Earth moving machine with depth and cross-shape controls

Claim 1

A blade loading scraper comprising: a main frame, an earth working blade supported on said frame, rear traction means supporting the rear portion of said frame, a yoke having a pair of rearwardly extending side arms pivotally connected to an intermediate portion of said frame, front traction means supporting the forward end of said yoke, a double acting hydraulic ram connected between the intermediate portion of said yoke and the forward portion of said frame for controlling the elevation of said main frame, first and second flow lines communicating with opposite ends of said hydraulic ram, first and second three-way selector valves in continuous communication with said first and second flow lines respectively, a first automatic control fluid line and a first manual control fluid line connected to said first selector valve, a second automatic control fluid line and a second manual control fluid line connected to said second selector valve, automatic control pressure fluid supply and return lines, a four-way manually closed control valve interposed between said automatic fluid supply and return lines and said first and second automatic control fluid lines, a valve actuator operative in one direction from a normal neutral position to move said automatic control valve and to connect said automatic supply and first fluid lines and said automatic return and second fluid lines and in the other direction to connect said automatic supply and second fluid flow lines and said automatic return and first fluid flow lines, said valve actuator being adapted to engage an elongated reference member disposed along the path to be traveled by said scraper, manual control pressure fluid supply and return lines, a manual control normally closed valve interposed between said manual control supply and return lines and said first and second manual control lines, a manually operated valve actuating element operative in one position to move said manual control valve and connect said manual supply and first manual control fluid lines and said manual return and second manual control fluid lines and in an other position to connect said manual supply and second manual control fluid lines and said manual return and first manual control fluid lines, said selector valves each being moveable in one position into communication with said manual fluid lines and in another position into communication with said automatic fluids lines, and means interlocking said manually operated valve actuating element and said selector valves to move said selector valves to said another position only when said manually operated valve is moved to its normal closed position.