Patent GB-349425-A (GB)
Title: Improvements in train-staff signalling apparatus
IPC: B61L23/24
Filed: 1929-11-12
Abstract: 349,425. Train staff signalling systems. DEMUROW, O. T., 77, Sowietskaia Strasse, Titlis, Russia,. Nov. 12, 1929, No. 34490. [Class 105.] In a train staff system in which a magneto generator that normally produces direct current to operate the staff release instruments is employed, a change-over switch is provided whereby a condenser is inserted in series with the magneto generator to generate alternating current to give a bell signal. The generator is driven through multiplying gearing to obtain a high frequency and thereby prevent operation of the staff instruments by the alternating current; the driving spindle is fitted with a helical spring fixed at one end to the frame and acting as a clutch to prevent rotation in the wrong direction. Telephone apparatus is also included. Fig. 1 shows a single staff instrument at a terminal station C<II>. and two staff instruments I, II at an intermediate station with a switch III whereby one instrument is associated with an additional bell 25 and the other with the magneto generator and telephone apparatus. To give a bell call at station C<II> the magneto generator A at station C' is operated and an alternating current flows from terminal 49 through the condenser D<II>, wire 47, 44, 59, 58, a bell 62, wire 40, upper contact of pushbutton d, wire 39, to terminal 37, then to the switch III and terminal 17 of staff instrument II, leaving at terminal 19 to earth, and entering terminal 19 of the staff instrument at station C<II> passes to 17 and then through the telephone and magneto apparatus (not shown) at station C<II> to terminal 18, through the staff instrument to terminal 20 and over the line wire back to station C' at terminal 20 and through the staff instrument II to terminal 18 and over the switch III to terminal 36 of the telephone and magneto apparatus, wire 63, upper contact of pushbutton d, wire 55, telephone arm 56, wires 42, 43, 45 to the magneto terminal 51. The bell 62 rings and the telephone is lifted for conversation. When a staff is demanded by station C<II> the pushbutton d is depressed and on operating the magneto a direct current flows from terminal 49 to wire 48, lower contact 61 of pushbutton d, wire 39, to terminal 37 and, as before, through the staff instrument II to earth and the distant instrument, returning over the line wire 20 and through the instrument II to terminal 18, over switch III to terminal 36, and then wire 63, lower contact 60 of pushbutton d, and wire 53 to the magneto terminal 51. A call from the station to the left of CI passes through the instrument I and rings the additional bell 25 but by transposing the switch III the magneto and telephone apparatus is then connected to the instrument I. The circuit for telephone conversation is shown in the enlarged diagram, Fig. 3. On receipt of a bell call by the alternating current from the magneto, the telephone is lifted from the hook and microphone current flows from a battery R over wire a, contact b, wire c, and through the primary transformer winding to the microphone connected across the terminals M. The telephone is connected across the terminals T, the lower of which leads to the transformer secondary, wire e, 42, hook 56, contact f, and wire g to the outgoing terminal 37 ; the return telephone current arrives at terminal 36 and passes by wire 63, upper contact j of pushbutton d, and wire 55, to the upper telephone terminal T.