US544312A - Trolley for underground electric railways - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1.

M. D. LAW. 1

TROLLEY FOR UNDERGROUND ELECTRIC RAILWAYS. No. 544,312. Patented Aug. 13,1895.

W itnesses:

Inventor.

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V M. 1). LAW. TROLLEY FOR UNDERGROUND ELECTRIC RAILWAYS.

No. 544,312. Patented Aug l3, 1895.

Inventory 'Wljron, .2 i

Nrrn TATES ATENT FFICEO MYRON D. LAW, OF. WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO ALBERT G. WHEELER, OF CHICAGO, ILLINOIS.

.TROLLEY FOR UNDERGROUND ELECTRIC RAILWAYS.

SPECIFICATION forming part of Letters Patent No. 544,312, dated August 13, 1895. Application filed January 31, 1894. Serial No. 498,646- (No model.)

To all whom it may concern:

Be it known that I, MYRON D. LAW, of \Vashington, District of Columbia, have in vented certain new and useful Improvements in Trolleys for Underground Electric Railways; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of refer-- is attached to the car and extends through the slot of the conduit, and through which the conducting-wires are carried.

In the operation of a railway system of this kind grounding of the circuit often occurs by wearing away of or injury to the insulation of the conductors in their parts which pass along the supporting-bar of the traveling'contact device, whereby connection is established through the medium of one of the side walls of the conduit-slot between one of the conductors and the ground, or by reason of imperfections in the insulation of the conductors on the truck or body of the car, by which electric connection is established through the truck-frame and carwheels between the conductor and the ground. The mere grounding of the conductor between the traveling contact device and the motor on one car, at either side of the motor, has no effect on the general operation of the railway system, such groundingmerely putting one pole of the dynamo in direct connection with the ground without any interposed motor resistance, with the result only of the loss of a certain proportion of the current, but without affecting the operation of the motor on the car at which the grounding takes place, or any of the motors then in operation on the system. Such grounding at one side of a motor therefore has no appreciable effect beyond throwing the circuit slightly out of balance, and it can only be detected by the instrument used to indicate the balance between the supply and return side of the circuit. In case, however, the insulation gives out and establishes a ground at two places in a section of road supplied by one source of. electric supply when the grounding in one case is at one side of a motor and the grounding in the other case at the opposite side of a motor, then an entirely difierent condition superveues, because under such circumstances both poles of the dynamo will be grounded, a short circuit will be established between both poles through the ground, and practically all resistance will be cutout of the system. When such grounding at both the positive and negative sides of the circuit takes place, therefore, the entire current from the dynamo will escape from the defective conductors irrespective of the location of the cars on which they are located, thereby stopping the operation of the motors on those cars, and also the operation of all other motors on that section or circuit. Furthermore, defects in insulation may develop on either the positive or negative side of the motors of two or more cars at the same time without producing any effect excepting leakage of current due to the defective insulation, and all of the cars will continue to run until one of the cars containing defective insulation is turned around, or the traveling con- .tact device containing the defective insulation is reversed, as occurs at the end of a route, when, by reason of the conductor having the defective insulation being brought on the opposite side of the circuit, the same conditions will prevail as before set forth, and a short circuit will occur by which all of the motors in the section will be thrown out of operation. t

In both overhead and underground electric railways, as heretofore constructed, a safetyfuse has been placed in the conductors on the car at some point at one side or the other of .the motor in order to prevent short-circuiting of the entire current through the conductors on the car in case of the burning out' of an armature, or of the grounding of the said conductor on the car through the car-frame and its supporting-wheels. Such fuse will prevent stoppage of the operation of any cars excepting the one at which the grounding occurs, it being obvious that a fuse located as described will be burned out and will interrupt the passage of the current through the conductors on a car as soon as grounding takes place at both sides of the circuit in the manner hereinbefore described. A fuse located on the car in the manner described, however, is not capable of preventing the short-circuiting of the current from the conductors on the trolley-arm of an underground system to the slot-rails of the slotted conduit of such system, or through the parts on the car by which the said supporting-arm is directly sustainedas, for instance, grounding of the circuit often occurs by a failure of the insulation of the conductors which pass along the supporting-bar of the traveling contact device, by which the current escapes to the side walls of the conduit-slot, as hereinbefore described, or such grounding may take place by the formation of a metallic connection, by reason of such failure of the insulation, through the metal of the supporting-bar itself and the parts on the car to which the supporting-bar is attached with the car-wheels.

In connection with the trolley-supporting arm and traveling contact devices of an underground electric system, I propose to employ as a means of avoiding the stoppage of the entire system by the presence of defective insulation at both the positive and negative sides of the motors, a fuse or fusible conductor-section located at the lower end of the trolley-supporting arm and interposed between the trolley-wheels (or other contact-pieces which may be employed in place of wheels) and the wires or conductors which extend along or within the trolley-arm, and which serve to connect the said trolley-wheels with the motor, which fuse will be melted bya current largely exceeding the current-carrying capacity of the motor, but less than the normal current from the generator supplying current, so that the short-circuiting of the entire current, through the contact devices of the same or separate cars, in the manner described, will instantly' result in the breaking of the connection between the traveling contact device and the defective conductor on one or both sides of the circuit, thereby throwing out of use the car at which the fuse is melted, but, at the same time, by preventing further short-circniting of the current, restoring to its normal working condition all the rest of the circuit.

