closed by said switch parts and brushes.

5. In a reversible dynamo, a rocking reversing switch arranged to rock in one direction or the other according to the direction of running, flexible switch brushes variably arranged so that certain of them contact as soon as the switch is rocked by the revolution of the armature, and electromagietic means operative upon said rocking switch in either direction of running, a circuit closed by the brushes making the first contact, the windings of said electromagnetic means being in said circuit.

6. In a reversible dynamo, a brush rocker, contacts fixed thereon. at about diametrically opposite points and in electrical connection with respective collecting brushes, positive and negative terminal switch brushes fixed to the framing of said dynamo and extending into the paths of said contacts in such manner that each brush will engage a diftereut contact when the direction of run ning is reversed, a main circuit, a second positive brush constituting a terminal of said circuit, and having its contacting ends in the paths of said contacts and in the rear of the contacting ends of the first positive brush, a shunt circuit, and electromagnetic means operative upon said brush rocker, the windings of said means being in the shunt circuit, which is closed by the engagement of said contacts with the first named brushes.

7. In a reversible dynamo, a brush rocker frame, commutator brushes thereon, arms and electromagnetic said support in the said support is operated of the brushes with the paths of,

carried on said frame and insulated there from, contact devices fixed on said arms and in electrical connection with respective brushes, spaced armature devices on said frame, an electromagnet fixed to the dynamo 7o framing, a pole of said magnet lying between said armatures, a negative brush and a positive brush each comprising two arms which extend into the paths of respective contact devices, the positive brush being oppositely arranged to the negative brush, a shunt circuit, the terminals of which are constituted by said brushes, :1 main circuit, and a second positive brush constituting a terminal of the main circuit said second so positive brush being arranged similarly to the first positive brush but having its extremities in arrear of those of the first positive brush.

8. In. a reversible shunt Wound dynamo, a a brush rocker frame, commutator brushes thereon, switch-contacts on said frame lnsulated therefrom and in electrical connection with respective commutator brushes, a switch brush fixed on said dynamo 9c and having arms extending within the arcual paths of said contacts, said brush constituting a positive terminal 'of the shunt field winding, an electromagnet operative upon said rocker frame in the same 9 sense as said frame is influenced by the en gagement of its brushes with the commutator in either direction of running the windings of said magnet being in the circuit of the shunt field Winding, a second switch brush fixed on said dynamo and having arms extending within the arcual paths of said contacts said brush being oppositely disposed to the first switch and constituting a negative terminal of both the shunt field winding and of the working circuit, and a third switch brush arranged alongside the first switch brush and having arms shorter than those of the first switch brush extending within the arcual paths of said contacts said third switch brush constituting the positive terminal of the working circuit.

9. In a reversible dynamo, an automatic switch. gear comprising a rocking support, commutator btbsh holders on the support, brushes in the rholders, switch parts on said support, interchangeable contacts mounted on the switch parts, cooperative contacts mounted in the paths of respective switch parts, and electromagnetic means operative upon said support in the same direction as the support is operated by the engagement of the brushes with the commutator.

10. In a reversible dynamo, a brush rocker frame, commutator brushes thereon, insulated switch contacts on said frame and in electrical connection with respective commutator brushes, liners removably arranged on said switch contacts, a switch brush fixed on said dynamo and having arms extending within the arcual paths of said contacts, said brush constituting a positive terminal of the shunt field winding, an electro-magnet operative upon said rocker frame in the same sense as said frame is influenced by the engagement of its brushes with the commutator in either direction of running the windings of said magnet being in the circuit of the shunt field winding, a working circuit, a second switch brush fixed on said dynamo and having arms extending within the arcual paths of said contacts, said brush being oppositely disposed to the first switch brush and constituting a negative terminal of both the shunt field winding and of the working circuit, and a third switch brush arranged alongside the first switch brush and having arms shorter than those of the first switch brush extending within the arcual paths of said contacts, saidthird switch brush constituting the positive terminal of the working circuit.

.11. In a reversible dynamo, a rocking reversing switch comprising two oscillatory contacts connected with respective commutator brushes, electromagnetic means operative upon said rocking switch in unison with the influence of the frictional engagement of the brushes with the commutator in either direction of running, a double switch brush arr'anged on one side of the commutator and having its ends in the paths of respective contacts and constituting a terminal of the shunt field winding circuit in which is included said electromagnetic means, a second double switch brush having its ends in the paths of respective contacts but arranged on the opposite side of the commutator constituting a negative terminal of the, shunt circuit and of the Working circuit, a pair of switch brushes insulated from one another and placed alongside the first switch brush each member of said pair of brushes adapted to be connected with the positive pole of a respective accumulator battery, and a double switch brush constituting a positive terminal of the consuming circuit and adapted to make contact with both members of said pair of brushes in the stationary condition of the dynamo, one member of said pair being moved away from the last named shunt field winding circuit in which is included said electromagnetic means, a working circuit, a second double switch brush having its ends in the paths of respective contacts, but arranged on the opposite side of the commutator constituting a negative terminal of the shunt circuit and of the working circuit, a pair of switch brushes insulated from one another and placed alongside the first switch brush each member of said pair of brushes adapted to be connected with the positive pole of a respective accumulator battery, a consuming circuit,'and a double switch brush constituting a. ositive terminal of the consuming circuit anti-adapted to make contact with both members of said pair of brushes in the stationary condition of the dynamo, one member of said pair being moved away from the last named double brush upon the attainment of a predetermined speed.

ALFRED HENRY BARKER.

Witnesses H. D. JAMISON, W. E. Rooms.

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