GB137756A - Improvements in or relating to electrical connection boxes, for electrically operated cranes or machinery - Google Patents

Abstract

137,756. Siemens Bros. & Co., and Wood, H. G. July 4, 1919. Couplings combined with electric switches. An electric connexion-box, such as is used for electric cranes and other electrically-operated machines, is provided with a plug, the handle of which controls consecutively the locking in place of the plug, the setting-up of a water-tight closure, and the completion of the electric connexions. The box a has a plug c fitted with a central spindle g which forms a disconnectible continuation of the switch spindle f and carries a handle g<1> serving to control the fixing of the plug, the setting-up of the water-tight closure, and the actuation of the switch. As shown in Fig. 1, the plug comprises an upper part c' fitted with contact blades d, and a lower sleeve c<x> which is separated from the upper part by a compressible ring or gasket i and a spring h<4>, and is supported from the spindle g by three radial arms c<3>. A locking-catch h guided by stops c<4> on one of the arms c<3> is jointed to a crank h<2> upon a slidable collar h<3> turning with the spindle g, so that when the handle g<1> is turned in one direction the catch is moved out into engagement with the lower edge of the socket or opening b<3> in the box. Further movement of the handle causes a projection g<5> at the top of the spindle to ride up a cam c<5> on the plug so that the parts of the plug are drawn together, expanding the gasket to make a water-tight joint between the plug and the box. Still further movement of the handle causes the switch contacts carried by the spindle f to engage with fixed contacts disposed below the cross-plate a<1> in the box. and, in this position, to prevent unauthorized disturbance of the parts, the handle is locked by a padlock to a projection on the plug. A key and groove b<4>, c<6> are provided to ensure the proper insertion of the plug. In a modification the movable sleeve c<x> is dispensed with, and three catches h working through holes in the cap allowing a slight up-and-down movement are provided, the bulging gasket i being replaced by a washer adapted to be pressed down on to a bead or ridge on the upper edge of the mouth or socket b<3>. After the plug has been removed, the socket is closed by a lid having a movable sleeve and gasket similar to the sleeve c<x> and gasket i, the spindle g having a square at its upper end to receive a detachable key or handle; movable catches h are not provided on the lid, but the radial arms of the sleeve fit between pairs of projections on the underside of the lid. The cranks operating the catches h may be replaced by inclines or slotted cams.