The practical result of the employment of the fuses arranged as described is that of avoiding the stoppage ofall of the cars on a section of track when the grounding of the current takes place at opposite sides of the circuit in the manner described, it being obvious that when such fuses are present the cars containing the defective insulation will be stopped, while all others will remain in operation, and the disabled cars maybe easily returned by the use of uninjured cars to a point at which repairs can be made. Commonly, however, by reason of the fact that two fuses are seldom exactly equal in their action, one fuse will be melted, so that one car only will be entirely disabled, the other car on which the insulation is defective continuing to operate as usual, but with a loss of current due to the defective insulation, as hereinbefore described.

The invention consists in the matters hereinafter described and setforth in the appended claims.

The invention may be more readily understood by reference to the accompanying drawings, in which Figure 1 is a view in side elevation of a traveling contact device provided with fusible strips or fuses in'accordance with my invention. Fig. 2 is a plan View of the parts shown in Fig.1. Fig. 3 is a diagram illustrating the supply and return wires of an electric railway, together with the traveling contact device belonging to several cars.

In the instance illustrated wherein I have shown my improvements as adapted to a form of trolley-bar support, and trolleys now in practical use in a system employing supply and return conductors which form a complete metallic circuit, the trolley-bar A is slotted to receive two connecting-wires a, the lower end of said trolley-bar being provided with or adording support for two independent arms B, carrying trolleys B each side of said bar, said connecting-wires a being adapted for connection at their upper ends to the terminals of the motor on a vehicle, and at their lower ends one to each trolley or collector B.

The trolley-bar A is of well-known construction, being provided centrally with two longitudinal slots, within which the insulated connecting-wires a are housed, and at its lower end with plates 0, having each a laterallyprojecting stud c, to which is attached an arm B, the free end of which carries a trolley-wheel or collector B, said plate 0 being separated from the trolley-bar A by a body A of insulating material.

As the construction and arrangement of the parts at the opposite sides of the trolley-bar A are identical, a description of those located on one side thereof will suffice.

In carrying my invention into effect, the lower end of a connecting-wire C6 is disconnected from the plate 0, which carries the trolley-arms B, and connected to a separate metallic plate or block D, which is insulated both from the plate 0 and from the trolleybar A, so that, as so far described, no current can pass from the trolley or collector B to the connecting-wire a.

To establish a circuit from the trolley-arm B or the plate 0 which supports it, to the connecting-wire a, I employ a metallic coupling E, one end of which I attach by means of a binding-screw a to said plate 0, the other end IIO of said coupling being similarly attached by a binding-screw d to the plate or block D, which forms the terminal of said connectingwire a. The couplingE is shown as comprising a length or strip c of fusible metal or alloy and end sections e of copper; shaped to form hooks, which engage the binding-screws c and d. The coupling E thus made and attached constitutes a well-known form of fusible coupling designed to be fused by the passage of an excess of current, and well adapted to the purposes of my invention; but it will be understood that I do not wish to confine myself in this application to this or any specitic form of fusible coupling, as other approved forms thereof may be used in carrying my invention into practical effect.

The fusible strip 6 is adapted to be fused on the passage through it of a current materially greater than that required for the operation of the motor on the vehicle, but less than the entire current supplied by the dynamo or generator by which current is supplied to the railway-section.

As here shown the trolley-bar A is composed of twoplates A A of metal, preferably steel, riveted together, the insulated connecting-wire a passing through a longitudinal slot formed centrally therein and being connected at its lower end to a contact-block D, which is insulated from the trolley-bar A by a body or bodies of insulating material A. A metal plate 0 is also attached to the lower end of the trolley-bar A, but electrically discon-" nected from said bar by the body of interposed insulating material A. The block 0 is provided with a stud 0 upon which the lower end of the trolley-arm B is secured, the upper end of said arm B being fitted with a collector B of any preferred form. The insulated plate 0 carrying the trolley-arms, and the insulated block D constituting the lower terminal of the connecting-wire a, are connected by the coupling E, the ends e e" of which are secured to studs or posts 0 and d, projecting from said plate and block by means of the binding-screws c and d, as hereinbefore described.

As shown in the drawings, the post a projects outward from a connecting strip or plate 0', the forward end of which is bolted to the plate 0, which supports the trolley-arm B; but it will be understood that specific construction is not essential, as said connecting-strip C may be made integral with the plate 0, forming a rearward extension thereof, and is so referred to herein.

Referring now to the diagram, Fig. 3, for the purpose of making more clear the purposes and advantages of the fuses arranged as above described, F F indicates the trackrails, G G the line-conductors, and H H H a plurality of traveling contact devices belonging to cars which rest and travel upon the track-rails, the trucks h h h together with supporting-wheels thereof, only being shown in the drawings.

