Patent GB-321426-A (GB)
Title: Improvements in electric signalling or indicating apparatus
IPC: B61L25/04
Filed: 1928-08-01
Abstract: 321,426. Relay Automatic Telephone Co., Ltd., British Power Railway Signal Co., Ltd., and Graham, J. H. Aug. 1, 1928. Selective signalling systems.-Relates to a signalling system more particularly for signalling from one signal cabin to another, descriptions &c. of trains or for indicating to passengers destinations of trains approaching a station or particulars of trains arriving at and departing from a platform. The apparatus is of such a character that descriptions may be received in the order in which they are transmitted, and if two or more descriptions are transmitted successively the subsequent descriptions are stored and are only transferred to the indicator when the displayed indication is cancelled. Information is transmitted to the receiver in the form of characteristic impulse codes. A code corresponding to a first indication is counted by a group of relays and a characteristic setting is transferred through subsequent groups of relays to a final group of relays which operates appropriate lamps in the indicator. The groups of relays preceding the final group are automatically reset ready to receive and store subsequent signals. Operation of signalling equipment shown in Figs. 1, 1<a>, and 1<b.> The Figures show a system for operating a platform indicator, Fig. 1<b>, wherein the destinations of trains are illuminated by groups of lamps b and the order of arrival of the trains is indicated by numerals selectively illuminated by lamps 52, 56. The destination of the first train is selected by an appropriate relay in the chain FIX, the setting of which is transferred from a group of relays F1 and the destination of the second train is similarly selected by the chain SIX which is operated by the chain SI. When the indicator corresponding to the first train is cancelled the setting of the chain SI is automatically transferred to the chain FI, so that the order of departure of the second train is altered into a ''' first " indication. The successively transmitted signals are all passed through the counting chain MK, BK and are automatically transferred to chains S, SI, FI, which store the signals until the " first " indication is cancelled, when the stored signals are transferred to the subsequent relay chains and the chain MK, BK is reset ready to receive a further signal. To transmit a train description the operator first operates switch d, Fig. 1, which energizes at the receiving station the line relay A to operate relay G. Relay G operates all the relays BK over contacts of corresponding relays MK to energize relay DM. Upon operation of relay DM the lowest relay MK is energized and the lowest relay BK is brought upon the control of line relay A. The description may now be transmitted by operating the impulse sender C to operate relay A by a characteristic number of impulses. Each impulse received causes operation of the MK relays in sequence and the release of the corresponding BK relays. In this manner a particular BK relay corresponding to the number of impulses received is released to select a relay in the chain S over contacts of relay DM. In order to adapt each of the chains S, SI, FI comprising only five relays to the tenimpulse cycle of the chain MK, BK, the sixth relay of the BK relays is adapted upon release to operate a relay BK6C which effects a discrimination in the relay chains S, SI, FI. At the end of impulsing, the prolonged operation of relay A effects the operation of a slow acting relay DC' to energize relay RH and thereby open the line circuit and operate relay MC. Relay MC closes a circuit over the contacts of the appropriate relay BK for the corresponding relay in the chain S. The selected relay S locks up in series with relay SCO which de-energizes relay MC and also releases all the operated relays in chains MK, BK. Release of relay MC operates relays RBC to prepare relays MK, BK for' the reception of a further signal. Relay SCO energizes a relay on the group SI corresponding to the selected relay in the group S and relays SICO, SBC are then operated in a manner similar to the relays SCO, RBC to prepare the relays S for the reception of a further signal. Relay SICO also transfers the setting of the relays SI to the FI relays. As long as a setting is held on a chain of relays a following setting cannot be transferred, since the energizing circuits are maintained open by relays FICO, SICO, SCO. To effect discrimination at the receiver, a relay S6C is operated by the relay BK6C when more than five impulses are transmitted. Relay S60 operates relay S16C which in turn operates relay F16C, the relays S16C, F16C associating back contacts of relays SI, FI with the last five relays in the auxiliary relay chains SIX, FIX. When the first train passes out of the station, a cancelling button h is operated, e.g. by the train, to erase the indication set up by the relays FI, FIX. Operation