US904788A - Automatic carrier system. - Google Patents

Description

v s. H. LIBBY.

vAUTOMATIC CARRIER SYSTEM.

APNJOA'I'IOR FILED MAR. 12, 190B.

Patented Nov. 24, 1908.

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S. H. LIBBY.

AUTOMATIC CARRIER SYSTEM.

APPLICATION rum) MAR.12, 190 6.

Patented Nov. 24, 1908.

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UNITED STATES PATENT OFFICE.

SAM H. LIBBY, OF EAST ORANGE, NE W JERSEY, ASBIGNOR TO SPRAGUE ELECTRIC COMPANY, A CORPORATION OF NEW JERSEY.

AUTOMATIC CARRIER SYSTEM.

Specification of Letters Patent.

Patented Nov. 24, 1908.

. Application filed March 12 1906. Serial No. 305,439.

To all whom it may concern:

Be it known that 1, SAM H. Liner, a citizen of the United States, residing zit-East Orange, county of Essex, State of New Jer soy, have invented certain new and useful Improvements in Automatic Currier Systen s. of which the following is a specification.

The present invention relates to systems wherein a carrier is adapted to be set in oporation at one station. as, for example, at a loading station, and thereafter travel to another station, such as a dumping station, where. it is automatically reversed and brought back to the first station at which it finally comes to rest, and has for its object to provide a simple and novel arrangement for automatically controlling the carrier.

To the above end the present invention consists in the construction and arrangement of parts to be hereinafter described and particularly pointed out in the claims.

The preseht invention will be more fully understood and its objects and advantages will more clearly appear from the following description taken in connection with the nccolnpunying' drawings, wherein Figure 1 illustrates diagrammatically the motor and control mechanism of a carrier together with the system or current distribution between the source of current supply and a number of stations, all arranged in ac rordance with one embodiment of the present invention; and Figs. 2 to 5 are similar views of modifications having parts omitted therefrom, including the parts. mounted upon the carrier, with the exception of the current collectors.

Reference being had to Fig. 1, A indicates a motor for moving a carrier along its track; I indicates a hoisting motor mounted on the carrier; C is a reversing syvitclrnssociated with the motor A; D is a controller for the hoisting motor; E is a limit switch of the usual type adapted to open the circuit of the hoisting motor and operate the reversing switch of the traverse motor so as to stop the hoisting motor after the load has been raised and set the traverse motor in operation to move the carrier to the dumping station; L and L indicate a source of current supply from which current is taken to operate the motors; R, R and R are resistance sections normally in the connection between the line out being stopped.

L and line Z, which is one of the trolley wires.

The carrier is Jrovided with a current collector F adapte to engage with a supply conductor 2 which may be connected to or form a continuation of the main conductor L. In addition, current collectors F and F are adapted to engage the supply conductor l.

F is a contact device electrically connected with the current collector F and adapted to 006 crate with a conductor Z running paralle with the supply conductors Z and Z. The supply conductor 1 is made continuous throughout. the entire distance over WhlCll the carrier is adapted to travel, while the sup ly conductors Z, on the other hand, is ma e in sections 1, 2 and 3, separated from each other by insulated sections 4 and 5; the sections 4 and 5 being adjacent the dumping stations and the sections 1, 2 and extending between the stations. The sections 1, 2 and 3 are permanently connected to l ne L through a conductor 13, while the sections 4 and 5 may be connected tothe same conductor by means of the switches S and S When the switch S is closed,the section 4 is energized, ,so that the circuit is not interrupted at the first dumping St1t10n 1111d th8 car is therefore free to pass this station wlth- If switch Si is also closed, section 5 is energized and the car'is free to pass to a succeeding dump np station. If either of the switches S or S is eft open, the section controlled thereby W111 remain dead and the car will stop when it enters upon that section. At the loading station there is an additional dead section 6.

