Patent GB-191421761-A (GB)
Title: Improvements in relating to Electrical Switches.
IPC: H01H21/02
Filed: 1914-10-30
Granted: 1915-10-28
Abstract: 21,761. Midland Electric Manufacturing Co., and Barber, W. L. Oct. 30. Switches, quick-action. -In a quick make-andbreak ironclad switch, the rotary spindle h upon which is secured the arm g carrying the contact blades d, which may be partly insulated, the conducting - ends being bridged by fuses, extends across the switch box i, Fig. 3, and is mounted at one end in one wall of the box and at the other end in a short hollow spindle l mounted in the opposite wall and carrying an external operating - handle k. The short spindle has a gapped flange l<2>, Figs. 3 and 5, and, adjacent to the flange, the crossing spindle h carries a gapped collar h<2>. An intermediate lever n, having a bush-like part n<1> rotatably mounted on the spindle h, as shown in Figs. 5 and 6, projects through the gap of the flange l<2>, and a side extension n<2> of the lever n projects into the gap of the collar h<2>. A V- or U-shaped link r is jointed at one end to the lever n, and at the other end is connected to a spring p secured to a fixed part of the casing. In the open position of the switch, the rear end g<2> of the contactcarrying arm g engages between the branches of a spring clip s and is retained thereby. In rotating the handle k to close the switch, after a certain amount of free movement, the flange l<2> engages with and rotates the lever n, moving the spring across the dead-centre position, so that, under the action of the spring, the extension n<2> engages the gapped collar h<2> and tends to draw the switch to the 'on' position. Throughout this movement of the handle, the switch is retained in the ' off ' position by its engagement with the spring clip s; but with continued movement of the handle, the collar n<2> and consequently the contact-carrying member g, is given a positive initial movement withdrawing it from the retaining-clips, whereupon the spring completes the closing movement rapidly. The movement to put the switch into the 'off' position is similar, except that no special retaining-means for the switch lever is employed. In a modification, the intermediate arm and the V- or U-shaped links connected thereto are dispensed with, and the crossing shaft is formed with a U-shaped crank to which one end of the coiled spring is secured, the switch-blade carrying arm being so coupled to the crossing shaft on which it is mounted as to provide the requisite lost-motion connexion to permit the quick make-and-break action of the switch. Contacts.-The contact blades d are wrapped with mica f and are attached to the ends of the arms c of a yoke-piece carried by the switch lever, and, in assembling the parts of the switch, the blades carried by the yoke-piece are arranged in position in the fixed contacts and the arm g brought down on to the yoke-piece. The tapped holes for securing the yoke-piece to the arm are made while the parts are in this position, to ensure correct alinement of the fixed and moving contacts in the finished switch. The pair or pairs of fixed forked terminals are secured upon mica-wound parts of conducting- bars e secured to the bottom of the switch bar.