Materials spreader machine

Claim 1

A MATERIALS SPREADER COMPRISING A TRANSVERSELY ELONGATED HOPPER INCLUDING END PLATES, SUPPLEMENTAL PLATES SECURED TO SAID END PLATES AND ADAPTED TO SECURE SAID HOPPER TO THE REAR OF A DUMP TRUCK, SAID HOPPER ALSO INCLUDING AN OPEN TOP ADAPTED TO BE POSITIONED IN ALIGNMENT WITH THE BOTTOM OF THE DUMP TRUCK, A DOWNWARDLY AND REARWARDLY INCLINED BAFFLE IN SAID HOPPER, A TRANSVERSE SPREADER DRUM ROTATABLE IN SAID HOPPER WITH THE BOTTOM OF SAID BAFFLE OVERLYING THE TOP OF SAID DRUM, SPACED STAGGERED PROTUBERANCES ON THE SURFACE OF SAID DRUM, A DRIVE GEAR FOR SAID DRUM AT ONE END THEREOF, A DRIVE SPROCKET ADJACENT SAID GEAR, A CHAIN CONNECTION BETWEEN SAID GEAR AND SAID SPROCKET, POWER MEANS FOR DRIVING SAID SPROCKET, A SHAFT EXTENDING ACROSS THE REAR UPPER EDGE OF SAID HOPPER BETWEEN SAID END PLATES, A PLURALITY OF INDIVIDUAL GATES PIVOTED ON SAID SHAFT AND DEPENDING TO A POINT ADJACENT THE REAR CENTER PORTION OF SAID DRUM, SAID BAFFLE, DRUM AND GATES NORMALLY COMPLETELY CLOSING THE OPEN BOTTOM AND REAR OF SAID HOPPER, INDIVIDUAL SPRING MEANS BIASING EACH GATE TOWARD ENGAGEMENT WITH SAID DRUM, MEANS FOR VARYING THE FORCE EXERTED BY SAID SPRING MEANS, AND MEANS LIMITING THE PIVOTAL MOVEMENT OF CERTAIN OF SAID GATES AGAINST THE BIAS OF SAID SPRINGS, TO HOLD SELECTED ONES OF SAID GATES COMPLETELY CLOSED.