The arran ment illustrated is adapted for a system l iiiving one loadin station and two dumping stations, but it W1 be seen that the same principle may be em loyed for a system wherein there are any esired num; ber of dumping stations. T e conductor Z- is dead throu hout its length and is provided at each of t e stations, either dumpmgpr loadin with short sections 7 8 and 9, insulate from each other and from the rest of the conductors. The sections 8 and 9 are connected in arallel to a series of conductors, 7, 8" an 9', extending throughout the length of the line. The conductors 7. 8 and 9' are in turn connected to line L through coils 7 8 and 9" which respectively actuate switches 10, 11 and 12, controlling the resistance sections R R R.

G is a relay having its actuating coil arranged in the connection between line L and supply conductor 1.

Assuming that the parts are in the positions illustrated, current will flow from line L through the field coil 0. of the traverse motor, through contacts 0 c and c of the reversing switch, through the armature a of the traverse motor, and thence through contacts a c and c of the reversing switch, to current collector F line Z, through the actuating coil of relay G, through resistance R, R and R to line L. The traverse motor will now begin to operate and thc carrier will move toward the left at a slow rate of speed by reason of the resistance in the supply circuit. \Vhen the contact device F comes into engagement with section 7 of the auxiliary conductor Z current flows from line L,

through this contact device and section 7, and' thence through the coil 7 b to line L. Coil 7", being energized, closes switch 10 and shortcircuits resistance section B, thus causin the current to the motor to be increased an the carrier to move at a higher rate of speed.

The switch 10 is prevented from opening again when the contact F 3 leaves section 7, by reason of a maintaining circuit which pas-es from line L, through contacts g of the relay G, and thence through the auxiliary contacts 1 1 associated with switch 10 and through the coil 7 to line L. 'When the carrier reaches section 8, current is supplied to coil 8 in the same manner as was previousl done in the case of coil 7", and switch 11 c oses and cuts out additional resistance sections R thereby still further increasing the speed of the carrier. Switch .11 is also maintained closed by means of a maintaining circuit passing through the contacts of the relay and through the auxiliar contacts 15 associated with the switch itse f. When the section 9 is reached, switch 12 is closed and resistance section B is eliminated, the motor now running at its highest speed. The carrier proceeds at this speed to the dumping station at which it is to be stopped. It is of course evident that the number of resistance steps is not confined to three, but may be an thin desired.

If it is esired to sto the carrier at the first dumping station, t e switch 8 is left open, maintaining section 4 dead, and a stop 17 is adjusted in the path of the arm, 18 which trips the reversing switch. When this dumping station is reached by the carrier, the current collector F enters upon the dead section 4 and the motor is oven-circuited. At the same time the circuit rough the coil of the relay and the actuating coils of the resistance switches is interrupted and the relay drops and the resistance switches open. The breaking of the motor circuit deenergizes the holding coil for the brake A and the brake is applied, bringing the carrier to rest. In the meantime the load has been dumped in any suitable manner and the arm 18, striking against stop 17, is moved out of en agement with the shoulder on cam 19 secured to the shaft of the reverser cylinder, permittin the spring 20 to throw the reverser into t e opposite running position from that shpwn. Current collector F still remains in contact with section 1 and this collector, which has heretofore been idle, now becomes active and collector F becomes inoperative. A circuit may now be traced from line 1 through field coil of the traverse motor, through contacts 0, c", c and 0, through the armature of the traverse motor, reverser contacts 0 c, a and 0 to current collector F and thence through section 1, through actuating coil of relay (1, and thence through resistance sections R, R and R to line L. It will be seen that the motor is now connected for operation in the reverse direction and the carrier proceeds slowly toward the loading station. When section 7, at the dumpin station, is reached, current will be supplie to this section 'from the contact device F and will flow through conductor 7" and thence throu h coil 7 to line L, causing ,the switch 10 to close and resistance R to be cut out. In the same way, as sections 8 and 9 adjacent the dumping station are reached, coils 8 and 9" are ener ized, causing the resistance sections R an R to be cut out. The resistance switches are maintained closed through the maintaining circuit, as before. The elimination of the several re sistance sections causes the motor to speed up and the carrier to travel toward the loading station at full speed. When the loading station is reached the current collector F runs onto the dead section 6 and the motor circuit is again interrupted and the brake applied to bring the carrier to rest. Also, the circuit throu h the relay coil and the actuating coils for t e resistance switches is interruptedand the resistance is cut in, leaving the system in condition to start the motor again upon a low current. Then the reversin switch is again operated to the position in icated, the carrier is started toward the dum ing stations in the manner previously escribed. It is evident that if it is desired to dum at the second dumping station the switch is closed and stop 17 is placed in o erative position, while stop 17 is maintains out of the path of movement of the arm 18. Therefore when section 4 is reached the circuits are not interrupted and the carrier is free to continue to the next dum ing station, at which oint the circuits wi be interrupted at section 5 and the carrier will be'reversed and returned to the loading station in the same manner as before.

