Patent ID: 6938399

Claim:
In an agricultural working implement including at least one working unit mounted thereon for movement between operating and non-operating positions, a single-acting, extensible and retractable actuator coupled to said working unit and including a chamber, a medium under pressure and a medium reservoir connected to said chamber by way of a first control arrangement operable for selectively coupling said chamber either to said medium under pressure or medium reservoir, and said actuator being coupled with said working unit in such a way that it brings the working unit into said non-operation position when the medium is applied to the chamber, and permits said working unit to gravitate to said operating position when the chamber is coupled to said reservoir, the improvement comprising: an accumulator; an accumulator control device coupled between said accumulator and said chamber for connecting said accumulator to said chamber both when said working unit is in, or moving toward, said operating position and for preventing said medium under pressure from flowing to said accumulator when said chamber is connected to said medium under pressure; said operating position is a position wherein said working unit is in ground contact; a relief valve being located between said chamber and said reservoir for establishing a maximum pressure in said chamber when said chamber is coupled to said accumulator; and said actuator being arranged such that a pressure existing in said chamber when said working unit is in said operating position defines a contact pressure on the ground of the working unit.