Patent GB-272156-A (GB)
Abstract: 272,156. Siemens & Halske Akt.- Ges. June 5, 1926, [Convention date]. Controlling and locking signals; signals and points, interlocking.-In a semi-automatic locking- frame system both the setting of the signals to "clear" and the locking are effected by the approaching train itself after preparation effected by the signalman. The train short-circuits a track relay in the approach section and by the above arrangement the "clear" signal is not given should the relay armature stick. As described, the track has an approach section, a points section with points leading to a branch line 21 and a release section. The approach section is bridged by a relay 30, in front of a signal 2 before the points section. The points section has a twophase relay 31, one winding 13 of which bridges the track, the other winding 14 being normally energized through a stick circuit including the front contact 16 of the relay. The release section is bridged by a release relay 32. The arrangements are such that release of the control lever 37 from "clear" position is effected only after the train has cleared the points section, and only if the contacts of relay 31 have been released and re-attracted, and the contacts of relay 32 have released. When the lever 37 has been returned to normal position, it can be reset again to give a "clear" signal only after the release section of the track has been cleared. A repeating relay 33 is provided energized over front contacts 8, 9 in series of the relays 31, 32 respectively, and therefore de-energized when either the points or release section of the track is occupied. Locking magnets 5, 12, normally energized, are respectively adapted when de-energized to lock the lever 37 in the "clear" and normal danger positions bv means of rods 38, 34. Magnet 12 is energized over front contact 11 of relay 33, and is therefore de-energized when either the points section or release section is occupied, so that under these conditions the lever 37 cannot be moved to give a " clear " signal. Magnet 5 is normally energized, as shown, over front contact 10 of relay 33 and front contact 7 of relay 30, but may also be erergized under pre-determined conditions, described below, over back contact 10, front contact 19 of an auxiliary relay 17 and front contact 8 of relay 31. The circuit 1 can be closed to set signal 2 to "clear" over a back contact 4 of magnet 5 and contacts bridged by a contact 3 on lever 37 when the lever is in the position shown in dotted lines. Assuming the track clear lever 37 is moved to the dotted line position, and the "clear" signal is given when the train enters the approach section, opening contact 7, de-energizing magnet 5, and completing the circuit 1 at contact 4. At the same time rod 38 locks the lever in "clear" position. When the train occupies the points section, relay 30 is re-energized, but magnet 5 remains de-energized owing to opening of front contact 10,when relay 33 is de-energized by opening of front contact 8 consequent on the shunting of winding 13 of relay 31. Winding 14 is also de-energized by the opening of stick contact 16. At the same time relay 17 is energized over back contact 18 of the relay 33 and the back contact 8 of relay 31, and is thereupon maintained energized independent of back contact 8 by closure of its stick contact 20. When the train occupies the release section of the track relay 32 is de-energized. This closes an energizing circuit for winding 14 over the back contact 15 of relay 32, and as winding 13 has been reenergized when the points section was cleared, the contacts of relay 31 are lifted, again closing a stick circuit for winding 14 over front contact 16, and also closing front contact 8. As the circuit of relay 33 is now broken at contact 9, the back contacts 10, 18 remain closed. Relay 17 remains energized over back contact 18 and stick contact 20. Magnet 5 is thus energized to release lever 37 over back contact 10 of relay 33, front contact 19 of relay 17 and front contact 8 of relay 31 by a process necessitating successively the de-energization of relay 31 de-energization of relay 32, and re-energization of relay 31. Magnet 12 being de-energized owing to contact 11 of relay 33 being open, the lever 37 when returned to normal position is there locked by the rod 34 so that it cannot be returned to give another "clear" signal until relay 33 is re-energized by the train clearing the release section and allowing front contact 9 to be closed.