of equipment shown in Figs. 3, 3a, 3<b>, and 3<c>. In this arrangement the apparatus is applicable more particularly for signalling descriptions of trains from one signal cabin to another by means of four figure codes. As shown in Fig. 3, the counting relay chains MK, BK are associated with tens, hundreds, and thousands relay chains TNS, HDS, THS. Each chain of relays, Fig. 3, is associated with a corresponding chain of relays in the groups of storage and indicator relays SS, FS, I, Fig. 3<a>, which control auxiliary relays IX, Fig. 3<b>, adapted to operate corresponding banks of indicator lamps. Successive train descriptions may be stored in the relay chains and may be transferred through the chains when the lamp indication is cancelled. The relays MK, BK operate in a manner similarto that previously described but the first digit is recorded by the chain THS, the second by the chain HDS, and so on, the chains THS, HDS, TNS being brought successively into association with the relays MK, BK by relays DM<1>, DM<2>, DM<3>. The final digit is recorded by relay MK, BK and upon cessation of impulsing relay RH energizes relay MC to operate the appropriate relays in the groups SS. Discrimination for more than five impulses is effected in a manner similar to that previously described. The setting of the relays SS is transferred to the relays FS, I in turn and the relays I are held operated over a "cancelling button" p, Fig. 3<c>, to operate corresponding relays in the bank IX and thereby illuminate the appropriate, lamps. Arrangement for re-transmitting or interpolating a description at the receiver. A dial transmitter, Fig. 3<c>, is provided in the cabin and comprises groups of contacts i operated by a cam k to transmit a four-digit code over the outgoing line circuit. The contacts i are connected to corresponding relays IX and the arrangements are such that the selected relays short-circuit subsequent contacts i so that upon rotation of the cam k a characteristic code is transmitted. Normally each group of contacts is short-circuited by contacts l, but upon rotation of the dial the short-circuits are removed successively by a cam k<1>. Impulses are transmitted only during the return movement of the dial after the initial setting operation. The impulse sender has an auxiliary disc e carrying a projection f which, when the dial is set, engages an electromagnet g and operates contacts z<1>, z<2>. The contacts z' operate a relay SC over contacts y<2>, which are closed upon operation of the dial, to complete the line circuit over relay L and a circuit for the electromagnet g is prepared. If the capacity of the receiving apparatus at the next signal cabin is " full," relay L remains de-energized since the relay RH at that station maintains. the line circuit open. Thus the electromagnet g is energized to hold the dial in its set position and prevent the transmission of a further signal. As soon as the relays MK, BK at that station become free the line circuit is closed and the electromagnet is de-energized to release the dial and transmit the appropriate signal. When the dial returns to its initial position a projection n opens contacts o in the locking circuits to release the relays I and cancel the lamp indications. Subsequently recorded signals are then transferred through the relay chains, Figs. 3 and 3<a>, and a fresh indication is displayed. The discs m, e and the parts carrying the cams k, k<1> of the impulse transmitter may be arranged on a common shaft and a free-wheel mechanism may be provided whereby the cams k, k<1> remain stationary during the initial setting operation but are rotated during the return movement of the discs m, e. Alternatively, the cams k, k<1> axe rotated during setting to the offnormal position but remain ineffective. If it is not desired to transmit the received indication to a following signal cabin, the indication may be cancelled by the operation of the button p. Moreover, a number or description of a train other than that recorded on the indicator may be interpolated and transmitted to the next station. To effect this, the recorded number &c. is suppressed but not cancelled by operation of the switch s. The operated indicator relays IX are energized over contacts of a relay S controlled by the button s. Operation of the button s has no effect upon the relays I so that the suppressed indication remains stored. In order to interpolate a, train number appropriate buttons u associated with independent windings on the relays IX are operated to set up the new indication provided only that the button s is operated. The impulse sending contacts i are appropriately marked, and transmission may be affected to a manner similar to that previously described. When the dial returns to normal, operation of contacts o is however without effect since the relays I remain energized over contacts of the relay S, but operation of contacts y<1>, y<2> cancels the interpolated number and again causes the suppressed number to b