A high-pressure unit (HPU) skid for greasing and actuating a frac tree valve includes one or more hydraulic pumps, a grease pump, a hydraulic reservoir, and two or more accumulators all of which are mounted on a portable frame. The HPU skid further includes fluidic connections to connect the frac tree valve to an output of the grease pump and fluidic connections to connect the frac tree valve to at least one of the two or more accumulators. The hydraulic pumps are configured to withdraw hydraulic fluid from the hydraulic reservoir for charging the accumulators, operating the grease pump, or charging the accumulators and operating the grease pump at a same time.

A working machine includes: a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator whose hydraulic pressure for actuation thereof is lower than that of the high-load hydraulic actuator; a plurality of direction switching valves each of which switches a direction of a hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator; and a dummy-load forming unit that forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A throttle assembly for a pressure control system in a vehicle includes at least one throttle valve. The at least one throttle valve defines an assembly cross-section of the throttle assembly, the assembly cross-section specifies a flow resistance acting on a pressure medium entering the throttle assembly, and the at least one throttle valve includes at least one controllable throttle valve configured to be controlled in accordance with an upstream pressure. The assembly cross-section of the throttle assembly is configured to be set, by control of the at least one controllable throttle valve, in such a way that an inlet volume flow of the pressure medium entering the throttle assembly can be limited to a limit volume flow in accordance with the upstream pressure, in order to set, in accordance with the upstream pressure, a power consumption of a pneumatic load in the pressure control system.

A hydraulic system of a construction machine includes: control valves interposed between a variable displacement main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: a regulator that changes a displacement of the main pump; and a second solenoid proportional valve connected to an auxiliary pump by a primary pressure line, the second solenoid proportional valve outputting a secondary pressure to the regulator through a secondary pressure line. A switching valve is interposed between the auxiliary pump and the first solenoid proportional valves, and includes a pilot port that is connected to the secondary pressure line by a pilot line.

A confluence control part of a slewing-type construction machine controls a confluence switch valve such that the confluence switch valve is switched to a suspension state when a slewing and boom raising manipulation action is performed. A pump capacity control part of the slewing-type construction machine executes a capacity control when the slewing and boom raising manipulation action is performed, the capacity control including regulating a first pump capacity and a second pump capacity respectively in such a manner that the first pump capacity increases and the second pump capacity decreases as an operating pressure difference resulting from the subtraction of a slewing operating pressure from a boom operating pressure increases, and the first pump capacity decreases and the second pump capacity increases as the operating pressure difference decreases.

Disclosed is a turbine fracturing apparatus. The turbine fracturing apparatus includes: a main power assembly and an auxiliary power assembly. The main power assembly includes a first power source and a piston pump connected to the first power source; the first power source outputs power to the piston pump, and the piston pump outputs a first liquid. The auxiliary power assembly includes a second power source, a load sensitive system connected to the second power source, and an auxiliary power device; the second power source outputs power to the load sensitive system, the load sensitive system is connected to the auxiliary power device and outputs a second liquid for the auxiliary power device. The first liquid is different from the second liquid, and the first liquid and the second liquid have certain pressure. The load sensitive system is configured to regulate a pressure of the second liquid in real time according to pressure of the second liquid required by the auxiliary power device.

There is provided an hydraulic actuation system for an aircraft, the hydraulic actuation system includes an actuator (A), a primary actuation arrangement to provide hydraulic fluid to control the actuator (A), wherein the hydraulic actuation system is configured to detect a fault in the actuator (A). The hydraulic actuation system also includes a secondary actuation arrangement to provide hydraulic fluid to control the actuator (A) in response to a detection of a fault in the actuator (A).

A multi-control valve unit includes a housing with built-in spools that are parallel to each other. The housing includes pilot chambers formed therein, the pilot chambers corresponding to both ends of the spools. Solenoid proportional valves are mounted to the housing, such that the solenoid proportional valves are connected to the respective pilot chambers. A hydraulic pressure generator is mounted to the housing, such that the hydraulic pressure generator is connected to the solenoid proportional valves. The hydraulic pressure generator includes an electric motor and a pump.

This disclosure relates to a hydraulic system for a hydro-mechanical machine comprising a rotary mechanism and a boom cylinder The hydraulic system includes a primary accumulator configured to receive and store high-pressure fluid in response to starting and stopping of the rotary mechanism. A control system configured to enable passage of the high-pressure fluid stored in the primary accumulator to a rotary control valve configured to control the rotary mechanism, and a boom control valve configured to control the boom cylinder through the hydraulic supply circuit, based on a predefined pressure threshold associated with the primary accumulator. A secondary accumulator coupled to the primary accumulator and the control system via the hydraulic supply circuit is configured to store surplus high-pressure fluid provided by the primary accumulator through the hydraulic supply circuit.