Patent GB-1082027-A (GB)
Title: Vehicle control installations
IPC: B61L3/00
Filed: 1965-11-04
Abstract: 1,082,027. Automatic train control. SIEMENS A.G. Nov. 4, 1965 [Nov. 12, 1964], No. 46865/65. Heading B7N. In an arrangement for controlling a vehicle moving over a track region which is divided by crossovers in an associated pair of line conductors into a number of equal length sections and in which each time the vehicle passes over a crossover positional information is transmitted from the vehicle to a central office controlling the region and stored therein, means are provided in the event of breakdown in the communication link to bring the vehicle to a halt and on restoration of the link to correct the stored indication of the vehicle's position. The vehicle apparatus is coupled to the line conductors L, which are supplied with signalling current from central office C1, via an aerial A and the change in signal level as the vehicle passes over a crossover develops an output pulse in unit E which is applied via a switching device U to an auxiliary counter Z1. In the event of failure of the signalling current the counter is fed with distance pulses generated on the train by wheel operated transmitter RP and occurring at the same time as the pulses generated on passing over a crossover. The counter Z1 is provided with a counting capacity equal to the number of sections in the maximum braking distance of the vehicle and the outputs of the counter stages which are energized when the counter registers zero are connected to NAND gate M2 and the similar outputs of all the stages except the first one connected to NAND gate M1, which is connected to braking means (not shown). The central office cyclically transmits an interrogation signal to the vehicle comprising a vehicle code and the number of the section occupied by the vehicle. The code is checked in unit CP and if correct a comparator V is released to allow a comparison of the number with that stored in the distance counter Z2 of the vehicle apparatus which has a counting capacity equal to the number of sections in the longest region. If the numbers coincide a signal is passed from the comparator to a store G which issues a " 0 " signal via the transmit/ receive device E to the central station indicating no change. When the vehicle moves over a crossover the generated pulse is applied via unit U to the auxiliary counter stepping it forward one position whereby NAND gate M2 provides one input to a coincidence gate K1, the following interrogation signal provides an output pulse from comparator U which is applied via delay device D to the other input of the coincidence gate. The output from the gate steps the counter Z1 back to its initial zero state and the distance counter Z2 forward one position, the output also triggers the store G to its " 1 " position and this information when transmitted to the central office changes the stored indication of the position of the vehicle. Should the transmission system fail the pulses from the distance pulse generator take the place of the crossover pulses and when the auxiliary counter (which is not stepped backwards under this condition) is stepped to its second position an output is applied from the NAND gate M1 to the braking circuit to stop the train. When the transmission system is restored a difference will exist between the last stored section occupied indication at the central office and the actual section now occupied by the train; however, as NAND gate M2 now supplies a signal to open gate K1 each interrogation pulse from the office steps the distance counter Z2 forward one position and the auxiliary counter Z1 back one position and also by switching store G to its " 1 " position steps the central office indication forward by one section position. This sequence repeats until the counter Z1 is stepped back to zero when the gate M2 ceases to provide an input to the coincidence gate K1 and the following interrogation pulse switches the store G to " 0." During this process the brake circuit is also deenergized. The Specification also describes with reference to Figs. 2-4 (not shown) how the positional information at the central office is corrected when during braking resulting from a breakdown in communication the vehicle moves from one region to an adjacent region.