463,411. Gas-blast switches. RUPPEL, S. Aug. 26, 1935, Nos. 23909, 23911, 23912. Convention dates, Aug. 25, 1934, Nov. 20, 1934, and Dec. 12, 1934. [Class 38 (v)] A switch of the kind in which the interruptionarc is quenched by a blast of pressure medium (gas or vapour) and pressure is generated by the arc being drawn into a tubular chamber, which is substantially closed by the movable contact and leads into the chamber containing the fixed contact, has an insulating filling member either arranged in the tubular chamber or movable thereinto after the movable contact, so as to make the cross-section of the chamber smaller than that of the movable contact or of the chamber itself. The filling piece and chamber wall may be of vulcanite or fibre or other material giving off quenching gas under the heating effect of the arc. In Fig. 1, the fixed contact 1 is fixed in a cylindrical metal case 3 in an insulator 5, which is formed with an exhaust 11 and with a tubular chamber 7 that is almost closed by the movable contact 2 in the switch-closed position shown. When 2 is lowered to open, the switch, the air is heated in the chamber 8 by the arc and a pressure is set up which is augmented when the arc is drawn into tube 7. A blast of gas follows the pin 2 as it emerges from tube 7 and extinguishes the arc. In order to produce adequate gaspressure with small currents, the pin 2 is followed by a spring-urged, insulating filler 9, which is of slightly less diameter than 2. This filler reduces the cross-section of the tube 7 and so augments the flow of gas therethrough and forces the arc more closely against cooling and decomposing surfaces. The springs 10 are adjusted so that 9 follows 2 at a distance, which distance is still further increased by gaspressure when heavy currents are being opened. The release of 9 may alternatively be made dependent on the operating mechanism of the switch. In Fig. 3, the filler 9 is attached to the pin 2 and, in order to localize the arc, iron may be placed in the tube wall or in the filler or the latter is grooved at 31 for a part of its length, but in Fig. 2 (not shown), no groove is provided and an arcing ring surrounds the bottom of 2, a metal insert being provided in the filler core to relieve the contact from the influence of the electric field and prevent reignition of the arc. The speed of movement of the pin 2 may be initially low, from one to three metres per second, for example, so as to give time for the pressure to be set up, and may be thereafter increased, and the speed may be dependent on the current to be broken. Modifications of the form shown in Fig. 3 comprise (1) making part of the wall of 7 movable towards the pin and filler by means of a spring which accommodates itself to the gas pressure, the movable part being of decomposable material, Fig. 6 (not shown); (2) the use of a current-reducing resistance connected between the main and an auxiliary fixed contact, Fig. 7 (not shown) ; (3) the use of a filler which widens at its lower end to accommodate both heavy and lightcurrent arcs, and is porous so as to draw up a vaporizable liquid from a well in the base of the case, Fig. 8 (not shown). Fig. 9 shows another form in which vaporizable liquid is drawn up from a well 51 by wicks 55 in a hollow, porous filler 9, which is fixed in the tube 7 and co-operates with a hollow movable contact 2. In a modification, a solid filler is used and the aperture by which the pin 2 is withdrawn from the exhaust 11 may be closed by a flap, Fig. 5 (not shown). In Fig. 10, the metal cylinder 23 carrying the contact 1 and tube 7 are movable downwards and the pin 2 and filler 9 with its iron core 60 are fixed. A gas-escape tube 56 of hard paper surmounts a metal guide 57 which is connected by a sliding contact 12 with the cylinder 23. This construction provides for a definite fixed distance between 2, 9, but the Specification refers also to a movable filler. In Fig. 11, the filler 9, which may be carried by, or follow, the pin 2, opens an orifice 65 after a certain downward travel, and allows a blast of gas to emerge therefrom. The parts may stop in the tube 7 at the position 9<1> or may be completely withdrawn to allow the blast to pass also through 7. The orifice 65 may be formed in conducting or insulating material, the arc in the former case being transferred thereto, and the tube 7 may have pressurerelief outlets venting into the chamber 8. The blast effect may be enhanced by admitting gas from an outside source through the tube 66, which gas may be mechanically compressed when the circuit is opened, and can be used for extinguishing small-current arcs, or for largecurrent arcs to increase the switch-capacity. In Fig. 13, a filler 75 integral with the pin 76 and carrying a stop 86, is urged by a spring 85 in the upward direction when the operating rod 79 is lifted. The pin 76 and filler 75 move up to the position shown, where they are arrested by 86, and the arm 89 leaves the contact 88 in the dotted position, so effecting a break in series with that 73, 76. The stop 86 is in the form of a blast-producing piston and a cap 87 deflects the issuing blast from the arc at 88, 89. The Specification as open to inspection under Sect. 91 shows also a form in which a fixed filler is surrounded in the closed position by a tubular movable contact. This subject-matter does not appear in the Specification as accepted, but appears in Specification 463,415.