250,686. Reyrolle & Co., Ltd., A., Clothier, H. W., and Allan, A. Jan. 20, 1925. High-potential switches; automatic circuitbreakers.-An outdoor oil-immersed switch with associated superimposed air-break isolating switches has an oil tank divided into sectorshaped compartments one for each phase surrounding a hollow supporting pedestal carrying the cover plate of the tank, the mechanism for raising and lowering the tank and that for operating the main and isolating switches being arranged inside the. hollow pedestal. In the construction shown in Figs. 2, 4 and 5, the three sections of the oil tank C are arranged around the pedestal A to which is secured the oil-tank cover B with the sections bolted to it. When the bolts are slacked off, the tank is supported by ropes C<2> secured one to each section, each passing over a pulley C<3> mounted in the cover and secured at the other ends to a spider C<5> screwing on an axial spindle J within the pedestal. By rotating this spindle, bv operation of the key J<4>, the spider is raised and the composite tank allowed to descend. The cover carries the usual fixed contacts of the switch which, in the closed position, are bridged by contactmembers D carried by a rod D<3> within the pedestal. The rod is controlled by a throw-off spring and is operated by links D<6>, Fig. 4, connected with a bell-crank lever F<1>, F which in turn is journaled to a pair of toggle links E<4>, E<5> the second of which is journaled to the crank arm E<2> having a spring-catch extension E<7>. The crank arm is operated by an external operating handle E<1>, Fig. 5, and serves to drive the linkage mechanism and raise the links D<6> to bring the switch into the closed position. In this position, shown in Fig. 2, the catch E<7> engages with a lever G, the toggle being held in the straightened position by a pivoted latch F' the roller end F<5> of which engages a cranked extension E<6> of the link E<4>. An overload trip H serves to knock out the catch and permit the switch contacts to fall to the off position, and, by taking the handle E<1> back to the off position, the toggle is again straightened and the latch reset, as shown in Fig. 2, ready for driving the switch back to the closed position where it is retained. The switch may be tripped by a slight backward movement of the handle which, in depressing the crank-arm E<2>, causes the lever G to operate the tripping latch F<3>. The pedestal has an hollow extension B<2>, Fig. 5, on which is mounted, on insulation, the contacts of isolating switches. The upper contacts, connected to the line, are fixedly mounted, but the lower contacts are adapted to slide longitudinally on the extension, being mechanically connected with the internal rod M<1> which is raised or lowered by operation of a hand-wheel M<4> at the base of the pedestal, through crank-arms. The off position of the isolating switches is indicated in dotted lines in Fig. 5. The oil switch and the isolating switches are interlocked; a cross-piece M<8>, Fig. 4, on the operating bar M' of the isolating switch lies in the path of movement of the crankarms E<2> and prevents closure of the oil switch if the isolating switches, are open. Moreover, if the isolating switch mechanism is operated first, the first movement of the bar M' trips the oil switch by engaging the tripping lever G, before the isolating switches have actually opened. The isolating switches may be operated by a pole and the internal mechanism dispensed with. In a modification shown in Fig. 8, contacts O<3> constituting extensions of the fixed contacts of the oil switch are adapted to engage fixed contacts R<1> so that lowering the oil tank as a whole the oil switch can be isolated from the line. In this construction, the tank cover is detachably held, by the bolts Q, to the pedestal and, in order to provide for the longitudinal movement of the fixed abutments with the cover), the operating mechanism includes gear wheels having a sliding but non-rotatable engagement with the operating shaft. According to the Provisional Specification, the isolating switches may be mounted on a supporting column of telescopic construction and operated by extending the column.