The motors belonging'to the several cars are indicated in the diagram by I I 1 while J indicates the dynamo which supplies the current.

I have shown the traveling contact devices and motors belonging to three cars only, but.

it, of course, will be understood that any number'of cars may be upon the track. Each of the several contact devices will be provided with fuses arranged in the manner hereinbefore described. Assuming the generator to supply a current of about one hundred and eighty-amperes and the motor on each car to have current-carrying capacity of about forty amperes, each fuse will be constructed to carry a current not exceeding about one hundred and twenty-five amperes without melting. fective on the supporting-bar on either side of any motor-that is to say, at the point on the supporting-bar between the point where the conductors are connected with the upper end of the same and the trolley-wheel or con tact-piece at the lower end thereofas, for instance, so as to establish a ground connection through the wheels of the vehicle, as indicated at K at the positive side of the motor 1 this will have the effect of grounding one pole of the dynamoin this instance, the positive pole. This, however, will have no appreciable effect on the motor I or on any of the others, but will merely throw out of balance the circuit and involve a loss of current to the extent of the leakage at the defective point. If, however, the insulation becomes defective at the opposite side of one of the motors-as, for instance, bythe formation of a connection through the medium of the trolley-supporting arm with the ground through the wheels of the vehicle from the negative side of the motor I, as indicated by the dotted line K'then both the supply and return wires will be grounded in the instance referred to, the supply-wires H, as indicated at K, and the returnwires G, as indicated at K. Under these circumstances a circuit may be traced from the dynamo or generator J through the supply-wire G, the trolley-wheel, the conductor connected therewith to its defective point, the frame and wheels of the truck, the ground, the frame and wheels of a second truck, the conductor leading to the motor I from its defective point to the trolley and the returnconductor G. Inasmuch as the ground furnishes a path for the current having practically no resistance, or at any rate much less resistance than any of the motors, practically all of the current will follow the course above indicated and all of the motors will go out of action. The same result would of course follow if a short circuit were formed through the slot rails of a slotted conduit, instead of through the frames and wheels of the cars, and this is a condition which it is the purpose of this invention especially to provide against, the diagram being made to show a short-circuitin g through the truck-frame, because this If new the insulation become de-- operation as before.

is much easier of illustration. As soon, however, as a current is established through the ground and through the trolleys running on opposite conductors, as described, the full current from the generator passes through the fuses connected with the defective conductors, and one or more of the two fuses will be instantly melted, thereby cutting out the motor of the car on which the burned-out fuse is located, but leaving all other motors in circuit as before. If the fuses were of exactly the same resistance both of those thus subjected to the full current would become fused at once and two cars would become disabled; but practically it is found that one fuse only will be burned out, so that the car having the fuse which was slower to act will continue in It follows that in practice only one car will be entirely disabled under the conditions stated, and that car only will need to be returned to the power-station or repair-shops by attachment to another car, or otherwise, While the car on which the other defective conductor is located will be ascertained by suitable test or examination in order that the defective insulation may be repaired and further loss of current thereby avoided.

The advantages derived from the construction herein proposed are obvious. A general advantage is, that in case of defective insulation and short-circuiting (such as described) the trouble locates itself and becomes apparent in one, or at most, two cars only. In other words, instead of leaving dead or inactive the entire system, or the entire section of road supplied by one circuit until each car can be tested and the defective conductor thus located, the burning out of one fuse throws one carout of action, but restores all of the remaining cars to their normal condition. The car following the one which is thrown outof action can therefore push the latter to the repair-shop and no interruption of traffic'will occur. A stoppage of traffic on an entire road or section of road being a matter involving most serious loss and inconvenience, the great practical utility of my invention is obvious.

I claim as my invention- 1. The combination with a slotted conduit, motor and two line conductors, of atraveling contact device embracing two trolley Wheels or contact pieces moving in contact with the line conductor, a supporting bar extending through the conduit slot, insulated connecting wires extending from the said trolley wheels or contact pieces along said supporting bar to opposite terminals of the motor, and fusible couplings or fuses interposed between the said trolley wheels or contact pieces and the said connecting wires, said couplings or fuses being constructed to carry a current greater than the current-carrying capacity of the motor but less than that supplied by the generator, whereby grounding of the current through the trolley wheels or contact pieces in contact with opposite line conductors, will cut out one or both of the motors which are in circuit with the defective conductors, substantially as described.

2. The combination with a car, two line conductors and a slotted conduit, in which the line conductors are located, of a supporting bar extending from the car into the conduit, trolley carrying arms mo'unted on, but insulated from the said bar, insulated conductors extending from the motor on the car along the supporting bar to the said arms, and fusible couplings or fuses interposed between the said insulated connecting wires and the said trolley carrying arms, said couplings or fuses being constructed to carry a current greater than the current-carrying capacity of the motor, but less than that sup plied to the conducting wires by the generator, substantially as described.

In testimony that I claim the foregoing as my invention I affix my signature in presence of two witnesses.

I MYRON D. LAW.

Witnesses:

O. A. NEALE, TAYLOR E. BROWN.

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