Abstract: A first printed circuit board (principal printed circuit board) is placed onto a housing frame having a stepped contour in a front edge region of the housing. The first printed circuit board is introduced into a receptacle of the frame provided with an entry bevel and, when put in place, is automatically interlocked by interlocked elements preferably arranged at an opposite side. Additional printed circuit boards can be inserted into guide elements present at the backplane, being inserted under this first printed circuit board. Their ultimate position is compelled by corresponding holder elements. In this ultimate position, each printed circuit board that is introduced and lies parallel to the backplane is interlocked by an interlock element that takes effect in this position. The additional, second printed circuit boards can be inserted independently of the first printed circuit board and are preferably provided for optional add-ons.

Abstract: A housing is provided with a base part to receive a plurality of equipment units, such as primed circuit boards. To facilitate access to terminal regions of the circuit boards, a two-part cover is securable to the base part, wherein a first cover part has an access opening to the terminal regions, and a ventilated second cover part covers the terminal region in a snap-fit manner. The terminal regions are thus easily accessible for measuring or testing. Preferably, the second cover part is manually releasable, without use of a tool.

Abstract: A hinge which provides for a simple and fast assembly or dismantling and for an automated assembly and for use with assumed planarly fashioned hinge pin receptacles which proceed parallel to one another. A region of the hinge is fashioned as an ondular washer or Belleville spring washer in a hinge spring which is inserted between the hinge pin receptacles. The hinge spring is bent arcuately back onto itself over the edge of one of the hinge pin receptacle and is fashioned with catch elements such that these engage into an annular groove of a hinge pin introduced into the aligning bores of the hinge pin receptacles and of the ondular washer or, respectively, Belleville spring washer region.