Patent ID: 7104486

Claim:
A recording tape cartridge comprising: a reel having a reel hub provided at an axially central portion of the reel, the reel hub having a cylindrical portion around whose outer peripheral surface a recording tape is wound and a floor plate portion closing one end portion of the cylindrical portion; an engaging gear which is formed in one of a form of internal teeth and a form of external teeth and at which a plurality of teeth provided in the reel hub are disposed along a circumference which is coaxial to the reel hub, a tooth surface in a lengthwise direction of each of the teeth being substantially parallel to an axis of the reel hub; a case rotatably accommodating the reel; and a braking member having a braking gear which is formed in one of a form of external teeth and a form of internal teeth and which can mesh with the engaging gear, the braking member being supported so as to be unable to rotate within the case with respect to the case and so as to be movable along an axis of the reel, and, by moving, the braking member can be selectively disposed at a rotation locking position, at which the braking gear is meshed with the engaging gear, and a released position, at which meshing of the braking gear and the engaging gear is released.