Gravimetric feeder

A feeder comprising a frame having first and second rollers, an endless belt extending around said rollers, a motor coupled to one of said rollers for driving said belt, a tracking and tensioning assembly, means mounting said assembly between upper and lower runs of said belt for movement in a vertical direction between an upper inoperative position and a lower operative position, said assembly including at least one tensioning roller disposed for rotation about an axis transverse with respect to the lower run of said belt, said tensioning roller being in contact with the juxtaposed inner surface of the lower run of the belt in the operative position of said assembly, said assembly including first and second shoes, each shoe being supported adjacent a different edge of the lower run of the belt, each shoe being rotatable about a vertical axis, said shoes being movable as a unit with said tensioning roller between said operative and inoperative positions of the assembly, said assembly being biased downwardly toward said operative position, and latch means supported by the frame for selectively retaining said assembly in its upper inoperative position.