US Patent 7971420 Draper platform suspension

A draper platform (102) with an elongate, laterally extending frame (110), has a suspension system has two independent hydraulic circuits (502, 504), that can be independently filled and emptied to selectively lift the left side and the right side of the draper platform (102). Two hydraulic cylinders (306, 406) are disposed on the left side of the draper platform (102) in fluid communication with a gas-charged accumulator (506) to form the first hydraulic circuit (502), and to support the draper platform (102) on a gauge wheel (218) and the left side of a feederhouse (104). Two additional hydraulic cylinders (510, 512 are disposed on the right side of the draper platform (102) in fluid communication with the second gas-charged accumulator (514) to form the second hydraulic circuit (504), and to support the draper platform (102) on a gauge wheel (220) and the right side of the feederhouse (104). Valves (518, 520) control flow to the first and second hydraulic circuits (502, 504), respectively, to permit an electronic control circuit (500) to separately and independently fill and empty the first and second hydraulic circuits (502, 504).