Belt driven cartridge with magnetic brake assembly

A belt driven data cartridge of the type in which a magnetic recording tape wound on a pair of tape spools, each mounted on a shaft affixed to a base, is reversibly driven from one said spool to the other by a thin, continuous flexible belt in contact with the periphery of each said spool, and tension maintaining the belt in driving contact with the respective spools is provided by stretching the belt around at least a portion of the periphery of a drive puck, the respective spools, and at least one roller,

• wherein said roller includes an outer periphery structured to contact said drive belt, an inner sleeve defining a bore structured to rotate on a shaft fixed to said base and in combination with said base, a magnetic brake assembly for controllably resisting rotation of the roller, thereby imparting controlled tension on said belt, said roller further having interior walls defining a recess, and within said brake assembly comprises a permanent magnet assembly mounted coaxially with said bore within said recess, a magnetizable member which is part of the base and extends radially around and coaxially with said shaft, and means for separating a top surface of said magnetizable member a predetermined distance from said permanent magnet assembly such that rotation of the roller and magnet assembly mounted therein with respect to the magnetizable member imparts a predetermined amount of drag resisting said rotation.