US Patent 10086868 Four wheel steering with independent control valves

Hydraulic cylinders controlled by electronic valves can be provided at each rear corner of an agricultural machine to improve four wheel steering. The valves can receive hydraulic fluid from a pump and release hydraulic fluid to tank, while independently controlling an amount of hydraulic fluid to each rear steering cylinder. The valves can be controlled by a controller that is also in communication with position sensors configured to sense positions of the front and rear steering cylinders, so that the rear steering cylinders can be correspondingly controlled to follow the front steering cylinders.