US Patent 7958707 Non-parallel four-bar linkage for suspending an agricultural implement header

A suspension system for agricultural implements having at least one floating head using a four-bar linkage and permitting the floating head to accommodate variations in ground surface elevation in a lateral or transverse direction. By permitting the floating head to float, a more consistent cutting height is realized when ground surface elevation varies in a transverse direction. A main frame is provided to which the ground engaging wheels are attached. A sub-frame is connected to the main frame via the four-bar linkage and the linkage arms of the four-bar linkage are not parallel to one another as viewed from above. The linkage arms of the four-bar linkage are pivotally attached to the main frame and sub-frame by spherical bearings.