In Fig. .1 I have illu trated a somewhat simpler arrangement wherein a single resistance section R is adapted to be included in the supply circuit in starting the motor and to he cut out after the carrier has moved a predetermined distance. L and L indicate the source of current supply, as before, and land l the supply conductors from which the current-collecting devices F, F and I take current. No auxiliary trolley wires are employed but the supply conductor 7, in addition to the sections corresponding to the several sections of the same supply conductor in Fig. 1, is provided With additional short sections 21 and 22, arranged, respectively, at the loading and dumping stations and insulated from the rest of the conductor. Normally, conductor-l is connected to supply main L through the contacts 12 of the relay H and resistance R. Sections 21 and 22, which are in electrical communication with each other, are connected to supply main L, thron h the actuating coil It of the relay H, ant resistance R. In starting. current flows from conductor I, through collector F, through the motor, through collector F, section 21, coil h, resistance R, to line L; the motor starting with the resistance in circuit and the core of the relay being lifted. The resistance remains in circuit long as current-collector F remains on section 21, but as soon as it passes into engagement with section 1 a new circuit is established from this current-collector through the contacts b of the relay, maintaining coil [L3 of the relay and thence directly to line L. Thus the resistance R is cut out and the motor travels at full speed until section of one of the dumping stations is reached. At this point the resistance is cut in again and the carriage is slowed down so that when the carrier enters upon the dead section the motor is stopped and 1'c\cr-ed as previously described, without undue strain upon the apparatus. The maintaining circuit for the relay is opened at the same time and the relay drops, so that in starting on its return journey the carrier is supplied with current which flows through section 22 and thence through coil and resistance R, to line L, as in starting from the loading station: the resistance be iug again cut out when the current-collector l" lea vcs section 22 and enters upon section 1. The purpose of the contacts h and the relay is to permit the carrier to receive current in case the currcnt'collectors leave the trolley wires while on section 1. This of course will cause the relay to drop, so that when the current -collectors are again brought into engagement with the trolley ires. current flows from section 1. through the contacts I! of the relay, and thence through re istance R to line L: the carri r being enabled to complete its journey to the station at the low speed. The modification shown in Fig. 2 may be employed to advantage for heavy service. since it enables the carrier to be gradually slowed down prior to being st oppcd and reversed.

In Fig. 3. two supply conductors l and I, together with independent conductor sec tions 23 and 24 at the loading and dumping stations, respectively, are employed. Section 1 is normally connected to line I; through resistance section I and coil 4' of relay I. Only three currcnt ciillectors. l F and I, are required, although an additional one. I may be provided for cooperation with the sections 23 and 2-1. .If the collector F is dispensed with, the sections 23 and 3! may be arranged in close proximity to the conductor 7 so as to be engaged by collector 1*. In starting from either station, current is supplied from line 7. to collector l". and thence passes through the motor and the current-collector l or F to trolley wire 7, and from trolley wire I the current passes through resistance I", coil of the relay I, to line L: Thus the resistance is included in the motor circuit. The parts are so proportioned that the current now passing through the coil of the relay is insufficient to'operate the relay. \Vhen, howc\ er. current-collector l or F, as the case may be, engages wit-h either section or 24-. dependent upon whether the carrier is moving from the loading or from the (lumping station, current passes directly from line I), through resist ance r, coil of the relay 1, to line L: the resistance 1* being so proportioned that the current now is of sutlicicnt strength to operate the relay to close the contacts 1', thereby cutting out resistance It. \Yheu the current-collector leaves the auxiliary section. the relay is maintained closed by the motor current.

