Header flotation system for an agricultural machine

A harvester comprising:

• a mobile base unit adapted for movement over the ground;
• a transversely extending crop harvesting header supported from the base unit for allowing pivotal movement about a generally fore-and-aft axis of the machine;
• a lateral flotation system for pivoting the header about the generally fore-and-aft axis and including a two way hydraulic actuator means extending between the header and the base unit for pivoting the header in the one or the other direction and positioning the header in a nominal position intermediate opposed extreme positions prior to starting flotation operation;
• a pressure source coupled by a pair of pressure fluid supply lines to the hydraulic actuator means;
• and energy storage means connected to the hydraulic actuator means;
• said energy storage means being in the form of a hydro-pneumatic accumulator coupled to each one of the pressure fluid supply lines and pressurized at a pressure greater than the working pressure of the hydraulic actuator means for pivoting the header, such that, when the header is positioned at a nominal position and meets an obstruction, said header is permitted to temporarily pivot from said norminal position for moving over said obstruction, this pivotal movement resulting in the gas in one hydro-pneumatic accumulator being temporarily compressed by the flow of pressure fluid out of the actuator means to store energy, this pressure fluid subsequently being released back to the actuator means to restore the header to its nominal position upon the header clearing the obstruction, the gas volume in the other hydro-pneumatic accumulator remaining unchanged during this pivotal movement away from and back to the nominal position, whereby said other hydro-pneumatic accumulator remains inoperative under this condition.