GB190422401A - An Improved Automatic Signalling Apparatus for Electric Tramways. - Google Patents

Abstract

22,401. Jewell, C. J. Oct. 18. Signalling- systems contacts, electric.-Relates to a signalling system for use on electric tramways, consisting of single lines with passing places where it is impossible for a car to be seen the whole length of the track. Each length of single line is traversed by four switch line-wires, two for each trolley wire, each pair being led into a switch at each end of the line to be protected. A car entering the single line, automatically lights a lamp or actuates a semaphore at each end of the single line, the signal ceasing when the car reaches the next passing place. Fig. 2 shows the apparatus diagrammatically for one trolley wire C. When the car enters the single line, the trolley head engages the tongue E so as to close contacts b, b<1>, thus completing a circuit from the the trolley wire C, through the solenoid F to earth. The attraction of the core H moves the ratchet-wheel K one step and causes the switch arm L to move to the next contact M or N as the case may be. All the contacts M of one switch are connected by the switch line-wire B to similar contacts M', at the other switch, and the contacts N to corresponding contacts N<1> by the line-wire A. The arm L thus closes a circuit through the lamps or semaphores S at each end of the single line. When the car reaches the second switch, it moves the arm L one step forward so as to break the circuit but so as to be ready to complete a signalling-circuit through the other line-wire when the next car moves the arm L at the first switch. Fig. 3 shows the practical construction of the switch. The ratchetwheel K is moved round by the core of the solenoid F, and is mounted on a spindle k<1>, bearing an arm L carrying an arched contact l, which connects the contact-ring P with the contacts M, N in turn. The contacts M, N are connected respectively to rings m, n, which are always in contact with the ends of the line-wires A, B.