Abstract: A steering system for a machine is disclosed. The steering system may include a first pilot system including a first pilot source and a first set of electrohydraulic valves, and a second pilot system including a second pilot source and a second set of electrohydraulic valves. The first pilot system and the second pilot system may be configured to move the steering valve via pilot flow of the hydraulic fluid. The steering system may further include an electrohydraulic selector valve configured to regulate pilot flow to the first set of electrohydraulic valves and the second set of electrohydraulic valves. The electrohydraulic selector valve may be a two-position, five-way valve.

Abstract: A steering system for a machine is disclosed. The steering system may include a first pilot system including a first pilot source and a first set of electrohydraulic valves, and a second pilot system including a second pilot source and a second set of electrohydraulic valves. The first pilot system and the second pilot system may be configured to move the steering valve via pilot flow of the hydraulic fluid. The steering system may further include an electrohydraulic selector valve configured to regulate pilot flow to the first set of electrohydraulic valves and the second set of electrohydraulic valves. The electrohydraulic selector valve may be a two-position, five-way valve.

Abstract: An electro-hydraulic steering system for an articulated machine includes an electrical circuit and a hydraulic circuit. The electrical circuit includes a controller, an electro-hydraulic valve assembly, and a spool position system. The hydraulic circuit includes a pump, at least one cylinder in selective fluid communication with the pump, and the valve assembly. The controller includes a computer-readable storage medium storing a steering system monitoring application which performs several steps. A desired flow of pressurized fluid to each cylinder and a desired spool position for the spool of the electro-hydraulic valve assembly, based upon the desired flow of pressurized fluid, are determined. The desired spool position and an actual spool position are compared to determine a spool-based flow error, which is summed over a period of time to determine a cumulative spool-based flow error. An event warning is issued when the cumulative spool-based flow error exceeds a threshold.

Abstract: A machine includes a hydraulic fan system for circulating cooling air through an engine compartment. Periodically, the fan rotation direction is briefly reversed in order to dislodge any material debris that may have accumulated at the inlet to the engine compartment. When a fan reversal event is initiated, the fan motor will continue to rotate due to angular momentum even after the pump output flow has been switched from a first motor port to a second motor port. During this continued rotation as the fan decelerates to zero speed, vacuum pressure levels can arise at the first motor port, and a pressure spike can develop at the second motor port. In order to alleviate these conditions, a pressure transfer valve briefly opens to facilitate fluid flow directly from the second motor port to the first motor port as the fan motor decelerates towards zero speed before reversing direction, simultaneously alleviating vacuum and pressure spike conditions.

Abstract: A machine includes a hydraulic fan system for circulating cooling air through an engine compartment. Periodically, the fan rotation direction is briefly reversed in order to dislodge any material debris that may have accumulated at the inlet to the engine compartment. When a fan reversal event is initiated, the fan motor will continue to rotate due to angular momentum even after the pump output flow has been switched from a first motor port to a second motor port. During this continued rotation as the fan decelerates to zero speed, vacuum pressure levels can arise at the first motor port, and a pressure spike can develop at the second motor port. In order to alleviate these conditions, a pressure transfer valve briefly opens to facilitate fluid flow directly from the second motor port to the first motor port as the fan motor decelerates towards zero speed before reversing direction, simultaneously alleviating vacuum and pressure spike conditions.