A control system may receive sensor data indicative of respective fluid levels of two or more hydraulic accumulators configured to operate at respective target fluid levels within a hydraulic system. The control system may determine respective errors of the hydraulic accumulators based on the respective fluid levels and respective target fluid levels of the hydraulic accumulators. The respective errors may correspond to pressure errors, fluid volume errors, or other types of errors of the hydraulic accumulators. Responsive to determining the respective errors, the control system may determine that the error of a given hydraulic accumulator is greater than errors of the other hydraulic accumulators and provide instructions to control a hydraulic valve to supply fluid from a single pump of the hydraulic system to the given hydraulic accumulator.

Pressure sensors are provided to detect the delivery pressure of a hydraulic pump, the output pressure of an engine revolution speed detecting valve, and the output pressure of a differential pressure reducing valve generating the differential pressure between the delivery pressure of the hydraulic pump and a maximum load pressure. A vehicle controller calculates virtually the displacement of the hydraulic pump by use of the detected pressures and an equation of motion about a swash plate of the hydraulic pump, calculates the power need of the hydraulic pump and the output of the engine using these values, and switches a motor between powering and generation control in accordance with the result of a comparison between the pump power need and the engine output. In this manner, the displacement of the hydraulic pump without using sensors to detect the tilting angle of the swash plate of the hydraulic pump.

The Construction machinery includes at least two actuators, a main pump that generates hydraulic energy for driving the actuators, control valves disposed between the main pump and the actuators, a hydraulic pump motor driven by the generator motor that generates energy to be added to the hydraulic energy, and a controller that reduces hydraulic energy generated by the main pump when the hydraulic pump motor driven by the generator-motor generates energy. The construction machinery further comprises changeover valves that selectively change a location at which the energy from the hydraulic pump motor driven by the generator-motor is to be added according to the actuators. The controller changes a reduction rate of the hydraulic energy generated by the main pump depending on a specific actuator to which the energy is to be added.

A construction machine having an actuator that is driven by a working fluid includes a state value detection unit that detects a state value indicating an operating condition of the actuator, a mode determination unit that determines an operating mode by comparing the state value with a determination condition value, and a condition value setting unit that modifies the determination condition value on the basis of a comparison result of the mode determination unit. The condition value setting unit sets the determination condition value such that the determination condition value is increased when the state value falls below the determination condition value and decreased when the state value rises above the determination condition value.

A fluid control system is provided for controlling flow of a process fluid through a pipeline. In one example, the pipeline can include a valve that defines an upstream and a downstream portion of the pipeline. The system can include one or more instruments configured to control operation of the valve. In one example, the system can include a compressor and an expander configured to selectively receive supply gas from the upstream portion of the pipeline via a supply line. In one example, supply gas flows to the compressor and the expander via the supply line when a differential pressure between the upstream and downstream portions of the pipeline is below a predetermined threshold and does not flow to the compressor and expander when the differential pressure between the upstream and downstream portions of the pipeline is above a predetermined threshold.

A hydraulic drive system includes a pump, a steering actuator, a loading/unloading apparatus actuator, a drive device, a relief valve, and an input unit. The drive device: flows hydraulic oil from the pump to the loading/unloading apparatus actuator when an operating tool is operated; flows the hydraulic oil from the pump to the steering actuator when a steering has become an operated state from a non-operated state regardless of an operation of the operating tool; and causes the hydraulic oil from the pump to be discharged to a tank via the relief valve to increase the torque of an engine when an increase instruction is inputted to the input unit and the steering is in a non-operated state.

A hydraulic control valve, a dual-cylinder extension system and an aerial work engineering machine. The control valve comprises a flow distributing and collecting valve, and control valve body is provided with a first oil opening, a second oil opening and a third oil opening. A first oil opening, a second oil opening and a third oil opening of said flow distributing and collecting valve are respectively communicated with the first oil opening, the second oil opening and the third oil opening of the valve body. The control valve has two working states, wherein, in the first working state, the oil path between the second oil opening and the third oil opening of the valve body is blocked; and in the second working state, the oil path between the second oil opening and the third oil opening of the valve body is opened.

The invention relates to a hydraulic system, method, and integrated valve block for a slewing mechanism, comprising a first and second cylinder. The rod cavity of the first cylinder connects to the rodless cavity of the second cylinder through the first oil circuit, first hydraulic control check valve, and fourth oil circuit. The rodless cavity of the first cylinder connects to the rod cavity of the second cylinder through the second oil circuit, second hydraulic control check valve, and third oil circuit. The first oil circuit is connected to the directional valve through the sixth oil circuit, and the second oil circuit is connected to the directional valve through the fifth oil circuit. The directional valve is connected to the hydraulic pump and oil tank. The first hydraulic control check valve is installed between the first and fourth oil circuits, and the second hydraulic control check valve is between the second and third oil circuits. The check valves' control circuits connect to the sixth oil circuit, ensuring braking stability of the slewing mechanism.

A hydraulic system includes a prime mover, a variable displacement first hydraulic pump to be driven by the prime mover to deliver hydraulic fluid, a first hydraulic actuator to be driven by fluid delivered by the first hydraulic pump, a variable displacement second hydraulic pump to be driven by the prime mover to deliver hydraulic fluid, a second hydraulic actuator to be driven by fluid delivered by the second hydraulic pump, and first and second restrictors configured or programmed to restrict an output of the respective first and second hydraulic pumps based on a load on the prime mover. The first restrictor is configured or programmed to change an output restriction of the first hydraulic pump based on priority information about the first and second hydraulic actuators and/or the second restrictor is configured or programmed to change an output restriction of the second hydraulic pump based on the priority information.

A pressure cylinder includes a working cylinder and an intensification cylinder that is divided by a separator block. A working piston is arranged in the working cylinder and connected to a working rod that extends to an end portion. An intensification piston and an intensification rod are arranged in the intensification cylinder. A pump is configured to provide a pressurized hydraulic fluid to the pressure cylinder. A fluid reservoir is configured to supply a hydraulic fluid to the pump. An overpressure circuit fluidly connects the advance working chamber and the retract passage, a pressure relief valve is arranged in overpressure circuit, the pressure relief valve is configured to open from a normally closed position to communicate fluid from the advance working chamber to the retract passage when the advance working chamber reaches an undesired threshold.