Road building machines

Claim 1

A ROAD BUILDING MACHINE COMPRISING: A MAIN FRAME; AT LEAST ONE WORKING TOOL FOR ROAD ENGAGEMENT SUPPORTED BY SAID FRAME; FRONT AND REAR GROUND TRACTION MEANS ON THE OPPOSITE SIDES OF SAID FRAME; FRAME SUPPORT MEANS CONNECTING SAID MAIN FRAME TO EACH OF SAID GROUND TRACTION MEANS SAID FRAME SUPPORT MEANS INCLUDING HYDRAULICALLY OPERATED RAMS FOR VERTICALLY ADJUSTING SAID MAIN FRAME WITH RESPECT TO EACH OF SAID GROUND TRACTION MEANS; THREE VALVES, TWO OF SAID VALVES BEING CONNECTED TO INDEPENDENTLY OPERATE THE HYDRAULIC RAMS ASSOCIATED WITH THE TWO GROUND TRACTION MEANS ON ONE SIDE OF SAID MAIN FRAME, THE HYDRAULIC RAMS ON THE OTHER SIDE OF SAID FRAME BEING DIRECTLY CONNECTED THROUGH A COMMON CONDUIT, AND THE REMAINING VALVE BEING CONNECTED THROUGH SAID COMMON CONDUIT TO COLLECTIVELY OPERATE THE HYDRAULIC RAMS ASSOCIATED WITH THE OTHER SIDE OF SAID MAIN FRAME; A HYDRAULIC FLUID PRESSURE SYSTEM CONNECTED TO SAID THREE VALVES; AND LONGITUDINALLY SPACED GRADE LEVEL CONTROL MEANS ON ONE SIDE OF SAID MAIN FRAME FOR ACTUATING SAID TWO VALVES TO OPERATE SAID RAMS AND TEHREBY CHANGE THE HEIGHT OF ONE SIDE OF SAID MAIN FRAME UPON DEVIATION OF THE ROAD SURFACE TRAVERSED FROM A PREDETERMINED GRADE, AND LEVEL CONTROL MEANS ON THE OTHER SIDE OF THE MAIN FRAME FOR ACTUATING SAID REMAINING VALVE THEREBY TO CHANGE THE HEIGHT OF THE SIDE OF SAID MAIN FRAME UPON DEVIATION OF THE ROAD SURFACE TRAVERSED FROM A PREDETERMINED CROSS-GRADE.