Patent GB-660101-A (GB)
Title: Improvements in or relating to train control systems
IPC: B61L3/12
Filed: 1947-05-30
Abstract: 660,101. Track apparatus actuating signals on trains. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., and LOMAS, P. May 5, 1948. [May 30, 1947] No. 14440/47. Class 105. The track magnet system actuating signals on a train through the control electrically of a valve serving to vent a quick-release vacuum chamber which controls the venting of a slowrelease vacuum chamber as described in Specification 563,966 is modified to allow three signals to be given at a signal location by employing three track magnets. The track magnets comprise a longitudinal permanent magnet 201 with N-pole ahead in the direction of traffic, a longitudinal electromagnet 202 with S-pole ahead, and a transverse permanent magnet 203 arranged so that only the N-pole is effective ; an associated winding 204 when energized renders the N-pole transverse permanent magnet 203 ineffective. For a clear signal (G aspect) the track electromagnet 202 and the neutralizing winding 204 for the N-pole transverse track magnet 203 are energized (over top contact 210) and accordingly the armature a of the train carried magnetic receiver b is deflected at permanent magnet 201, restored at electromagnet 202 and unaffected at N-pole magnet 203. The armature a when deflected to contact 70 energizes a slow release relay 71 while at open contact h the venting magnet 3 is dropped. The almost immediate restoration of the armature a to contact h picks up the venting magnet 3 over front contact 73 of the slow release relay 71. Thus the quick venting chamber is released and then closed to give a clear signal (electric bell) as described in Specification 563,966. At a caution signal (Y aspect) the track electromagnet 202 and the neutralizing winding 204 for N-pole track magnet 203 are de-energized and accordingly the armature a of the traincarried receiver b is deflected on to contact 70 at its passage over the track permanent magnet 201 and remains there while passing and after leaving the location. Thus the venting magnet 3 is dropped and a braking will ensue unless the driver operates an acknowledgment push to restore the armature a and pick up the venting magnet 3 over front contact 73 of slow release relay 71. The additional signal given by the present invention (a YY aspect) is provided by energizing the track electromagnet 202 but with the N-pole track magnet 203 not neutralized (contact 211 closed and contact 210 on its bottom point). The armature a of the train-carried receiver is thus deflected to contact 70 at track permanent magnet 201, restored to contact h at track electromagnet 202, and again deflected to contact 70 at N-pole track magnet 203. On the brief restoration of the armature a to contact h a thermal delayed release relay 208 is picked up and stuck. The venting magnet 3 after being picked up remains energized from the front contact 212 of the thermal delayed release relay 208 and the front contact of slow release relay 71 for the thermal delay time period but will thereafter drop unless the driver performs an acknowledgment action and so restores the armature a to contact h. A horn 209 sounds during the thermal delay period.