The modification shown in Fig.4 is somewhat similar to that of Fig. 1. except that the controlling relay is omitted. l. and l) are the source of current supply, I and l are the trolley wires or supply conductors. The auxiliary conductor I corresponds in all rcspects to conductor of Fig. l, and there is an additional conductor 1". (ondnctor I" is sectionalized in exactly the same manner as conductor I. In addition to thelnain current collectors F, F and F", two additional collectors I l are provided. 'lhrce resistance sections It, F and R are controlled by switches Hi. 11 and 12, and these switches are controlled respectively by elcctromagm-as T", 8" and 9". Starting from the loading station. current flows from line l. through collector I, through the motor, through collector F, section 1 'of trolley resistances It", It and lt to line L. 'hen current-collector I engages section 7 of the auxiliary conductor 1*, current tiows from line L, through collectors F and F section 7,

through actuatin coil of the electromagnet 7", to line L. T is causes switch 10 to be closed and resistance section B to be removed from the circuit. As soon as the switch 10 closes, it establishes a maintainin circuit for itself from line L, collectors and F auxiliar contacts 25 associated with the switch 10, tience through the actuating coil of the electromagnet 7, to line L. Therefore the switch 10 is maintained closed after the carrier passes beyond section 7. In the same way, switches 11 and 12 are closed and held closed by meansof the maintaining circuits established through the auxiliary contacts 26 and 27 associated therewith. In returning from the dumping station, the operation of cutting out the resistance is repeated as the carrier passes the sections 7, 8 and 9 at the dumping station.

In Fi 5 a further modification is illustrated w erein it is necessary to have only one conductor extending throughout the system for properly connecting the sections corresponding to sections 7,8and9 in the previous figures to the resistance controlling apparatus. L, L, Z, P, l and l in this figlire and in Fig. 4 indicate corresponding parts, except that only two auxiliary sections 7 and '8 are required adjacent each station in the conductor l. Similarly, current collectors F, F F, F and F correspond to the current collectors in Fig. 4 having similar reference characters. Resistance sections R R and R are controlled by switches 10, ll

and 12, and the switches are actuated by electromagnets 7, 8 and 9. The electromagnets are controlled by a relay K. In

starting, current flows from line L, to 001- lector F, through the motor, through collector F section 1 of trolley wire l, resistance sections R, R and R, to line L. When collector F engages section 7 of the auxiliary conductor 2*, current flows from line L, through collectors F and F, throu h section 7, wire 28, which connects all of t e sections 7 and 8 throughout the system together, through the actuating coil in of the relay, and thence to line L. The energizing of the relay causes it to close its contacts k, and the circuit may now be traced from line L, through collector F and F, auxiliary conductor I, through the actuating coil of the electromagnet 7, through the contacts k of the relay, through the interlocking contacts 29 and 30 associated with lsu'titches 11 and 12, respectively, to line L. The electromagnet 7 being thus energized; closes switch 10 and cuts out resistance section K. As soon as the switch 10 (310595,il? establishes a maintaining circuit for its actuating electromagnet through auxiliary contacts 31, so that current, after passing through the coil of the electromagnet. flows throu h the contacts 31 and then .directly to ine L, independently of the relay and the reul'aining ing reversed switches. hen the carrier leaves section 7, the circuit containing the coil of the relay is interrupted and the relay drops. As soon as the rela drops, a circuit ma be traced from auxi iary conductor 1, t rough the coil of electromagnet 8, through auxiliary contacts 32 associated with switch 10, through contact k in the relay, and thence through contacts 30 associated with switch 12, to line L. Electromagnet 8, being thus energized, closes switch 11 and cuts out resistance R, at the same time establishing a maintaining circuit for itself to line L directly through auxiliary contacts 33 associated therewith.

