Patent GB-532263-A (GB)
Title: Improvements relating to electro magnetic relays for railway signalling systems
IPC: B61L23/16
Filed: 1939-07-20
Abstract: 532,263. Railway signalling systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 20, 1939, No. 21111. Convention date, Feb. 23. [Class 105] [Also in Group XXXVII] A relay, Fig. 2, specially adapted for use in railway signalling systems, has four armatures which are operated in different ways according to whether the current supplied to the windings 9a, 9b, is of positive or negative polarity and steady or intermittent. A neutral armature N and a polarized armature P are associated with a main magnetic structure, and two neutral armatures XN and NC are associated with an auxiliary magnetic structure inductively coupled to the main structure. This inductive coupling may be effected by secondary windings 20a, 20b, on the main structure which supply current through a rectifier 21 to windings 19a, 19b on the auxiliary structure when the current to the windings 9a, 9b is intermittent. Alternatively a transformer may be used, Fig. 4 (not shown). The armature XN is mechanically coupled to the armature N and serves to prevent the armature N releasing when the current in 9a and 9b reverses and so passes through a zero point. The armature P is polarized by a permanent magnet 10 and moves into engagement with a contact 14a or 14b according to the direction of the current and irrespective of whether it is steady or intermittent. The armature N is attracted whatever the nature of the current. The armature NC is only attracted when the current is intermittent. A single reversal of current is not sufficient to operate it. The relay is shown, Fig. 1c, in use in a railway signalling system. One section only of the line is shown, the relay is designated HD and its three armatures N, P and NC control three sets of contacts. When a train W is on the section of the line as shown a track relay TR de-energizes the relay HD the armatures of which assume the positions shown. When there is no train on the section, the relay HD receives current from lines 4a, 5a and this current may be positive or negative, steady or intermittent according to the condition of the relay HD in the ahead section of line. Each section has a signal with two arms, L, U which may each assume a horizontal, vertical or an intermediate position according to whether the condition of the relay HD allows no current, a single current along a line 30 or 32 or two currents along lines 30, 31 or 32, 33 to flow to the operating mechanisms of the signals L, U respectively from a source B to a line C. Different combinations of the arms L, U will thus indicate the condition of the line ahead, e.g. that the first three blocks ahead are clear and the fourth occupied. The relay HD also controls a relay PC and a coder CT which when energized causes intermittent current to be supplied to the rear section from source B through contacts 25, 26. With the parts in the position shown, positive steady current is supplied from source B, through contacts 34, 35 to the lines 4a, 5a leading to .the relay HD of the rear section. This latter relay assumes a corresponding position and causes negative steady current to be supplied to the relay HD of its preceding section. This will cause negative intermittent current to be supplied to the next relay HD which will cause positive intermittent current to be supplied to the next one.