Snow plow structure with means to exert down pressure on slade

Claim 1

A SNOW PLOW COMPRISING A MOBILE FRAME, A MOUNTING PLATE UNDERLYING SAID FRAME AND PROJECTING LONGITUNIDALLY THEREFROM, MEANS PIVOTALLY MOUNTING AN INTERMEDIATE PORTION OF SAID PLATE ON SAID FRAME FOR PIVOTAL MOVEMENT ABOUT A TRANSVERSE HORIZONTAL AXIS, AN ARCUATE PLOW BLADE RIGIDLY ATTACHED TO SAID PLATE AT THE END THEREOF PROJECTING FROM THE FRAME, A SPRING INTERCONNECTING THE PLATE AND SAID FRAME FOR BIASING THE END RELATION TO THE TRANSVERSE PIVOTAL AXIS OF THE POINT OF CONNECTION OF THE PLATE TO THE FRAME FOR BIASING THE END OF THE PLATE HAVING THE BLADE THEREON IN A DOWNWARD DIRECTION, AND A HYDRAULIC PISTON AND CYLINDER ASSEMBLY INTERCONNECTING THE PLATE AND THE FRAME INTERMEDIATE THE SPRING AND THE PIVOTAL CONNECTION BETWEEN THE PLATE AND FRAME FOR LIFTING THE BLADE WHEN THE PISTON AND CYLINDER ASSEMBLY IS EXTENDED THUS OVERCOMING THE RESILIENT EFFECT OF THE SPRING.