Patent GB-166879-A (GB)
Title: Improvements in electric relays
IPC: H01H53/10
Filed: 1921-05-13
Abstract: 166,879. General Railway Signal Co., (Assignees of Howe, W. K.). July 19, 1920, [Convention date]. Induction-motor relays, especially suitable for railway signalling, comprise a motor element driving a shaft through a friction clutch which permits the motor to overrun, the shaft carrying rollers which engage rollers on a rocking arm on which the movable blade contacts are mounted to co-operate with fixed contacts both sets of contacts being mounted on the underneath of the cam of a rectangular box having glass sides in which the whole mechanism is contained. The operative connection of the operated parts to the motor element is detachable so that on loosening the cover, the whole of the operated parts may be removed together therewith. The motor mechanism consists of a multiple laminated core structure comprising a laminated ring 11 which may be contracted to clamp together within it the T-shaped laminated pole-pieces 12 on which former-wound coils 19 connected together to form a two-phase winding are first arranged, the core structure being bolted to a non-magnetic spider 15 secured to the bottom of the main casing and having a cover 17 through which the motor shaft extends. The spider and the cover constitute an inner casing for the moving elements of the motor. The inner, laminated cylindrical core 10 is secured on an upwardly extending portion of the base, and the armature, in the form of a light metal shell 21 is mounted in the air gap and is secured to a hub 20 moving freely on the shaft 22. The shaft has jewelled bearings the lower one being spring mounted to take shocks. The hub 20 has downwardly projecting arms engaging projections on a. washer which is loose on the shaft 22 but in frictional engagement on either side with washers keyed to the shaft. This friction clutch connection permits the motor to overrun after the switching movement has been made, without damaging the mechanism. The shaft carries a pointer 90, visible through the glass sides 5 of the casing and indicating the degree of movement of the armature. It carries also a roller 63 mounted eccentrically in relation to the shaft and acting as a cam on one or other depending on the direction of movement of the armature of two rollers 62, Fig. 14, mounted on the ends of a U-shaped hanger H adjustably secured to the underpart of the contact-carrier C which is trunnioned at 38. The carrier has mounted upon it and insulated from it spring- blade contacts 43 extending on one or both sides and in number depending on the use to which the relay is to be put. The carbon ends 44 of the blades co-operate with upper and lower silver disc contacts 49, 49a mounted adjustably in connection with terminals B on the insulating cover of the casing. A gravity control is provided in the form of a small spindle 70 having two arms 73, 75 fixed thereon which carry adjustable weights 74 and rollers 76 respectively. One or other of a pair of eccentrically mounted rollers 77 on tho motor shaft engage the rollers 76 and any movement from the central zero position takes place against the returning action of the weights 74. The contact-carrying arm C may carry the gravity centralizing control afforded by adjustable pivotally-mounted weightarms 85, 82, Fig. 14, one or other of which is lifted by a pin 81 on a lateral extension of the contact arm when the arm leaves the central position. In the case of a two-position relay, the control is provided by a counter-weight on the contact-carrying arm. In a. modified form, the motor drives through speed-reduction gearing, an auxiliary shaft on which the switch actuating and control parts are mounted.