Expandable modular switching unit

Abstract

A cabinet for holding modules containing printed circuit boards and components within a module casing so that the modules are easily installed and removed. The cabinet, which is intended for mounting on a vertical surface, has a base with a transversely extending hinge pin mounted thereto, spaced outwardly from the base. Each module has on its lower end edge, adjacent its inner edge, a hinge pin receiving slot. A plurality of vertically oriented guiding walls extend outwardly from the base, and adjacent walls are spaced apart by a distance slightly greater than the thickness of a module to position a module being installed in a transverse direction. A guiding rib is located between each adjacent pair of guiding walls and extends outwardly from the base by a distance slightly less than the distance the hinge pin is spaced from the base whereby a module being installed is placed between appropriate guiding walls with the module corner defined by the inner edge and the lower end edge against the respective guiding rib. The module is then moved downwardly until the hinge pin receiving slot receives the hinge pin. The module is then rotated about the hinge pin like a lever until contacts on the module inner edge, which are connected with the circuitry on the printed circuit board therein, engage with contact members mounted on the base, which may be connected to external circuitry.