In order to obtain the proper time inter val between the closing of switches 10 and 11, the relay may he made slow acting, or

' the sections 7 may be made of considerable length so that the relay, after being once opened, cannot immediately close again. When section 8 is reached, the relay is agaln lifted and current passes from conductor Z through the coil of electromagnct 9 through auxiliary contacts $4 associated with switch 11, through contacts 1 0 on the relay, to line L. The switch 12 is therefore closed and is held closed b a maintaining circuit which it establishes through auxiliary contacts connected with this switch. As the carrier passes on, the rela is again de'einer gized, but all the switc es are maintained closed until the dead section at the dumping station is reached, whereupon all the circuits will be interrupted and the carrier will be caused to start on its return trip with all resistance in circuit, which resistance will thereafter be automatically' cut out again in the manner just describe For the sake of clearness many of the connections, whereby there may be any number of stations at any one of which the carrier may be automatically stopped and reversed, have been omitted from the last four figures. These connections may, however, be the same as those for accomplishing this same purpose in Fig. 1, or other suitable arrangements may be employed if desired.

It will now be seen that the present invention provides simple and effective means whereby a carrier may be set in operation and automatically accelerated, thereafter beand again accelerated. and finally returned to the starting point without requiring the attention of the operator or making it possible to apply too heavy currents to the motor. in starting, as often happens where the acceleration is controlled by the operator.

In the foregoing description and m the drawings I have disclosed referred embodiments of my invention, at it Wlll of course be understood that in its broader aspects the invention may be otherwise carried out than in these specific forms so disclosed,

mally in said circuit and located at a fixed' point, a carrier receiving current from said circuit. and means automatically controlled by said carrier-tor eliminating said resistance.

2. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, a resistance normally in said circuit and located at a fixed point, a switch for eliminating said resistance, a carrier receiving current from said circuit, and means controlled by said carrier for operating said switch.

3. In an electrically-operated carrier tem, a source of current supply, a circuit connected to said source, a resistance nor mally in said circuit and located at a fixed point, a. switch for controlling said resistance, electro-magl'ietic actuating means for said switch, a carrier receiving current from said circuit. and means associated with said carrier for completing a. circuit through said actuating means.

4. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, a resistance normally in said circuit and located at a fixed point, a traveling carrier receiving current from said circuit, and means automatically controlled by said carrier for eliminating said resistance when the carrier reaches a predetermined point in its travel.-

5. In an electricallymperated carrier systern, a source of current supply, a circuit connected to said source, a resistance normally in said circuit and located at a fixed point, a. switch for eliminating said resistance, a traveling =arrier receiving current from said circuit, and means automatically controlled by said carrier for operating said switch when the carrier reaches a predetermined point in its travel.

(5. In an electrically-operated carrier tem, a source of current supply, a circuit connected to said source, a resistance in said circuit, a switch for controlling said resistance, actuating means for said switch, a controlling circuit for said actuating means, a carrier receiving current from said first mentioned circuit, and means associated with said carrier for completing said control circuit when the carrler reaches a predetermined point in its travel.

7. In an electrically-operated carrier system, a source of current supply, acircuit connected to said source, resistance in the said circuit, a circuit controlling and resistance regulating device in said circuit, a control circuit for said controlling and regulating device, a traveling carrier receivingcurrent. from said supply circuit, a contact in said control circuit adjacent the path of movement of the carrier, and a contact on said carrier adapted to cooperate with said first contact to complete said control circuit.

8. In an electrically-operatcd carrier system, a source of current supply, a circuit connected to said source, resistance normally in said circuit and located at a fixed point, traveling carrier receiving current from said circuit, and means automatically controlled by said carrier for eliminating said resistance when the carrier reaches a predetermined point in its travel.

9. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, resistance normally in said circuit aml located at a fixed point, a traveling carrier receiving current from said circuit, and means automatically controlled by said carrier for gradually eliminating said resistance during the travel of the carrier.

10. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, resistance normally in said circuit and located at a fixed point, a carrier receiving current from said circuit, and means automatically controlled by said carrier for eliminating said resistance step-by-step.

11. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, resistance normally in said circuit and located at a fixed point, a traveling carrier receiving current from said circuit, and means automatically controlled'by said carrier for eliminating said resistance step-by-step as the carrier reaches predetermined points in its travel.

12. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, a resistance normally in said circuit and located at. a fined Joint, a traveling carrier receiving current 'rom said circuit, a loading station and a dumping station, and means automatically controlled by said carrier for eliminating said resistance from said circuit after the carrier has moved a prcdctcrmiued distance from either station toward the other.

1?}. 111 an electric-ally-o wrated carrier system, a source of current: supply, a. circuit connected to said source, resistance normally in said circuit and located at a fixed point, a loading and an unloading station, a carrier receiving current from said circuit and adapted to travel between said stations, and lncans automatically controlled by said carrier for eliminating said resistance step-bystqias the carrier moves from either slation toward the other.

14. In an electrically-operated carrier system, a source of current supply, a c1rcu1t connected to said source, a resistance in said circuit, a loading station and an unloadin station, a carrier receiving current from sai circuit and ada ted to travel between said stations, a switc ances, electromagnetic actuating means for said switch, and means for energizing said actuating means when the carrier has moved a predetermined distance from either station toward the other. i

1.5. In an electrically-operated. carrier system, a source of current suppl a circuit connected to said source, a resistance in said circuit, a resistancecontrolling switch, a switch-controlling circuit, a plurality of stations, a carrier receiving current from said circuit and adapted to travel between said stations, and means comprising cooperating devices on said carrier and at each of said stations for controlling the switch-controlling circuit. 7

16. In an electrically-operated carrier system, a source of current supply, a circuit connected to said source, a resistance in said circuit, a switch for eliminating said resistance, a switch-controlling circuit, a plurality of stations, a carrier receiving current from said circuit and adapted to travel between said stations, a contact adjacent each of said stations arranged in said switch-controllin circuit, and a cooperating contact mounted on said carrier.

17. In an electrically-operated carrier systern, a suppl circuit, resistance in said cir cuit, a plura ity of switches controlling said resistance, a traveling carrier receiving cur rent from said circuit, and means controlled by said carrier for operating said switches in automatic progression during the travel of the carrier.

18. In an electrically-operated carrier system, a supply circuit, resistance in said supply circuit, a plurality of switches controlling said resistance, a traveling carrier receiving current from said circuit. and means controlled by the carrier for o erating said switches in automatic succession during a predetermined movement of said carner. 19. In an electrically-operated carrier system, a supply circuit, resistance in said circuit, switches for controlling said resistance, a plurality of stations, a carrier receiving current from said circuit and adapted to travel between said stations, and means for causing said switches to operate in automatic succession as the carrier moves from either station toward the other.

20. In an electrically-o erated carrier systom, 0. loading station an unloading station, supply conductors joining stations,'a travelm carrier receiving current from said con uctors, means at one of said stations cofor controlling said resist operating with means on the carrier for automatically reversing the carrier, and means automatically operated by said carrier varying the difference of potential between said sup ly conductors as the carrier moves from eltlier station toward the other.

21. In a traveling carrier system, a source of current-supply, a circuit including r main conductor connected to said source, a resist ance in said circuit, a carrier adapted to receive current from said main conductor, an electromagneticallyoperated switch for eliminating said resistance from said circuit, a contact in the ath of movement of the car rier for controlling the actuating circuit for said switch, and a maintaining circuit for said switch.

22. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source, a resist ance in said circuit, a carrier adapted to receive current from said main conductor, nu electromagneticallyoperated switch for eliminating said resistance from said circuit, a contact in the ath of movement of the carrier for controlling the actuating circuit for said switch, and auxiliary contacts associated with said switch for com plating a maintaining circuit for said switch.

23. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source, a sectional resistance in said circuit, a carrier ada ted to receive current from said main cont uctor, a plurality of electromagnetically-operated switches for eliminating said resistances. and contacts in the path of movement of the carrier adapted to control the actuating circuits for said switches.

24. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source. a sectional resistance in said circuit. -a carrier adapted to receive current from said main conductor. a plurality of electromagnetics allv-opcrated switches for eliminating said res tances. contacts in the path of movement of the carrier adapted to control the actuating circuits for said switches, and means associated with said switches for completing maintaining circuits for the switches.

25. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source, a resistance in said circuit, a plurality of stations, a carrier adapted to travel between said stations and receiving current from said main conductor, an electromagnetically-controlled switch for eliminating said resistance from said circuit, and a contact near each of said stations for controlling the controllin -circuit for said switches, said contacts ciug in the path of movement of the carrier.

26. In a traveling carrier system, a source ricr having a main current electromagnetica of" current supply, a circuit including a main conductor connected to said source, a resistv ance in said circuit, a plurality of stations,

a carrier adapted to travel between said sta tions and receiving current from said main conductor, an electromagnetically-controlled switch for eliminating said resistance from; said circuit, a contact near each of said stations for controllin the controlling-circuit for said switch, ant? an auxiliary trolley on said carrier for engaging said contacts.

27. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source, a resistance in said circuit, a switch for eliminating said resistance from said circuit, a control.- ling circuit for said switch, a traveling carcollector adapted to receive current from said main conductor, a contact in the switch-controlling circuit, and an auxiliary current collector in electrical onnection with the main current collector, said auxiliary collector bein arranged to enga e with the said contact in t e switch-, control mg circuit.

28. In a traveling carrier system, a source of current supply, a circuit including a main conductor connected to said source, a resistance in said circuit, a plurality of stations, u carrier adapted to travel between said stations, a main current-collector on said carrier adapted to engage said main conductor an ly-actuated switch for eliminating saldresistance from said circuit, a contact near each of said stations' for controlling the actuating circuit of said switch, an auxiliary current collector on said carrier adapted to engage said contacts, and a main tainmg circuit for said switch.

29. In a traveling carrier system, a source of current supply, a loading station and an unloading station, a resistance, a main conductor extendin between said stations and connected to said source through said resistance, a dead section in said main conductor at said unloading station, an electromagnetically-actuated switch for cutting out said resistance, a carrier having a main current collector adapted to engage said main conductor, a contact adjacent each station and connected to the actuating circuit for said Switch, an auxiliary current collector'on said carrier adapted to engage said contacts, and means for maintaining said switch in its actuated position.

30. In a traveling carrier system, a source ofcurrent supply, a loading station and an unloading station, a resistance, a main conductor extendin between said stations and connected to said source through said resistance, a dead section in said main conductor at said unloading station, an electromagnetically-actuated switch for'cutting' out said resistance, a carrier having a main current collector adapted to engage said mainconductor, a contact adjacent each station and connected to the actuating circuit for said switch, an auxiliary current collector on said main carrier adapted to engage said contacts, a maintaining circuit for said switch in series with said main current collector, and cooperating members at the unloading station and upon the carrier for reversing the carrier when the main current collector enters upon the dead section.

31. In a traveling carrier system, a source of current supply, a loading station and a plurality of unloading stations, a main conductor comprising a main section between each two successive stations, and a dead section at each station, a connection between said main sections and said source including a resistance, means for connecting or dis-- connecting the dead sections at the unloading stations to the source, an electrornagnetical1yactuated switch for cutting out said resistance, a contact near each station for controlling the actuating circuit of said switch, a, carrier adapted to travel between said stations, a main current collector engaging said 1nain conductor, an auxiliary current collector adapted to engage said contacts, and a maintaining circuit for, said switch in series with the main current collector.

In witness whereof, I have hereunto set my hand this eighth day of March 1906.

SAM H. LiBBY. Witnesses:

Rocnn H. Bn'r'rnnwon'rn,

ANNA M. GILLIN.

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