Patent GB-517967-A (GB)
Title: Improvements in electric signalling systems for train describing purposes
IPC: B61L25/04
Filed: 1938-06-09
Abstract: 517,967. Electric signalling systems. STANDARD TELEPHONES & CABLES, Ltd., GRIFFITHS, J. B., BROWN, A., and TERVET, E. J. June 9, 1938, No. 17155. [Class 40 (i)] Train descriptions or platform indications are transmitted to remote indicators in the form of codes made up of a fixed number of positive and negative impulses, and a plurality of indicaitons are stored ready for display in sequence. The system is particularly suitable for operating train describers of the type wherein descriptions of successive trains are displayed in turn as each train departs from the receiving point. Each description is coded by ten impulses, the first five impulses relating to the train destination and the last five impulses to the stations at which the train does. not stop. The descriptions are 'stored ready for display 'on individual rows of pins Al, B1 and so on supported on the surface of a drum 1 which is adapted to be rotated through the distance between neighbouring rows each time a record is made. The pins in each row are selectively depressed against spring control by magnets 33 which are selectively energized by the incoming coded impulses. The selected pins are held depressed by a mechanical latching bar-provided for each row of pins and adapted to be moved longitudinally by a fixed abutment to restore the pins after one revolution of the drum; alternatively the pins in a row may be reset by means actuated by a "cancel" code. The first and second recorded descriptions are displayed by a lamp indicator board which is operated by sequence-type switches marked by rows of wipers 30, 31 carried on a detector device 28 which is carried round with the drum during registering but is rotated in the opposite direction through the distance between the rows of pins when it is desired to display the subsequently recorded descriptions. The drum 1 and the carrier are operated by independent motors which when started rotate through one complete revolution. Incoming code impulses are received over line L1, L2, Fig. 4. and each impulse operates relay 1R irrespective of its polarity whilst relay 1P is operated by positive impulses only. The initial impulse is negative and of long duration to condition the equipment Fig. 4 for operation. The next ten impulses operate the chain of relay CA .... CL in sequence. The relays CA .... CL prepare the circuits of corresponding relays AA .... AK which are operated only when the impulses are of positive polarity. The relays AA .... AK prepare the operating circuits of the code-pin setting magnets MA .... MD. The last impulse of the series is a long impulse which pulls up relay OK and operates stopping relay SR to switch in motor 1 and drive the code drum forward to position the next row of pins under the setting magnets MA .... MD, When this movement is completed relay TR is pulled up and the magnets MA .... ML are operated to set the pins of the code drum. Relay TR also releases relays OK, SR and the circuit is restored to normal to await the transmission of the next train descriptions. The descriptions set up on the drum may be cancelled by transmitting a code which selects relay AK and operates magnet MCL which actuates the locking bar of the pins. If a fault code is transmitted and relay CL remains inoperative the long final pulse operates relay NG instead of relay OK. The relays SR, TR operate in the manner described but relay TR fails to actuate the magnets MA .... MD. The codes set up on two rows of pins are detected for display by rows 'of contacts 30, 31 the first five contacts of the row 30 being associated with a fast sequence switch 1SS, Fig. 5, to give the destination and the second five contacts with a second switch 2SS for the non- stop data. The first five contacts in the row 31 are associated with the switch 3SS for providing the destination description of the second train due. Each sequence switch has five cam discs, the cams, B, C, D being cut to advance the switch to positions determined by the code pins and the cams A, E being arranged to effect control of the clutch magnets C, and restoration of the switches to normal position. When a relay DR is operated over the contacts 30, 31 corresponding-clutch magnet C is operated and the switch is driven into a position determined by the code pins. The switches are provided with further sets of cams F which control the lamp circuits of the indicator boards. The circuit breaker CB prevents illumination of the indicators during movement of the sequence switches. The code-arm elements F used in the " non-stop" indicator switch may be produced from standardized comb-like elements selected teeth of which may be broken off manually. This facilitates ready alteration of the indications associated with any one code transmission. When the "first trains due" leave a station a track relay operates a relay HR, which effects restoration of the sequence switches and starts up the motor II to rotate the detector contacts 30, 31 into engagement with the following rows of pins. The sequence switches are then re-operated to effect the new displays. Each sequence switch is driven by the common motor through gearing comprising a flexible disc which is normally held out from engagement with a driving wheel on the motor shaft by the spring - controlled armature of the clutch magnet. When the magnet is energized the flexible disc is freed and engages the driving wheel. A fixed rubber buffer co-operates with the flexible disc to brake the movement of the switch when the magnet is de-energized.