Faulty insertion preventive device for cartridges

Claim 1

In combination with a receiving chaMber having a rectangularly shaped opening with the longer sides extending vertically and the shorter sides extending horizontally, and a cartridge having outer enclosing surfaces providing substantially the same rectangular cross-sectional shape as said opening and adapted to be inserted therein to operative position, a faulty insertion preventive device comprising the upper shorter horizontal side of said opening having an element fixedly positioned to project into said chamber closely adjacent said opening; said cartridge having an upper horizontally disposed surface corresponding to said shorter horizontal side of said opening; two rows of fixed spaced protrusions located on said upper surface of said cartridge so as to form a slot therebetween in a center area of said upper surface and extending the full length of said upper surface, each said row located on an outer edge of said upper surface, said slot being of a size to allow said element to be positioned in said central area during said insertion; and stop means positioned transversely of said slot and mounted on said upper surface to comprise a transverse protrusion connecting said rows and located adjacent the end of said cartridge remote from an end that is inserted, said stop means adapted to be placed into abutment with said element when said cartridge is completely inserted to operative position.