Abstract: Feeders for transporting materials in strip, sheet, or filament form include an adjustable stop mechanism for setting the clearance between feed rolls. The stop mechanism allows the rolls to be moved apart to release the material form the rolls. In one embodiment, the stop mechanism includes a spring, the force of which is overcome to allow release of the rolls. The stop mechanism includes an eccentric mounting for precisely setting clearance between feed rolls. In another embodiment, a pair of articulated levers are provided, a first of which carries an adjustment screw bearing against the second lever. A cam engages the second level to cause the rolls to move to a material-releasing position. The cam can be driven by the drive system of machine on which the feeder is mounted so that the material can be released in relation to machine operation.