GB704613A - Improvements relating to hand operating mechanism for electric switchgear - Google Patents

Abstract

704,613. Actuating heavy-current switches. SWITCHGEAR & EQUIPMENT, Ltd., and SHARPLES, F. A. Nov. 28, 1951 [Nov. 30, 1950], No. 29363/50. Class 38(5) [Also in Group XXIV] In a manual operating mechanism, particularly for a large outdoor polemounted switch, the operating force is transmitted from an operating handle 25 to the moving contact (not shown) through two levers 17, 23 pivoted about spaced parallel axes 18, 24 and connected by a pivot 21 capable of sliding along one of the levers, which are arranged so that their mechanical advantage is at its greatest when the movable contact of the switch is on the point of breaking away from the fixed contact. In the Figures, the lever 23 carries the handle 25 and is slotted at 22 to slidably receive the pivot pin 21 which is carried by the lever 17, the latter being a bell-crank lever with its shorter arm 16 pivoted to a connecting rod 15 which is pivoted to a universal joint 12 interconnecting a switch operating rod 11 and a guide rod 13. Fig. 1 shows the position occupied by the mechanism when the switch is closed and on opening the switch, the initial movement of the lever 23 to the position shown in Fig. 3 is effective to take up any lost motion in the linkage, so that the switch contacts are about to separate. In this position the lever 23 is in line with the fixed pivots 18, 24 so that the pin 21 has moved along the slot into its nearest position to the fixed pivot 24, the greatest mechanical advantage of the levers being obtained. Thereafter the mechanical advantage decreases as the pin 21 moves along the slot 22 as the lever 23 is moved to complete the opening movement of the movable contact. Members 26 are provided to permit the locking of the lever 23 when the switch is fully closed or fully open.