A vibrating screen feeder unit comprising; a rectangular fixed base; a vibration drive isolation assembly including a longitudinal counterbalance member supported by a plurality of spaced apart upward extending coil steel isolation springs extending from selected positions on each side of said fixed base to said longitudinal counterbalance member; a screening unit including a rectangular vibrating screen housing fixedly connected to free ends of a plurality of upward extending sub-resonant tuned steel coil drive springs extending upward from said longitudinal counterbalance member, and said housing attaching to free ends of a plurality of flat bar stabilizers comprising upward extending leaf springs extending from said longitudinal counterbalance member to said screening unit to guide the movement of said drive springs and provide a uniform stroking action, said vibrating screen housing having at least one screen, an input hopper having a vibratory motor, and at least two output apertures; a vibration drive assembly for vibrating said screening unit, said vibration drive assembly mounting to a rear end of said longitudinal counterbalance member including a plurality of electrically adjustable variable speed alternating current AC motors having output shafts extending from top and bottom ends with unbalanced eccentric weights mounted on said shafts in mechanical time with one another and electrically adjustable over the complete range of zero to maximum output having a maximum running speed less than the natural frequency of said drive springs to reduce inter-particle friction and stratify the material into layers by particle size; wherein said variable speed AC motors having a programmable controller being operatively arranged for dynamically adjusting vibration intensity during a timed cycle including an electrical control enabling a full zero to maximum output adjustment by means of adding a standard variable frequency VFD combined with adjustable timers so that a vibratory stroke required screening provides a momentary pulsing of at least 60 hertz for a time of from 3 to 5 seconds, which generates a pulse to said screening unit for clearing screen media and for breaking free accumulated layers of cohesive particles; said AC motors having weights synchronized with one another and capable of driving said AC motors at a selected speed and of periodically changing said speed for a selected time interval by a selected amount; and said steel coil drive springs configured to produce the portion of the load that opposes the vibratory motion, a plurality of flat bar stabilizers configured to guide the motion, and the AC motors configured to produce the remaining portion of the load that resists it. a rectangular fixed base; a vibration drive isolation assembly including a longitudinal counterbalance member supported by a plurality of spaced apart upward extending coil steel isolation springs extending from selected positions on each side of said fixed base to said longitudinal counterbalance member; a screening unit including a rectangular vibrating screen housing fixedly connected to free ends of a plurality of upward extending sub-resonant tuned steel coil drive springs extending upward from said longitudinal counterbalance member, and said housing attaching to free ends of a plurality of flat bar stabilizers comprising upward extending leaf springs extending from said longitudinal counterbalance member to said screening unit to guide the movement of said drive springs and provide a uniform stroking action, said vibrating screen housing having at least one screen, an input hopper having a vibratory motor, and at least two output apertures; a vibration drive assembly for vibrating said screening unit, said vibration drive assembly mounting to a rear end of said longitudinal counterbalance member including a plurality of electrically adjustable variable speed alternating current AC motors having output shafts extending from top and bottom ends with unbalanced eccentric weights mounted on said shafts in mechanical time with one another and electrically adjustable over the complete range of zero to maximum output having a maximum running speed less than the natural frequency of said drive springs to reduce inter-particle friction and stratify the material into layers by particle size; wherein said variable speed AC motors having a programmable controller being operatively arranged for dynamically adjusting vibration intensity during a timed cycle including an electrical control enabling a full zero to maximum output adjustment by means of adding a standard variable frequency VFD combined with adjustable timers so that a vibratory stroke required screening provides a momentary pulsing of at least 60 hertz for a time of from 3 to 5 seconds, which generates a pulse to said screening unit for clearing screen media and for breaking free accumulated layers of cohesive particles; said AC motors having weights synchronized with one another and capable of driving said AC motors at a selected speed and of periodically changing said speed for a selected time interval by a selected amount; and said steel coil drive springs configured to produce the portion of the load that opposes the vibratory motion, a plurality of flat bar stabilizers configured to guide the motion, and the AC motors configured to produce the remaining portion of the load that resists it.