Abstract: An autonomous steering control unit for a hydraulic steering control system has a pilot selector valve, primary and secondary electro-hydraulic (EH) steering valves, and an output selector valve. In a primary autonomous steering mode, the primary EH steering valve operates to output pilot fluid from the pilot selector valve through the output selector valve to the steering control system to control steering of a work machine while the pilot selector valve and the output selector valve isolate the secondary EH steering valve from the steering control system. In a secondary autonomous steering mode, the secondary EH steering valve operates to output pilot fluid through the output selector valve to the steering control system while the primary EH steering valve is isolated from the steering control system. In alternative embodiments, a load sense selector valve alternately connects an dynamic load sense line to the operative steering valve.

Abstract: A work machine includes an electric drive system. The work machine includes a prime mover, a machine controller, and a hydraulic control system. The hydraulic control system includes a pump, a control valve and a retarding control valve. The pump is configured to supply pressurized fluid to the hydraulic control system via a supply line. The control valve is fluidly coupled to the pump via the supply line, and includes a pressure relief valve. The retarding control valve is fluidly connected to the pump and the control valve. The retarding control valve includes a solenoid valve, an orifice and a check valve. The solenoid valve is coupled to the machine controller, the orifice restricts a flow of the pressurized fluid through the supply line, and the check valve is coupled to a discharge line, which branches from a point along the supply line between the solenoid valve and the orifice.

Abstract: An autonomous steering control unit for a hydraulic steering control system has a pilot selector valve, primary and secondary electro-hydraulic (EH) steering valves, and an output selector valve. In a primary autonomous steering mode, the primary EH steering valve operates to output pilot fluid from the pilot selector valve through the output selector valve to the steering control system to control steering of a work machine while the pilot selector valve and the output selector valve isolate the secondary EH steering valve from the steering control system. In a secondary autonomous steering mode, the secondary EH steering valve operates to output pilot fluid through the output selector valve to the steering control system while the primary EH steering valve is isolated from the steering control system. In alternative embodiments, a load sense selector valve alternately connects an dynamic load sense line to the operative steering valve.

Abstract: A brake wear analysis system is presented for use within a work machine. The brake wear analysis system includes a brake charge system as well as at least one accumulator connected to the brake charge system. The at least one accumulator operable to flow a fluid from the accumulator to a brake control valve based on an executed braking action. A change of pressure within the at least one accumulator being received by a pressure sensor connected to the brake charge system and transmitted to a brake wear analysis module within the controller of the work machine. The brake wear analysis module being configured to compare the flow of fluid from the at least one accumulator with a predetermined condition resulting in a determination of whether or not a braking mechanism of the work machine is functioning in a worn condition.

Abstract: A hydraulic fan circuit is provided. The hydraulic fan circuit includes a tank, a motor having a fluid inlet and a fluid outlet and a pump to draw fluid at a low pressure from the tank and discharge the fluid at elevated pressures to the motor via the fluid inlet. The hydraulic fan circuit further includes a directional control valve disposed between the fluid outlet of the motor and the tank. The directional control valve is operable to move between a flow blocking position and a flow passing position. Further, the directional control valve is configured to reduce a positive speed of the motor below a lowest positive speed attainable through control of pump output. Furthermore, the hydraulic fan circuit includes a pressure control circuit configured to provide a pilot fluid flow at varying pressure to move the directional control valve.

Abstract: A hydraulic tank fill system for a machine includes a tank, a valve operatively coupled to the tank, and a supply line in communication with the valve and the tank. The supply line supplies a fluid into the tank from a fluid source. A breather device installed on a top portion of the tank exerts a pressure on the fluid in the tank for controlling at least one of an operating pressure associated with the tank. A vent line in communication with the valve and the top portion of the tank to receive an excess quantity of the fluid based on the exertion of pressure on the fluid in the tank. An orifice disposed in the vent line exerts a back pressure on the excess quantity of the fluid received into the vent line.

Abstract: A hydraulic fan circuit is provided. The hydraulic fan circuit includes a tank, a motor having a fluid inlet and a fluid outlet and a pump to draw fluid at a low pressure from the tank and discharge the fluid at elevated pressures to the motor via the fluid inlet. The hydraulic fan circuit further includes a directional control valve disposed between the fluid outlet of the motor and the tank. The directional control valve is operable to move between a flow blocking position and a flow passing position. Further, the directional control valve is configured to reduce a positive speed of the motor below a lowest positive speed attainable through control of pump output. Furthermore, the hydraulic fan circuit includes a pressure control circuit configured to provide a pilot fluid flow at varying pressure to move the directional control 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 line vent arrangement is provided to selectively vent pressurized fluid from an actuator in an electro-hydraulic system when an engine of a machine has been shut down. This is accomplished by providing a pressure storage arrangement in parallel with a source of pressurized pilot fluid and an electrically controlled valve that is movable to a position to connect the pressure storage arrangement to the electro-hydraulic directional control valve when the engine of the machine has been shut down.

Abstract: A control arrangement operates in conjunction with a control scheme to control the maximum pressure level within a conduit network of a fluid system without the need to have high flow pressure relief valves. The control arrangement provides a low flow pressure relief valve connected in parallel with an electrically actuated valve mechanism to trim any over-pressure conditions so that the control scheme has more time to move the electrically actuated valve mechanism to a flow bypassing, pressure relieving position.

Abstract: A low cost, electromagnetic efficient integrated electrohydraulic actuator includes a sleeve disposed within a housing and an annular electric coil formed as an integral part of the sleeve so that the coil is deeply integrated in the housing. An armature slidably disposed within an axial bore of the sleeve has the fluid metering functions integrally formed thereon so that the armature functions as a valve spool for controlling communication between an inlet port and an outlet port and between the outlet port and a tank port. The armature is thus the only movable part of the actuator.