Patent GB-836625-A (GB)
Title: Improvements in or relating to the automatic control of railway traffic at junctions
IPC: B61L19/06
Filed: 1957-04-02
Abstract: 836,625. Photo-electric control of stencil switches. BRITISH TRANSPORT COMMISSION, and DELL, R. June 6, 1958 [April 2, 1957], No. 10771/57. Class 40 (3). [Also in Groups XXX and XXXVII] A machine, for the automatic control of railway traffic at junctions, termini and like locations where track points and signals have to be set in accordance with the required routes of the trains and which machine is able to take the place of a signal man at such locations for closing in prearranged groupings a plurality of electrical circuits for activating track signal and/or points operating mechanisms, comprises a plurality of contacts 31, one for each of the said circuits carried by a movable member such as a rocking bar 28, and a band 19 adapted to be passed step-by-step through the machine to co-operate with feelers 34, Fig. 4, associated with the contacts 31 to modify, in different positions of the band, the movement of some of the contacts 31 when the bar 28 is rocked to determine which of the said circuits are closed. The band 19 is passed over a platten 43, Fig. 4, formed with a row of holes such as 49, each hole being in the path traversed by a respective feeler 34 carried on the contact arm 32 carrying the contact 31 in turn insulatedly carried on the rocking bar 28 pivoted at 29, Fig. 4, in the upright side members 12, 13 of the frame 10, Fig. 1, the band being formed with groups of holes 35, Fig. 1, in different arrangements according to the circuits it is desired to close and adapted to be brought successively into register with holes 49 in the platten 43. The band 19 is carried on two rollers 17, 18 mounted in a carrier 16 removably received into vertical grooves in pillars 12, 13 of the frame 10, the rollers being driven by an electric motor 21 through selectively-operated electromagnetic clutches so that one roller, viz. 17, drives in one direction to advance the band under the control of a ray of light from a source 64, Fig. 4, passing through an elongated hole in the platten and a hole 67, Fig. 1, in an opaque longitudinal strip 66 of the band overlying the elongated hole in the platten. The motor drives in the other direction to rewind the band on the roller 18 and is stopped under the control of a ray of light from the source 64 passing through a hole adjacent the front end of the band so positioned as to line up with the elongated hole in the platten when the band has been rewound to its starting position which is effected by known means. The selection of the clutches depends upon the operation of one of two switches 88, 89. The two rays of light from the source 64 fall upon photo-electric cells 62, 63, Fig. 8. Movement of the motor 21 is dependent upon the closure of contacts 85, 86, Fig. 8, when the rocking bar 28 is in its normal position, the contact 85 being carried on an arm 84, Fig. 1, and the contact 86 on a resilient arm 87, Fig. 1, secured to the bar 56 on the frame 10 but contact 85 moving away from the contact 86 before the feelers 34 have entered the holes 35 in the band 19. The feed circuit for the motor 21 in the forward direction is over front contacts P1, D1 of relays P, D respectively, relay P being operated by the closing of contacts 85, 86 and relay D being operated by the closing of front contact S1 of relay S which is in turn operated by the closing of contact 88 by, e.g. a clock mechanism or by track circuit mechanism responsive to the approach of a train. Relay S is held over front contact S2 and the relays pull-up circuit is interrupted at back contact H1 of a relay H pulled up over front contact S3. Relay FP is energized when light falls upon the photoelectric cell 62 and at front contact FP1 prepares the holding circuit for relay S and at back contact FP2 opens an alternative operating circuit for the relay D by-passing the contact S1. The movement of the band resulting from the starting of the motor causes the light from the source 64 to the cell 62 to be interrupted with consequent de-energization and falling off of relay FP and at front-contact FP1 de-energizing relay S but the relay D circuit remains closed over back contact FP2 and retains the motor circuit closed. The motor then runs until the next hole 67 lines up with the elongated hole in the platten and light again falls on the cell 62, energizing and pulling up relay FP to deenergize relay D at back contact FP2 to interrupt the motor circuit and energize the brake solenoid BS over a circuit including front contact FP1 front contact P2 and back contact S4, to apply a brake and stop the movement of the band. Closing of back contact D3 energizes a solenoid CV actuating a valve to admit compressed-air to the cylinder 78, Fig. 4, to operate a piston 81 against spring action 83 to rock the bar 28 about its pivots thereby breaking the contacts 85, 86 and urging the feelers 34 towards the platten 43, those feelers opposite a hole 35 in the band being able to continue their movement, entering through a hole 49 in the platten and allowing the closure of contacts 31, 33 in a signal or points control circuit. The parts remain in this position until the contact 88 is again closed to operate relay D which at back contact D3 de-energizes the solenoid CV to allow the rocking bar 28 to return to its normal position under the action of springs 83 to again close contacts 85, 86 for repeating the stepping operation. During the above operations relay RD is de-energized and at back contact RD1 energizes the clutch 68(27) for forward driving. When the machine has completely gone through the programme carried by the band, the contact 89 is closed by clockwork or other means to operate relay RD over back contact RDS of relay RDS, front contact 89, back contact D2 of relay D and the relay RD is held over front contact RD4 and back contact RDS. At back contact RD1 the energizing circuit of clutch 68(27) is interrupted and at front contact RD1 the energizirg circuit of the return driving clutch 68(26) is completed for the rewinding of the band. Front contact RD3 closes the motor driving circuit. Contact 89 reopens as soon as rewinding commences. When the round hole adjacent the end of the band 19 comes into line with the elongated hole in the platten 43, the photo-electric cell 63, Fig. 8, is energized to operate the relay RDS to open its back contact RDS to release the relay RD. The machine is then ready to repeat the programme.