Patent GB-184847-A (GB)
Title: Improvements in relays
IPC: H01H50/54
Filed: 1921-05-12
Abstract: 184,847. Day, S. M. May 12, 1921. Relays.-The binding-post of a relay of the multiple-contact type for railway signalling has a squared elongated head 42 fitting into a recess in the top plate 1, an insulating sleeve 48 surrounding the post between the plate 1 and the wire-attaching nuts 47. The relay has an unpolarized armature, and a polarized armature can additionally be fitted if desired. Various improvements in the body, armatures, contacts, binding-posts, mounting, insulation and general lay-out are described. The body comprises a top plate 1, Fig. 1, of moulded porcelain which is unglazed and is dipped into insulating varnish or the like after finishing; a base 2 of aluminium, rustless iron or the like having a ventilator 9 covered with gauze which may be blocked with paint if desired, and glass walls 3 which are either in one piece or united at their edges by sheetmetal clips, and abut on cork gaskets 8 treated with shellac. The relay is resiliently supported either by three springs 87 or by a bent leaf-spring which engages the U- shaped bracket 10 and is fastened to a wall. The bracket 10 carries a porcelain block 12 bearing the line and coil terminals. The coils 19 are mounted on a non-magnetic plate 17 which fits over a square hole in the top-plate 1, the abutting surface being ground to ensure a tight fit. Large square pole-nieces 21 carry residual pins 30 and are recessed to receive the ends of a brass or like stop-bar 31 which extends between them, the neutral armature 25 being provided with a set-screw 33 for regulating the minimum air-gap. The armature 25 is pivoted at 2E and carries six contact fingers 34 of brass or the like, these being attached by insulated screws 3E as shown in Fig. 7. The screws 36 are formed with grooves 36a and slot 36<b>, and are embedded in moulded insulation 37. The nuts 38 engaging these screws are locked by a plate 39 bent up as shown in Fig. 1. The fingers 34 are provided with front and back contact springs 50, 51, whose tips 52 are adapted to wipe over the fixed con tacts 57, 64. These tips mav be of coin silver or the like riveted and soldered to the springs 50 51, or attached thereto by soft rivets hammered into square holes. In place of the tips 52, carbor buttons 67, Fig. 10, with bevelled edges may be mounted in metal cups 68 attached to the springs 50, 51, by prongs 69 which are stamped out of the cups, pass through slots in the springs, and are bent over and soldered. For each contact finger there are three binding posts B, F, H, staggered in height as shown. Each post comprises a standard 42 of square cross-section fitting into a square hole with ridges 43 adapted to exclude water. The standards 42 and the screws 6 connecting the top plate and base are protected by insulating casings 48, 7. Each heel terminal H is connected to this contact finger 34 by a pigtail 41. Each front terminal F is connected to a front fixed contact, which may comprise a block 57 of carbon impregnated with from 5 to 15 per cent of copper. This material gives a low and constant contact resistance and is non-fusible. It is made by grinding oil or gas carbon to a fine four, pressing the latter with a binder at high temperature, and impregnating it with copper by a combined vacuum and pressure process. The block 57 of this material is held in jaws by a stem 55 which is screwed into the shank 44 so that the height of the contact 57 can be adjusted. Each back terminal B is clamped to a bracket 60 bearing a back fixed contact which may comprise either a carbon block or a set-screw 62 bearing a thin silver or like wafer 64. The adjustment of the contacts 57, 64, cannot be interfered with without opening up the body of the relay. To prevent jarring of the contacts during shipment, a cord 92 is looped over the middle two fingers 34 and clamped by a screw 94. The relay as above described is unpolarized. When a polarized armature is to be added, a shorter unpolarized armature, carrying four contact fingers 34 instead of six, is substituted for the armature 25, and correspondingly four of the outside binding posts F, F, B, B, are removed from their holes in the top plate 1, which are then plugged with screws. In place of them, four binding posts P are mounted as shown in Fig. 3, these posts being similar to the posts F described above, except that they are shorter and carry, instead of the blocks 57, square vertical contact blocks 82 of carbon or graphite. The polarized armature comprises two horse-shoe magnets 70 embracing the pole-pieces 21 and mounted back to back, above the unpolarized armature 25, on a crosspiece 73 which is pivoted at 75 so that the magnets can swing in a horizontal plane. The crosspiece 73 carries on one side a counterweight 78, and on the other a frame C bearing the contact fingers 77 which are similar to the fingers 34.