US759453A - Electric railway. - Google Patents

Description

PATENTED MAY 10, 1904.

T. MAHONEY.

ELECTRIC RAILWAY.

APPLIOATION FILED JULY 1. 1903.

N0 MODEL.

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UNITED STATES Patented May 10, 1904.

PATENT OFFICE.

ELECTRIC RAILWAY.

SPECIFICATION forming part of Letters Patent No. 759,453, dated May 10,1904. Application filed July 1, 1903. Serial No. 163,863. (No model.)

To (LZZ whom it may concern.-

Be it known that I, TIMOTHY MAHONEY, a citizen of the United States, residing in the city and county of San Francisco, State of California, have invented an Improvement in Electric Railways; and I hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to improvements in electric-railway systems of the third-rail type.

Heretofore it has been common in third rail systems to employ a main feed-wire and to connect this wire at intervals with the sectional third or trolley rail, using suitable switch mechanism operatable by the moving car to cut in or out the current to a section of the trolley-rail, the current passing from the latter through the car, and thence down to the car-rails to complete the circuit. The chief objection to all these systems has been the danger of the third rail remaining alive after the car has passed and of some one stepping on the positive third rail and on one of the negative car-rails at the same time. Other objections are the necessity and expense of bonding the track-rails and the loss of power through leakage or short-circuiting of the current between the third rail and its nearby return-conductor, the track-rail.

The object of my invention is to do away entirely with a separate feed-wire and to obviate the necessity of using the car-tracks as return-conductors by connecting the two ends of the third rail direct to the dynamo and providing means for shunting the current from the third rail through the car and back to the third rail again.

Having reference to the accompanying drawings, Figure 1 is a longitudinal central section of car-truck and track with diagrammatic wiring. Fig. 2 is a plan view of track and connections. Fig. 3 is a longitudinal central section of switch-box. Fig. 4 is a transverse central section of same.

A A represent the tracks of an ordinary street-railway, and 2 is an intermediate and parallel surface third rail whose sections are insulated one from another. The sections are adapted to be normally connected electrically in series by means of suitable switches'disposed relative to the adjacentends of the sections. These switches each comprise a box 3, of insulating material, in the bottom of which are two separated insulated copper plates 4, and a soft-iron plate 5, normally resting by gravity on the two plates 4 and bridging the space between them. The adjacent surfaces of the plates 4 5 are adapted to have a close surface-contact of considerable area. Preferably the armature-plate 5 has a copper facing 5 on its under side which serves as a conductor of least resistance between plates 4 when the switch is closed, and

one of plates 4 is connected electrically with one section of rail 2, as indicated by the positive sign The other plate 4 is connected with the succeeding section, as indicated by the negative sign Thus when armature 5 rests on plates4 the circuit between any two adjacent third-rail sections is closed, and as the third rail is practically continuous the current from the dynamo or other source of electrical energy, 6, may pass out over one leg of the loop formed by the third rail and return over the other leg. The box is hermetically sealed by the insulated cover 7,

which latter also forms the separation between two adjacent sections of the third rail.

The car B, which is adapted to travel over the tracks A, carries the trolley shoes 8, which are in constant contact with the third rail. One of these shoes is placed at each end of the car.

Disposed between the car-trucks and supported thereon parallel with the car axis is a bar 9, having a plurality of soft-iron projections 10, extending downward close to the ground and immediately above the line of switch-plates 5. The core projections 10 are wound to form electromagnets, the adjacent magnets being so wound as to be of opposite polarity. This line of magnets is designed to present a magnetic surface substantially equal in length to the distance between the trucks, whereby the period is prolonged in which the magnets may act to lift an armature 5 and cut the current through the car. The magnets 10 are in a shunt-circuit between the two trolley-shoes 8, and as these shoes always straddle the adjoining ends of two or more sections of rail 2 the magnets are in a constant state of excitation whether the car is moving or standing still.

The main circuit through the car to the controller 11 is indicated at 12. The motor is represented at 13. One pole of the motor is connected with the controller by a conductor 14 and the other pole with the forward trolleyshoe by the negative wire 15.

The length of the several sections of the third rail is preferably less than the length of the line of magnets, since it is desired that the magnets should always be over a switch to lift an armature and so break the circuit through the third rail and cause it to pass through the car before returning to the third rail. The moment the car has passed a switch the arma ture falls to complete the circuit through that portion of the third rail lately traversed by the car. Hence in operation at whatever point along the line of track the car may be the armature directly beneath the car is lifted, thus breaking the circuit through the third rail at that point and shunting the current through the car to actuate the motor. From the motor the return-circuit to the dynamo is completed through the portion of the third rail in advance of the car and not through the car-tracks or other separate conductor.

In this invention that portion of the third rail on one side of the car is positive, that on the other is negative. It is impossible for one to step on both the positive and negative portions of the third-rail at once and get a shock even where the going and return sections of the third-rail conductor may be on the same street. Moreover, the farther these portions are apart the less loss is there from leakage across the intervening space.

The advantages of this system are, first, its safety; second, the elimination of an independent feed-wire and the doing away with all bonding of the car-rails, thereby resulting in a considerable saving in cost of construction, and, third, the saving of power effected, since there is no return-conductor close by the third rail for the latter to short-circuit with.

Having thus described my invention, what I claim, and desire to secure by Letters Patent,

1. The combination with a car or like movable body, of a sectional conductor comprising alined separated sections, of removable switch-boxes interposed between and in the line of the sections, contact members in each of said boxes, one of said members connected electrically with one adjacent section and the I other member with the other adjacent section, an armature-plate normally resting by gravity on said contacts, and a plurality of connected alined magnets on the car in the plane of said armatures, alternate magnets being of opposite polarity t0 the intermediate magnets.

2. In an electric-railway system, the combination with a sectional conductor and switches normally connecting the sections of said conductor, of a plurality of alined connected cooperating magnets carried by the car, said line being substantially equal to the distance between the switches, and said magnets being wound so that alternate magnets are of opposite polarity t0 the intermediate magnets whereby a line of magnetic attraction of practically uniform strength throughout its length is produced.

In witness whereof I have hereunto setmy hand.

TIMOTHY MAHONEY. Witnesses:

OLIVER DIBBLE, G. M. D. Teens.

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