In a hydraulic system, such as for a tractor or other agricultural vehicle, a main supply pump supplies fluid to a steering system through a steering circuit and a second pump supplies fluid to a cooling fan motor. The second pump is connected with the steering circuit to provide a second a source of fluid to the steering system when the main supply pump is unable to meet demand. A prioritization valve regulates the flow of fluid from the second pump to the motor. The second pump acts as a secondary pump for the steering system and drives a cooling fan.

A method for operating a motor vehicle, wherein the motor vehicle has a steering system for steering at least one wheel of the motor vehicle by means of a drive. In doing so, it is provided that a time span is determined for at least one countermeasure limiting a hazard to a vehicle occupant upon an at least partial failure of the steering system, within which time span the countermeasure deploys an effect, and that a state variable (T) influencing the operating capacity of the steering system is determined and extrapolated over time and a point in time (t.sub.1) is calculated in which the state variable (T) exceeds a limit value (T.sub.1), wherein the countermeasure is introduced when the point in time (t.sub.1) is less than the time span in the future.

A valve assembly for use with a main pump, a reserve pump, a steering valve with a second load signaling connector, and a first pressure switch includes an adjustable first orifice and a flow control valve. The valve assembly further includes a fluid flow path running from a first high pressure connector via the first orifice, further via a control point, further via the flow control valve, to a first low pressure connector. The first orifice is loaded in the opening direction by the pressure at the first high pressure connector, and the first orifice is loaded in the closing direction by a spring and by the pressure at the first load signaling connector. The control point is connected permanently to the first measuring connector.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

The disclosure relates to an electro-hydraulic control system for directing fluid to at least one hydraulic actuator, the system comprising at least one electronic controller; first and second pilot valves being electrically connected to the at least one electronic controller which is arranged to control the operation of the first and second pilot valves, third and fourth pilot valves being electrically connected to the at least one electronic controller which is arranged to control operation of the third and fourth pilot valves. A pilot operated main valve is configured to control fluid flow to at least one hydraulic actuator. Each of the first and second pilot valves and the third and fourth pilot valves is a fail-safe pilot valve arranged to drain a regulated outlet port to a low pressure reservoir if a spool of the fail-safe pilot valve becomes stuck in an open state.

The disclosure relates to an electro-hydraulic control system for directing fluid to at least one hydraulic actuator, the system comprising at least one electronic controller; first and second pilot valves being electrically connected to the at least one electronic controller which is arranged to control the operation of the first and second pilot valves, third and fourth pilot valves being electrically connected to the at least one electronic controller which is arranged to control operation of the third and fourth pilot valves. A pilot operated main valve is configured to control fluid flow to at least one hydraulic actuator. Each of the first and second pilot valves and the third and fourth pilot valves is a fail-safe pilot valve arranged to drain a regulated outlet port to a low pressure reservoir if a spool of the fail-safe pilot valve becomes stuck in an open state.

A redundant steering system comprises a primary power source; a secondary power source; first and second pumps operatively coupled to the primary and secondary power sources, respectively, to output first and second supplies of hydraulic fluid to a steering cylinder based on operation of the primary and secondary power source, respectively; first and second pairs of selector valves respectively coupled to the first and second pumps; and a charge circuit coupled to respective control inputs of the first and second pairs of selector valves to selectively supply hydraulic fluid to the control inputs of the first and second pairs of selector valves to stop hydraulic fluid from only one of the first pump and the second pump from being provided to the steering cylinder and to provide hydraulic fluid to the steering cylinder from only one of the other of the first pump and the second pump.