Abstract: A contact operating mechanism is disclosed which employs a hydraulic motor means for moving contact members between closed and tripped positions, an accumulator for supplying hydraulic fluid under pressure to the motor means, and a separate gas supply means in fluid communication with the accumulator. The accumulator includes a piston or separating means for dividing the interior of the accumulator into two separate pressure chambers. One of the pressure chambers is connected to the hydraulic motor means and the other is connected to the gas supply means. Preferably, the gas supply means is separately disposed from and permanently connected to the accumulator with a sufficient volume of pressurized gas such that in the event that the piston repositions so as to completely fill the accumulator with hydraulic fluid sufficient gas under pressure is available to stroke the accumulator piston and operate the motor means.

Abstract: A method for forming an electrical equipment cover, whose temperature will not appreciably increase when used in an environment of high-strength, time-varying magnetic fields, is provided. The cover is formed from a strong, relatively inexpensive magnetic steel which would ordinarily become heated in such an environment by hysteresis and eddy current losses. In order to prevent this heating, a circular blank or disk of this steel is determined and cut. Selected segments of the blank are removed to form slots in a polygonal pattern concentric with the disk and to form slots along a diameter of the disk or circular blank. All of the slots are filled with strips of a non-magnetic metal, preferably of low electrical resistance, which are then welded to the disk or circular blank. The welds are then ground to smooth the surface of the circular blank. Openings for current-carrying bushings are established in the blank to connect ends of adjacent slots.