A mechanism for centering and locking a tape reel or a tape hub on a drive shaft in a tape drive. A mechanism which can be actuated manually to lock a reel or hub in place and to unlock the reel or hub and also which will automatically lock the reel or hub in place by centrifugal force. A housing with radial passages for balls, with the housing and a subplate mounted on a drive shaft, and a plunger in the housing spring loaded to a non-locking position and manually movable to a locking position, with a latching mechanism for holding the plunger in the locking position.