Patent GB-406418-A (GB)
Title: Improvements in or relating to traffic control installations more particularly for railways
IPC: B61L7/08
Filed: 1932-10-31
Abstract: 406,418. Electric signalling and distant control systems. GENERAL RAILWAY SIGNAL CO., Rochester, New York, U.S.A.-(Assignees of Preston, N.D.; 287, Aberdeen Street, Rochester, New York, U.S.A.) Oct. 31, 1932, No. 30567. Convention date, Nov. 5, 1931. [Class 40 (i).] For code control of signals and points at a number of field stations over a circuit from a central office, the manual control means at the office are set to positions corresponding with the desired setting of the points and the desired direction of movement over the route set up by the points, thereby to impress on the circuit a code determined by the contemporaneous collective positions of the manual control means ; the apparatus at the field station is such that the points and signals are separately operable but no signal is cleared unless both the points and the code-selected relay for the signal control have correctly responded. If, for example, the manual control means are set to clear a signal for East bound movement over the points at normal the code is such that a routestoring relay NER and a polarized pointsmotor relay SMR are energized, the latter relay SMR causing the independent operation of the points but no signal is cleared unless the points setting, as indicated by the contact 199 of the points repeater relay WP, corresponds with that required by such relay NER. When a number of non-conflicting routes can be set up at a field station the code cycle may be lengthened and divided into groups, the different groups serving for the control of the different non-conflicting routes. Fig. 1 shows that part of the central office equipment and Figs. 2A, 2B that part of the equipment at one of the stations along the line which is necessary to an understanding of the code control of the signals and points at one end of a passing siding. The code selection of the station is effected as described in Specification 377,971 by the first three steps of the particular code maintaining the relay SO energized only at this one station. A lever SML controls the points and a lever SGL when moved from the middle position to the left or right initiates a code to actuate the points and clear a westbound or eastbound signal for the main track or siding, according to the points setting and subject to control by track occupation. The points may be actuated, without moving the signal lever SGL to clear a signal, by depressing a push SB. A code transmission is started by opening the stick circuit of a relay ST which drops its contact 66 to pick up the code relay CD. The code is applied to a line wire and comprises positive and negative pulses spaced by dead intervals, the polarity being determined by the setting of a relay CS, the spacing by a relay IM, and the start and finish of the cycle by a relay CC. The code cycle sequentially energizes a chain of relays at the office and at the stations ; the first three relays of each chain and the polarity of the pulses serve to select one particular station by maintaining the relay SO energized, as described in the Specification referred to above. The Figures show only the later chain relays, d ... h at the office, and 4 .... 8 at the station. To actuate the points without clearing the signal the points lever SML is set to reverse, for example, thereby energizing a relay R electrically interlocked over a back contact 63 of the normal relay N. The push SB is then depressed to open the stick circuit of the relay ST and initiate a code transmission as described above. On the dead interval of the third step of the code, negative potential is applied over front contact 73 of relay R, front contact 75 of relay CD, back contacts 82 ... 86 of chain relays d .. h, and back contact 88 of quickacting relay LR‹, to relay CS whereby the fourth pulse will be made negative. At the station the relay IS is negatively energized on the fourth step and accordingly in the dead interval the points control relay SMR is energized negatively from contact 109 at the left, over back contact 111 of quick-acting relay LR, front contact 113 of relay SO, back contacts 115 ...118 of chain relays 8 ... 5, and front contact 119 of chain relay 4. The points are thus set to reverse by energization of the points machine SM over reverse contact 123 of relay SMR and contact 121 of a relay ALP which is energized under clear traffic conditions. To set the points and clear the appropriate signal for a particular direction of movement (west or east) the two levers SML, SGL are appropriately set. For example the lever SGL is put to the right (contact 150 to the left) to clear the main eastbound signal 1A with the points at normal. A relay NE is thus energized over back contact 148 of code relay CD, left hand contact 150 of the signal lever SGL, and back and front contacts 153, 155 respectively of relays R, N. The relay NE opens contact 21 to open the stick circuit of relay ST which energizes relay CD to start the code as above described ; the relay NE is then held by a stick circuit over its front contact 162 and the make-before-break front contact 148 of code relay CD. A relay S is de-energized by the lifting of contact 33 of relay NE, but owing to its slowness does not close its contact 193 in time to prevent the opening of the circuit of relay ST. The contacts 164 ... 167 of relay NE apply their particular code polarities to the fifth to eighth pulses whereby the station relays 1CR .... 4CR are correspondingly energized under the control of the chain relays 5 ... 8. On the eighth pulse, contact 68 of chain relay h opens the circuit to code relay CD which drops to end the cycle. In due time the slow relay SL drops, whereby its back contact 130 applies potential over the front contacts 132, 134 of relays SO and 8 which are not yet dropped as they are de-energized only when relay SL has dropped, and contacts of the relays 1CR ... 4CR, positioned in accordance with the particular code, to pick up a relay NER which then sticks over its own contact 184, back contact 142 of a relay SR and front contact 191 of the track relay T. Only one relay such as NER can be picked up since a contact 57 thereof then opens the circuit to a relay CK, a contact 183 of which opens the pick-up circuit of the relays NER .... The front contact 202 of relay NER energizes the signal control relay 1AG over contacts 197, 199 of a points repeater relay WP and front contact 194 of track relay T, but subject to control by the ahead traffic conditions through a relay 1H. The passage of the train drops the track relay contact 191 to break the stick circuit for relay NER so that the signal goes to and remains at danger. A track repeater relay TP shortly afterwards closes contact 207 so that if a fresh code were transmitted during the train passage the relay such as NER would be stuck up in readiness to clear the signal. To return the signal to danger before a train has accepted such signal the lever SGL is returned and the push SB operated to initiate a code as described above. The relay S is energized over the back contacts 33, 34 .... of the relays NE, RE ... which are deenergized by the lever SGL being at neutral The front contacts 126 ... 129 of relay S apply their particular code on the fifth to the eighth steps whereby the relay SR at the station is briefly energized, so that its contact 142 opens the stick circuit of any relay such as NER which by de-energizing the signal control relay lAG puts the signal 1A to danger. A relay M is now energized over the back contacts 37 .... 40 of the signal control relays 1AG ...and lifts its contact 49 to energize a time-delay-device heating element 42 over back contact 44 of an approach relay AL which was de-energized when energization of the signal control relay 1AG de-energized the relay M. In due time the contacts 211, 50 of the device respectively close and open, the contact 211 then picking up relay AL and as the heating element 42 no longer receives full current it cools off and the subsequent closure of contact 50 energizes relay ALP. Not until relay ALP is thus re-energized can the points be changed. If the train has already reached the detector section T the relay AL is picked up over the back contact 194 of relay T so that the relay ALP is energized immediately after the passage of the train. The codes for operating the signals are so chosen that they differ from each other on at least two steps. The points may be of the form described in Specification 338,826, [Class 105, Railway signals &c.], to permit operation by the driver after the consent of the central office has been given.