US Patent 9723778 Agricultural system

A hydraulic control system for controlling the down force on an agricultural implement comprises a hydraulic cylinder containing a movable ram, a source of pressurized fluid coupled to the hydraulic cylinder on a first side of the ram by a first controllable valve, a fluid sump coupled to the hydraulic cylinder on the first side of the ram by a second controllable valve, and an electrical controller coupled to the valves for opening and closing the valves. The valves may be self-latching valves that remain in an open or closed position until moved to the other position in response to a signal from the controller.