Mechanism for preventing loosening of magnetic recording tape of tape cassette

A mechanism for preventing loosening of a magnetic recording tape in a tape cassette, comprising:

• a reel shaft having an axis, the reel shaft being rotatably mounted to a magnetic recording tape running apparatus equipped with means for rotating the reel shaft;
• a tape cassette housing having a wall which has an opening, the reel shaft extending through said opening when the tape cassette housing is mounted to the magnetic recording tape running apparatus;
• a magnetic recording tape loaded in the tape cassette housing;
• a reel hub rotatably mounted within the tape cassette housing and including means for engaging the reel shaft of the recording tape running apparatus, the reel hub serving to wind the magnetic recording tape, the reel hub being movable between a first position where one side edge of the magnetic recording tape wound around the reel hub is spaced from said wall of the tape cassette housing and a second position where the one side edge of the wound magnetic recording tape abuts against said wall of the tape cassette housing, and the reel hub being rotatable wherein said first position by the reel shaft inserted through said opening of said wall of the tape cassette housing and engaged with the reel hub;
• an abutment member mounted within the tape cassette housing, and being movable between a third position where the abutment member is spaced from the other side edge of the magnetic recording tape wound around the reel hub located in the first position and a fourth position were the abutment member abuts against the other side of the magnetic recording tape wound around the reel hub located in the second position by the reel shaft inserted through said opening of said wall of the tape cassette housing;
• and
• urging means mounted within the tape cassette housing for urging the abutment member toward its fourth position.