Patent GB-816163-A (GB)
Title: Improvements in or relating to railway classification systems
IPC: B61L17/00
Filed: 1957-04-02
Abstract: 816,163. Railway retarder systems. GENERAL RAILWAY SIGNAL CO. April 2, 1957 [April 13, 1956], No. 10744/57. Class 103 (1). In a railway car classification system of the kind shown in Fig. 1, comprising a hump retarder preceding branch tracks each having an appropriate group retarder, the control systems for the hump and group retarders respectively are shown in more detail in Figs. 2A and 2B. The hump retarder, which has in advance of it a weighing rail 20, includes near to its leaving end a directional antenna 11 beamed to transmit a high-frequency signal towards approaching cars and, by the Doppler principle, obtaining a beatfrequency giving a measurement of the, car's speed. These signals are applied through the discriminator 12 and control relay 13 to the retarder operating mechanism 14 to effect the required braking on the car wheels by the brake shoe beams. The hump retarder has associated with it a second directional antenna 15 which directs a beam on to the receding cars. Signals corresponding to the speed of a car on leaving the hump retarder are then passed through a transmitter-receiver 16 to the pulse-forming gating and counting circuits 18, where by combination with signals received from the control relay 13, a measure of a car's leaving speed is obtained, which is passed on to the hump leaving speed storage and transfer circuits 19. The car speed information is established as a multi-digit code, the code for each respective car remaining identified with that car during its progress through the retarder. The operation of the retarder mechanism 14 is also subject to the influence of signals received from the weight storage relay block 22. Signals from the hump leaving speed storage and transfer circuits are passed, over line 26, to the reference entering speed circuits 27. Since the acceleration between the hump and the group retarders will depend on the length of a car "cut," a control is provided from the cut length detector 28 over lines 29 to the reference entering speed circuits 27 so that this factor may be taken into account. The cut length detector 28 is controlled by both the weight detector 30 associated with No. I Group Retarder and the track relays H-TR and G-TR, shown in Figs. 2A and 2B. A voltage analogue of reference entering speed is provided over lead 33 to the modifier 34. The modifier also receives, over lead 35 from discriminator 36, a voltage analogue of the actual speed of the car at any instant as it approaches and passes through No. I Group Retarder. In the modifier 34, the actual speed of the car at a predetermined location is compared with the reference entering speed. The difference in these two values represents the comparative "rollability " of the car, and is multiplied in the modifier 34 by a factor dependent upon the intended route for the car after it leaves the group retarder. A group manual modifying control 38a comprises a manually-operated multi-position switch, which can be positioned in accordance with track fullness so that each car can be released from the group retarder with a speed that will enable it to reach coupling speed at any one of various selected zones. It also exerts a controlling influence over lead 39 to the reference leaving speed circuits 40. Both No. I and No. 2 Group have a directional antenna and transmitter-receiver associated therewith providing car speed responsive signals which are fed to Retarder Control Relays governing the Retarder Operating Mechanism. Specification 811,821 is referred to. Reference has been directed by the Comptroller to Specification 781, 904.