Hydraulic circuits for earth scraping machines

Claim 1

AN EARTH SCRAPING MACHINE COMPRISING: A MOBILE DIRT-CARRYING CONTAINER HAVING UPRIGHT SIDE WALLS, A LONGITUDINALLY MOVABLE REAR WALL AND A LONGITUDINALLY MOVABLE BOTTOM WALL SECTION AT THE FRONT OF SAID CONTAINER, SAID SECTION CARRYING A DOWNWARDLY EXTENDING DIRT-SCRAPING BLADE AT ITS FORWARD EDGE; AN ENDLESS SCRAPER-TYPE CONVEYOR MOUNTED IN SAID CONTAINER BETWEEN SAID SIDE WALLS; HYDRAULIC RAM MEANS FOR RAISING AND LOWERING THE FRONT END OF SAID CONTAINER WITH RESPECT TO THE GROUND; HYDRAULIC RAM MEANS FOR MOVING SAID REAR WALL FORWARDLY AND REARWARDLY; HYDRAULIC RAM MEANS FOR MOVING SAID BOTTOM WALL SECTION FORWARDLY AND REARWARDLY; ROTARY HYDRAULIC MOTOR MEANS FOR OPERATING SAID CONVEYOR; A POWER SOURCE INCLUDING TWO HYDRAULIC PUMPS AND A RESERVOIR OF HYDRAULIC FLUID; A FIRST HYDRAULIC CIRCUIT INCLUDING CONDUIT MEANS CONNECTING ONE OF SAID PUMPS WITH SAID MOTOR AND A MOTOR FLOW CONTROL VALVE FOR CONTROLLING THE FLOW OF HYDRAULIC FLUID IN SAID CIRCUIT; A SECOND HYDRAULIC CIRCUIT SEPARATE FROM SAID FIRST CIRCUIT AND INCLUDING CONDUIT MEANS CONNECTING THE OTHER OF SAID PUMPS WITH THE HYDRAULIC RAM MEANS ASSOCIATED WITH THE FRONT END OF SAID CONTAINER, SAID BOTTOM WALL SECTION AND SAID REAR WALL, SAID SECOND CIRCUIT INCLUDING A LIFT FLOW CONTROL VALVE ASSOCIATED WITH THE RAM MEANS FOR MOVING THE FRONT END OF THE CONTAINER; A DUMP FLOW CONTROL VALVE ASSOCIATED WITH THE RAM MEANS FOR OPERATING THE BOTTOM WALL SECTION AND REAR WALL; MEANS ASSOCIATED WITH SAID DUMP VALVE FOR SEQUENTIALLY OPERATING THE LAST-NAMED RAM MEANS; AND A TRAILING SCRAPPING MACHINE MECHANICALLY COUPLED TO AND OF THE SAME CONSTRUCTION AS SAID FIRST-NAMED SCRAPING MACHINE, SAID TRAILING MACHINE HAVING HYDRAULIC RAM MEANS FOR RAISING AND LOWERING ITS FRONT END, HYDRAULIC RAM MEANS FOR MOVING ITS REAR WALL, HYDRAULIC RAM MEANS FOR MOVING ITS BOTTOM WALL SECTION AND ROTARY HYDRAULIC MOTOR MEANS FOR OPERATING ITS CONVEYOR AND WHEREIN SAID MOTOR LIFT AND DUMP FLOW CONTROL VALVES ARE THEREPOSITION, FOUR-CONNECTION SPOOL VALVES EACH HAVING TWO CONTROL PORTS AND TWO WORK PORTS, SAID FIRST HYDRAULIC CIRCUIT INCLUDING A SECOND MOTOR FLOW CONTROL VALVE CONNECTED IN SERIES WITH SAID FIRST-NAMED MOTOR FLOW CONTROL VALVE, SAID SECOND HYDRAULIC CIRCUIT INCLUDING A SECOND LIFT VALVE IN SERIES WITH SAID FIRST-MENTIONED LIFT VALVE, A SECOND DUMP VALVE IN SERIES WITH SAID SECOND LIFT VALVE, SAID FIRST-MENTIONED DUMP VALVE BEING IN SERIES WITH SAID SECOND DUMP VALVE.