GB557540A - Improvements in or relating to railway signal and/or points control systems - Google Patents

Abstract

557,540. Railway route-control systems. STANDARD TELEPHONES & CABLES Ltd., BROWN, A., and MARSHALL, T. A. May 22, 1942, No. 7000. [Class 105] A railway route-control system effects control by the use of three relays ZCR, ZNR, ZCPR functioning as described below. The invention may be used by itself or, as described in combination with a rotary sequence-switch system of the kind described in Specification 496,495. The Specification gives a simple layout comprising a down line (route 3) and an up line (route 6) connected by a cross-over (route 4) and assumes, for illustration, that route 6 cannot be carried on the switch controlling routes 3, 4, the arrangement shown in Fig. 3 being used to avoid the provision of a separate switch to control route 6. When the panel switch for selecting route 6 is operated the circuit of relay ZCR is closed from positive B over a cam 1 BB of the sequence switch for setting conflicting route 4 (its contact 2 being open when route 4 is set), reverse contacts 6 R of the panel key, other relay contacts 6 VRX, relay ZCR to negative. Relay ZCPR is then energized over back contacts of restoring relays ZNPR, ZNR (proving that these relays are de-energized) and front contact ZCR1 of relay ZCR (proving that the interlocking circuit is complete and contact 6R closed. As routes 4, 6 are mutually conflicting front contacts of relay ZCPR (not shown) are included in the circuit of the sequence switch controlling route 4. Contacts of this relay (not shown) also effect the point-setting and signal clearing for route 6. If required a relief relay ZCP2R may be provided for relay ZCPR. Restoration of the route to normal is effected by restoring the panel key thus opening its reverse contacts 6R and closing its normal contacts 6N. Circuit of the restoring relay ZNR is then closed over contacts 6N, front contacts ITR1, 2TRI and back contacts 2HR4, 4HR4 which must be closed before restoration of route 6 to normal is safe, and back contact ZCR (proving that the relay ZCR is de-energized). Contacts of relay ZNR (or of a relief relay ZNPR provided if necessary) effect restoration of route 6 to normal in known manner. A stick circuit for relays ZNR, ZNPR is closed over front contact ZNR3 of relay ZNR. Contact ZNR in circuit of relay ZCPR, and contact ZCR in circuit of relay ZNR prevent simultaneous energization of these relays. Cessation of current when the system is in normal condition effects no change, but when in the reverse condition such cessation releases all reverse contacts but does not energize relay ZNR. Relay ZCR is sufficiently slow in releasing to hold up while any sequence switch of the system carrying conflicting routes is rotating.