Abstract: A steering system and method is described for a vehicle having steerable front and rear wheels, and a steering input device for receiving manual steering input. Front and rear hydraulic steering devices may be coupled, respectively, to the front and rear wheels. Front and rear valve assemblies may be configured, respectively, to steer the front and rear wheels. In a manual steering mode, the front valve assembly may be disabled with respect to the front steering device, and the front hydraulic steering device may steer the front wheels based upon the manual steering input. In a rear steering assist mode, a rear steering command may be determined based upon the manual steering input, and the rear wheels steered based upon the rear steering command. In an automated steering mode, the front and rear wheels may be automatically steered based upon a target path of travel for the vehicle.

Abstract: A steering system and method are described for a vehicle having steerable wheels. A steering device may be coupled to one or more of the wheels. A parked state of the vehicle and a present orientation of the hydraulic steering device may be determined. The present orientation of the steering device may be compared with a neutral orientation of the steering device. Based upon a determined parked state of the vehicle and the comparing of the present and neutral orientations of the steering device, the steering device may be moved from the present orientation toward the neutral orientation.

Abstract: A steering system and method are described for a vehicle having steerable wheels, with steering of the wheels controlled, at least in part, by a valve assembly. A ground speed of the vehicle may be determined. Whether a steering command is being provided to a valve assembly may also be determined. An operational pressure at the valve assembly may be determined with a pressure sensor. A threshold pressure may be determined based upon the ground speed and/or whether a steering command is currently being provided. The operational pressure may then be compared with the operational pressure, and steering control with the valve assembly disabled based upon the comparison.

Abstract: A four-bar linkage is provided as a mechanical interface for transferring respective outputs from a speed/direction control device and a hydraulic steering cylinder to displacement control arms of a pair of pumps of a dual-path hydrostatic transmission including a pair of motors respectively coupled for driving a pair of front wheels of a vehicle. The hydraulic steering cylinder is fixed and has a piston rod slidably coupled to an input arm of the four-bar linkage in such a way that a rotation speed decrease occurs as the arm and a linked control plate are pivoted from a neutral position, the control plate transferring pivotal movement to effect differential movement of the displacement control arms. This results in the vehicle speed decreasing during a turn.

Abstract: An integrated steering control system includes a primary, automatic and rear control valves. A steering wheel operates the primary steering control valve and is of a type which includes a leakage characteristic. Steering wheel movement is sensed and a signal is sent which results in the automatic steering control valve being operated for adding fluid that supplied to a steering cylinder by the primary steering control valve in order to compensate for leakage, the amount of added fluid being a function of vehicle ground speed. An electric actuator with position feedback is used for ground speed control. Whenever the actuator position shows that the ground speed is set to zero and a switch in the hydro-handle slot shows that the handle is in the Park position, the automatic steering control valve is activated to move the steering cylinder to a neutral, straight ahead position, as determined by a sensor in a mechanical linkage of the steering control.

Abstract: An integrated steering control system includes a primary, automatic and rear control valves. A steering wheel operates the primary steering control valve and is of a type which includes a leakage characteristic. Steering wheel movement is sensed and a signal is sent which results in the automatic steering control valve being operated for adding fluid that supplied to a steering cylinder by the primary steering control valve in order to compensate for leakage, the amount of added fluid being a function of vehicle ground speed. An electric actuator with position feedback is used for ground speed control. Whenever the actuator position shows that the ground speed is set to zero and a switch in the hydro-handle slot shows that the handle is in the Park position, the automatic steering control valve is activated to move the steering cylinder to a neutral, straight ahead position, as determined by a sensor in a mechanical linkage of the steering control.

Abstract: A four-bar linkage is provided as a mechanical interface for transferring respective outputs from a speed/direction control device and a hydraulic steering cylinder to displacement control arms of a pair of pumps of a dual-path hydrostatic transmission including a pair of motors respectively coupled for driving a pair of front wheels of a vehicle. The hydraulic steering cylinder is fixed and has a piston rod slidably coupled to an input arm of the four-bar linkage in such a way that a rotation speed decrease occurs as the arm and a linked control plate are pivoted from a neutral position, the control plate transferring pivotal movement to effect differential movement of the displacement control arms. This results in the vehicle speed decreasing during a turn.

Abstract: An agricultural harvester includes a traction unit and a crop harvesting header coupled with the traction unit. The header includes a main frame with a right hand (RH) side and a left hand (LH) side. A RH gauge wheel is movably coupled with the RH side of the main frame, and a RH hydraulic cylinder is coupled between the RH gauge wheel and the main frame. A first hydraulic circuit is coupled with the RH hydraulic cylinder and configured to control an operating height of the RH gauge wheel. A LH gauge wheel is movably coupled with the LH side of the main frame, and a LH hydraulic cylinder is coupled between the LH gauge wheel and the main frame. A second hydraulic circuit is coupled with the LH hydraulic cylinder and configured to control an operating height of the LH gauge wheel. The second hydraulic circuit is independent from the first hydraulic circuit.

Abstract: An agricultural harvester includes a traction unit and a crop harvesting header coupled with the traction unit. The header includes a main frame with a right hand (RH) side and a left hand (LH) side. A RH gauge wheel is movably coupled with the RH side of the main frame, and a RH hydraulic cylinder is coupled between the RH gauge wheel and the main frame. A first hydraulic circuit is coupled with the RH hydraulic cylinder and configured to control an operating height of the RH gauge wheel. A LH gauge wheel is movably coupled with the LH side of the main frame, and a LH hydraulic cylinder is coupled between the LH gauge wheel and the main frame. A second hydraulic circuit is coupled with the LH hydraulic cylinder and configured to control an operating height of the LH gauge wheel. The second hydraulic circuit is independent from the first hydraulic circuit.

Abstract: An agricultural implement includes a header or platform suspended from a main frame by a suspension permitting movement of the header between a lowered working position and a raised transport position. The suspension includes single-acting float cylinders and a single-acting lift cylinder controlled by an electrohydraulic control system including a programmable microprocessor in which a signal representative of a minimum acceptable float pressure may be set. The microprocessor contains an electronic switch that couples a warning device lead to ground to effect energization of the warning device in response to the microprocessor receiving an electronic signal representative of a float circuit pressure below the minimum acceptable float pressure.

Abstract: A vehicle has a parking brake system including spring-applied, pressure-released brakes. An electrohydraulic control system is provided for selectively energizing a solenoid-operated brake control valve so that release pressure is supplied to the brakes when the transmission control lever is not in neutral or when the vehicle tachometer is indicating a ground speed other than zero.