A hydraulic arrangement for a utility vehicle. The arrangement may include a hydraulic displacement pump which is connected via a pump output to a supply connection as a hydraulic interface for supplying hydraulic consumers of the utility vehicle. In addition, the device may include a hydraulic auxiliary pump and an auxiliary supply connection as a hydraulic interface for alternatively supplying at least some of the consumers. The device may include a displacement control unit which is dependent on an output pressure of the auxiliary pump for displacing the displacement pump in such a manner that a hydraulic working connection of a displacement cylinder of the displacement control unit is connected to an output of the auxiliary pump.

A hydraulic arrangement for a utility vehicle. The arrangement may include a hydraulic displacement pump which is connected via a pump output to a supply connection as a hydraulic interface for supplying hydraulic consumers of the utility vehicle. In addition, the device may include a hydraulic auxiliary pump and an auxiliary supply connection as a hydraulic interface for alternatively supplying at least some of the consumers. The device may include a displacement control unit which is dependent on an output pressure of the auxiliary pump for displacing the displacement pump in such a manner that a hydraulic working connection of a displacement cylinder of the displacement control unit is connected to an output of the auxiliary pump.

A hydraulic steering system (1) includes a steering command device (2) having a steering sensor (3), a steering motor (6), a wheel sensor (9), a pressure source (P), and control means (12) controlling a fluid supply from the pressure source (P) to the steering motor (6), wherein the control means (12) has an open loop control (19). Such a steering system should have a good relationship between steering input from the operator and steering behaviour of the vehicle to be steered. To this end the control means (12) include in addition to the open loop control (19) a closed loop control (20), wherein cross-over transition means (21) are provided which are connected to the open loop control (19) and to the closed loop control (20) and control a transition between the open loop control (19) and the closed loop control (20).

A hydraulic steering system (1) includes a steering command device (2) having a steering sensor (3), a steering motor (6), a wheel sensor (9), a pressure source (P), and control means (12) controlling a fluid supply from the pressure source (P) to the steering motor (6), wherein the control means (12) has an open loop control (19). Such a steering system should have a good relationship between steering input from the operator and steering behaviour of the vehicle to be steered. To this end the control means (12) include in addition to the open loop control (19) a closed loop control (20), wherein cross-over transition means (21) are provided which are connected to the open loop control (19) and to the closed loop control (20) and control a transition between the open loop control (19) and the closed loop control (20).

A steering device includes a control unit that includes a hydraulic abnormality determiner. The hydraulic abnormality determiner is configured to determine a hydraulic abnormality to be present in a pair of liquid chambers of a power cylinder of the steering device, in response to satisfaction of a condition that a total torque of a steering torque measured by a torque sensor and a motor assist torque provided by an electric motor is greater than a predetermined threshold torque. The control unit is configured to increase the motor assist torque in response to satisfaction of a condition that the hydraulic abnormality determiner determines the hydraulic abnormality to be present.

A steering device includes a control unit that includes a hydraulic abnormality determiner. The hydraulic abnormality determiner is configured to determine a hydraulic abnormality to be present in a pair of liquid chambers of a power cylinder of the steering device, in response to satisfaction of a condition that a total torque of a steering torque measured by a torque sensor and a motor assist torque provided by an electric motor is greater than a predetermined threshold torque. The control unit is configured to increase the motor assist torque in response to satisfaction of a condition that the hydraulic abnormality determiner determines the hydraulic abnormality to be present.

A steering device includes a control unit that includes a hydraulic abnormality determiner. The hydraulic abnormality determiner is configured to determine a hydraulic abnormality to be present in a pair of liquid chambers of a power cylinder of the steering device, in response to satisfaction of a condition that a total torque of a steering torque measured by a torque sensor and a motor assist torque provided by an electric motor is greater than a predetermined threshold torque. The control unit is configured to increase the motor assist torque in response to satisfaction of a condition that the hydraulic abnormality determiner determines the hydraulic abnormality to be present.

A steering device includes a control unit that includes a hydraulic abnormality determiner. The hydraulic abnormality determiner is configured to determine a hydraulic abnormality to be present in a pair of liquid chambers of a power cylinder of the steering device, in response to satisfaction of a condition that a total torque of a steering torque measured by a torque sensor and a motor assist torque provided by an electric motor is greater than a predetermined threshold torque. The control unit is configured to increase the motor assist torque in response to satisfaction of a condition that the hydraulic abnormality determiner determines the hydraulic abnormality to be present.

The invention relates to a power steering system for a working machine, said power steering system comprising at least one steering cylinder comprising two compartments separated by a piston, a tank, a steering unit comprising a steering valve and a metering device, for supplying one compartment of the steering cylinder with a metered liquid flow, a hydraulic pump for pumping liquid from the tank to the steering unit through a supply line (SL), a return line (RL) through which the liquid flows back to the tank, a recirculation line connecting the RL to the SL, a check valve being arranged on said recirculation line to prevent liquid from flowing from the SL to the RL, two control lines, respectively connecting the steering unit to the two compartments and a liquid accumulator connected through a branch to the RL. A relief valve is arranged on the RL between the tank and an accumulator connection point.

The invention relates to a power steering system for a working machine, said power steering system comprising at least one steering cylinder comprising two compartments separated by a piston, a tank, a steering unit comprising a steering valve and a metering device, for supplying one compartment of the steering cylinder with a metered liquid flow, a hydraulic pump for pumping liquid from the tank to the steering unit through a supply line (SL), a return line (RL) through which the liquid flows back to the tank, a recirculation line connecting the RL to the SL, a check valve being arranged on said recirculation line to prevent liquid from flowing from the SL to the RL, two control lines, respectively connecting the steering unit to the two compartments and a liquid accumulator connected through a branch to the RL. A relief valve is arranged on the RL between the tank and an accumulator connection point.