Patent ID: 7555883

Claim:
A header lift and flotation system interconnecting a header and frame of an agricultural harvesting machine, comprising: a hydraulic cylinder connecting the header to the frame and controllably operable for raising and lowering at least a portion of the header relative to the frame; an electro-hydraulic circuit in fluid connection with the hydraulic cylinder, a source of pressurized hydraulic fluid, an accumulator, and a fluid reservoir, the circuit including a first fluid path in connection with the cylinder and the source of pressurized fluid, a second fluid path in connection with the cylinder and the accumulator, and a third fluid path in connection with the second path, the source of pressurized fluid and the fluid reservoir, the first fluid path including at least one valve controllably operable for allowing pressurized fluid from the source of pressurized fluid to flow to the cylinder for raising the header, the second fluid path including at least one signal controlled valve controllably operable for connecting the cylinder in fluid communication with the accumulator in a flotation mode and with the third fluid path, the third fluid path including at least a signal controlled proportional pressure relief valve; and an electronic programmable controller connected to at least one input device for receiving inputs therefrom, and to the at least one signal controlled valve of the second fluid path and to the proportional pressure relief valve for outputting signals thereto, the controller being programmed so as to automatically control at least one valve of the second fluid path and the proportional pressure relief valve for allowing fluid flow from the cylinder to the fluid reservoir for lowering the header responsive to a first predetermined input; and control the proportional pressure relief valve for charging the accumulator to a pressure level for providing a predetermined flotation force, responsive to a second predetermined input.