Patent GB-190227476-A (GB)
Title: Improvements in or relating to Electric Railway or Tramway Traction on a Surface Contact or like System.
Inventor: BOULT WILFRID SWANWICK
Filed: 1902-12-12
Granted: 1903-11-12
Abstract: 27,476. Boult, W. S., and Boult, C. R. Dec. 12. Electric railways and tramways on a surfacecontact or like system. The object is to provide consecutive connections of the surface contacts with a main continuous covered conductor, only when they are covered by the moving vehicle, and their disconnection before the vehicle again uncovers them. Polarized magnetic relays operated b y magnets carried on the vehicle are provided, which control the working of electromagnetic switches, whereby a circuit is completed between the main conductor and the studs or sectional conductors, o n which contact is made by the skate carried by the vehicle. One of the methods adopted is shown in Fig. 1. The skate C carried by the vehicle makes contact with the studs A, A<1>, near which are fixed the electromagnetic switches comprising two magnets D, D' having a tongue or other contact-piece D' working between them, the coils of the magnets D, D<1> being connected in series with the conductor E which is normally energized. The magnets H, H<1> carried by the vehicle are of opposite polarity, the poles operating the relays which consist of a tongue F and contacts F<1>, F<2>. The magnets cause the tongues F to make contact as shown, short-circuiting the forward coil D' and the rear coil D ; consequently the tongue D<2> of the switch is attracted by the coil D at the forward end, and the circuit is completed from the main conductor G through the tongue D<2> to the stud A<1> ; at the same time, the circuit between the stud A at the rear end and the conductor G is broken. The distance between the magnets is greater than that between the studs, so that the leading stud is energized before the rear magnet cuts out the rear stud. The magnets H, H<1>, shown in dotted lines, are for use when running in the opposite direction. Various modifications are described in which the car is furnished with two magnets or with one only. Another modifi. cation is shown in Fig. 5 ; in this, sectional conductors A<3>, A<4> are used in place of studs, the car being furnished with collectors J, J for making contact. The magnet Hand collector J shown in full lines are used when the car is travelling in the direction of the arrow X, the magnet H and collector shown in dotted lines being used in the opposite direction. In the position shown, assuming the car to be travelling in the direction of the arrow X, the tongue F is deflected, thus short-circuiting the coil D of the centre switch and the coil D<1> on the left, causing the tongues D', D<5> to be attracted by the coils, as shown, and to complete the circuit from the main conductor G through the tongues D', D<5> to the conductor A<3>, and at the same time breaking the circuit through the tongue D<2> of the centre switch to the conductor A<4>. In a further modification, the switches are arranged in open circuit, and, when they are operated by the relays, a circuit from the conductor is completed through the switches to earth. The relay is fitted in a pit beneath the track, and collecting-bars connect the relay with castings which are flush with the track, the castings, collecting- bars, and relay furnishing a path for the magnetic lines of force from the travelling magnet, and the direction of the lines being at right-angles to the normal position of the relay tongue. The collectors, when sectional rails are employed, are made in two or more sections, each capable of turning independently about a horizontal axis, so that, should any small obstruction be upon the rail, the particular plate of the section only which comes in contact with the obstruction is raised. In the Provisional Specification, details are described of a suitable form of switch, consisting of two coils, between which is placed a permanent bar magnet, having a tongue pivoted to it, the free end of the tongue being thrown backwards and forwards by the coil. The tongue has parts adapted to enter mercury cups for making contact ; or a " chopper " arrangement with spring contacts may be used.