GB478654A - Improvements in electrical relays - Google Patents

Abstract

478,654. Electromagnetic interrupters. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 21, 1936, No. 20193. Convention date, Jan. 16. [Class 38 (v)] Electromagnetic interrupters, which may be employed as track or line relays in railway signalling systems employing for the control of the signalling devices direct current which is periodically interrupted or coded at different frequencies have two sets of opposed polepieces magnetized by a permanent magnet and a magnetizable armature extending longitudinally between the sets of polepieces which are so arranged that the polepieces on the same side of the armature are of the same polarity, the armature being movably supported at one end outside the magnetic circuit of the polepieces and armature and the latter being surrounded by an energizing coil between the sets of polepieces. As shown in Figs. 1 and 2, two pairs of polepieces 9a, 9b and 11a, 11b are clamped in magnetic bars 7a, 7b secured by bolts to the main magnetic framework 2. These polepieces are magnetized by a permanent magnet 13 secured to the rear face of the framework 2 by a strap 14 and bolts 15. To the lower end of this member is clamped a spring blade 17 supporting the armature 20 which extends upwardly between the pole faces 10a, 10b and 12a, 12b. Mounted between the pole faces surrounding the armature is a coil 23 to which the supply currents, for example, interrupted D.C. of varying frequencies, is led. Normally the armature is biassed towards the right-hand poles by springs 38a, 38b acting on the contact mechanism, Fig. 3. These springs act on blade members 33a, 33b secured at their ends to brackets depending from the terminal base 1 of the relay, the free ends of the blades 33a, 33b carrying contact blades 32a, 32b co-operating with front and back contacts 44a, 45a and 44b, 45b. The free ends of the contact blades bear against recesses in an insulating member 35 attached to the upper end of the armature and when an interrupted D.C. current traverses the coil the variation of the polarity induced in the armature causes it to vibrate between the polepieces. The polepieces are adjustable and the upper pair are formed with inclined faces so that they may be parallel to the armature in its opposite inclined positions. To prevent sticking of the armature its opposite faces are provided with non- magnetic pins 21. The edges of the members 18 confining the armature-supporting spring 17 may be rounded to prevent damage to the spring during the armature vibration. In an alternative arrangement the lower end of the armature is supported on a knife-edge first. A cylindrical glass casing 4 surrounds the relay, being clamped with interposed gaskets between the upper and lower plates 1, 3.