Patent GB-275170-A (GB)
Title: Improvements in or relating to electrical relays
IPC: H01H50/54
Filed: 1927-05-23
Abstract: 275,170. General Railway Signal Co., (Assignees of Field, O. S.). July 27, 1926, [Convention date]. Electromagnetic switches; contact-making relays.-In direct current relays for railway signalling purposes the armature is pivotally mounted on a horizontal axis, a contact member being rigidly fixed to the armature and insulated therefrom, the contact member consisting of two pivotally-connected members maintained in a predetermined relation by a coil spring, one of the members having a front contact attached and the other bearing a resilient back contact. As shown in Figs. 1 and 2 the armature 26 is mounted in bearings 32, 39 adjustable to take up end play, these bearings being carried by trunnion members 31, 36 which are held in arms 29, 30 secured to a bearing plate 22. The plate 22 is secured between nuts 25 on studs 21 depending from the base plate 1 carrying the operating electromagnet 8, the air gap 6 between the armature and the poles 4 being adjusted by raising or lowering the bearing plate. Non- magnetic rivets 40 prevent the armature sticking on the pole faces. One of the trunnionmembers 31 is secured to its carrying arm 29 and the other 36 is arranged to be detachable from its carrying arm 30, having a peripheral groove 36 engaged by a clamping screw 37 so that the armature may be removed without disturbing the end play adjustment. Each of the sets of movable contact members as shown in Fig. 4 is carried by a channel-shaped member 45 clamped at one end by a screw 45 and nut 52 with an intermediate insulating cylinder 41 to the armature 26. The member 45 may be adjusted by being flexed by rotation of a nut 50 on a screw 42 secured to but insulated from the armature, the adjustment varying the position of both contacts with respect to the armature. The front contacts are, however, independently adjustable by being mounted on a channel member 67 pivoted on a stud 70 projecting from the member 45 and provided with an adjusting nut aud bolt 73, 75 acted upon by a compression spring 78. The outward movement of the front contact is limited by an enlarged portion of a bent over end of the lever 67 passing through the slotted end of the member 45. The front contact is formed of silver gauze 83 detachably carried on arms 81 of a springing frame 82 rivetted to the member 67 and connected to the arm 45 by a flexible connection 69, a similar connection 117 connecting the member 45 to a corresponding terminal passing through the insulating top plate 89 of the relay casing. The fixed contact co-operating with the member 83 consists of a carbon block 98 clamped in a holder consisting of side plates 110, 111 secured by a screw 107 to the square end 100 of the terminal post 99 suitable means for preventing displacement of the brush and holder being provided. The back contacts are of silver, the movable ones 58 being carried by a blade 57 rivetted to the member 45 and the fixed contact 96 by a bracket 94, 97 carried by a terminal stud 95, bent-over portions 61, 62 of the spring 57 being formed to limit the motion of the movable contact relaytively to its carrying arm 45. A glass casing 123 is secured by a bolt and nut 130 with rubber washer 131 to the insulating top plate 89 the top of the casing being thereby clamped against a rubber gasket 121. The top plate 89 is secured by screws 20 to the electromagnet base plate 1, which may also carry a wall bracket 132. The glass casing may be arranged to rest on springs 126.