Erasure preventing thumbwheel for single reel cartridges

摘要

An erasure preventing thumbwheel is located in the front wall of a cartridge and is rotatable in an opening in the front wall. The thumbwheel has a larger diameter central portion which is exposed through the opening and includes a flat section which corresponds in size and shape to the opening. When the flat section registers with the opening, the tape is write-protected. The thumbwheel has a circumferential ridged gripping portion at one edge of the central portion which extends around the non-flat cylindrical section of the thumbwheel. The gripping portion does not extend along the edge of the flat section.