Patent GB-597370-A (GB)
Title: Improvements relating to remote control systems
IPC: B61L7/08
Filed: 1945-08-17
Abstract: 597,370. Railway signals. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Aug. 17, 1945, No. 21021. Convention date, Nov. 10, 1944. [Class 105] [Also in Groups XXXVIII and XXXIX] Local stations are selected by the transmission of a series of contiguous trains of impulses of successively different frequency: At the transmitter, a tapped inductance L3 determines the frequency of oscillator V3. The five tappings, corresponding to five frequencies, are selected in groups of three by push buttons P1, P2, P80. On depressing button P2, relay T2 is energised to energise relay T3 which energises relay T1 which locks up over its contact a. and completes the anode circuit of the oscillator V3 over contact d of button P2 so as to transmit a train of impulses of frequency f1. Relay T1 de-energises slow release relay T2 to switch the oscillator circuit from contact d of button P2 to contact c thus transmitting a train of impulses of frequency f2. The release of relay T2 deenergises slow release relay T3 to switch the oscillator circuit to contact b of button P2 and transmit a train of impulses of frequency f3. Release of button P2 deenergises relay T1.. At the receiving station designed to re. spond to the code produced by button P2 the incoming signals are applied to'circuits L1, C1, tuned to the frequency f1. The signal across condenser C1 is applied to cold cathode value V1 to energise relay R1 which breaks the circuit of valve V1 so thah relay R1 vibrates. The energisations of relay R1 charge condenser C4 to a value sufficient to cause cold cathode valve V2 to conduct; relay R2 is thus actuated by a continuous signal to energise slow release relay L but is not actuated by shock or impress excitation. When the incoming signal f1 ends, relay R1 ceases to vibrate and relay R2 releases to energise relay S1 over the contacts of slow release relay L. Relay S1 tunes inductance L1 to the frequency f2, so that when the signal of frequency f2 arrives, the valve V1 is again actuated and relays R1, R2 are again energised, to re-energise relay L and to hold relay S1 over contacts of relay R2. Relays R2, L, S1 energise relay-S2 to tune inductances L1 to frequency f2. When the incoming signal of frequency f2 ceases, relay; R1, R2, S1 release but relay S2 is held over the contacts -of slow release relay L, so that the circuits L1, C1, and L1, C2 are tuned to frequency f3. A signal of this frequency causes energisation of relays R1, R2 again to hold relay L and complete the circuit of buzzer BZ over the contacts of relays S2, S1, R2, and L. For controlling railway points. the switch W comprises contact arms. 46: 48 on a shaft carrying a segment 25 which is held by a padlock in the position shown. The train crew remove the padlock to allow segment 25 to rotate until it engages the latch 27 thus closing contacts 46, 47 so that the central office can send the code appropriate to the receiving station associated with the points to energise buzzer BZ and relay WL which withdraws the latch 27 allowing the segment to be rotated fully to change the points and close contacts 48, 49 to transmit an answer back signal over the vibrating contacts of relay R1 which is received on the loud-speaker LS at the central office. Specification 589,3 3 2, [Group XXXVIII], is referred to.