Patent GB-802413-A (GB)
Abstract: 802,413. Train control and cab-signalling apparatus. FORGES ET ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE JEUMONT. Dec. 12, 1956 [Jan. 18, 1956], No. 37949/56. Class 105. In a train control and cab signalling apparatus the impulse frequency in the track circuits and which controls the track relay decreases progressively when a vehicle axle passes given points of the track at which slow down of the vehicle is to commence, the vehicle being provided with pick-up devices responsive to the current impulses and with a comparator for comparing the frequency of the current impulses received by the pick-up devices with a locally generated frequency proportional to the speed of the vehicle, the differential output of said comparator being applied to effect the indication instructions to the driver as to desired speeds and stops of the train or automatically to initiate the controls for such speeds and stops. As shown in Fig. 2, a motor m driven by power from a source e may be of the asynchronous or self-starting synchronous type, drives a rotary switch p associated with a flywheel v provided, if desired, with an adjustable brake f, e.g. of eddy-current type, arranged for adjustability or suppression. The switch p energizes e.g. the grid of an electronic control device forming part of the impulse generator 3A, which switch is adapted to close, e.g., five times per second, unless the armature of relay 27, controlled by track conditions, is dropped whereupon the supply to the motor is interrupted and the motor continues to rotate under its inertia, decreasing progressively in speed with the frequency F of the impulses likewise decreasing to zero at the end of time T, fixed for the particular track circuit according to its length LA, Fig. 1, and its gradients. The rails 1, 2 may be electrically continuous, as shown, or each action such as LA may be insulated from adjacent sections. The impulses in the track circuit are picked up by train-carried inductive coils 29, 30, Fig. 1, and applied to a frequency comparator 31 as well as the frequency proportional to the current speed of the train and generated in generator 32. If the frequency from generator 32 is higher than that from the track circuit, the contact arm 34 moves to energize the circuit 36 which is arranged to actuate an appropriate signal or else to initiate automatically the lowering of the speed or stopping of the train. If the frequency from the track circuit is greater than that from the generator 32, then the contact arm 34 moves to energize the circuit 35 which is arranged to signal permission for the train to travel faster or else automatically to accelerate the train. The relay 27 is de-energized to drop its armature and hence to cut out the motor feed, whenever the home signal S is at " danger " and the train passes the distant signal SA at " caution " since the track relay 6 associated with the signal S would be dropped away and the track relay 6A would be released by the train entering the section LA, thus isolating the relay 27 from its energizing source 28. To ensure that any faulty performance of the comparator should err in the direction of safety, the arrangement shown in Fig. 6 is employed. The movable arm 34A terminates in two spring blades. When the two input frequencies are equal, the circuit 35A only is energized and arranged to maintain normal working. If the speed of the train is too high the contact arm 35A moves so that both circuits 35A and 36A are de-energized to cause a slow-down signal or corresponding automatic control. If the train speed is too low, the contact arm moves to energize both circuits 35A, 36A simultaneously, which causes the signal " accelerate " or corresponding automatic control.